The moral brain and moral behaviour in patients with Parkinson's disease: a review of the literature

Morality is a complex and versatile concept that necessitates the integrated activity of multiple interacting networks in the brain. Numerous cortical and subcortical areas, many of which are implicated in either emotional and cognitive control or Theory of Mind, are involved in the processing of moral behaviour. Different methods have been used to investigate various aspects of morality, which has lead to confusing and sometimes opposing results. Emotional, cognitive and personality changes have long been recognized in Parkinson's disease (PD) patients, suggesting a potential impact on moral aspects of behaviour in daily living situations. Alterations in social cognition have been described in all stages of PD but these are rather directly related to PD pathology and not to dopaminergic or DBS treatment. There are no convincing data supporting the hypothesis that dopaminergic treatment or deep brain stimulation of the STN per se interfere with morality in PD patients, although subgroups of patients may display socially unacceptable behaviour. Research in social cognition in PD patients is a fascinating topic that needs further attention in view of the impact on quality of life for PD patients and their caregivers.