筋強直性ジストロフィー1型の社会的認知障害

Social Cognitive Impairment in Myotonic Dystrophy Type 1

筋強直性ジストロフィー1型（DM 1）では自閉症スペクトラムに類似した行動を示すことが報告されており，これは社会的認知機能の低下として捉えることができる。表情認知の検討では，怒りや嫌悪などネガティブな表情に対する感度の低下がみられ，また心の理論については，言語・非言語の両面から機能低下が示されている。こうした異常は島皮質，側頭葉前方部，前頭葉底部の白質の異常と関連があるものと推察される。

Abstract

Myotonic dystrophy type 1 (DM 1) is a heritable, multisystem disease that affects not only the muscles but also the brain. DM 1 is often accompanied by developmental behavioral disorders, such as autism spectrum disorders. The autistic traits in DM 1 may be related to social cognitive dysfunction. The social cognitive function of patients with DM 1 was examined with respect to facial emotion recognition and theory of mind, which is the specific cognitive ability to understand the mental states of other people. With respect to facial emotion recognition, the sensitivities to disgust and anger were lower among patients with DM 1 than among healthy subjects, and this difference could not be attributed to visual impairment. To examine the theory of mind ability, the “Reading the Mind in the Eyes” test and the faux pas recognition test were used. Patients with DM 1 were found to be impaired in both tests, but the results were not attributed to visual ability and lexical comprehension. The possible causes of social cognitive dysfunction in DM 1 are the l cerebral atrophy and white matter abnormalities in the temporal, frontal, and insular cortex. Dysfunctions in these areas may affect the emotional and theory of mind abilities in DM 1, which result in the behavioral and communication disorders.