Neurocognitive Test Performance in relation to symptom severity and age of onset of trichotillomania

Prior research has yielded inconsistent findings on neurocognitive deficits, particularly in response inhibition and set shifting, when comparing patients with trichotillomania (TTM) to healthy comparison groups. This study used baseline data (N = 36) from a clinical trial of behavior therapy for TTM to test two possible explanations for these mixed results: (a) neurocognitive deficits are only noted among more severely symptomatic patients with TTM; and (b) age of onset is differentially associated with deficits in response inhibition vs. set shifting. Results were inconsistent with these hypotheses. Age of onset was not significantly correlated with either neurocognitive assessment. Interviewer ratings of TTM symptom severity or impairment were not significantly related to neurocognitive test performance. Self-reported symptom severity correlated significantly with motor response inhibition, but in the direction opposite to our expectation, such that faster reaction times to inhibit a dominant response were associated with more severe symptoms. Discussion centered on several possible explanations, including the possibilities that either (a) measurement methods or (b) variation across samples in the prevalence of ADHD comorbidity, not measured in this study, could explain mixed findings on the neuropsychological profile of TTM.