Malcolm Amy, Brennan Sarah N, Grace Sally A, Pikoos Toni D, Toh Wei Lin, Labuschagne Izelle, Buchanan Ben, Kaplan Ryan A, Castle David J, Rossell Susan L
Centre for Mental Health, Faculty of Health, Arts & Design, Swinburne University of Technology, Hawthorn, VIC, Australia.
The Royal Children's Hospital, Melbourne, VIC, Australia.
Aust N Z J Psychiatry. 2021 Apr;55(4):381-390. doi: 10.1177/0004867421998762. Epub 2021 Feb 26.
Current understanding of cognitive functioning in body dysmorphic disorder is limited, owing to few studies, small sample sizes and assessment across only limited cognitive domains. Existing research has also shown inconsistent findings, with both intact and impaired cognition reported in body dysmorphic disorder, which might point towards cognitive heterogeneity in the disorder. This study aimed to examine the cognitive profile of body dysmorphic disorder in a large sample across eight cognitive domains, and to explore whether cognitive subgroups might be identified within body dysmorphic disorder.
Cognitive domains of inhibition/flexibility, working memory, speed of processing, reasoning and problem-solving, visual and verbal learning, attention/vigilance and social cognition were assessed and compared between 65 body dysmorphic disorder patients and 70 healthy controls. Then, hierarchical clustering analysis was conducted on the body dysmorphic disorder group's cognitive data.
Group-average comparisons demonstrated significantly poorer cognitive functioning in body dysmorphic disorder than healthy controls in all domains except for attention/vigilance and social cognition. Cluster analysis identified two divergent cognitive subgroups within our body dysmorphic disorder cohort characterised by (1) broadly intact cognitive function with mild selective impairments (72.3%), and (2) broadly impaired cognitive function (27.7%). However, the clusters did not significantly differ on clinical parameters or most sociodemographic characteristics.
Our findings demonstrate considerable cognitive heterogeneity among persons with body dysmorphic disorder, rather than uniform deficits. Poor performances in the broadly impaired subgroup may have driven group-level differences. However, our findings also suggest a dissociation between cognitive functioning and clinical characteristics in body dysmorphic disorder that has implications for current aetiological models. Additional research is needed to clarify why some people with body dysmorphic disorder demonstrate cognitive deficits while others do not.
由于研究较少、样本量小且仅在有限的认知领域进行评估，目前对身体变形障碍认知功能的了解有限。现有研究结果也不一致，身体变形障碍患者既有认知功能完好的报告，也有认知受损的报告，这可能表明该障碍存在认知异质性。本研究旨在对一大样本的身体变形障碍患者在八个认知领域进行认知特征分析，并探讨是否能在身体变形障碍患者中识别出认知亚组。
对65名身体变形障碍患者和70名健康对照者进行了抑制/灵活性、工作记忆、加工速度、推理与问题解决、视觉与言语学习、注意力/警觉性和社会认知等认知领域的评估与比较。然后，对身体变形障碍组的认知数据进行分层聚类分析。
组间平均比较显示，除注意力/警觉性和社会认知外，身体变形障碍患者在所有领域的认知功能均显著低于健康对照者。聚类分析在我们的身体变形障碍队列中识别出两个不同的认知亚组，其特征分别为：(1) 认知功能大致完好但有轻度选择性损害 (72.3%)，以及 (2) 认知功能大致受损 (27.7%)。然而，这两个亚组在临床参数或大多数社会人口学特征上并无显著差异。
我们的研究结果表明，身体变形障碍患者存在相当大的认知异质性，而非统一的缺陷。广泛受损亚组的较差表现可能导致了组水平的差异。然而，我们的研究结果也表明，身体变形障碍患者的认知功能与临床特征之间存在分离，这对当前的病因模型具有启示意义。需要进一步研究以阐明为何一些身体变形障碍患者表现出认知缺陷而另一些则没有。
