Internalizing and externalizing comorbidity and symptom burden in a VA ADHD specialty evaluation clinic

The purpose of this study was to evaluate psychiatric diagnosis and symptom comorbidity in veterans diagnosed with attention-deficit/hyperactivity disorder (ADHD). Study design was retrospective chart review from an ADHD evaluation clinic at a Veterans Affairs hospital. Participants were 227 military veterans who completed a standardized ADHD assessment and produced valid Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF) profiles. There were no differences in rates of internalizing or externalizing psychiatric conditions diagnosed in inattentive compared to combined ADHD presentations. However, compared to a subsample with no psychiatric diagnoses, individuals diagnosed with ADHD endorsed significantly more internalizing symptom burden, with combined ADHD veterans also endorsing significantly greater levels of negative emotions and neuroticism. Base rates of comorbid classes of psychiatric diagnoses were not increased in individuals with ADHD, though higher rates of trauma disorders were seen in the combined group compared to the inattentive group. Multivariate base rates of MMPI-2-RF Restructured Clinical scales across various subgroups are presented. There was evidence for differential phenotypes of psychiatric symptoms across ADHD presentations in clinically referred veterans, predominantly related to higher rates of internalizing symptoms.