Impairment in Theory of Mind in Parkinson's Disease Is Explained by Deficits in Inhibition.

Jennifer A Foley,Elena Poznyak,Olga Borejko,Thomas Foltynie,Claire Lancaster,Elaine Niven,Lisa Cipolotti,Sharon Abrahams

doi:10.1155/2019/5480913

Abstract

Objective Several studies have reported that people with Parkinson's disease (PD) perform poorly on tests of ‘Theory of Mind' (ToM), suggesting impairment in the ability to understand and infer other people's thoughts and feelings. However, few studies have sought to separate the processes involved in social reasoning from those involved in managing the inhibitory demands on these tests. In this study, we investigated the contribution of inhibition to ToM performance in PD. Methods 18 PD patients and 22 age-matched healthy controls performed a ToM test that separates the ability to infer someone else's perspective from the ability to inhibit one's own. Participants also completed a battery of standard measures of social and executive functioning, including measures of inhibition. Results The PD patients performed worse on the ToM test only when the inhibitory demands were high. When the level of inhibition required was reduced, there were no significant group differences. Furthermore, executive impairments in PD patients were limited to measures of inhibition, with disadvantages associated with poorer ToM performance in this group. Conclusions This study provides convincing evidence that the apparent impairment observed on ToM tests in PD is explained by deficits in inhibition.

Highlights

Several studies have reported that people with Parkinson’s disease (PD) perform poorly on tests assessing the ability to infer the beliefs, desires, and intentions of others [1,2,3].ese functions fall under the umbrella term of “ eory of Mind” (ToM), considered essential for the development and maintenance of successful social relationships [4].ToM has been separated into cognitive and affective components [5]
Executive impairments in PD patients were limited to measures of inhibition, with disadvantages associated with poorer ToM performance in this group
Pearson correlations were conducted to explore further the relationship between ToM and executive functioning. ese revealed that performance on the false belief test in high inhibition condition correlated with performance on the Hayling (r 0.52, p < 0.01) and Elevator Counting with Distraction tests only (r .61, p < 0.001)

Summary

Objective

Several studies have reported that people with Parkinson’s disease (PD) perform poorly on tests of ‘ eory of Mind’ (ToM), suggesting impairment in the ability to understand and infer other people’s thoughts and feelings. Few studies have sought to separate the processes involved in social reasoning from those involved in managing the inhibitory demands on these tests. 18 PD patients and 22 age-matched healthy controls performed a ToM test that separates the ability to infer someone else’s perspective from the ability to inhibit one’s own. E PD patients performed worse on the ToM test only when the inhibitory demands were high. Executive impairments in PD patients were limited to measures of inhibition, with disadvantages associated with poorer ToM performance in this group. Conclusions. is study provides convincing evidence that the apparent impairment observed on ToM tests in PD is explained by deficits in inhibition

Introduction

Methods

ToM Test