The Significance of a Higher Prevalence of ADHD and ADHD Symptoms in Children Who Stutter

Abstract

Purpose:

Research suggests that attention-deficit/hyperactivity disorder (ADHD) and its symptoms occur more frequently in individuals who stutter. The purpose of this study was to document the prevalence of ADHD diagnoses and ADHD symptoms in children who stutter and examine potential relationships between ADHD and stuttering characteristics.

Method:

A total of 204 children between the ages of 5 and 18 years (M = 9.9 years; SD = 3.5 years) and their parents participated in the study. Parents completed the ADHD Rating Scale (ADHD-RS) indexing Inattention and Hyperactivity–Impulsivity symptoms, and children completed the age-appropriate version of the Overall Assessment of the Speaker's Experience of Stuttering assessing the adverse impact of stuttering. Chi-square proportions and Mann–Whitney U tests were used to assess differences in demographic and other variables of interest between children with and without an ADHD diagnosis. Multiple linear regression was used to assess relationships between ADHD symptoms and stuttering characteristics.

Results:

Parents reported that 17.2% of children who stutter in our sample had been diagnosed with ADHD. Over 40% of children without an ADHD diagnosis had ADHD-RS scores that met the criteria for further evaluation. No significant relationship between ADHD symptoms and stuttering severity was found, but child age and inattention scores significantly, albeit modestly, predicted the adverse impact of stuttering.

Conclusions:

Researchers and clinicians might be privy to a child's ADHD diagnosis, but they should recognize that many children who stutter without an ADHD diagnosis may exhibit elevated symptoms of inattention and hyperactivity–impulsivity. These symptoms can complicate both research outcomes and the treatment of stuttering.

Supplemental Material:

https://doi.org/10.23641/asha.28899620

Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder affecting approximately 8% of children worldwide (Ayano et al., 2023) and up to 11.4% or 7 million children living in the United States (Danielson et al., 2024). Children with ADHD often struggle with the ability to focus, disorganization, overactivity, and impulsivity (American Psychiatric Association, 2013). Although not a diagnostic criterion, speech and language disorders co-occur frequently in children diagnosed with ADHD. Baker and Cantwell (1987) followed 300 children diagnosed with speech and language disorders for five years and reported that attention-deficit disorder (ADD) diagnoses doubled in their cohort of children from 16% at initial testing to 37% in follow-up testing. Tirosh and Cohen (1998) found that up to 45% of children with ADHD were also diagnosed with a developmental language disorder. A recent meta-analytic review concluded that the comorbidity of expressive, receptive, and pragmatic language deficits in children with ADHD is common enough to warrant a language screening as part of an ADHD assessment battery (Korrel et al., 2017). Fluency disorders such as developmental stuttering, or childhood-onset fluency disorder and cluttering, have also been linked to ADHD. Several studies have found a higher prevalence of ADHD diagnoses among people who stutter (Briley & Ellis, 2018; Tichenor et al., 2021) and an increased presence of inattention and hyperactivity–impulsivity symptoms in children and adults who stutter (Donaher & Richels, 2012; Druker et al., 2019; Tichenor et al., 2021). While this study focuses exclusively on stuttering, it should be noted that cluttering, another fluency disorder, has also been associated with ADHD (Scaler Scott, 2017). While there is sparse research on this topic, it has been suggested that people who clutter with symptoms of inattention constitute a subgroup of individuals with ADHD (Ward & Scaler Scott, 2011). A preliminary study of 15 individuals diagnosed with cluttering described in Ward and Scaler Scott (2011) revealed that the adults and children in their sample also manifested symptoms of inattention on a screener.

The significance of the frequently reported comorbidity of ADHD diagnoses/ADHD symptoms and stuttering is unclear, but it has been noted that both ADHD and stuttering have high heritability rates, affect more males than females, and may share neurobiological underpinnings. Stuttering has heritability rates between 40% and 85% (Frigerio-Domingues & Drayna, 2017); similarly, ADHD also has a robust genetic contribution with an estimated heritability rate of 74% (Faraone & Larsson, 2019). Both conditions affect more males than females with an estimated male-to-female ratio of 2:1 in ADHD (Danielson et al., 2024) and 3:1 in stuttering (Bloodstein et al., 2021). Stuttering and ADHD may also share common neurological underpinnings that include differences in the neural circuitry interconnecting the cortex, basal ganglia, and thalamus (Alm, 2004; Chang & Guenther, 2019; Posner et al., 2014), anomalies in dopaminergic pathways (Alm, 2004; Barkley, 2018; Chang & Guenther, 2019; Gao et al., 2019), and atypical connectivity between the default mode network (DMN) and networks governing attention among other functions (Chang et al., 2018; Gao et al., 2019; Kessler et al., 2014; Sripada et al., 2014; Uddin et al., 2008; Xuan et al., 2012).

Although not an explanation for the apparent comorbidity, it is important to note that both stuttering and ADHD may have negative consequences for psychosocial development (Beilby, 2014; G. Johnson et al., 2023; McAllister, 2016; Wehmeier et al., 2010), academic achievement or occupational success (Arnold et al., 2020; Gerlach et al., 2018; Küpper et al., 2012; O'Brian et al., 2011; Van Borsel et al., 2011), and overall quality of life (Craig et al., 2009; Danckaerts et al., 2010; Koedoot et al., 2011; Wehmeier et al., 2010). Stuttering is a heterogenous condition, and identifying potential contributors to this heterogeneity provides insight into mechanisms underlying the condition, informs diagnostics, and enhances treatment efficacy (Yairi, 2007). Critically, having increased symptoms of ADHD can negatively impact treatment success in children who stutter (Riley & Riley, 1979) and young children who stutter with increased symptoms of ADHD require increased time to make therapy gains (Druker et al., 2019). The overarching aim of this study is to document the prevalence of ADHD/ADHD symptoms in children who stutter and examine potential relationships between ADHD symptoms and stuttering characteristics including adverse impact and stuttering severity in children.

Prevalence of ADHD in Children Who Stutter

There is an oft-cited ADHD comorbidity range of 4%–26% in school-aged children who stutter established by two older studies conducted by Arndt and Healey (2001) and Riley and Riley (2000). Yet, it is difficult to draw firm conclusions as these studies were not necessarily undertaken to establish prevalence of ADHD diagnoses in children who stutter. Riley and Riley, for example, probed the presence of components hypothesized to contribute to the development of stuttering in their multifactorial theoretical model (Riley & Riley, 1979). They assessed the component of an “attending disorder” in a sample of 50 children who stutter aged 3 to 9 years by having parents complete two subtests of an assessment of children's behavioral issues, the Burks Behavior Rating Scale (BBRS; Burks, 1969). Riley and Riley documented poorer attending and impulse control in 26% of their sample but clarified that their results did not necessarily establish an “attending disorder” as a risk factor for stuttering. Moreover, it is unclear if attending disorder, as measured by the BBRS, fully captures the range of ADHD symptomatology. In Arndt and Healey's (2001) study, 241 practicing speech-language pathologists (SLPs) were surveyed about the presence of diagnosed concomitant speech, language, and other disorders in children who stutter on their caseloads. In a subgroup of 109 children who stutter with a suspected concomitant diagnosis (i.e., speech, language, or other disorder), SLPs indicated approximately 4% might have ADD/ADHD. This lower percentage could be due to SLPs being hesitant to report that they suspected ADD/ADHD considering it was outside their scope of clinical practice to make this judgment.

Noting the limitations of prior investigations, Blood et al. (2003) sought to establish the prevalence of concomitant speech, language, and other disorders in children who stutter. They recruited 1,184 SLPs nationwide, asking them to report diagnoses of co-occurring disorders in 2,628 children who stutter on their caseloads that could be documented through assessments, student records, or parent report. SLPs then selected from a list of 18 nonspeech/language disorders including ADD. The three most frequently reported co-occurring conditions were learning disabilities, followed by literacy disorders, and then ADD. The prevalence of ADD in their sample, however, was ~6%, just slightly higher than the prevalence of ADD in the general school-age population estimated to be 3%–5% at that time (Anastopoulos & Shelton, 2001). Diagnoses of ADHD in the general child population were significantly lower 20 years ago than they are today (Ayano et al., 2023; Danielson et al., 2024), and a far higher prevalence of ADHD in children who stutter was recently documented by Briley and Ellis (2018). Their study accessed data from the 2010–2015 National Health Interview Survey (Centers for Disease Control and Prevention, National Center for Health Statistics, n.d.) to establish the comorbidity of developmental disorders in children who stutter. Caregivers answered yes/no to whether their child had a list of conditions that included “stuttering or stammering” during the past 12 months. Caregivers also indicated if a health professional informed them that their child had specific disorders including ADHD/ADD. The presence of stuttering in the sample of 62,450 children aged 3–17 years was approximately 2%. Children who stutter were over three times more likely to have ADHD compared to children who did not stutter indicating a prevalence of 25.6% compared to 8.6% in children who do not stutter (Briley & Ellis, 2018). Taken together, these studies suggest that ADHD diagnoses may be higher in children who stutter, yet the prevalence is unclear ranging from only slightly higher to substantially higher than the prevalence in the general population.

ADHD Symptoms in Children Who Stutter

Given reports of higher rates of ADHD in children who stutter, Donaher and Richels (2012) documented the presence of ADHD symptoms in children who stutter without a clinical diagnosis to further understanding of the relationship between ADHD symptoms and stuttering. Parents of 36 children who stutter aged 3 through 17 years completed the ADHD Rating Scale (ADHD-RS; Power et al., 2001) and potential relationships between ADHD symptoms and family history of stuttering, concomitant diagnoses, and stuttering severity were assessed. Remarkably, 58% of their sample of children who stutter were “symptomatic” for ADHD having met the criteria established by this measure for further referral. Children who were symptomatic for ADHD were more likely to have concomitant diagnoses. They did not find significant relationships between ADHD symptoms and family history or stuttering severity. Although this study included a modest sample of children spanning a wide age range, the proportion of their sample demonstrating elevated ADHD symptoms is high and warrants further investigation.

Druker et al. (2019) documented ADHD symptoms in preschoolers who stutter and explored potential effects of ADHD symptoms on stuttering treatment outcomes. The parents of 185 preschool children who had completed or been discharged from stuttering treatment within 3 months of the study's onset participated in the study. Parents completed a detailed case history report and the ADHD-RS–IV Home Version (McGoey et al., 2007; Power et al., 2001). The outcome variable, “number of sessions,” was obtained from children's clinical treatment records. Pre- and post-treatment stuttering severity rates were determined by calculating the number of syllables stuttered during conversational speech samples. Nearly half of their sample of preschool children who stutter had “elevated ADHD symptoms” per parent report meeting the criteria for further evaluation. They did not find differences between groups of preschoolers with and without elevated ADHD symptoms with respect to children's sex, family history of stuttering, or disfluency type, although a weak correlation suggested that greater stuttering severity was associated with increased ADHD symptoms. Notably, preschoolers who stutter exhibiting elevated ADHD symptoms required a greater number of speech therapy sessions to reach discharge criteria (≤ 2% syllables stuttered and a rating of 2 or less on a caregiver perceptual scale) compared to preschoolers without elevated ADHD symptoms.

Adverse Impact of ADHD and Stuttering

Concerningly, ADHD can impact children's psychosocial development with far-reaching consequences (Barkley, 2018). Children with ADHD may encounter difficulty navigating social interactions and are more likely to be rejected by peers and to engage in conflict with peers, parents, and other adults (Barkley, 2002; Nijmeijer et al., 2008; Wehmeier et al., 2010). Children with ADHD experience stigma across their development (for review, see Lebowitz, 2016) and often report poorer self-esteem and reduced overall quality of life compared to children without ADHD (Danckaerts et al., 2010; Harpin et al., 2016; Wehmeier et al., 2010).

Stuttering is also a stigmatized condition (Boyle, 2018) and our recent findings suggest that some children who stutter experience stuttering self-stigma (C. A. Johnson et al., 2024). Stuttering can also negatively impact children and adolescents' psychosocial development (Beilby, 2014; G. Johnson et al., 2023; McAllister, 2016), interpersonal relationships (Van Borsel et al., 2011), and overall quality of life (Craig et al., 2009; Koedoot et al., 2011). Recent studies reveal that children and adolescents who stutter, such as adults who stutter, experience adverse impact related to stuttering (AIS; Samson et al., 2021; Tichenor et al., 2023; Walsh et al., 2023). AIS is the summative effect of the negative thoughts, feelings, and behaviors that a person develops in reaction to stuttering combined with the real-world limitations that result from living with the condition (Tichenor & Yaruss, 2019; Yaruss & Quesal, 2004). AIS in children and adolescents may be compounded by co-occurring ADHD and symptoms of hyperactivity–impulsivity and inattention, although there have been no studies in children who stutter to examine this possibility. A survey study with 254 adults who stutter by Tichenor et al. (2021), however, revealed that adults who reported a greater number of inattention characteristics were more likely to engage in repetitive negative thinking and to experience AIS as measured by the Overall Assessment of the Speaker's Experience of Stuttering (OASES; Yaruss et al., 2016). This suggests that AIS is greater in adults who stutter displaying more frequent ADHD characteristics, lending support to the hypothesis that AIS may be compounded in children who stutter with ADHD diagnoses/ADHD symptoms. Identifying factors underlying AIS in children is critical to advance understanding of how individuals experience stuttering and for guiding intervention strategies uniquely tailored to meet the needs of a child who stutters with ADHD/ADHD symptoms.

The Current Study

The prevalence of ADHD in children who stutter is unclear, although evidence suggests that ADHD diagnoses in children who stutter are higher than ADHD diagnoses in the general child population (e.g., Briley & Ellis, 2018). Elevated ADHD symptoms have been documented in preschoolers who stutter (Druker et al., 2019) and preliminary evidence indicates that older children who stutter and adults who stutter may also demonstrate subclinical ADHD symptoms (Donaher & Richels, 2012; Tichenor et al., 2021). This study seeks to document ADHD diagnoses and assess ADHD symptoms in a relatively large sample of children who stutter spanning early childhood through adolescence. We investigate potential relationships between ADHD/ADHD symptoms and adverse impact related to stuttering and stuttering severity. We predicted that children with ADHD and children manifesting increased ADHD symptoms would report greater AIS as suggested by recent findings in adults who stutter (Tichenor et al., 2021). The results from earlier studies exploring the relationship between stuttering severity and ADHD symptoms have been mixed (Donaher & Richels, 2012; Druker et al., 2019), but given overlapping neurological differences, we predicted children diagnosed with ADHD and/or increased ADHD symptoms would manifest more severe stuttering. Examining the overlap between stuttering and ADHD/ADHD symptoms will shed light on the comorbidity of these neurodevelopmental conditions and lay the groundwork for tailored intervention approaches.

Method

Data presented in this study were collected as part of an ongoing study on the development of stuttering and its adverse impact on children in the Developmental Speech Lab at Michigan State University. Note that OASES data in the current study have also been presented for many of these participants in other publications (Tichenor et al., 2022, 2023; Walsh et al., 2023). This research was approved by the Institutional Review Board Office at Michigan State University (STUDY# 00001704).

Participants and Recruitment

Two hundred four dyads of children who stutter and their parent, legal guardian, or primary caregiver (henceforth, parent) participated in this study. Children (n = 204; 157 males) were between the ages of 5 and 18 years (M = 9.9 years; SD = 3.5 years). Families were recruited through purposive, convenience, and snowball sampling methods. We contacted SLPs employed in schools, outpatient clinics, university clinics, and specialty stuttering clinics around the United States asking them to disseminate information about the study to prospective families. We intentionally targeted schools and clinics in urban and suburban areas in the effort to enhance the diversity of our participant pool. We also advertised the study through word-of-mouth and through closed forums and social media outlets for SLPs working with children who stutter and parents of children who stutter (see Table 1 for parent and child demographic information).

Table 1.

Parent and child demographic data.

Demographic variable	Value (SD)
	Caregiver/parent (n = 204)	Child (n = 204)
Age
M (SD)	N/A	9.9 years (3.5 years)
Range, min–max	N/A	13; 5–18 years
Sex
Female	162 (79.4%)	46 (22.5%)
Male	17 (8.3%)	157 (77.0%)
Prefer not to say/missing data	25 (12.3%)	1 (0.5%)
Race
Asian	5 (2.4%)	4 (2.0%)
Black or African American	15 (7.4%)	18 (8.8%)
American Indian/Alaskan Native	0 (0.0%)	2 (1.0%)
White	164 (80.4%)	156 (76.5%)
Mixed/other	11 (5.4%)	24 (11.8%)
Missing data/prefer not to say	9 (4.4%)
Ethnicity
Hispanic/Latinx	10 (4.9%)	17 (8.3%)
Non-Hispanic/Latinx	187 (91.7%)	181 (88.7%)
Prefer not to say/missing data	7 (3.4%)	6 (2.9%)
Concomitant diagnoses		ADHD+ (n = 35)	ADHD− (n = 169)
Neurodevelopmental disorders (autism spectrum disorders, other)		6/35 (17.1%)	9/169 (5.3%)
Learning disorders		3/35 (8.6%)	3/169 (1.7%)
Internalizing disorders (anxiety/depression)		10/35 (28.6%)	16/169 (9.5%)
Other speech and language disorders		20/35 (57.1%)	69/169 (40.8%)

Surveys and Instruments

Survey data for the study was collected from parents and children via the internet with Qualtrics software (Qualtrics, 2023). Parents were e-mailed a link to a brief screening survey to confirm that their child met inclusionary criteria (child who stutters, aged 5–18 years, ability to understand and speak English). Parents were then sent personalized links to parent and child surveys that could only be completed once. Parents and children gave informed consent or assent, respectively, prior to taking each survey. Parents provided demographic information for their child including age, race, ethnicity, and sex (see Table 1), as well as additional information about their child's stuttering. Ninety-five percent of children had been diagnosed with stuttering by a professional (e.g., SLP), and approximately 94% of children had received speech therapy for stuttering per parent report. Parents also indicated whether a first- through third-degree relative stuttered/had ever stuttered to establish a positive family history of stuttering (Walsh et al., 2021) and reported whether their child had been diagnosed with ADHD, any treatment their child was receiving if they had ADHD, and if their child had ever been diagnosed with a speech or language disorder other than stuttering. Finally, parents rated the severity of their child's current stuttering using an 8-point Likert scale from 0 (not severe at all) to 7 (extremely severe). Parents who completed this 30–40 min survey, which included additional items related to our larger project on the adverse impact of stuttering in children, received a $30 Amazon gift card as compensation for their time.

ADHD-RS

Evaluations for ADHD involve multiple components and rely on a multi-informant approach combining behavioral rating scales completed by parents and teachers with additional testing conducted by a qualified health professional. For this study, we focused on input from one informant, the child's parent. Two-hundred and two parents completed the ADHD-RS Home Version (DuPaul et al., 2016). This measure is routinely used in the screening and assessment processes for ADHD in children and incorporates diagnostic criteria for ADHD derived from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5; American Psychiatric Association, 2013). The ADHD-RS is based on a large sample of children representative of the U.S. population in terms of race, ethnicity, geographical region, and family income and includes a form for parents of younger children, aged 5–10 years, and a form for older children, aged 11–18 years. Cutoff scores for both screening and diagnostic purposes are provided with the understanding that the accuracy of an ADHD diagnosis is dependent upon both parent and teacher ratings. The parents of two children diagnosed with ADHD did not complete the ADHD-RS. The ADHD-RS has sections measuring Inattention and Hyperactivity–Impulsivity scores using the diagnostic criteria for ADHD established by the DSM-5 (American Psychiatric Association, 2013). Parents indicate how often their child exhibits 9 inattentive symptoms and 9 hyperactive–impulsive symptoms using a 4-point Likert scale: 0 = never or rarely, 1 = sometimes, 2 = often, and 3 = very often. Separate scores for inattention and hyperactivity–impulsivity are computed by summing the 9 items in each scale. The Total score is obtained by summing over all items and ranges from 0 to 54, with higher scores indicating greater severity of ADHD symptoms. We identified participants who screened positive for ADHD indicating the need for further evaluation using established criteria (i.e., the child's Total, Inattentive, or Hyperactivity–Impulsivity scores were at or above the 80th percentile cutoff based on their age and sex using established norms (DuPaul et al., 2016) that have been implemented in a prior study of ADHD in children who stutter (Druker et al., 2019).

Adverse Impact of Stuttering

AIS was measured using the age-appropriate version of the OASES (Yaruss & Quesal, 2016). Parents of children who stutter (CWS) aged 5–6 years completed the Early Childhood Parent (OASES-EC-P; Yaruss & Yaruss, 2021), while children aged 7–12 years completed the OASES-Student and children aged 13–18 years completed the OASES-Teen (Yaruss & Quesal, 2016). Parents could read or explain OASES questions for their child but were asked not to answer for or influence their child's response. The OASES assesses the impact of stuttering on a person's life, following the World Health Organization's International Classification of Functioning, Disability and Health (WHO, 2001) that was adapted to stuttering (Tichenor & Yaruss, 2019; Yaruss, 1998; Yaruss & Quesal, 2004). Each version of the OASES has four sections of questions—General Information, Reactions to Stuttering, Communication in Daily Situations, and Quality of Life—answered with a 5-point Likert scale indicating frequency or level of agreement. Impact scores are computed by dividing the total number of points in each section by the total number of items completed in each section, and a total score is established by summing all the points and dividing by the total number of items completed. If there are missing responses, the average is taken over the questions respondents answered. OASES scores are interpreted on the following scale: mild impact (1.00–1.49), mild/moderate impact (1.50–2.24), moderate impact (2.25–2.99), moderate/severe impact (3.00–3.74), severe impact (3.75–5.00).

Data Analysis

We calculated the number of children diagnosed by a medical professional with ADHD per parent report out of the total number of children to establish the prevalence of ADHD in our sample and to form two groupings of children who stutter: those with an established ADHD diagnosis (ADHD+) and those without an ADHD diagnosis (ADHD−). Chi-square proportions tests (α = .05) were conducted to examine differences in the categorical variables sex assigned at birth, family history, and concomitant speech and language diagnoses proportions between these two groups. Mann–Whitney U tests were used to compare ADHD+/ADHD− groups on the variables Age, Stuttering Severity, and OASES Total scores. Rank-biserial correlation coefficients were used to assess the direction and effect size of the Mann–Whitney U tests (r_pb = 1 − 2 U/n1·n2).

We assessed children's ADHD-RS Total scores to determine the proportion of children in the ADHD− group who screened positive for ADHD using criteria delineated in the ADHD-RS manual (scores at or above the 80th percentile cutoff given a child's age and sex). Inattention and Hyperactivity–Impulsivity subscale scores were also used as predictors in the multiple regression analysis.

Multiple linear regression was used to examine the relationships between Group (ADHD+/ADHD−), Age, and ADHD-RS Inattention and Hyperactivity–Impulsivity subscale scores and AIS captured by OASES Total Score (Model 1) and Stuttering Severity (Model 2). Both models were investigated for linearity, normality of residuals, homoscedasticity, and the presence of influential values via diagnostic plots in accordance with the underlying assumptions of linear regression. All assumptions were met. Diagnostic plots indicated that predictors and outcome variables in both models showed a linear relationship. Error was also judged to be normally distributed. Residuals in both models demonstrated a constant variance and independence of error terms (i.e., that no observation was more than three times the mean; see Cook, 1979). See Supplemental Material S1 for diagnostic plots.

Internal Consistency

The ADHD-RS and OASES are robust and often-used measures. We computed reliability measures assessing the internal consistency of items comprising the two ADHD subscales and four OASES sections (see Table 2). Cronbach's alpha ranged from poor to excellent for the four sections of the three OASES versions (George & Mallery, 2002). Section 1 General Information of the OASES-EC-P received the lowest alpha, which suggests that the items in this section do not converge on a single underlying construct. Nevertheless, we included data from the OASES-EC-P Section 1 in the analysis as the Total OASES score for each participant reflects the average of items answered across all sections, thus mitigating the concern regarding low alpha of this specific section. Moreover, a recent study by our group (Tichenor et al., 2022) computed statistics with and without Section 1 from the OASES-EC-P and found no difference in significance levels or effect sizes. Cronbach's alpha for the two subscales of the two versions of the ADHD-RS for younger/older children all achieved excellent reliability.

Table 2.

Cronbach's alpha for Overall Assessment of the Speaker's Experience of Stuttering (OASES) and ADHD-RS subscales.

Factors	OASES-EC-P	OASES-S	OASES-T	ADHD-5 Child	ADHD-5 Adolescent
OASES Sec 1. Gen Information	.24	.70	.74	—	—
OASES Sec 2. Reactions to Stuttering	.89	.93	.93	—	—
OASES Sec 3. Communication in Daily Situation	.80	.93	.92	—	—
OASES Sec 4. Quality of Life	.87	.88	.94	—	—
ADHD-5 Inattention Subscale	—	—	—	.91	.93
ADHD-5 Hyperactivity–Impulsivity Subscale	—	—	—	.93	.83

Note. Em dash indicates item is nonapplicable. OASES-EC-P = OASES (Early Childhood Parent version); OASES-S = OASES (Student version); OASES-T = OASES (Teen version); ADHD-5 = Attention-Deficit/Hyperactivity Disorder Rating Scale–5 Home (Child and Adolescent versions).

Results

ADHD Prevalence in Children Who Stutter

The prevalence of documented ADHD diagnoses in our sample of children who stutter per parent report was 17.2% (35 out of 204 children). Chi-square Proportions Tests did not reveal significant differences between the ADHD+/ADHD− groups of children in sex assigned at birth, family history of stuttering, or concomitant speech and language diagnoses (see Table 3). Mann–Whitney U tests indicated that Age was significantly higher for the ADHD+ group (Mdn = 10.00 years) compared to the ADHD− group (Mdn = 9.00 years; U = 2297.500, p = .037, rpb = .22, representing a small effect size). Children in the ADHD+ (M = 11.03 years; SD = 3.47 years) were, on average, 1.31 years older than children in the ADHD− group (M = 9.72 years; SD = 3.51 years). Parent-rated stuttering severity was statistically higher for the ADHD+ group (Mdn = 4.00) compared to the ADHD− group (Mdn = 3.00; U = 1979.00, p = .002, rpb = .33, also representing a small effect size). Parents of children in the ADHD+ group rated their child's stuttering severity to be, on average, “moderate” on the 8-point Likert scale (M = 4.14; SD = 1.48) while parents of children in the ADHD− group rated their child's stuttering severity, on average, to be “mild–moderate” (M = 3.27; SD = 1.40). Children in the ADHD+ group had OASES Total Scores showing, on average, mild–moderate impact (M = 2.21; SD = 0.54) and children in the ADHD− group also had OASES Total Scores indicating mild–moderate impact (M = 2.24; SD = 0.59). OASES Total Score was not significantly different between the ADHD+ group (Mdn = 2.21) and the ADHD− group (Mdn = 2.23; U = 1832.00, p = .10, rpb = .0006).

Table 3.

Chi-square proportions test results.

Variable	ADHD+		ADHD−		Total
	n	%	n	%	n	%
Child sex at birth
Male	4	2.0	42	20.6	46	22.6
Female	31	15.2	126	61.8	157	77
Missing data	0		1	.49	1	.49
χ2 = 3.26; df = 1; p = .20
Family history of stuttering
Yes	15	7.4	94	46.1	109	53.4
No	20	9.8	75	36.8	95	46.6
χ2 = 1.90; df = 1; p = .17
Concomitant speech/language disorders
Yes	21	10.3	73	35.8	94	46.1
No	14	6.9	96	47.1	110	53.9
χ2 = 3.30; df = 1; p = .07

Note. ADHD = attention-deficit/hyperactivity disorder.

ADHD Symptoms in Children Who Stutter

Over 40% of children (5–10 years) in the ADHD− group had Total ADHD scores that were “symptomatic” of ADHD warranting further evaluation (i.e. their scores were at or above the 80th percentile; see Table 4). Nineteen percent of adolescents (11–18 years) in the ADHD− group also had Total ADHD scores symptomatic of ADHD. Approximately 67% of children and over 56% of adolescents in the ADHD+ group had Total ADHD scores symptomatic of ADHD indicating that many children's symptoms in the ADHD+ group were being managed. We documented that 13 children in the ADHD+ group took daily ADHD medications. Four of these children also received behavioral therapy per parent report, whereas five children received behavioral intervention alone for ADHD. Three parents indicated that their child was not receiving any treatment for ADHD, and 14 parents did not specify whether their child was receiving treatment for their ADHD. Table 4 provides a breakdown of ADHD scores by subscale for the two groups.

Table 4.

ADHD Rating Scale (ADHD-RS) results.

Group	Total ADHD score at or above 80th percentile	Inattentive score at or above 80th percentile	Hyperactivity–Impulsivity score at or above 80th percentile
Children without ADHD diagnosis	43/107 (40.2%)	41/107 (38.3%)	47/107 (43.9%)
Adolescents without ADHD diagnosis	12/63 (19.0%)	12/63 (19.0%)	22/62 (35.5%)
Children with ADHD	12/18 (66.7%)	17/18 (94.4%)	11/18 (61.1%)
Adolescents with ADHD	9/16 (56.3%)	10/16 (62.5%)	11/16 (68.8%)

Note. ADHD = attention-deficit/hyperactivity disorder.

Multiple Linear Regression

Table 5 and Figures 1A to 1C and Figures 2A to 2C present the results of the two multiple linear regression models. Because the Mann–Whitney U test revealed statistically similar distributions between the two child groups with respect to OASES Total scores, multiple linear regression (Model 1) assessed whether ADHD Inattention and Hyperactivity–Impulsivity scores and Age (but not Group) predicted AIS. This model was statistically significant, F(3, 162) = 6.56, p < .001, R² = .11, R² adjusted = .09, f² = .10, indicating a small effect size (Cohen, 1988). In this model, ADHD Inattention scores (β = .29, p = .002) and Age (β = .24, p = .002) significantly predicted AIS (Figures 1A and 1C), while ADHD Hyperactivity–Impulsivity score did not (β = −.13, p = .18; Figure 1B).

Table 5.

Multiple linear regression results.

Model	Predictor variable	B	SE B	β	τ	p
Model 1: AIS	ADHD-I score	0.03	0.009	.29	3.08	.002
	ADHD-H score	−0.01	0.009	−.13	−1.35	.18
	Age	0.04	0.01	.24	3.18	.002
Model 2: Stuttering Severity	ADHD-I score	0.032	0.021	.14	1.56	.12
	ADHD-H score	0.02	0.02	.08	0.90	.37
	Age	0.09	0.03	.23	3.16	.002
	Group	−0.44	0.30	−.11	−1.48	.14

Note. Bolded cells indicate significant effects. AIS = adverse impact of stuttering; ADHD = attention-deficit/hyperactivity disorder; ADHD-I = ADHD Inattentive; ADHD-H = ADHD Hyperactivity–Impulsivity.

Figure 1.

Individual data points presenting a child's AIS (OASES Total Score) plotted against their ADHD-RS Inattention subscale score (A), ADHD-RS Hyperactivity–Impulsivity subscale score (B), and Age (C). AIS = adverse impact related to stuttering; OASES = Overall Assessment of the Speaker's Experience of Stuttering; ADHD-RS = Attention Deficit Hyperactivity Disorder Rating Scale.

Figure 2.

Individual data points presenting parent ratings of stuttering severity for their child based on an 8-point Likert scale plotted against their child's ADHD-RS Inattention subscale score (A), ADHD-RS Hyperactivity–Impulsivity subscale score (B), and Age (C). OASES = Overall Assessment of the Speaker's Experience of Stuttering; ADHD-RS = Attention-Deficit/Hyperactivity Disorder Rating Scale.

Given a significant difference in stuttering severity between ADHD+/ADHD− groups on the Mann–Whitney U test, Model 2 assessed whether Group, ADHD Inattention and Hyperactivity–Impulsivity scores, and Age significantly predicted Stuttering Severity. Model 2 was also statistically significant, F(4, 196) = 6.37, p < .001, R² = .12, R² adjusted = .10, f² = .11, indicating a small effect size (Cohen, 1988). In this model, Age (β = .23, p = .002) was the only significant predictor of Stuttering Severity (Figure 2c).

Discussion

Previous research suggests that there is a higher prevalence of ADHD/ADHD symptoms in children who stutter, though interpretation of this overall trend has been limited by divergent findings, small sample sizes, and different methods of measuring the presence of ADHD or ADHD symptoms. This study documented the prevalence of ADHD in children who stutter via parent-report and explored potential relationships between ADHD and stuttering characteristics. We found a higher prevalence of ADHD diagnoses in our sample of children who stutter compared to prevalence rates in the general population. A significant proportion of children who stutter without an ADHD diagnosis displayed elevated symptoms of inattention and hyperactivity–impulsivity warranting further evaluation. We did not find differences between ADHD+/ADHD− groups of children who stutter in terms of sex, family history of stuttering, or concomitant speech and language diagnoses. Children in the ADHD+ group were 1.31 years older, on average, than children in the ADHD− group. This is intuitive given that ADHD is most often diagnosed around the age of 7 years (Barkley, 2018). Parents of children in the ADHD− group rated their child's stuttering severity to be slightly less severe than parents of children in the ADHD+ group. We did not find a statistically significant relationship between ADHD symptoms and stuttering severity; however, there was a modest relationship between the frequency of Inattention symptoms and the AIS.

ADHD Prevalence and ADHD Symptoms in Children Who Stutter

Approximately 17.2% of our sample of 204 five- to eighteen-year-old children who stutter were diagnosed by a professional with ADHD per parent report. This represents a 5.8% increase in ADHD diagnoses in this population compared to the 11.4% prevalence of ADHD in the general population of U.S. children (Danielson et al., 2024). Our prevalence rate is lower than the 25.6% parent-reported prevalence in a community sample of children who stutter in a study by Briley and Ellis (2018), but higher than the ~6% prevalence rate reported by (Blood et al., 2003) over 20 years ago. The prevalence of ADHD has risen over the last decade not only due to increased awareness (Abdelnour et al., 2022) but also due to significant changes in diagnostic criteria in the DSM-5 (American Psychiatric Association, 2013). The DSM-5 raised the age of symptom onset from 7 years to 12 years and required a history of ADHD symptoms, but no longer the criterion that ADHD symptoms negatively impact an individual's life, as stipulated by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (Barkley, 2018). Our finding of higher prevalence rates of ADHD in children who stutter corroborate findings from studies now spanning two decades that included different reporters (i.e., parents, SLPs) and children across clinical and community samples (Blood et al., 2003; Briley & Ellis, 2018). Compellingly, we also found that a significant proportion of our sample, over 40% (43/107) of children and 19% (12/63) of adolescents, without an ADHD diagnosis scored at or above the 80th percentile cutoff, indicating the need for further evaluation for ADHD.

Druker et al. (2019) reported that 50% of their sample of 185 preschoolers had elevated symptoms of inattention and hyperactivity–impulsivity and Donaher and Richels (2012) found that 58% of their sample of 36 children who stutter aged 3 to 17 years were symptomatic for ADHD. The slightly lower percentages that we noted could be explained by differences in the age of participants across studies and by differences in the criteria to be considered “symptomatic” for ADHD. Symptoms of inattention and hyperactivity–impulsivity are higher in preschool-aged children, and Druker's sample focused exclusively on this age group. Donaher and Richels' study included fewer children who stutter that spanned a wider age range including children as young as 3 years. A higher prevalence of ADHD symptoms that we and others have identified in children who stutter may persist into adulthood, as Tichenor et al. (2021) found that 23% of their sample of 254 adults who stutter had significant symptoms of inattention and 8% had significant symptoms of hyperactivity–impulsivity.

Clearly, stuttering and ADHD are distinctly different neurodevelopmental conditions, yet the frequent comorbidity of ADHD/ADHD symptoms in CWS suggests that there may be common underlying neural mechanisms that contribute to stuttering and clinical (or subclinical) ADHD. There is evidence of anomalous resting-state connectivity within the default mode network a network of brain regions activated when individuals are not focused on the external environment, and between the DMN and “task positive” networks such as the frontoparietal network and dorsal and ventral attention networks in both ADHD (e.g., Gao et al., 2019; Kessler et al., 2014; Sripada et al., 2014; Uddin et al., 2008) and stuttering (Chang et al., 2018; Xuan et al., 2012). Differences in the neural circuitry interconnecting the cortex, basal ganglia, and thalamus (cortico–striato–thalamo–cortical [CSTC]) critical for sensorimotor, cognitive, and limbic functions has been implicated in both ADHD and stuttering (Alm, 2004; Chang & Guenther, 2019; Posner et al., 2014). Alm (2004) and Chang and Guenther (2019) suggested that anomalous CSTC circuitry plays a key role in the pathophysiology of stuttering, in part, by interfering with the precise initiation of speech motor programs. Posner et al. (2014) proposed that connectivity anomalies in CSTC circuitry underlies executive and limbic system functioning manifesting as the major symptoms associated with ADHD. Interestingly, Chow and Chang (2017) noted decreased growth rates of white matter tracts connecting prefrontal and basal ganglia in children who stutter that could affect attentional processes. Stuttering and ADHD have also been linked to the dysregulation of dopaminergic pathways. Finally, dopamine is a neurotransmitter involved in cognition, movement, and mood regulation among other functions. Dopamine regulating gene deficiencies result in reduced dopamine in prefrontal and striatal brain regions, which is suggested to affect executive function (EF), attention, and impulse control in ADHD (Barkley, 2018; Gao et al., 2019). The potential role of dopamine in stuttering is less clear owed to the differential effects of dopamine on direct and indirect basal ganglia pathways (see Alm, 2004, and Chang & Guenther, 2019, for discussions). However, dopamine imbalances are suggested to affect speech motor control in developmental and neurogenic stuttering (Alm, 2004; Chang & Guenther, 2019; Civier et al., 2013; Wu et al., 1997).

There has been considerable interest in the role of attentional processes and EF (working memory, inhibitory control, and cognitive flexibility) in childhood stuttering given well-established linkages between EF and children's speech (other than stuttering) and language skills (e.g., Blain-Brière et al., 2014; Gooch et al., 2016; Kaushanskaya et al., 2017; Netelenbos et al., 2018; Torrington Eaton & Ratner, 2016; Veraksa et al., 2020). Studies exploring potential differences between children who do and do not stutter in EF and attentional processes using parent-report temperament questionnaires or dedicated experimental paradigms have yielded some inconsistent findings, with some studies revealing differences between children who stutter and controls (e.g., Anderson & Wagovich, 2017; Eggers et al., 2010; Eggers & Jansson-Verkasalo, 2017; Eichorn et al., 2018; Ntourou et al., 2018; Rocha et al., 2019) and other studies finding no significant differences between these groups (e.g., Anderson & Wagovich, 2017; Eggers et al., 2012, 2018; Kefalianos et al., 2014, 2017; Piispala et al., 2016; Tichenor et al., 2021; Walsh et al., 2019). One meta-analysis did not confirm differences in attention and inhibition between CWS and children who do not stutter (CWNS) based on their analysis of several behavioral studies (Ofoe et al., 2018). On the other hand, when they synthesized findings across five parent-report studies of children's inhibition skills, they found that children who stutter scored nearly half a standard deviation below the mean compared to children who do not stutter. Similarly, parents of children who stutter rated their child's attentional focusing skills to be one third a standard deviation below the mean reported by parents of children who do not stutter (Ofoe et al., 2018). Interestingly, Alm (2014) also noted that studies of temperament and stuttering have found that aspects of attention and inhibition differentiate CWS from CWNS (Anderson et al., 2003; Eggers et al., 2010; Embrechts et al., 2000), with these aspects yielding the largest effect sizes (see Alm, 2014, Table 2). This suggests that what has been interpreted as overall temperamental differences between CWS and CWNS may instead reflect clinical or subclinical characteristics of ADHD.

Researchers should be aware of the frequent comorbidity of ADHD/ADHD symptoms in individuals who stutter and how these may affect findings. It is possible that the variability across studies on attention and EF in children who stutter may be due, in part, to the inclusion of children with clinical (or subclinical) ADHD. Many participants in these aforementioned studies were preschool aged (3–6 years old) children who stutter which is younger than the average age of ADHD diagnosis around age 7 or later if the child has milder symptoms (Barkley, 2018). Moreover, earlier studies provided exclusionary criteria that often included “neurological” disorders. ADHD has been classified as “neurodevelopmental” since the DSM-5 was published in 2013. Parents may not have been aware, for example, when asked to indicate whether their child had been diagnosed with a neurological disorder that this necessarily included ADHD. Ultimately, we are not suggesting that studies exclude children who have or show symptoms of ADHD. Instead, given the prevalence of these children in our and others' samples, researchers should aim to recruit more clinically representative samples of children who stutter and account for coexisting conditions in their analyses.

ADHD Symptoms and Stuttering Characteristics

Adverse Impact of Stuttering

Prior studies in children who stutter have not investigated potential relationships between ADHD/ADHD symptoms and AIS, but it is reasonable to speculate that children diagnosed with ADHD and/or showing increased ADHD symptoms would report greater AIS due to “collateral” effects of both disorders (Tichenor et al., 2021). We did not, however, find a significant difference in AIS indexed by OASES Total Scores between children who stutter with and without an ADHD diagnosis. Symptoms of Inattention, but not Hyperactivity–Impulsivity, were, however, associated with greater AIS. It is possible that Hyperactivity–Impulsivity was not associated with AIS because many indicators of hyperactivity–impulsivity on the ADHD-RS (and DSM-5) are predicated upon speech behaviors (e.g., talking excessively, not playing quietly during activities, answering questions before they are asked, finishing others' sentences, and interrupting). Children who stutter may have a reduced tendency to display speech behaviors indicative of hyperactivity–impulsivity. Increased symptoms of Inattention did predict greater AIS. Inattention has been associated with poorer emotional regulation skills (Christiansen et al., 2019; Shaw et al., 2014). It is possible that having poorer emotional regulation could amplify a child's reactions to their own stuttering causing them to feel more frustrated, anxious, or guilty about their stuttering, as measured by the OASES. Heightened Inattention symptoms can result in academic challenges (Daley & Birchwood, 2010) and contribute to strained relationships with family members (Johnston & Mash, 2001; Lifford et al., 2008). Children with increased symptoms of Inattention may have responded more negatively to OASES items probing how stuttering affects their life or their self-confidence.

Finally, Age was also significant in Model 1 with older children reporting on average, higher AIS. Children with ADHD were slightly older than children without a diagnosis contributing to this finding. Although each child is unique and even preschoolers can experience AIS as Figure 1 reveals, a child may accrue more negative experiences the longer they live with stuttering and encounter more complex communication situations.

A comprehensive stuttering assessment should assess potential adverse impact as well as speech behaviors regardless of whether that child has concomitant ADHD. The OASES is designed to be sensitive to the adverse impact associated with stuttering, and the limited relationships between ADHD symptoms and AIS suggest that perhaps the combined effects of stuttering and ADHD require broader outcome measures. Internalizing disorders such as depression or anxiety co-occur in children with ADHD (Karustis et al., 2000; Meinzer et al., 2014; Sciberras et al., 2014). Children who stutter may also be at greater risk for anxiety, particularly social anxiety, compared to CWNS (Bernard et al., 2022; Smith et al., 2014). Critically, we found that parents of children who stutter with ADHD more often reported that their child had been diagnosed with an internalizing disorder, such as anxiety, than parents of children without ADHD (see Table 1). A more general measure of self-esteem, anxiety, or overall quality of life may be a more robust measure to capture collateral effects of stuttering and ADHD/ADHD symptoms.

Stuttering Severity

Parents of children in the ADHD- group rated their child's stuttering severity to be less severe, on average, than parents of children in the ADHD+ group. This finding, however, may have been related to the fact that children in the ADHD+ group were slightly older than children in the ADHD− group. Overall, Model 2 predicted stuttering severity; however, only child Age, not Group or ADHD Inattention and Hyperactivity–Impulsivity scores, was statistically associated with parent-reported ratings of stuttering severity. Parents tended to judge younger children's stuttering to be less severe than parents of older children. Druker et al. (2019) found a significant, albeit weak, positive correlation between baseline stuttering severity and ADHD symptoms in their study of 185 preschool CWS. On the other hand, Donaher and Richels (2012) found no difference in stuttering severity measured by the Stuttering Severity Instrument–Fourth Edition (Riley, 2009) between groups of CWS who met or did not meet the criteria for referral based on their ADHD symptoms. They included children spanning preschool through adolescence as we did in this study. ADHD symptoms may be predictive of stuttering severity in preschoolers who stutter; however, this relationship may not hold over development.

Clinical Implications

ADHD/ADHD symptoms present challenges to stuttering (and cluttering) assessment and intervention. Findings from Lee et al. (2017) suggest that diagnosing stuttering in children manifesting ADHD symptoms may be difficult as these children have inherently higher rates of stuttering-like (e.g., prolongations, repetitions, blocks) and other disfluencies (e.g., interjections, multisyllabic word or phrase repetitions, revisions) seen in both conditions. SLPs working with children with ADHD may need to develop intervention plans to address stuttering and concomitant language disorders as language disorders frequently co-occur in children with ADHD (Baker & Cantwell, 1992; Korrel et al., 2017; Tirosh & Cohen, 1998), and we noted a higher co-occurrence of speech and language disorders in the ADHD+ cohort compared to the ADHD− cohort (see Table 1). Symptoms of inattention and hyperactivity–impulsivity can complicate speech therapy and may have a negative impact on treatment success (Druker et al., 2019; Riley & Riley, 1979).

Healey and Reid (2003) recognized that most clinicians lack specialized training to prepare them for the challenges of working with children with ADHD and offered valuable guidance in their tutorial published over 20 years ago. Many of their “gold standard” recommendations are still applicable today. We summarize these and other intervention principles derived from the educational and psychology research literatures here, but we recommend that clinicians review these (and other) citations for more comprehensive guidance on how to best support CWS with ADHD/ADHD symptoms.

The most effective classroom strategies for supporting children with ADHD comprise proactive and reactive measures (Pfiffner & DuPaul, 2018). Proactive measures help prevent challenging behaviors from occurring. Healey and Reid (2003) proposed conducting speech therapy in a classroom corner or clinic room rather than in an open setting to minimize environmental distractions. They also recommend maintaining a brisk pace of instruction and breaking up activities into smaller ones or working on activities for shorter periods of time to help children maintain focus. DuPaul and Stoner (2014) suggest using brightly colored visual aids to reduce the need for verbal directives. This strategy would work well with speech therapy rules, reminders, or when learning techniques that require several steps. Computer-assisted interventions are recommended for children with ADHD as children are attentive to these approaches (Pfiffner & DuPaul, 2018). Chaudhary et al. (2022) provide a helpful review of technological interventions for stuttering that includes benefits and drawbacks to these approaches for the interested reader. Finally, Healey and Reid advised conducting therapy either one-on-one or in a small group with thoughtfully selected peers and allowing brief intervals of physical movement. Pfiffner and DuPaul (2018) also recommend these strategies and the appropriate use of manipulative “fidget” toys.

Reactive measures encompass behavioral management strategies such as positive reinforcement to reward desired behaviors and specifying consequences for undesired behaviors (Pfiffner & DuPaul, 2018). Children with ADHD may not respond to rewards as strongly or as quickly as other children, so Pfiffner and DuPaul (2018) recommend “frequent and powerful” reward systems. Children can select awards they would like to earn during speech therapy to promote autonomy keeping in mind that rewards can be switched out if they lose their effectiveness. DuPaul and Stoner (2014) suggest consulting parents for behavioral management strategies used at home to promote consistency across settings. Parents could also be consulted for high-interest topics that the child might be motivated to talk about in therapy. SLPs should also communicate with a child's classroom teachers about accommodations that best help that child learn, and about behavioral interventions and management strategies that could be extrapolated to therapy.

ADHD is associated with educational impairment. Between 50% and 80% of children with ADHD report learning or achievement problems (DuPaul & Stoner, 2014). For ADHD children who stutter with concomitant ADHD and language deficits, curriculum-based language interventions could address language goals while providing a valuable opportunity to scaffold academic skills (Meaux & Norris, 2018). Finally, although feedback provided to children in speech therapy is typically faded as soon as possible to promote generalization, this might not be the most effective strategy for some children with ADHD/ADHD symptoms. Dupaul and Stoner (2014) recommend providing frequent and immediate feedback while allowing frequent responses from the child to maintain their focus. To foster generalization, Pfiffner and DuPaul (2018) also recommend having children with ADHD evaluate their performance and reward themselves based on their evaluation. Clinicians can provide children with tactics for self-monitoring and self-reinforcement, as these strategies are often incorporated into stuttering intervention (Reardon-Reeves & Yaruss, 2017).

Therapy for AIS often incorporates desensitization strategies and/or emphasize acceptance and openness about stuttering (e.g., Blomgren, 2013; Reardon-Reeves & Yaruss, 2017; Yaruss et al., 2012). Yet, it is unclear how acceptable these approaches would be to children who may also be struggling with social interactions, peer rejection, reduced self-esteem, and stigma related to their ADHD (Harpin et al., 2016; Lebowitz, 2016; Nijmeijer et al., 2008; Wehmeier et al., 2010). There is a clear need for clinical research to determine the best ways to support CWS who have co-occurring conditions, such as ADHD, to guide effective intervention planning. In the meantime, SLPs should involve children in clinical decision making to foster their engagement and tailor the pace or presentation of treatment approaches to enhance their acceptability and success.

Limitations

While this study provided valuable insights into the relationship between ADHD/ADHD symptoms and stuttering, there are several limitations to acknowledge to ensure a transparent and comprehensive understanding of our findings. We recruited children from urban, suburban, and rural locations across the United States in the attempt to diversify our sample. The proportion of children in our study identifying as “White” and “Mixed Race” is similar (i.e., within 2 percentage points) to U.S. demographic data (childstats.gov), yet we included slightly fewer (2% vs. 6%) Asian children and (9% vs. 14%) Black children. We included far fewer (8% vs. 26%) children identifying as “Hispanic/Latinx” children compared to U.S. demographic reports. To draw firmer conclusions and promote generalization of our findings to the pediatric stuttering population at large, particularly regarding the relationship between ADHD symptoms and AIS, data from a more diverse sample are critical to better understand the experiences that children with ADHD and stuttering face.

Assessment of stuttering, such as ADHD, typically involves multiple components, and we acknowledge that a parent severity rating based on an 8-point scale may represent a limited view. Nevertheless, prior studies using objective measures (e.g., standardized stuttering assessment or disfluency counts) also failed to find a clear relationship between ADHD characteristics and severity of overt stuttering symptoms (Donaher & Richels, 2012; Druker et al., 2019). Moreover, Onslow et al. (2018) concluded that parent-report severity and percentage of syllables stuttered yielded statistically similar outcomes based on data from three randomized control trials. Finally, this study also adopted a direct, yet simplistic, analysis of the relationship between ADHD symptoms and AIS. We acknowledge that this approach does not capture the complex intersectionality among ADHD symptoms, stuttering behaviors, and other factors, for example, temperament profiles or the presence of internalizing disorders that could moderate relationships between ADHD symptoms and AIS.

Conclusions

ADHD has been described as a dimensional disorder, despite its categorical diagnosis as stipulated by the DSM-5 (Barkley, 2018). Children who stutter displayed symptoms of inattention and hyperactivity–impulsivity across a continuum. Although researchers and clinicians may be privy to a child's ADHD diagnosis, they should be aware that a significant proportion of children without an ADHD diagnosis may display symptoms of inattention and/or hyperactivity–impulsivity that can complicate research findings and stuttering treatment. These children may require specialized intervention to enhance the efficacy and generalizability of speech therapy to meet their specific needs.

Author Contributions

Bridget Walsh: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing. Seth E. Tichenor: Conceptualization, Formal analysis, Project administration, Visualization, Writing – review & editing. Katelyn L. Gerwin: Conceptualization, Project administration, Writing – review & editing.

Data Availability Statement

Deidentified data are available upon request by contacting the first author, Bridget Walsh, via her e-mail (walshb16@msu.edu).

Funding Statement

This research was supported by the National Institute on Deafness and Other Communication Disorders Grant R01DC018000 (awarded to Bridget Walsh).