5 - (IOP 16) Predicting Trichotillomania Treatment Outcomes: The Differential Roles of Response Inhibition and Cognitive Flexibility

Introduction: Neuropsychological research suggests that adults with TTM demonstrate impairments in some neurocognitive domains, particularly response inhibition and cognitive flexibility, compared to healthy controls. However, the relationship between these neurocognitive deficits, TTM severity, and treatment outcomes remains unclear. This study examined relationships between performance on response inhibition and cognitive flexibility tasks and TTM symptom severity at baseline, and tested whether baseline neurocognitive functioning predicted treatment outcome.

Methods: The sample included 88 adults with TTM (90% female, 10% male; M age= 36.4(SD=12.87), 81% White, 13% Black, 6% not reported) who participated in a randomized control trial comparing 12 weeks of acceptance-enhanced behavior therapy( AEBT) to psychoeducation and supportive therapy(PST). Participants completed the Object Alternation Task (OAT) measuring cognitive flexibility and the Stop Signal Task (SST) measuring response inhibition. TTM severity was assessed using the Massachusetts General Hospital Hairpulling Scale (MGH-HS) and National Institute of Mental Health Trichotillomania Severity Scale (NIMH-TSS).

Results: At baseline, poorer cognitive flexibility performance (perseverative errors on the OAT) was correlated with higher TTM severity on the NIMH-TSS (r=.23, p=.045) but not MGH-HS (p>.05). Baseline response inhibition was not related to baseline TTM severity.

Examining predictors of outcome, better response inhibition at baseline predicted treatment response status (B=-0.01, p=.033, OR=0.55) and lower post-treatment symptom severity on both the MGH-HS (B=0.03, p=.015) and NIMH-TSS (B=0.02, p=.004), regardless of treatment condition. Cognitive flexibility did not predict treatment outcomes (ps>.05).

Discussion: These findings highlight the distinct relationships between neurocognitive functions and TTM: cognitive flexibility correlates with symptom severity at baseline, while response inhibition predicts treatment outcomes regardless of intervention type. These results have clinical implications. Response inhibition may be a marker of treatment readiness, and pre-treatment interventions targeting response inhibition might enhance patients' ability to engage with and benefit from standard TTM therapy. Additionally, addressing cognitive flexibility deficits could potentially influence TTM symptom severity. Overall, these findings advance our understanding of the neurocognitive underpinnings of TTM and offer promising directions for enhancing treatment efficacy through targeted cognitive interventions.