Referral pathways to an adult attention-deficit/hyperactivity disorder outpatient clinic: sociodemographic and clinical correlates

Introduction

Attention-deficit/hyperactivity disorder (ADHD) presents with distinct subtypes, including Combined, Inattentive, and Hyperactive-Impulsive, which may differ in clinical severity, comorbidity patterns, and functional outcomes. Understanding these differences is crucial for personalized treatment approaches.

Objectives

This study examined correlations between ADHD subtypes and severity with sociodemographic characteristics, clinical traits, duration of untreated illness (DUI), psychiatric comorbidities (depression, anxiety, emotional dysregulation, internet addiction), family psychiatric history, pharmacological treatment patterns and quality of life in a clinical sample of adults with ADHD.

Methods

A total of 215 adults with ADHD (mean age 26.12 years, 44% female) attending a specialized outpatient clinic were assessed using the Diagnostic Interview for ADHD in Adults (DIVA). ADHD subtypes were classified as Combined (n = 142) or Inattentive (n = 70); the Hyperactive subtype (n = 3) was excluded from analyses. Psychometric measures included the Zung Self-Rating Depression Scale, State-Trait Anxiety Inventory (STAI), Difficulties in Emotion Regulation Scale (DERS), and Internet Addiction Test (IAT). Associations with psychiatric comorbidities, family psychiatric history, and pharmacological treatment were assessed using logistic regression models. Multivariate analysis of covariance (MANCOVA), logistic regression, chi-square tests, independent samples t-tests, and effect size calculations were conducted.

Results

MANCOVA did not reveal a significant multivariate effect of ADHD subtype on psychometric functioning (Wilks’ Λ = .939, F(5,162) = 2.10, p = .068, partial η² = .061). Univariate analyses indicated that individuals with the Combined subtype exhibited significantly greater emotional dysregulation (F(1,166) = 4.93, p = .028, partial η² = .029) compared to the Inattentive subtype, whereas no significant differences emerged for depressive symptoms, state anxiety, trait anxiety, or problematic internet use. Logistic regression showed that ADHD subtype did not significantly predict mood disorder comorbidity (OR = 0.75, 95% CI [0.32, 1.75], p = .502) or family psychiatric history (OR = 1.69, 95% CI [0.88, 3.24], p = .117). In contrast, ADHD subtype significantly predicted substance use disorder comorbidity (OR = 4.79, 95% CI [1.58, 14.49], p = .006).

ADHD subtype was not associated with DUI (F(1,90) = 1.17, p = .282, partial η² = .013) or current pharmacological treatment (OR = 1.75, 95% CI [0.90, 3.40], p = .100). Educational level emerged as a significant predictor of pharmacological treatment (OR = 0.61, 95% CI [0.38, 0.99], p = .045).

Conclusions

The Combined ADHD subtype was associated with greater emotional dysregulation compared to the Inattentive subtype, whereas no differences emerged in depressive symptoms or other psychometric dimensions. These findings suggest that subtype differences may be more specific to emotional regulation processes rather than reflecting broad differences in internalizing symptomatology. Subtypes did not differ significantly in most categorical comorbidities; however, the Combined subtype showed significantly higher odds of substance use disorder. These findings highlight the importance of assessing emotional and affective symptoms in adults with Combined ADHD and suggest that subtype classification may have limited utility for predicting most categorical comorbidities. Future research should explore dimensional approaches to ADHD symptomatology and investigate mechanisms underlying the association between Combined ADHD and emotional dysregulation.

References

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