Cognition in trichotillomania: a meta-analysis

Abstract

Objective: trichotillomania (TTM) is a mental health disorder characterised by repetitive urges to pull out one’s hair. Cognitive deficits have been reported in people with TTM compared to controls, however current literature is sparse and inconclusive about affected domains. We aimed to synthesise research on cognitive functioning in TTM and investigate which cognitive domains are impaired.

Methods: after pre-registration on PROSPERO, we conducted a comprehensive literature search for papers examining cognition in TTM versus controls using validated tests. 793 papers were subjected to title, abstract and full-text searches using pre-established inclusion/exclusion criteria, yielding 15 eligible studies. Random effects meta-analysis was conducted for 12 cognitive domains using RevMan software. Quality scores were used for moderator analysis.

Results: meta-analysis demonstrated significant deficits in motor inhibition and extradimensional (ED) shifting in TTM versus controls as measured by the Stop Signal task (Hedge’s g = 0.45, [CI: 0.14, 0.75], p = .004) and ED Set Shift task respectively (g = 0.38, [CI: 0.13, 0.62], p = .003). There were no significant between-group differences in the other cognitive domains tested: verbal learning; intradimensional (ID) shifting; road map spatial ability; pattern recognition; non-verbal memory; executive planning; spatial span length; Stroop inhibition; Wisconsin card sorting and visuospatial functioning. Findings were not significantly moderated by study quality scores.

Conclusions: motor inhibition and ED set-shifting appear impaired in TTM. However, cautious interpretation of results is necessary as samples were relatively small and frequently included comorbidities. Treatment interventions seeking to improve inhibitory control and cognitive flexibility merit exploration for TTM.

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Identifiers

ORCID for Samuel R. Chamberlain: orcid.org/0000-0001-7014-8121

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