Prevalence of Attention Deficit Hyperactivity Disorder in an Adult Mental Health Service in the Republic of Ireland.

Objective Attention Deficit Hyperactivity Disorder (ADHD) is well recognised in childhood. However, recognition that it commonly persists into adulthood is relatively recent. This study is the 2nd phase of a two-phase epidemiological investigation of the prevalence of adult ADHD in outpatients in Ireland. Method In phase-1, 634 participants were screened with Adult ADHD Self-Report Scale (ASRS) and Wender Utah Rating Scale (WURS). Those scoring positive in both scales have been invited to participate in the 2nd phase where the scales Conners' Adult ADHD Diagnostic Interview (CAADID), Mini International Neuropsychiatric Interview (MINI), and Global Assessment of Functioning (GAF) were administered, plus clinical evaluation based in DSM-5. Results 131 were eligible, 110 participated (84.0%). Using the CAADID (DSM-IV criteria) 71 were diagnosed with ADHD. Projecting to the total sample (N = 634) the prevalence was 13.25%, CI:95%:10.71-16.14. Converting the DSM-IV criteria to DSM-5, 89 had ADHD (prevalence:16.72%, CI: 13.9-19.86). Using clinical evaluation, 86 were diagnosed with ADHD (prevalence:16.09%, CI:13.31-19.18). Only 3 cases were diagnosed before with ADHD. Comorbidity was higher in those with ADHD, with the median number of additional diagnoses 2 (min 0 max 8, IQR 3) Also, they had significantly higher rates of depression and recurred depression. Agreement between DSM-IV and DSM-5 was high (rho = 0.90, p < .0001). Conclusions High rates of undiagnosed ADHD were found to be present among AMHS attendees. Clinicians in AMHS need to be knowledgeable and alert to possible ADHD among their caseloads, and offer appropriate intervention. Interventions are urgently required to increase the detection and treatment of adult ADHD.