Social Cognition in Parkinson's Disease: A Case-Control Study

Social cognition is the study of how people make sense of themselves and others. Impairment in several domains of social cognition is increasingly being recognized in Parkinson's disease (PD).

We aimed to study multiple domains of social cognition in Indian PD patients using a culturally appropriate, validated instrument.

We recruited 52 individuals with PD and 31 healthy volunteers (HV) and used the Social Cognition Rating Tools in Indian Setting (SOCRATIS) tool to assess theory of mind (ToM), attributional biases and social cue perception. Quality of life (QoL) was assessed using the PDQOL scale.

Baseline characteristics were comparable between PD and HV. The mean (SD) FOT index (first order ToM index) was 0.86(0.18) in PD and 0.99(0.07) in HV [P < 0.001]. The PD group showed higher Externalizing Bias [EB, 4.42(3.91)], compared to HV [1.58(3.22), P = 0.001]. The mean (SD) Faux Pas Composite Index (FPCI ALT) was 0.69(0.09) in PD and 0.78(0.13) in HV [P < 0.001]. Social cognition indices were not associated with QoL in PD. Clinical parameters-age, gender, HAM-D, MOCA, education, levodopa equivalent daily dose of medication, number of PD drugs and trihexyphenidyl use did not predict social cognition.

PD patients were less successful than age, gender matched controls in understanding social situations and other's thought processes and had higher tendency to attribute undesirable events to external causes. Deficits in social cognition did not impair the quality of life.