Emotion recognition and social behavior in early and mid-stage parkinson's disease

Social cognition refers to the ability to assess one's own and others' emotions and behavior. It is essential for interpersonal relationship and is frequently impaired in Parkinson’s disease (PD), even in early stages. Three domains are relevant in social cognition: emotion recognition, social behavior and theory of mind. Many studies have investigated theory of mind processing, but few studies exist on emotion recognition and social behavior in patients with PD. Evidence from patients with neurodegenerative disease show that emotion recognition primarily involves the semantic-appraisal network (SAN), which includes the anterior temporal lobe, nucleus accumbens, caudate, putamen, and orbitofrontal cortex. On the other hand, social behavior predominantly corresponds with the salience network (SN) consisting of cortical (anterior insula, anterior cingulate cortex) and subcortical (amygdala, hypothalamus, midbrain PAG) regions. Dopamine is the major neurotransmitter of the SAN, which originates in the ventral tegmental area (VTA). While the degeneration of nigrostriatal dopaminergic system predominates in PD, the mesolimbic dopaminergic pathways that include regions of the SN and SAN are also often affected, although to a lesser extent. Due to the gradual impairment of the mesolimbic system, it is expected that social cognition will be mildly affected in early disease stages and more severely impaired in advanced PD, independent of cognitive decline. Few studies have investigated whether emotion recognition and social behavior change with disease progression in patients with dopaminergic medication and treatment fluctuations. The goal of the study is to investigate social cognition with a focus on emotion recognition and social behavior in de novo patients with PD in the early stages before administration of a dopaminergic drug and in more advanced patients with wearing-OFF fluctuations that occur during treatment. The findings will be compared with age-, sex- and education-matched controls. We expect that emotion recognition will be impaired in early, mild cognitive impairment stages of PD, and that social behavior dysfunction occur in later disease stages. We also anticipate that degree of social cognitive impairment will be lower during ON- than OFF-medication. 30 non-demented de novo patients with PD and 30 matched healthy controls, 30 mid-stage patients with PD and 30 matched healthy controls will be included. Patients with severe depression measured by the Beck Depression Inventory (BDI) and severe behavioral disorders measured by the UPDRS will be excluded. Emotion recognition will be assessed using the video-based Basel version of the Awareness of Social Inference Test – Emotion Recognition (BASIT-ER) test and the Facial Emotion Intensity Rating Test – Congruent and Incongruent (FEIRT-CIC) test. For the evaluation of social behavior the Revised Self-Monitoring Scale (RSMS), the Behavioural Dysfunction Questionnaire (BDQ) and the Saarbrücker Persönlichkeitsfragebogen (SPF) will be used. To distinguish between PD and controls, we will apply general linear models using the assessments of social cognition as explanatory variables, controlling for age, sex, depression, general cognitive and executive functioning, and daily levodopa equivalent dose.