Cognitive and affective theory of mind deficits in Parkinson's disease

Abstract

Recent studies have highlighted impairment in social – cognitive abilities in patients with Parkinson's disease. The hallmark of the social cognition is Theory of Mind (ToM), ability to infer about mental states (beliefs, desires) of other people. Cognitive impairment in fronto – striatal circuits is related to difficulties in understanding of other people minds. The aim of the study was to assess deficits in cognitive and affective ToM in Parkinson's disease. Secondary aim was to evaluate, whether deficits in ToM are related to cognitive impairment. Sample consisted of 88 patients with Parkinson's disease and 30 healthy individuals. Mean age of patients was M = 62.19 and SD = 9.69. Comic Strip Task (Cognitive ToM), Reading the Mind in the Eye Test (Affective ToM) and neurocognitive battery was administered. We found significant differences across groups in Comic Strip Task (t = −4.171, p < .001, d = −0.79) and Eyes Test (t = −4.313, p < .001, d = −1.10). Comic Strip Task was related to several neurocognitive domains. We found weaker associations for Eyes test. Both tests were moderately to strongly related to working memory task. We found deficits in both domains of ToM in patients with Parkinson's disease. Neurocognitve impairment characteristic for patients was related to social – cognitive abilities. That's very important finding, because such non-motoric symptoms have even greater impact on patients´ quality of life than motoric symptoms, even in the early stages of the disease.