Assessing Attention-Deficit/Hyperactivity Disorder in Post-9/11 Veterans: Prevalence, Measurement Correspondence, and Comorbidity With Posttraumatic Stress Disorder

ABSTRACT

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is common among Veterans but overlapping symptoms with other prevalent psychiatric disorders (e.g., posttraumatic stress disorder [PTSD]) complicate diagnosis. This study aims to (1) assess the prevalence of ADHD, (2) evaluate the correspondence between ADHD self-report measures, and (3) examine the association between ADHD and PTSD in a sample of combat-deployed post-9/11 Veterans.

Materials and Methods

A total of 332 combat-deployed post-9/11 Veterans from VA Boston Healthcare System completed the Clinician-Administered PTSD Rating Scale, 2 ADHD self-report questionnaires (Wender Utah Rating Scale–25 and the Adult ADHD Self-Report Scale v1.1), and report of the presence/absence of a historical ADHD diagnosis. Attention-deficit/hyperactivity disorder status via Wender Utah Rating Scale ([WURS-25] criterion standard) was compared to historical ADHD diagnosis and the ASRSv.1.1 screener. Log-binomial regression models assessed the relationship between ADHD and PTSD. This study was reviewed and approved by the VA Boston Institutional Review Board.

Results

In all, 12.7% of the sample met criteria for ADHD per the WURS-25. The WURS-25 demonstrated poor sensitivity with historical ADHD diagnosis (27.7%) but adequate specificity (90.3%). Poor sensitivity (60.7%) and specificity (60.8%) were observed between the WURS-25 and the ASRS-v.1.1. The prevalence of ADHD was 2.5 times as high for Veterans with a history of PTSD (Prevalence Ratio [PR] = 2.53, 95% CI: 1.11, 7.28) and over twice as high for those with current PTSD (PR = 2.19, 95% CI: 1.17, 4.38).

Conclusions

Attention-deficit/hyperactivity disorder is prevalent in this sample of Veterans and is associated with an increased risk of current and lifetime PTSD. The low correspondence across self-report ADHD measures illustrates the complexity of assessing ADHD in this highly comorbid population. When evaluating ADHD in Veterans, clinicians should carefully consider alternative and contributory symptom etiologies, such as PTSD, to ensure accurate diagnosis and treatment.

The Diagnostic and Statistical Manual of Mental Disorders-fifth Edition (DSM-5) defines Attention-Deficit/Hyperactivity Disorder (ADHD) as a neurodevelopmental disorder, involving persistent symptoms of inattention and/or hyperactivity present by the age of 12 years that occur in at least 2 settings (e.g., academic, social, etc.) and interfere with functioning.¹ The prevalence estimates for adult ADHD among Veterans range from 7% to 10%,^2,3 which are far higher than their civilian counterparts (1% to 5.4%).^4,5 These estimates have increased dramatically in recent years, as more Veterans seek assessment and treatment for ADHD symptoms in adulthood.⁶ The structured environment of the military, especially during training, may help those with ADHD symptoms function efficiently. However, problems can return if deployed to combat, where greater unpredictability and traumatic stress can contribute to symptom resurgence^7,8 or upon reintegration into unstructured civilian life after military service.⁹

Attention-Deficit/Hyperactivity Disorder is often considered a childhood disorder; however, for many, symptoms persist into adulthood. Estimates of symptom remittance vary, and many people experience periods of symptom resurgence over their lifetime.^10–12 A longitudinal study of 558 children with ADHD by Sibley and colleagues found that symptoms improved in 30% of individuals over time; however, only 9% achieved lasting remission. Two-thirds of participants experienced a relapsing-remitting pattern of symptom recurrence during adulthood.¹² Numerous factors influence remittance patterns, including the age of onset and severity of childhood symptoms.¹¹ Adults who receive ADHD diagnoses in childhood have greater impairments in daily functioning and increased rates of mental illness, regardless of symptom remittance.^11,12

Attention-Deficit/Hyperactivity Disorder diagnosis later in life relies on retrospective self-report, as symptom onset must occur before the age of 12 years.¹ The gold standard for diagnosing ADHD is a clinical assessment, which may consist of an interview, medical history review, symptom rating scales (both self and informant), neuropsychological testing, and behavioral observations.^7,13,14 Diagnosis of ADHD ultimately depends on the clinician’s judgment of these assessments.⁴ Many validated self-report inventories with strong psychometric properties exist to assist with ADHD diagnosis.¹³ One self-reported measure, the Wender Utah Rating Scale (WURS-25), retrospectively assesses childhood symptoms of ADHD.¹⁵ The WURS-25 can aid in differentiating ADHD from other mental health conditions, and demonstrates a good measure of separability (area under the curve [AUC] = 0.97), high sensitivity (91%), and high specificity (92%).¹⁶

The WURS-25 successfully identifies retrospective childhood ADHD at an equivalent or higher rate than other ADHD clinical scales such as the Adult ADHD Self-Report Scale (ASRS-v1.1; AUC = 0.90).¹⁷ The ASRS-v1.1 is an 18-item questionnaire frequently used to identify adult ADHD symptoms.¹⁸ The short form of the ASRS-v1.1 is a screener that includes 6 of the 18 questions and is more sensitive and specific than the long form for clinical and community samples.¹⁹ The fast and easy administration of the ASRS-v1.1 short form lends well to use in primary care settings, where it demonstrates high sensitivity (100%) and negative predictive value (100%), with moderate specificity (71%) and positive predictive value (52%).²⁰ Among deployed soldiers, one study found that 10.4% screened positive for ADHD on the ASRS-v1.1.²¹

Accurate diagnoses are crucial for proper treatment identification and initiation.²² Diagnosis of ADHD in childhood may be overlooked, only to be recognized later in life when triggered by a lack of structure and greater demands in adulthood.²³ Several types of providers other than psychiatrists and psychologists can diagnose ADHD, including primary care providers (PCPs). A study by Alder and colleagues found that approximately 50% of PCPs report low confidence in their ability to diagnose ADHD, particularly in adult patients.²⁴ Lower confidence may stem from unclear diagnostic guidelines and difficulty ruling out differential diagnoses, such as other mental health disorders.²⁴ The overlap of ADHD symptoms (e.g., inattention) with other common co-occurring psychiatric diagnoses, such as posttraumatic stress disorder (PTSD), can complicate the clinical picture and pose challenges for accurate diagnosis.²⁵ For example, difficulties with concentration are features of both ADHD and PTSD; however, PTSD concentration impairments typically result from hypervigilance and intrusive memories,⁷ whereas ADHD-related inattention is neurodevelopmental. These attentional deficits may manifest as problems with task completion in both conditions, with very different causes.

To further complicate the clinical picture, PTSD is highly comorbid with ADHD.^22,26 One pilot study examining Veterans with PTSD found higher rates of ADHD compared to other mental health disorders, suggesting that those with ADHD may be more vulnerable to developing PTSD.²⁷ Another Veteran cohort study found that among participants with PTSD, approximately 11.5% also met diagnostic criteria for ADHD. Further, the severity of ADHD symptoms significantly correlated with the severity of PTSD symptoms.²² A study utilizing the ASRS-v1.1 screener noted a significant association with the PTSD Checklist–Military Version, specifically showing that PTSD symptoms correlated with both the hyperactivity/impulsivity and combined subtype.²¹ A more recent study found that PTSD was the most likely psychiatric diagnosis to co-occur with ADHD compared to depression, psychotic or bipolar disorder, and substance use disorders.⁶

In the current study, we hypothesize that our post-9/11 Veteran sample will have a higher prevalence of ADHD compared to civilian populations, and the presence of ADHD will be associated with PTSD diagnosis. This study also aims to assess the correspondence between self-report ADHD screening measures to inform clinical practice. Three different ADHD assessment methods are evaluated: (1) historical ADHD diagnosis, (2) childhood ADHD per the WURS-25, and (3) adult ADHD per the ASRS-v1.1.

METHODS

Participants and Procedure

Participants were selected from a sample of active duty service members and deployed post-9/11 Veterans enrolled in the Translational Research Center for Traumatic Brain Injury and Stress Disorders (TRACTS). A detailed description of the longitudinal TRACTS research study methodology can be found in McGlinchey et al. (2017).²⁸ A total of 382 Veterans completed the WURS-25, the primary ADHD measure in this study. Veterans with a (1) history of neurological illness, including seizures unrelated to traumatic brain injury (TBI); (2) a severe psychiatric illness, such as schizophrenia or other psychotic disorders; (3) current active suicidal and/or homicidal ideation; or (4) cognitive disorder unrelated to TBI were excluded from this study. Additionally, participants who failed or did not complete a performance validity measure, the Medical Symptom Validity Test (n = 41),²⁹ or had a history of moderate or severe TBI (n = 9) were excluded from the sample, resulting in a final sample of 332 Veterans. This study was reviewed and approved by the VA Boston Institutional Review Board.

ADHD Measurement Methodologies

The presence of ADHD was evaluated using three methods: (1) historical diagnosis—participants were asked, “Have you ever been diagnosed with ADD or ADHD?” (i.e., yes or no); (2) retrospective self-report measure of childhood ADHD—participants completed the WURS-25 and scores ≥ 46 were considered highly predictive of childhood ADHD¹⁵; (3) self-report measure of adult ADHD—participants completed the ASRS-v1.1 and those who endorsed 4 or more symptoms out of 6 screened positive for adult ADHD.¹⁹

The WURS-25 and the ASRS-v1.1, and their associated cutoffs, are commonly used and validated in the existing literature. The WURS-25 cutoff of ≥46 has demonstrated 86% sensitivity and 99% specificity,¹⁵ indicating high internal consistency and criterion validity for retrospectively identifying childhood ADHD. The ASRS-v1.1 is a clinical scale used to screen adult ADHD symptoms based on the DSM criteria. The ASRS-v1.1 six-item screener was adapted from the full 18-item ASRS-v1.1 and outperforms the 18-item version¹⁹ on measures of sensitivity (91.4%), specificity (96.0%), construct validity (AUC = 0.94), internal consistency (0.63–0.72), and test-retest reliability (0.58–0.77).^30,31 The ASRS-v1.1 screener was added to the TRACTS study protocol in 2015, limiting the availability of adult ADHD data to 171 of the total 332 participants in this sample.

The WURS-25 was chosen as the primary measure of ADHD in this study for several reasons. First, the strong psychometric properties of the WURS-25 are well-established and it is considered the criterion standard in the field for self-report questionnaires.^15–17 Additionally, the WURS-25 assesses childhood ADHD symptoms, which is critical for accurate ADHD diagnosis since ADHD symptoms must present before the age of 12 years.¹ The ASRS-v1.1, on the other hand, only captures adult ADHD symptoms and cannot confirm the presence of symptoms in childhood. Given the high overlap between ADHD and PTSD symptoms and the high rates of both conditions in the Veteran population, the ASRS-v1.1 may not be well suited to differentiate between PTSD symptoms and adult ADHD symptoms in this sample. Finally, as outlined in prior literature, most children diagnosed with ADHD continue to experience ADHD symptoms either persistently or episodically into adulthood.¹² Therefore, it was determined that the WURS-25 was the most appropriate measure of ADHD in this sample of post-9/11 Veterans.

Clinical Interview

A doctorate-level psychologist conducted clinical interviews using the Clinician-Administered PTSD Scale for DSM-IV to assess current and lifetime PTSD diagnosis and severity.³² Clinicians also administered the Boston Assessment of Traumatic Brain Injury-Lifetime to evaluate lifetime and military history of TBI,³³ the Traumatic Life Events Questionnaire to assess trauma exposure history,³⁴ and the Structured Clinical Interview for DSM-IV to assess general mental health disorders including alcohol use disorder (AUD).³⁵ Interview data were reviewed at consensus meetings where all diagnoses were confirmed by at least 3 doctorate-level clinicians.

Statistical Analyses

Differences in demographic and clinical conditions between ADHD groups were examined. For continuous outcomes, we used the Wilcoxon-Mann-Whitney test, given that values were not normally distributed within groups. For discrete outcomes, we used the chi-squared test except when contingency tables had an expected cell count <5, in which case Fisher’s exact test was used to provide a conservative estimate. The correspondence between (1) historical ADHD diagnosis and childhood ADHD per the WURS-25, and (2) childhood ADHD per the WURS-25 and adult ADHD per the ASRS-v1.1 was evaluated using measures of validity (i.e., sensitivity, specificity, positive, and negative predictive values). As measures of disease prevalence, positive and negative predictive values are most applicable to clinical practice. Estimated values above 0.80 were considered “good” according to generally accepted standards.

Finally, we explored the association between ADHD and PTSD diagnosis relative to other common conditions among Veterans including AUD, childhood trauma, and history of TBI after adjusting for demographic characteristics such as age, gender, and education. Given the high prevalence of ADHD (>10%) in our sample, log-binomial regression models were used to estimate prevalence ratios and their corresponding 95% CIs. Statistical analyses were conducted using SAS (version 9.4) and R (version 3.6.0).

RESULTS

A sample of 332 Veterans was included in the current analysis. The sample was mostly male (88.6%) and White (76.2%). The mean age was 35.7 years (SD = 9.6). Participants had 14.6 years of education (SD = 2.3) on average. Almost 13% (n = 42) of the sample met criteria for childhood ADHD per the WURS-25. On average, Veterans who met criteria for childhood ADHD were more likely to identify as Black or African American (mean = 21.4% vs. 9.7%; P = .034) and reported greater service-connected disability for injuries sustained or aggravated during active military service (64.5% vs. 49.4%; P = .036) compared to those who did not meet criteria for ADHD. Additional demographics using the WURS-25 classification and full sample are presented in Table 1 and clinical characteristics are presented in Table 2.

Table 1.

Demographic information stratified by childhood ADHD status using the WURS-25

			Childhood ADHDa
		Full sample (n = 332)	No ADHD (n = 290)	ADHD (n = 42)
Covariates	n	Mean ± SD/N (%)	Mean ± SD/N (%)	Mean ± SD/N (%)
Demographics
Age	332	35.7 ± 9.6	35.8 ± 9.8	34.7 ± 8.0
Education	332	14.6 ± 2.3	14.6 ± 2.3	14.5 ± 2.0
Malesb	332	294 (88.6%)	257 (88.6%)	37 (88.1%)
Race and ethnicity	332
Hispanic		58 (17.5%)	53 (18.3%)	5 (11.9%)
White		253 (76.2%)	226 (77.9%)	27 (64.3%)
Black/African Americanb		37 (11.1%)	28 (9.7%)	9 (21.4%)*
AI/Alaskan Nativeb		4 (1.2%)	3 (1.0%)	1 (2.4%)
Asianb		10 (3.0%)	7 (2.4%)	3 (7.1%)
Native Hawaiian/PIb		3 (0.9%)	2 (0.7%)	1 (2.4%)
Otherb		11 (5.4%)	8 (4.5%)	3 (11.5%)
Number of post-9/11 deployments	332	1.7 ± 1.2	1.7 ± 1.1	1.6 ± 1.3
Service-connected disability status	217	51.4 ± 36.1	49.4 ± 35.9	64.5 ± 35.0*

AI = American Indian, PI = Pacific Islander.

^aChildhood ADHD status determined using WURS-25 cutoff of 46.

^bIndicates Fisher’s exact test.

^* P < .05: Statistically significant difference between ADHD and no ADHD groups.

Wilcoxon-Mann-Whitney test was used for all continuous variables. The chi-squared test was used for all discrete variables unless noted otherwise.

Table 2.

Clinical characteristics stratified by childhood ADHD status using the WURS-25

			Childhood ADHDa
		Full sample (n = 332)	No ADHD (n = 290)	ADHD (n = 42)
Covariates	n	Mean ± SD/N (%)	Mean ± SD/N (%)	Mean ± SD/N (%)
Clinical characteristics
ADHD WURS Total Score	332	22.1 ± 18.5	16.9 ± 12.7	57.8 ± 11.9*
Childhood trauma	329	259 (78.7%)	222 (77.4%)	37 (88.1%)
Mild TBI 332
Lifetime		220 (66.3%)	191 (65.9%)	29 (69.1%)
Total		1.9 ± 3.7	1.6 ± 2.3	3.5 ± 8.3
PTSD
Lifetime diagnosis	332	237 (71.4%)	200 (69.0%)	37 (88.1%)
Current severity	330	46.2 ± 28.6	43.2 ± 27.6	66.9 ± 27.0*
Current diagnosis	332	177 (53.3%)	147 (50.6%)	30 (71.4%)*
AUD
Current symptoms	95	0.7 ± 2.0	0.7 ± 2.0	0.7 ± 1.5
Current diagnosis	332	54 (16.3%)	47 (16.2%)	7 (16.7%)
Lifetime symptoms	331	3.6 ± 3.2	3.3 ± 3.1	5.5 ± 3.2*
Lifetime diagnosis	332	210 (63.3%)	176 (60.7%)	34 (80.9%)*

^aChildhood ADHD status determined using WURS-25 cutoff of 46.

^* P < .05: Statistically significant difference between ADHD and no ADHD groups.

Wilcoxon-Mann-Whitney test was used for all continuous variables. The chi-squared test was used for all discrete variables.

Discrepancies in Childhood ADHD per the WURS-25 and Historical ADHD Diagnosis

A total of 316 participants answered the historical ADHD diagnosis question. Approximately 1% (n = 47) reported a historical ADHD diagnosis (see Table 3). Of those with a historical diagnosis, slightly over a quarter (27.7%; n = 13) met criteria for childhood ADHD on the WURS-25. Of those who reported no historical ADHD diagnosis (n = 269), one-tenth (9.7%; n = 26) met criteria for childhood ADHD on the WURS-25. Sensitivity between measures was 27.7%, specificity was 90.3%, positive predictive value was 33.3%, and negative predictive value was 87.7%.

Table 3.

Discrepancies between Childhood ADHD Defined using the WURS-25^a, Self-Reported History of ADHD Diagnosis, and Adult ADHD Defined Using the ASRS-v1.1^b

WURS-25
		ADHD	No ADHD
Self-reported history (n = 316)	ADHD	13	34
	No ADHD	26	243
ASRS-v1.1 Screener (n = 171)	ADHD	17	56
	No ADHD	11	87

^aChildhood ADHD status determined using WURS-25 cutoff of 46.

^bAdult ADHD status met criteria if the individual endorsed 4+ symptoms on the screener.

Association between Childhood ADHD (WURS-25) and Adult ADHD (ASRS-v1.1)

Around half of the sample (n = 171) completed both the WURS-25 and the ASRS-v1.1 six-item screener. The ASRS-v1.1 screener demonstrated moderate correspondence with the WURS-25. Of those who met criteria for childhood ADHD per the WURS-25 (n = 28), 60.7% (n = 17) also screened positive for adult ADHD per the ASRSv1.1. Of those who did not meet for childhood ADHD (n = 143), 39.2% (n = 56) screened positive for adult ADHD. Sensitivity between measures was 60.7%, specificity was 60.8%, positive predictive value was 23.3%, and negative predictive value was 88.8%.

Association between Childhood ADHD (WURS-25) and PTSD Diagnosis

Of the 332 Veterans included in this analysis, 9.0% (n = 30) met criteria for both ADHD and PTSD, 44.3% (n = 147) had PTSD only, 3.6% (n = 12) had ADHD only, and 43.1% (n = 143) had neither PTSD nor ADHD. Results from the adjusted regression model showed that PTSD had the strongest association with ADHD of all clinical conditions examined. Participants who met criteria for childhood ADHD per the WURS-25 were 2.5 times more likely to have met diagnostic criteria for PTSD at least once over their lifetime (i.e., lifetime PTSD) compared to those who had never met criteria for PTSD (PR = 2.53, 95% CI [1.11, 7.28]) (Table 4). Additionally, Veterans who met criteria for childhood ADHD were more than twice as likely to meet diagnostic criteria for current PTSD (PR = 2.19, 95% CI [1.17, 4.38]). Lifetime AUD was the only other condition associated with childhood ADHD, with a two-fold increased prevalence of ADHD (PR = 2.06, 95% CI [1.03, 4.71]).

Table 4.

PRs for ADHD^a and PTSD Diagnoses (n = 329)

	Model 1	Model 2
	PR (95% CI)	PR (95% CI)
Current PTSD	2.17 (1.19–4.28)	2.19 (1.17–4.38)
Current AUD		0.97 (0.42–1.92)
Childhood trauma		1.97 (0.89–5.55)
TBI		1.01 (0.56–1.95)
Age		0.99 (0.96–1.02)
Male		1.00 (0.46–2.77)
Education		1.02 (0.89–1.16)
	PR (95% CI)	PR (95% CI)
Lifetime PTSD	3.00 (1.35–8.53)	2.53 (1.11–7.28)
Lifetime AUD		2.06 (1.03–4.71)
Childhood trauma		1.90 (0.87–5.33)
TBI		0.95 (0.53–1.83)
Age		0.99 (0.96–1.02)
Male		1.01 (0.47–2.80)
Education		1.03 (0.90–1.16)

^aADHD status determined using WURS-25 cutoff of 46.

DISCUSSION

This study evaluated the prevalence of ADHD in a sample of post-9/11 Veterans and evaluated the correspondence between 3 ADHD self-report measures (i.e., historical ADHD diagnosis, the WURS-25 for childhood ADHD, and the ASRS-v1.1 for adult ADHD). Additionally, the relationship between ADHD and PTSD, 2 common conditions among Veterans, was examined relative to other common clinical conditions. Consistent with previous studies, the TRACTS sample had a higher prevalence of ADHD (13%) compared to the general population,¹³ and a slightly higher prevalence than other Veteran studies.^2,3 Regarding ADHD measure correspondence, the results showed poor sensitivity between historical ADHD diagnosis and childhood ADHD per the WURS-25. Moderate sensitivity was observed between adult ADHD per the ASRSv1.1 and childhood ADHD per the WURS-25. Finally, both lifetime history and current PTSD were strongly associated with ADHD, and these conditions were highly co-prevalent in this sample.

The high rates of ADHD observed in this Veteran sample and other Veteran studies might be explained, at least in part, by the overrepresentation of men in this population. Boys receive ADHD diagnoses at higher rates than girls, and men disproportionately enlist for service.³ The highly structured, physically and mentally stimulating work environment of the military might also appeal to Veterans with ADHD and could drive self-selection for service enrollment. After deployment, many Veterans have difficulty transitioning home^9,36 but those with ADHD may struggle more to readjust to the lack of structure in civilian life, which could adversely impact employment and attainment of secondary education.¹³ Increased awareness about ADHD among post-9/11 Veterans can improve access to proper assessment and treatment, and aid reintegration.

Assessment and treatment of ADHD in Veterans is complex, as evidenced by the low sensitivity across diagnostic measures. Only 13 (4.1%) Veterans from the sample met criteria for childhood ADHD per the WURS-25 and had a historical ADHD diagnosis. Approximately 8% of participants met for childhood ADHD according to the WURS-25 but never received a formal diagnosis, demonstrating poor correspondence between childhood ADHD diagnosis and symptoms. Recent increases in awareness of and screening for ADHD may explain this discrepancy,⁶ particularly for Veterans who did not have access to ADHD assessment during childhood. Thirty-four (10.8%) Veterans did not meet for childhood ADHD per the WURS-25 but reported receiving an ADHD diagnosis at some point in the past. This raises the possibility of misdiagnosis as symptom onset of ADHD must be during youth.¹ When the onset of inattentive and/or hyperactivity symptoms occurs later in life, other contributing factors and differential diagnoses such as PTSD must be carefully considered and ruled out.^22,27,37

Correspondence improved when comparing childhood ADHD per the WURS-25 and adult ADHD per the ASRS-v1.1 six-item screener; 60% of participants who met criteria for childhood ADHD also met the criteria for adult ADHD. The misalignment in childhood and adult ADHD may be explained by previously described fluctuations in ADHD symptoms over the life course.^10–12 Concerningly, 39% of Veterans who did not meet for childhood ADHD per the WURS-25 screened positive for adult ADHD per the ASRS-v1.1 six-item screener. Again, this raises the possibility that the etiology of symptoms may not be attributable to ADHD, but to another condition like PTSD.

Analyses examining the relationship between ADHD and PTSD in this sample confirmed the high co-occurrence of these disorders, as cited in prior literature.²² Compared to individuals without ADHD (1.6–3.3%), those with ADHD have greater rates of PTSD (10.0–11.9%).^22,38,39 Within our sample, 9% of Veterans met criteria for both PTSD and childhood ADHD. Of the participants who met criteria for childhood ADHD per the WURS-25 (n = 42), 71% also had current PTSD (n = 30). These findings further reinforce the high co-prevalence estimates of ADHD and PTSD among Veterans and emphasize the need for heightened screening of both conditions. For Veterans who screen positive for both ADHD and PTSD, in-depth follow-up assessments can help identify how each condition contributes to inattention, executive dysfunction, irritability, sleep disturbance, and other common symptoms. Understanding the interaction between these conditions can inform treatment planning with more targeted therapies, thereby improving treatment outcomes and daily functioning.²²

These results highlight the diagnostic barriers and the need for further characterization of ADHD in Veterans with comorbid PTSD. Given the high rates of PTSD among this population, differential diagnosis may be more challenging in Veterans than in their civilian counterparts. Assessing adult ADHD may also be difficult for clinicians,²⁴ as retrospective assessment can be prone to reporting bias,¹³ and ADHD shares clinical features with many other psychiatric conditions.⁵ When differentiating between ADHD and other conditions, clinicians should focus on the context and timeline of symptom presentation.^5,7 For Veterans with both ADHD and PTSD, treatment planning should initially address whichever disorder causes the most severe distress and dysfunction.⁵ Veterans with comorbid diagnoses may also benefit from transdiagnostic treatment approaches designed to target overlapping symptoms, such as combined trauma-focused therapy, cognitive-behavioral therapy, psychoeducation, vocational rehabilitation, and pharmacological treatments.^5,36

The primary limitation of this study is the methodology used to identify ADHD. The true gold standard for ADHD diagnosis is a psychological interview with a qualified clinician.¹⁴ This study relied on retrospective self-report measures to assess ADHD, introducing the possibility of recall bias. However, the WURS-25 is most often viewed as the criterion standard for self-report of ADHD; it is a commonly used retrospective measure for childhood ADHD symptoms and demonstrates strong internal reliability and criterion validity in adult populations with and without an ADHD diagnosis.^15,17,40 A second limitation is the convenience sample design of the TRACTS Research Study, which has resulted in a largely White and male cohort. As women represent a minority of Veterans, they are underrepresented in this sample. Although gender discrepancies in ADHD prevalence exist between men and women, the demographics of this sample limit the generalizability of the findings to the general population. Future research should further examine the differences between men and women Veterans with ADHD.

In conclusion, the present study confirmed the high prevalence of ADHD among post-9/11 Veterans and high co-prevalence with PTSD. The results also demonstrated a poor correspondence between 3 measures of ADHD, including retrospective childhood ADHD (WURS-25), historical ADHD diagnosis, and adult ADHD (ASRS-v1.1). Overlapping symptomatology between PTSD and ADHD likely contributes to difficulty differentiating between these conditions, particularly in Veterans, a population with a higher burden of both conditions. Clinicians conducting ADHD evaluations in Veterans should consider the age of onset and time course of symptoms, carefully assess common comorbid conditions like PTSD, and should not rely on a single ADHD screening measure for diagnosis. Identifying the most common overlapping symptoms between ADHD and PTSD (e.g., difficulty with attention, sleep disturbances, memory complaints, and irritability) may help clinicians identify when patients warrant dual assessment. For Veterans who meet diagnostic criteria for both ADHD and PTSD, transdiagnostic treatment options should be considered.

FUNDING

The Translational Research Center for TBI and Stress Disorders (TRACTS), a Veterans Affairs Rehabilitation Research and Development (VA RR&D) Traumatic Brain Injury National Network Research Center (B3001-C). M.K.N. is funded by the National Institute of Mental Health (T32MH019836) award. C.B.F. is funded by VA RR&D Merit Award (RX004535).

CONFLICT OF INTEREST STATEMENT

None declared.

DATA AVAILABILITY

The data are owned by the U.S. Department of Veterans Affairs and therefore will not be made publicly available. Inquiries to access data can be made to the Translational Research Center for TBI and Stress Disorders (TRACTS) through the corresponding author.

INSTITUTIONAL REVIEW BOARD (HUMAN SUBJECTS)

This study was approved by the VA Boston Healthcare System (VABHS) Institutional Review Board (IRB) (RHC-A-00-000). Exempt status was obtained by the VABHS IRB for this study.

INSTITUTIONAL ANIMAL CARE AND USE COMMITTEE (IACUC)

Not applicable.

INSTITUTIONAL CLEARANCE

Not applicable.

INDIVIDUAL AUTHOR CONTRIBUTION STATEMENT

A.R.K. and S.K. conceptualized and drafted the original manuscript. A.C. and A.L. analyzed the data and created the tables/figures. W.P.M. and C.B.F. obtained funding. M.K.N., W.P.M., and C.B.F. reviewed and edited the manuscript. All authors read and approved the final manuscript.