Empathy and theory of mind in Parkinson's disease: A meta-analysis

In contrast to well-documented deficits in the core social cognitive domains of social perception and theory of mind (ToM), how Parkinson's disease (PD) affects one's empathic capacity remains poorly understood. The current study provides the first meta-analytic review of both ToM and empathy as broad constructs, and also breaks these constructs down to clearly differentiate their overlapping (affective ToM and cognitive empathy) and distinct (affective empathy and cognitive ToM) components. A total of 38 studies contributed to these analyses, with results revealing that, relative to controls, PD is associated with significant and substantial deficits in the domain of cognitive ToM (g = -0.78), as well as the overlapping domains of affective ToM/cognitive empathy (g = -0.69). However, no group differences were identified for affective empathy (g = -0.08). These data speak to there being a potential preservation of affective empathic processing in PD, but because of the relatively limited research base on this topic, recommendations for future research are highlighted.