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

After preregistration on the International Prospective Register of Systematic Reviews (PROSPERO), we conducted a comprehensive literature search for papers examining cognition in people with TTM versus controls using validated tests. A total of 793 papers were screened using preestablished inclusion/exclusion criteria, yielding 15 eligible studies. Random-effects meta-analysis was conducted for 12 cognitive domains.

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

Motor inhibition and ED set-shifting appear impaired in TTM. However, a 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.

拔毛癖 (TTM) 是一种精神健康障碍，其特征是反复拔掉自己的头发。据报道，与对照组相比，TTM 患者存在认知缺陷；然而，目前关于受影响领域的文献很少且没有结论。我们的目的是综合 TTM 中认知功能的研究，并调查哪些认知领域受到损害。

在国际前瞻性系统评价注册库 (PROSPERO) 上进行预注册后，我们对使用经过验证的测试检查 TTM 患者与对照组认知能力的论文进行了全面的文献检索。使用预先制定的纳入/排除标准筛选了总共 793 篇论文，产生了 15 项合格的研究。对 12 个认知领域进行了随机效应荟萃分析。

荟萃分析表明，通过停止信号任务 (SST) 测量，TTM 患者与对照组相比，在运动抑制和超维度 (ED) 转变方面存在显着缺陷（Hedge's g  = 0.45，[CI：0.14，0.75]，p  = .004 ) 和 ED set-shift 任务 ( g  = 0.38, [CI: 0.13, 0.62], p  = .003)。测试的其他认知领域没有显着的组间差异：语言学习、维度内（ID）转换、路线图空间能力、模式识别、非语言记忆、执行计划、空间跨度长度、斯特鲁普抑制、威斯康星卡片分类和视觉空间功能。研究质量分数并未显着影响研究结果。

TTM 中运动抑制和 ED 设定转换似乎受损。然而，由于样本相对较小且经常包含合并症，因此有必要对结果进行谨慎的解释。寻求改善抑制控制和认知灵活性的治疗干预值得 TTM 探索。