Neuropsychiatric symptoms, behavioural disorders, and quality of life in Parkinson's disease.

Parkinson's disease is a complex neurodegenerative disorder characterized by motor and non-motor symptoms, with neuropsychiatric manifestations among the most frequent non-motor symptoms. Health-related quality of life is a patient-reported outcome that reflects the impact of the disease on physical, mental, and social wellbeing, and on other aspects of patient' life. Although older studies on health-related quality of life in Parkinson's disease mainly investigated the role of the motor impairment, recent research focused on non-motor symptoms has highlighted the critical role that behavioural disturbances due to neuropsychiatric symptoms play in determining health related quality of life. A considerable number of studies have demonstrated the importance of depression as a determinant of health-related quality of life in this population, but less evidence is available regarding the role of other neuropsychiatric symptoms such as anxiety, apathy, psychosis, and impulse control disorders. This narrative review analyses recent literature on this topic, focusing on studies in which neuropsychiatric symptoms were investigated as potential determinants of quality of life using regression techniques, including discussion of the assessment tools used.