This study estimates the symptomatology of attention deficit–hyperactivity disorder (ADHD) in adult mental health services (AMHS) outpatient clinics.

All consecutive patients attending any of the outpatients’ clinics in Sligo/Leitrim AMHS were invited to participate. Participants completed the Adult ADHD Self-Report Scale (ASRS) and the Wender Utah Rating Scale (WURS) self-report. Clinical notes were reviewed to identify those with a pre-existing ADHD diagnosis.

From 822 attending the clinics, 62 did not meet inclusion criteria, 97 declined to participate and 29 had incomplete data in either of the screening scales, leaving 634 (77%) eligible for full study analysis. Mean age was 40.38 (s.d.: 12.85), and 326 (51.4%) were females. In total, 215 (33.9%) screened positive on the WURS for childhood onset ADHD and 219 (34.5%) participants scored positive on the ASRS. Applying a more stringent criteria of scoring above cut-offs on both scales, suggested 131 (20.7%) screened positive on both. Only three (2.3%) had a prior clinical diagnosis.

This preliminary study suggests the possibility of relatively higher rates of ADHD in a general AMHS than previously thought, however, given the possibility of overlapping symptoms with other major psychiatric disorders in adulthood and recall bias further research is needed before drawing firm conclusions.