A-083 A Lesser Form of ADHD? Exploring the Neuropsychological Profiles of Adult ADHD Diagnostic Subgroups

Abstract

Abstract Objective Many individuals experience clinically-elevated symptoms of attention-deficit/hyperactivity disorder in adulthood that were absent, sub-threshold, or unapparent prior to age 12 (late-onset ADHD). These individuals might be experiencing a less-severe form of ADHD. We explored whether the neuropsychological performance profiles of different diagnostic ADHD subgroups of community-dwelling individuals in the Pacific Northwest, USA, supported this form of ADHD. We compared individuals who endorsed clinically-elevated ADHD symptoms in adulthood only (ADHD-A), in both childhood and adulthood (ADHD-CA), and individuals who did not endorse symptoms (None). Method Subgroup placement was determined based on symptom endorsement on the Adult ADHD Clinical Diagnostic Scale in accordance with DSM-V criteria. Our sample included n = 41 placed in the ADHD-CA group (mean age = 39.12, range 18–71), n = 12 in the ADHD-A group (mean age = 51.83, range 20–73), and n = 50 in the None group (mean age = 50.52, range 18–86). ANCOVAs with pairwise comparisons were conducted to compare group performance on the CVLT-II, WMS-V Spatial Addition and Visual Reproduction, and D-KEFS Verbal Fluency Letter and Color-Word Inhibition tasks after controlling for age. Result Group differences were found on the D-KEFS Color-Word Inhibition task where the ADHD-A group’s score was higher than that of the ADHD-CA group (d = 1.37, p = .340) but lower than that of the None group (d = −1.03, p = .462). No other group differences were found. Conclusions Adults with late-onset ADHD may display a less-severe impairment on neuropsychological measures closely related to ADHD symptomology (e.g. inhibitory control) than those meeting full ADHD diagnostic criteria. There is no evidence that this pattern extends to other neuropsychological domains.