Social Cognition in Frontotemporal Dementia, Motor Neurone Disease, and Alzheimer's Disease

Abstract

The orbitofrontal cortex and ventromedial prefrontal cortex have been implicated in many aspects of social cognition, and conditions that affect these regions are thereby accompanied by deficits in interpersonal behaviour. In order to assess social cognition across a number of neurodegenerative diseases, a test battery and two questionnaires were administered to frontal variant frontotemporal dementia (fvFTD), motor neurone disease (MND), Alzheimer`s disease, and healthy control participant groups. This included the newly developed Social Rule Break Cartoons task, which is a visually presented test tapping several aspects of social cognition. An exercise-smoking Implicit Association Test (IAT) and sweets or alcohol-healthy food IAT were also administered to investigate whether an inability to automatically access associated social knowledge may underlie some of the behavioural alterations seen in fvFTD, and increased appetite, sweet food preference, and drinking and smoking in particular. The FTD patient group was found to score significantly lower than the MND and control groups on faux pas detection and theory of ming questions on the Faux Pas Test, as expected. Their scores on social rule knowledge questions of the Social Rule Break Cartoons task also tended towards being significantly lower, and they demonstrated overall behaviour changes on the family-rated Frontal Systems Behavior Scale. This pointed towards a social cognition deficit in the FTD group, possibly seated in social knowledge impairments. No other significant differences were found across patient groups on the social cognition tests or the IATs, though individual patient performance fell in line with previous findings in terms of neural substrates, behavioural manifestations, and disease progression. Future studies including larger patient groups may provide further insight into the specificity and sensitivity of the Social Rule Break Cartoons task, and allow for a pattern in IAT performance to emerge.