Basal ganglia contributions to social cognition: evidence from movement disorders.

Introduction and method: Over the last few decades many studies have demonstrated that various populations with movement disorder exhibit a variety of difficulties with social cognition. This brief review paper summarises the major findings of social cognitive research conducted in various hypo- and hyper-kinetic movement disorders (Parkinson's disease, Huntington's disease and Tourette syndrome), with a focus on findings that may shed new light on the functions of the basal ganglia.Results: Task impairments include more predictable difficulties with embodied processes involving the motor system, such as problems with facial expressions and other non-verbal gestures. The cognitive and emotional changes associated with broader frontostriatal dysfunction may also explain some deficits, particularly difficulties with verbal tasks or perspective taking, with impacts varying according to the type of disorder and disease stage. Most intriguingly, transdiagnostic comparisons reveal patterns implying that the role of the basal ganglia in social cognition may be more important than previously recognised.Conclusions: Movement disorders show remarkable overlap in terms of atypical intention attribution across various tasks, as well as relationships between social cognition and behavioural or motivational symptoms (e.g., apathy; anhedonia; impulsivity). The possible mechanisms underlying these similarities are explored with a view to guiding future research.