Psychometric Evaluation of the Turkish Mind Excessively Wandering Scale in Adolescents With ADHD: Exploratory Findings on Age‐Related Differences in Excessive Mind Wandering

ABSTRACT

This study examined the psychometric properties of the Turkish version of the Mind Excessively Wandering Scale (MEWS) in adolescents and investigated age‐related differences in excessive mind wandering (EMW) among adolescents with ADHD. The sample included 156 adolescents (80 with ADHD, 76 controls; mean age = 15.08 ± 1.85 years). ADHD diagnoses were established using a semi‐structured clinical interview. Participants completed the MEWS, DERS‐16 and S‐UPPS‐P. Confirmatory factor analysis (CFA), reliability analyses, group comparisons and regression analyses were conducted. The MEWS showed a unidimensional structure with acceptable model fit and high internal consistency (α = 0.93). EMW was significantly higher in the ADHD group than in controls. EMW was strongly associated with emotion regulation difficulties and moderately associated with impulsivity and ADHD symptoms. A significant age × group interaction was observed, indicating that the relationship between age and EMW differed across diagnostic groups. Older adolescents with ADHD tended to report higher EMW scores than younger adolescents with ADHD, whereas no comparable age‐related pattern was observed in the control group. The original 12‐item Turkish MEWS demonstrated good psychometric performance in the present adolescent sample. The present findings suggest that EMW may show age‐related differences among adolescents with ADHD. Whether these differences reflect developmental changes across adolescence requires confirmation in longitudinal studies.

The Turkish Mind Excessively Wandering Scale demonstrated satisfactory psychometric performance in adolescents. Older adolescents with ADHD reported higher levels of excessive mind wandering than younger adolescents, whereas a similar age‐related pattern was not observed in the control group.

1. Introduction

Attention‐deficit/hyperactivity disorder (ADHD) is among the most prevalent psychiatric disorders worldwide. Although prevalence estimates vary across regions and methodological approaches, two‐stage epidemiological studies have consistently reported a pooled prevalence of approximately 4.8% (Popit et al. 2024). As a neurodevelopmental disorder, ADHD symptoms typically emerge in childhood and may persist into adolescence and adulthood in a substantial proportion of individuals. ADHD can lead to significant impairments in both academic and social functioning and is also known to impose a considerable economic burden, amounting to millions of dollars globally (American Psychiatric Association 2022; Popit et al. 2024). Therefore, clarifying diagnostic and treatment processes may be important not only for improving functional outcomes but also for reducing the associated economic costs.

ADHD comprises three core symptom domains: inattention, hyperactivity and impulsivity (Fu et al. 2025). However, beyond these core symptoms, ADHD diagnosis is also associated with additional functional challenges. For instance, adolescents with ADHD have been reported to exhibit poorer emotion regulation abilities (Ágrez et al. 2025). Recent studies have emphasized the importance of examining ADHD‐related difficulties not only at the behavioural level but also in terms of maladaptive internal mental experiences. One such internal mental pattern is maladaptive daydreaming, a condition marked by persistent and immersive fantasy activity that involuntarily diverts attention away from ongoing external demands towards internally generated imaginative experiences (Kandeğer et al. 2025). Although maladaptive daydreaming represents one form of internally oriented mental activity, recent literature has increasingly focused on another related but distinct construct: excessive mind wandering (EMW).

MW refers to the common experience of attention shifting away from an ongoing task towards internally generated thoughts (Smallwood and Schooler 2015). MW is a common experience that may account for up to 50% of daily thinking time (Killingsworth and Gilbert 2010). Although MW is associated with attentional lapses, certain forms may serve adaptive functions such as future planning, creativity and problem solving (Smallwood and Schooler 2015). Contemporary models distinguish between deliberate (intentional) MW and spontaneous (unintentional) MW. Deliberate MW involves purposeful and relatively controllable engagement in task‐unrelated thoughts, whereas spontaneous MW occurs involuntarily and with reduced perceived control (Gao et al. 2024; Seli et al. 2016). Importantly, evidence suggests that ADHD symptoms are more strongly associated with spontaneous MW than with deliberate MW (Mowlem, Agnew‐Blais, et al. 2019; Seli et al. 2015).

When MW becomes pervasive, difficult to control and functionally impairing, it has been conceptualized as EMW, a construct closely associated with ADHD (Mowlem, Agnew‐Blais, et al. 2019). EMW refers to a cognitive pattern marked by a rapid flow of loosely linked thoughts that shift continuously, resulting in distractibility, sustained mental restlessness and a sense of ongoing cognitive overactivity independent of negative emotional states (Kandeğer et al. 2024). EMW is conceptualized as internal or mental hyperactivity and is regarded as one of the most distinctive features of adult ADHD (Kooij et al. 2019). However, empirical studies focusing on EMW in adolescents remain limited. Adolescence represents a particularly vulnerable developmental period for individuals with ADHD, characterized by ongoing neurodevelopmental changes alongside increasing academic, social and emotional demands (Murray et al. 2019). This heightened vulnerability underscores the need for a more systematic investigation of EMW during adolescence.

Indeed, the developmental cognitive control literature indicates that both the propensity for EMW and the frequency of task‐unrelated thoughts reported during task performance may vary meaningfully across different stages of adolescence and tend to increase with age (Vannucci et al. 2022). More recent evidence further suggests that these age‐related differences are particularly evident for EMW, with early adolescents reporting fewer such episodes compared to late adolescents and young adults, highlighting the importance of considering developmental stage when examining EMW during adolescence (Gyurkovics et al. 2020). In this context, systematic evaluation of EMW in adolescents with ADHD, together with the use of validated assessment tools, may contribute to delineating the EMW profile in this developmental period and to clarifying the factors associated with EMW during adolescence.

One of the most commonly used instruments for assessing EMW is the Mind Excessively Wandering Scale (MEWS). The MEWS is a self‐report scale originally consisting of 12 items and was specifically developed to capture characteristic thought patterns observed in individuals with ADHD. These patterns reflect a distinct mental state associated with ADHD, including the continuous flow of thoughts, rapid shifts of mental focus across different topics and the simultaneous processing of multiple streams of thought (Mowlem, Agnew‐Blais, et al. 2019). The Turkish validity and reliability study of the scale has previously been conducted in adult populations (Aksoy et al. 2022).

Adolescence represents a distinct developmental period in which brain maturation is still ongoing, with pronounced structural and functional reorganization, particularly in neural systems involved in cognitive control, attentional regulation and responsiveness to emotional stimuli (Spear 2013). Moreover, attentional control abilities, which are thought to be closely related to EMW, are still developing during adolescence (Stawarczyk et al. 2014). In this context, the level and phenomenology of EMW accompanying ADHD during adolescence may differ from those observed in adulthood. Moreover, given that emotion regulation difficulties closely associated with EMW are also prominent during this developmental period (Frick et al. 2020), the psychometric adaptation of the MEWS for adolescents may enable a developmentally sensitive assessment of EMW symptoms associated with ADHD.

The first aim of the present study was to evaluate the psychometric properties of the Turkish version of the MEWS in adolescents with ADHD and adolescents without psychiatric disorders, thereby extending the psychometric literature on EMW in adolescent populations. Although the validity and reliability of the MEWS have previously been examined in a large sample spanning adolescence to older adulthood (ages 16–83) based on self‐reported ADHD diagnoses (Mowlem, Agnew‐Blais, et al. 2019), no study to date has specifically evaluated the psychometric properties of the MEWS exclusively in a drug‐naive adolescent sample with clinically assessed ADHD diagnoses. The second aim was to explore whether the cross‐sectional association between age and EMW differed between adolescents with and without ADHD.

2. Materials and Methods

2.1. Participants and Study Design

The sample consisted of 156 adolescents (mean age = 15.08 years, SD = 1.85), including 80 individuals diagnosed with ADHD and 76 typically developing controls. ADHD diagnoses were established by a child and adolescent psychiatrist using Schedule for Affective Disorders and Schizophrenia for School‐Age Children, Present and Lifetime Version (KSADS‐PL) (Ünal et al. 2019). Exclusion criteria for the ADHD group included the presence of any psychiatric disorder other than oppositional defiant disorder and the presence of chronic systemic medical conditions (e.g., neurological, endocrinological or rheumatological diseases, as well as significant visual or hearing impairments). All participants in the ADHD group were treatment‐naïve and had no lifetime history of psychotropic medication use. The control group consisted of adolescents who attended the outpatient clinic for counselling or psychoeducational guidance regarding normative adolescent development, family communication, peer relationships, academic guidance and questions related to puberty and sexual development. Following clinical evaluation, none met DSM‐5 diagnostic criteria for a psychiatric disorder.

All adolescents in both groups completed the MEWS, the Difficulties in Emotion Regulation Scale–Brief Form (DERS‐16) and the Short Version of the UPPS‐P Impulsive Behaviour Scale (S‐UPPS‐P). Parents completed the Turgay DSM‐IV–Based Screening and Evaluation Scale for Attention Deficit and Disruptive Behaviour Disorders–Parent Form (T‐DSM‐IV‐S). All self‐report instruments were completed independently by the adolescents in a quiet assessment setting. A researcher was available to clarify procedural questions or item wording when necessary, without influencing participants' responses. The study was approved by the Selçuk University Local Ethics Committee (date: 08.04.2025; approval number: 2025/199). Written informed consent was obtained from all parents prior to participation. The study was conducted in accordance with the principles of the Declaration of Helsinki.

2.2. Measurement Tools

2.2.1. MEWS

The MEWS was developed by Mowlem, Skirrow, et al. (2019). The scale is a 12‐item self‐report measure rated on a 4‐point Likert scale and is designed to assess the severity of EMW in individuals with ADHD. The MEWS captures characteristic patterns of mental activity observed in ADHD, including difficulties in controlling thoughts, rapid shifts between thoughts and persistent mental overactivity. Example items include: ‘I have difficulty controlling my thoughts’, ‘I have two or more different thoughts going on at the same time’ and ‘I find it difficult to think clearly, as if my mind in a fog’. In the original validation study, the scale demonstrated good internal consistency, with a Cronbach's alpha coefficient of 0.78 (Mowlem, Skirrow, et al. 2019).

Although a Turkish adaptation of the MEWS has previously been conducted in adults (Aksoy et al. 2022), the final version recommended in that study consisted of 11 items following the removal of Item 6 based on psychometric analyses. Because the aim of the present study was to evaluate the original 12‐item MEWS in an adolescent sample, permission to translate and use the MEWS was obtained from the original scale developers prior to the study. In line with their recommendations, the 12‐item version of the MEWS was used. The scale was translated into Turkish following a standard forward–backward translation procedure. First, the original English version was independently translated into Turkish. Subsequently, the Turkish version was back‐translated into English by an independent bilingual translator who was blinded to the original version. The back‐translated version was reviewed by the original scale developer, and minor revisions were made based on their feedback to ensure conceptual and linguistic equivalence with the original instrument. After final approval, the Turkish version of the MEWS was used in the present study.

2.2.2. DERS‐16

The DERS‐16 is a 16‐item self‐report measure developed by Bjureberg et al. (2016) and rated on a 5‐point Likert scale. Higher scores indicate greater difficulties in emotion regulation. The Turkish version of the scale has demonstrated good validity and reliability, with a Cronbach's alpha coefficient of 0.92 for the total score (Yiğit and Guzey Yiğit 2019).

2.2.3. S‐UPPS‐P

The S‐UPPS‐P is a 20‐item self‐report scale that evaluates five impulsivity dimensions using a four‐point Likert format, with items scored such that higher values reflect greater impulsive traits (Cyders et al. 2014). In the Turkish validation study, the first item was removed, and the resulting 19‐item version demonstrated acceptable validity and reliability (Eray et al. 2023).

2.2.4. T‐DSM‐IV‐S

The T‐DSM‐IV‐S is a parent‐report scale developed by Turgay (1994) to assess the severity of ADHD and related disruptive behaviour disorders. The scale consists of 41 items rated on a 4‐point Likert scale, including 9 items assessing inattention, 9 items assessing hyperactivity/impulsivity, 8 items assessing oppositional defiant disorder and 15 items assessing conduct disorder. The Turkish version of the scale has been shown to be valid and reliable (Ercan 2001). In the present study, ADHD symptom severity was assessed using the first 18 items corresponding to the inattention and hyperactivity/impulsivity subscales, whereas the eight ODD items were used to assess ODD symptom severity.

2.3. Data Analysis

All statistical analyses were conducted using IBM SPSS Statistics (Version 27) and LISREL 8.7. Participants with incomplete questionnaires were excluded before the analyses; therefore, no missing data imputation procedure was applied. Prior to the main analyses, the normality of the variables was assessed using skewness and kurtosis values, with values between −2 and +2 accepted as indicating a normal distribution (George 2011). As all MEWS items met this criterion, maximum likelihood estimation was used for the confirmatory factor analysis (CFA). Assumptions for Pearson correlation and regression analyses, including linearity and normality, were evaluated before conducting the analyses. Between‐group differences in age and sex distributions were examined using an independent‐samples t‐test and a chi‐square test, respectively. To evaluate the factorial validity of the MEWS, CFA was performed using the maximum likelihood estimation method. Model fit was evaluated using multiple goodness‐of‐fit indices, including the chi‐square to degrees of freedom ratio (χ ²/df), the root mean square error of approximation (RMSEA), the standardized root mean square residual (SRMR) and the comparative fit index (CFI). Model fit was considered acceptable when χ ²/df < 3, RMSEA < 0.08, SRMR < 0.08 and CFI ≥ 0.90. Internal consistency of the scale was evaluated using several reliability indices, including Cronbach's alpha (α), McDonald's omega (ω) and composite reliability (CR). Item–total correlations were also calculated to examine the contribution of each item to the overall scale score. Structural convergent validity was evaluated using the average variance extracted (AVE), which reflects the proportion of variance in the items explained by the underlying latent construct. Convergent validity with external constructs was further examined using Pearson correlation analyses between MEWS scores and theoretically related variables, including emotion regulation difficulties, impulsivity and ADHD symptom dimensions. Group differences in scale scores were examined using independent‐samples t‐tests. Effect sizes were calculated using Cohen's d for continuous variables and Cramér's V for categorical variables. In addition, receiver operating characteristic (ROC) analyses were performed at both the item and total scale levels, and the area under the curve (AUC) was calculated to evaluate the known‐groups discriminative performance of the MEWS. Finally, a linear regression model was applied with the MEWS as the dependent variable. Age (continuous), diagnostic group (ADHD vs. control) and their interaction (age × group) were included as predictors. Age was mean centred prior to creating the interaction term. The age × group interaction was the primary effect of interest. When a significant age × group interaction was identified, follow‐up simple slope analyses were conducted separately within the ADHD and control groups to further characterize the association between age and EMW within each diagnostic group. For all analyses, statistical significance was set at p < 0.05.

3. Results

3.1. Independent Samples t‐Test for Demographic Data and Scale Scores in ADHD and Control Groups

An independent samples t‐test was conducted to compare demographic and clinical variables between individuals with ADHD and controls.

Among the adolescents with ADHD, 13 participants (16.3%) met DSM‐5 criteria for oppositional defiant disorder (ODD). As presented in Table 1, there were no statistically significant differences between the groups in terms of age or gender distribution. However, individuals with ADHD demonstrated significantly higher levels of inattention, hyperactivity/impulsivity, ODD symptoms, EMW, S‐UPPS‐P total scores and emotion regulation difficulties compared with the control group.

TABLE 1.

Comparison of demographic data and scale scores.

	ADHD N = 80	Control N = 76	t/x 2	p	d
Age	14.86 ± 1.90	15.30 ± 1.78	1.49	0.138 a	−0.24
Gender
Male	39	35	0.114	0.751 b	0.02 c
Female	41	41
Inattention (T‐DSM‐IV‐S)	17.66 ± 4.60	7.29 ± 4.53	−13.81	< 0.001 a	2.27
Hyperactivity/impulsivity (T‐DSM‐IV‐S)	9.88 ± 5.34	5.70 ± 4.22	−5.41	< 0.001 a	0.87
Oppositional defiant disorder (T‐DSM‐IV‐S)	11.77 ± 5.34	6.52 ± 4.62	−6.332	< 0.001 a	1.05
Excessive mind wandering	20.18 ± 9.43	13.36 ± 6.99	−5.09	< 0.001 a	0.82
S‐UPPS‐P‐total scores	47.97 ± 8.63	42.32 ± 6.85	−4.46	< 0.001 a	0.72
Emotion regulation	29.03 ± 15.15	18.56 ± 14.21	−4.41 a	< 0.001 a	0.71

Note: d, Cohen's d effect size.

Abbreviations: ADHD = attention deficit hyperactivity disorder, S‐UPPS‐P = Short Version of the UPPS‐P Impulsive Behaviour Scale, T‐DSM‐IV‐S = Turgay DSM‐IV Disruptive Behaviour Disorders Rating Scale.

^a Independent‐samples t‐test was performed.

^b Chi‐squared test was performed.

^c Cramér's V effect size.

Large effect sizes were observed for inattention (d = 2.27), ODD symptoms (d = 1.05), hyperactivity/impulsivity (d = 0.87) and EMW (d = 0.82). Moderate‐to‐large effect sizes were also found for S‐UPPS‐P total scores (d = 0.72) and emotion regulation difficulties (d = 0.71), indicating notable group differences between individuals with ADHD and controls across these clinical measures.

3.2. Construct Validity

Construct validity was evaluated using CFA. Because Item 6 was excluded from the Turkish adult validation of the MEWS due to its negative impact on model fit (Aksoy et al. 2022), an alternative one‐factor CFA model excluding this item was estimated to examine whether a similar pattern would emerge in an adolescent sample. This model was compared with the original 12‐item model, in which Item 6 was retained. Following inspection of the modification indices, a correlated residual between Items 5 and 6 was specified only in the original 12‐item model because these items reflect conceptually related aspects of persistent mental activity. No correlated residuals were estimated in the alternative 11‐item model. The resulting path diagrams are shown in Figure 1.

FIGURE 1.

Comparison of confirmatory factor analysis (CFA) results for the 11‐item and 12‐item versions of the Mind Excessively Wandering Scale. Standardized factor loadings are presented for each model. The original 12‐item model showed lower χ ²/df, RMSEA and SRMR values than the alternative 11‐item model, whereas both models yielded the same CFI value.

The alternative 11‐item model demonstrated acceptable standardized factor loadings ranging from 0.48 to 0.86. However, its overall fit was less favourable, with χ ²(44) = 109.88, χ ²/df = 2.50, RMSEA = 0.098 (90% CI = 0.075–0.12), SRMR = 0.054 and CFI = 0.98. In comparison, the original 12‐item model showed standardized factor loadings ranging from 0.44 to 0.95. After specifying a theoretically justified correlated residual between Items 5 and 6, the model showed more favourable fit indices: χ ²(53) = 99.79, χ ²/df = 1.88, RMSEA = 0.075 (90% CI = 0.052–0.10), SRMR = 0.048 and CFI = 0.98. Although both models yielded the same CFI value (0.98), the 12‐item model demonstrated lower χ²/df, RMSEA and SRMR values than the alternative 11‐item model. Taken together, these findings provide psychometric support for retaining Item 6 and using the original 12‐item structure in the present adolescent sample. A comparison of the fit indices for the two models is presented in Table 2.

TABLE 2.

Comparison of CFA fit indices between the alternative 11‐item and the original 12‐item versions of the Mind Excessively Wandering Scale.

Fit index	11‐item model (Item 6 removed)	12‐item model (Item 6 retained)
Residual covariance (Items 5–6)	Not specified	Specified
χ 2	109.88	99.79
df	44	53
χ 2 /df	2.50	1.88
RMSEA (90% CI)	0.098 (0.075–0.120)	0.075 (0.052–0.100)
SRMR	0.054	0.048
CFI	0.98	0.98

Abbreviations: CFA = confirmatory factor analysis, CFI = comparative fit index, CI = confidence interval, df = degrees of freedom, χ ² = chi‐square statistic, χ ²/df = chi‐square divided by degrees of freedom, RMSEA = root mean square error of approximation, SRMR = standardized root mean square residual.

3.3. Reliability

The internal consistency of the MEWS was evaluated using multiple reliability indices, including Cronbach's alpha, McDonald's omega and CR, with all obtained values presented in Table 3.

TABLE 3.

Reliability coefficients for the Mind Excessively Wandering Scale.

Reliability index	Value
Cronbach's alpha (α)	0.927
McDonald's omega (ω)	0.929
Composite reliability (CR)	0.923

As seen in Table 3, Cronbach's alpha for the total scale was 0.927, indicating excellent internal consistency. McDonald's omega was also estimated at 0.929, providing a complementary measure that accounts for potential unequal factor loadings or violations of tau‐equivalence assumptions, and the CR was 0.923, further supporting the scale's overall reliability. In addition, item‐total correlations were calculated to examine the contribution of each item to the total score, with values ranging from 0.46 to 0.85. These results indicate that all items were adequately correlated with the overall scale, contributing meaningfully to the measurement of the underlying construct. Taken together, these findings demonstrate that the MEWS exhibits high internal consistency and that its items reliably capture the construct of EMW.

3.4. Convergent Validity

Structural convergent validity was first assessed to determine whether the MEWS items adequately captured the latent construct of EMW. This was evaluated using the AVE, which quantifies the proportion of variance in the items explained by the underlying factor. The MEWS demonstrated an AVE of 0.50, indicating that half of the variance in the items is accounted for by the latent construct, thereby supporting factor‐level convergent validity (Fornell and Larcker 1981; Hair et al. 2010).

Discriminant validity was subsequently evaluated using the Fornell–Larcker criterion (Fornell and Larcker 1981). The square root of the AVE (√AVE = 0.71) was lower than the correlation between the MEWS and the DERS in the total sample (r = 0.77), indicating that discriminant validity between these constructs was not fully supported in the present sample.

Finally, bivariate correlations between the MEWS and theoretically related constructs were examined to further characterize its pattern of associations with external variables. Table 4 presents the correlations observed in the total sample.

TABLE 4.

Correlations among excessive mind wandering, emotion regulation, S‐UPPS‐P total scores, inattention and hyperactivity/impulsivity in the total sample.

Variable	1	2	3	4	5
1. Excessive mind wandering	—
2. Emotion regulation	0.77**	—
3. S‐UPPS‐P total	0.55**	0.48**	—
4. Inattention	0.38**	0.33**	0.48**	—
5. Hyperactivity/impulsivity	0.33**	0.27**	0.28**	0.48**	—

Abbreviation: S‐UPPS‐P = Short UPPS‐P Impulsive Behaviour Scale.

^* p < 0.05.

^** p < 0.01.

EMW showed a strong positive correlation with emotion regulation difficulties (r = 0.77, p < 0.01). In addition, moderate positive correlations were observed with S‐UPPS‐P total scores (r = 0.55, p < 0.01), inattention (r = 0.38, p < 0.01) and hyperactivity/impulsivity (r = 0.33, p < 0.01).

The within‐group correlations between EMW and the study variables are presented separately for the ADHD and control groups in Table 5.

TABLE 5.

Correlations of excessive mind wandering with study variables in the ADHD and control groups.

Variable	ADHD (n = 80) r	Control (n = 76) r
Age	0.24*	−0.09
Emotion regulation	0.72**	0.78**
S‐UPPS‐P total	0.49**	0.47**
Inattention (T‐DSM‐IV‐S)	−0.11	0.59**
Hyperactivity/impulsivity (T‐DSM‐IV‐S)	0.12	0.29*

Note: Values represent Pearson correlation coefficients (r).

Abbreviations: S‐UPPS‐P = Short UPPS‐P Impulsive Behaviour Scale, TDSM‐IV‐S = Turgay DSM‐IV‐Based ADHD Rating Scale.

^* p < 0.05.

^** p < 0.01.

In the ADHD group, EMW was significantly positively correlated with emotion regulation difficulties (r = 0.72, p < 0.01), S‐UPPS‐P total scores (r = 0.49, p < 0.01) and age (r = 0.24, p < 0.05), whereas no significant associations were observed with inattention or hyperactivity/impulsivity scores. In the control group, EMW showed significant positive correlations with emotion regulation difficulties (r = 0.78, p < 0.01), S‐UPPS‐P total scores (r = 0.47, p < 0.01), inattention (r = 0.59, p < 0.01) and hyperactivity/impulsivity (r = 0.29, p < 0.05), although no significant association was found with age. Inspection of the score distributions showed that MEWS scores covered the full possible range (0–36) in both groups, whereas parent‐rated inattention scores ranged from 6 to 27 in the ADHD group and from 0 to 22 in the control group.

3.5. Known‐Groups Discrimination

To evaluate the known‐groups discriminative performance of the MEWS, ROC analyses were conducted at both the item level and the total scale score level to examine how well the scale distinguished adolescents diagnosed with ADHD (coded as 1) from those without ADHD (coded as 0).

Item‐level ROC analyses further highlighted the discriminatory contributions of individual items. Items 8 (AUC = 0.709) and 10 (AUC = 0.718) demonstrated the highest discrimination between groups, whereas Items 6 and 7 demonstrated lower discriminative ability (AUC = 0.567–0.571). These results suggest that some items are more sensitive indicators of ADHD and play a stronger role in differentiating between groups.

Total MEWS score ROC analysis yielded an AUC of 0.718 (p < 0.001, 95% CI = 0.635–0.801), indicating acceptable known‐groups discrimination between adolescents with and without ADHD. Although the discriminative performance of individual items varied, the total MEWS score demonstrated acceptable overall discrimination between the ADHD and control groups, further supporting the scale's known‐groups validity.

In adolescents with ADHD, age was positively correlated with MEWS, whereas no comparable association was observed in controls. To formally test whether the age–EMW relationship differed between groups, a linear regression model including age, diagnostic group and their interaction was conducted. The overall model was significant, F(3,151) = 11.02, p < 0.001, explaining 18.0% of the variance in MEWS scores (R ² = 0.180, adjusted R ² = 0.163). Diagnostic group was a significant predictor of MEWS scores (B = 6.999, SE = 1.332, β = 0.390, 95% CI [4.367, 9.631], p < 0.001). The main effect of age was not significant (B = −0.379, SE = 0.533, β = −0.078, 95% CI [−1.433, 0.675], p = 0.478). However, the age × group interaction was significant (B = 1.564, SE = 0.722, β = 0.237, 95% CI [0.136, 2.991], p = 0.032), indicating that the association between age and EMW differed between the ADHD and control groups. Follow‐up simple slope analyses indicated that age was significantly associated with higher MEWS scores in the ADHD group (B = 1.18, β = 0.24, 95% CI = 0.10–2.27, p = 0.033), whereas no significant association was observed in the control group (B = −0.38, β = −0.10, 95% CI = −1.29–0.53, p = 0.407). This pattern is illustrated in Figure 2.

FIGURE 2.

Association between age and EMW in adolescents with ADHD and controls. Each dot represents an individual participant, and solid lines indicate group‐specific linear curve fits with 95% confidence intervals. The age × group interaction was statistically significant (p = 0.032). Within the ADHD group, adolescents at older ages exhibited higher EMW scores, whereas no comparable age‐related pattern was observed in the control group.

4. Discussion

In this study, the psychometric properties of the MEWS were examined in an adolescent sample, providing evidence for the reliability and psychometric performance of the MEWS in an adolescent sample. CFA supported the hypothesized unidimensional structure, with standardized factor loadings ranging from moderate to high and model fit indices indicating an acceptable to good fit. Structural convergent validity was demonstrated by an AVE of 0.50, indicating that a substantial proportion of the variance in the items was explained by the underlying construct, whereas external convergent validity was supported by moderate to strong correlations with theoretically related constructs, including emotion regulation, impulsivity and attentional dimensions. Known‐groups discrimination was supported by ROC analyses and independent‐samples t‐tests, with the MEWS demonstrating acceptable discrimination between adolescents with and without ADHD. Finally, internal consistency indices, including Cronbach's alpha, McDonald's omega and CR, were all high (approximately 0.93), and item–total correlations indicated that each item contributed meaningfully to the total score. Taken together, these findings support the psychometric performance of the MEWS as a measure of EMW in adolescents and its ability to capture meaningful individual differences within our study sample. An additional finding of the present study was that age was positively associated with EMW severity in the ADHD group, whereas no such association was observed in the control group.

Both the original version of the MEWS developed by Mowlem, Skirrow, et al. (2019) and the Turkish adaptation conducted by Aksoy et al. (2022) were validated in adult samples. In the present study, which was conducted in an adolescent sample, the findings were largely consistent with those reported in the original adult validation study by Mowlem, Skirrow, et al. (2019). Specifically, the findings supported a unidimensional factor structure of the MEWS in adolescents and acceptable known‐groups discrimination between adolescents with and without ADHD. When compared with the Turkish adult validation study by Aksoy et al. (2022), our CFA analysis supported the unidimensional structure of the MEWS in the adolescent sample, with standardized factor loadings ranging from moderate to high (0.44–0.95) and overall model fit indices indicating an acceptable to good fit. Notably, satisfactory model fit was achieved with only a minor modification involving a correlated error term between two conceptually similar items, suggesting that the underlying factor structure of the scale was largely preserved. This correlated error may reflect the conceptual overlap between Items 5 and 6, both of which assess the continuous and persistent nature of excessive mental activity. These findings indicate that the MEWS provides a coherent representation of EMW in adolescents and provide further support for the structural validity of the scale in this population. The present findings further indicate that, although the scale showed satisfactory psychometric properties in adult samples, its performance in the adolescent sample was particularly robust. In addition, reliability coefficients observed in the adolescent sample were higher than those reported in adult samples. Taken together, these findings suggest that the MEWS is a highly functional and psychometrically sound instrument for assessing EMW in adolescents.

In the present study, the associations between MEWS scores and clinically relevant symptom domains yielded several noteworthy findings. Most prominently, EMW was significantly correlated with core ADHD symptom dimensions, including both inattention and hyperactivity/impulsivity severity in the total sample. However, when the correlations were examined separately within each group, several important differences emerged. The most striking difference between the ADHD and control groups was observed in the associations between EMW and ADHD symptom severity. Specifically, EMW was not significantly correlated with core ADHD symptoms within the ADHD group, whereas significant positive correlations were observed in the control group. This apparently paradoxical pattern warrants careful interpretation. One possible explanation is restricted variability in parent‐rated inattention scores within the clinically diagnosed ADHD sample. Although MEWS scores covered the full possible range in both groups (0–36), the observed score distribution did not suggest an obvious ceiling effect, as only two adolescents with ADHD (2.5%) obtained the maximum possible score. In contrast, parent‐rated inattention scores showed a more restricted distribution in the ADHD group (range = 6–27) than in the control group (range = 0–22), with scores clustered towards the upper end of the scale. This restricted variability may have attenuated within‐group correlations. In addition, the control group consisted of help‐seeking adolescents rather than a community‐based normative sample. Therefore, residual subclinical attentional or psychosocial difficulties may also have contributed to the relatively strong association between MEWS and inattention in the control group. These explanations are not mutually exclusive and should be examined in future studies.

Beyond these potential methodological explanations, the overall pattern of associations observed in the present study also provides important conceptual insights into the relationship between EMW and ADHD. EMW was significantly correlated with age in the ADHD group, whereas no such association was observed in the control group. Finally, the variables that were consistently correlated with EMW in both groups were emotion regulation difficulties and impulsivity measured by the S‐UPPS‐P. The literature on this topic presents somewhat mixed findings. Whereas some studies have reported significant associations between EMW and ADHD symptoms (Figueiredo et al. 2020), other studies have suggested that EMW is more strongly related to sluggish cognitive tempo symptoms rather than ADHD symptoms per se (Fredrick and Becker 2021). These discrepancies may partly be explained by differences in the assessment tools used as well as variations in sample characteristics, such as psychotropic medication use and the inclusion or exclusion of psychiatric comorbidities. In our study, the positive association between EMW and emotion regulation difficulties, rather than ADHD symptom severity, may indicate that emotion regulation represents an important factor in the relationship between ADHD and EMW. Indeed, previous research has demonstrated that EMW in adolescents is associated with emotion regulation difficulties independently of ADHD symptoms (Dekkers et al. 2025; Frick et al. 2020). Therefore, when examining the relationship between EMW and ADHD during adolescence, emotion regulation may represent a particularly important domain that deserves special attention. It should also be considered that ADHD symptom severity was assessed using parent‐report measure, whereas EMW, emotion regulation difficulties and impulsivity were assessed using adolescent self‐report measures. These cross‐informant differences may partly explain the lack of a significant association between EMW and ADHD symptom severity within the ADHD group and should be taken into account when interpreting the present findings. Future studies integrating adolescent self‐report together with parent‐ and teacher‐report measures may help clarify the influence of cross‐informant differences on the observed associations.

One potential variable that may act as a linking mechanism when interpreting this finding is emotion regulation. Adolescence is considered a particularly vulnerable developmental period for emotion dysregulation compared with both childhood and adulthood (Bunford et al. 2018). In addition to this vulnerability, adolescence is also characterized by increasing environmental demands and greater reliance on emotion regulation strategies (Steinberg 2005). Whereas emotion regulation abilities generally improve with age in typically developing adolescents, emotion dysregulation in adolescents with ADHD may contribute to difficulties in daily functioning (Bunford et al. 2018). In our study, the observed association between emotion regulation difficulties and EMW appears to be consistent with previous research (Dekkers et al. 2025; Frick et al. 2020). Cognitive strategies known to support emotion regulation, such as cognitive reappraisal and situation modification, may be used less effectively or may become more difficult to sustain in the presence of MW (Dekkers et al. 2025). Taken together, increasing age, greater EMW severity and difficulties in emotion regulation may represent interconnected processes. In this context, longitudinal studies examining the relationship between emotion regulation and EMW in adolescents with ADHD may be particularly important for further clarifying the developmental mechanisms underlying these associations.

Analyses conducted in line with the second aim of the present study revealed that older adolescents with ADHD tended to report greater EMW severity, whereas no comparable age‐related pattern was observed in the control group. This cross‐sectional finding may be consistent with developmental differences in the expression of EMW during adolescence. ADHD symptoms may be expressed differently across development, with overt hyperactivity becoming less visible and cognitively experienced forms of overactivity becoming increasingly salient over time (Yacoub et al. 2025). In parallel, studies of adults with ADHD have highlighted the importance of internally experienced symptoms, including persistent mental activity, difficulty disengaging from ongoing thoughts and subjective cognitive restlessness (Chua et al. 2026). Given the conceptual overlap between EMW and internally experienced cognitive overactivity, older adolescents with ADHD may report higher levels of EMW as these subjective manifestations become more prominent. From a clinical perspective, the observed association may also be meaningful. Given that the total MEWS score ranges from 0 to 36 and the observed standard deviation in the ADHD group was 9.43 points, the estimated age‐related difference corresponds to approximately 1.2 additional MEWS points between adolescents differing by 1 year of age (approximately 0.13 of the observed standard deviation). Prospective studies with larger samples are needed to further investigate the clinical implications of differences of this magnitude.

Another finding that may support this interpretation is the differential performance of Item 6 across studies. In the Turkish adult validation study (Aksoy et al. 2022), Item 6 was excluded from the final model, whereas in the present adolescent sample the original 12‐item model demonstrated better overall fit than the alternative 11‐item model. Nevertheless, Item 6 showed relatively low discriminatory performance in the item‐level ROC analysis. Taken together, these findings suggest that although Item 6 may represent an important aspect of EMW in adolescence, its ability to distinguish adolescents with ADHD from healthy controls appears to be limited when considered in isolation. Accordingly, Item 6 should be interpreted as part of the overall MEWS construct rather than as an individually discriminative indicator. Future studies directly comparing adolescents and adults, as well as larger longitudinal studies, are needed to determine whether the contribution of Item 6 reflects developmental differences in the expression of EMW or whether its discriminative performance differs across developmental stages.

A complementary neurocognitive explanation may also be considered for our findings. During typical adolescent development, executive functions and working memory continue to mature, accompanied by increasing recruitment of executive control networks and more effective suppression of the default mode network during cognitively demanding tasks (Satterthwaite et al. 2013). In contrast, previous studies have suggested that ADHD is characterized by altered default mode network regulation and impaired interactions between default mode and executive control networks, which have been linked to EMW (Bozhilova et al. 2018; Christoff et al. 2016). Within this framework, the age‐related differences in EMW observed specifically in the ADHD group may reflect persistent difficulties in regulating internally generated thoughts despite ongoing neurocognitive maturation. This interpretation should be examined in studies incorporating direct measures of executive functioning and neurobiological correlates. Nevertheless, further research is needed to determine whether these neurocognitive mechanisms are specific to ADHD or reflect broader processes shared across other psychiatric conditions characterized by executive dysfunction, altered default mode network regulation and EMW.

Beyond supporting an association between emotion regulation difficulties and EMW, the present findings also raise a broader conceptual question regarding the nature of EMW itself. Contemporary models conceptualize MW as one form of spontaneous thought that occupies an intermediate position between relatively unconstrained internally generated cognition and more automatically constrained forms of thought, such as rumination and obsessive thinking (Christoff et al. 2016). Within this broader framework, EMW may be conceptualized as a maladaptive manifestation of spontaneous thought characterized by persistent mental overactivity and reduced control over internally generated cognition. Although EMW and rumination are conceptually distinct, they are not entirely independent. EMW is characterized by rapid, continuously shifting and difficult‐to‐control streams of thought that are largely independent of negative emotional content, whereas rumination involves repetitive, negatively valenced and self‐focused thinking. Nevertheless, previous studies have demonstrated moderate associations between these constructs, suggesting that they represent related but distinct dimensions of internally generated cognition (Kandeğer et al. 2024). In this context, the strong association between EMW and emotion regulation difficulties observed in the present study may indicate that emotion dysregulation is linked not only to negatively valenced repetitive thinking but also to maladaptive spontaneous thought processes. Accordingly, a key conceptual question arising from the present findings is whether the MEWS measures an ADHD‐specific manifestation of internal cognitive hyperactivity or indexes a broader transdiagnostic dysregulation phenotype that is elevated in ADHD but not exclusive to it. This interpretation is also consistent with the present psychometric findings. Although the MEWS demonstrated acceptable convergent validity and satisfactory known‐groups discrimination, the Fornell–Larcker criterion did not fully support discriminant validity with respect to emotion regulation difficulties. Accordingly, the present findings suggest that EMW is closely related to emotion dysregulation during adolescence, although the extent to which it represents a distinct construct remains to be established. Future studies directly comparing ADHD with other psychiatric disorders characterized by emotion dysregulation and maladaptive internally generated thought processes may help clarify this conceptual distinction.

4.1. Strengths and Limitations

The present study has several strengths. First, ADHD diagnoses were established through a formal semi‐structured clinical interview conducted by a child and adolescent psychiatrist, which enhances diagnostic accuracy. Similarly, the control group underwent comprehensive psychiatric and general medical evaluations, ensuring the reliable exclusion of psychiatric and systemic conditions. In addition, the inclusion of emotion regulation difficulties, ADHD symptom severity and impulsivity in the analyses allowed for a more comprehensive examination of EMW and may have strengthened the validity of the findings. Finally, the inclusion of drug‐naive participants reduces the potential influence of psychotropic treatment on the study findings.

Despite these strengths, several limitations should be acknowledged. The single‐centre and cross‐sectional design limits the generalizability of the findings and precludes causal inferences. In addition, the relatively modest sample size may also limit the generalizability of the results. Another limitation is that the control group was recruited from adolescents seeking counselling or psychoeducational guidance rather than from a community‐based sample. Although these participants sought consultation primarily regarding normative developmental issues and did not meet DSM‐5 criteria for any psychiatric disorder following clinical evaluation, the use of a help‐seeking control sample may limit the generalizability of the findings and could have influenced the observed associations between study variables. Participants with comorbid ODD were included in the ADHD group. Future studies comparing adolescents with ADHD with and without comorbid ODD may help clarify the potential influence of oppositional symptoms on EMW. Furthermore, symptoms of depression and anxiety were not formally assessed or controlled for, which may represent a potential confounding factor given their known associations with EMW (Figueiredo et al. 2020). Similarly, the developmental analyses did not simultaneously account for other clinically relevant dimensions, including ODD symptoms, impulsivity, emotion regulation difficulties and ADHD symptom severity, all of which may have contributed to the observed patterns of EMW. In addition, ADHD symptom severity was assessed using parent‐report, whereas EMW, emotion regulation difficulties and impulsivity were assessed using adolescent self‐report measures. These cross‐informant differences may have influenced the observed associations, particularly those between EMW and ADHD symptom severity. Future studies incorporating multi‐informant assessments, including adolescent self‐report together with parent‐ and teacher‐report measures, may help clarify the influence of informant differences on these relationships. The observed age‐related differences in EMW among adolescents with ADHD were based on cross‐sectional data. Future research using prospective developmental designs will be important to further elucidate the developmental course and clinical significance of EMW. Moreover, formal measurement invariance across the ADHD and control groups was not examined. Given the relatively modest sample size, multi‐group CFA may not have provided sufficiently stable parameter estimates (Meade and Lautenschlager 2004). Future studies with larger samples are needed to establish measurement invariance across diagnostic groups and to confirm the between‐group differences observed in the present study. Although maximum likelihood estimation was considered appropriate based on the observed distributional characteristics of the items, the MEWS consists of four‐category ordinal items. Therefore, future studies may benefit from evaluating the factor structure using robust estimation methods based on polychoric correlations, such as the weighted least squares mean and variance‐adjusted (WLSMV) estimator, which is specifically designed for ordinal data. Finally, due to difficulties in re‐contacting participants, test–retest reliability could not be evaluated, which constitutes another limitation of the study.

5. Conclusion

The findings of the present study suggest that the MEWS is a psychometrically promising instrument for assessing EMW in adolescents. The Turkish version of the MEWS demonstrated a unidimensional structure, good internal consistency, satisfactory convergent validity and acceptable known‐groups discrimination in the present adolescent sample, supporting its promising psychometric performance. EMW was strongly associated with emotion regulation difficulties and was more pronounced in older adolescents with ADHD, whereas no comparable age‐related pattern was observed in the control group. This finding may suggest that older adolescents with ADHD are particularly prone to experiencing EMW. Although the present study was designed to characterize this age‐related pattern rather than identify the factors underlying it, future studies are needed to investigate the specific developmental, cognitive, emotional and clinical factors that may contribute to this association. From a clinical perspective, the MEWS may complement comprehensive clinical assessment by providing additional information on EMW in adolescents with ADHD, particularly when evaluating subjective attentional experiences that are not routinely captured during standard diagnostic interviews. In addition, further research will be important to clarify whether EMW primarily reflects an ADHD‐specific characteristic or a broader transdiagnostic cognitive‐affective dysregulation dimension.

Author Contributions

H.A.G.: conceptualization, data curation, investigation, methodology, supervision, validation, writing – original draft. B.B.: methodology, formal analysis, writing – review and editing, validation. Ü.H.A.: data curation, investigation, methodology. M.E.T.: investigation, supervision, writing – review and editing. A.K.: conceptualization, formal analysis, writing – review and editing, visualization.

Funding

The authors have nothing to report.

Ethics Statement

Ethics approval was obtained from the Selçuk University Local Ethics Committee (08.04.2025; Approval Number: 2025/199).

Consent

All participants provided written informed consent, and the study was conducted in accordance with the principles of the Helsinki Declaration.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request. The corresponding author had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.