Mild behavioural impairment in Parkinson’s disease: a systematic review

Abstract Behavioural symptoms are common manifestations of Parkinson’s disease (PD). Early behavioural symptoms characterise mild behavioural impairment (MBI). The prevalence and intensity of MBI in people with PD (PwP) have been studied across various cohorts. However, methodological differences have obscured our understanding of MBI in these individuals. This systematic review examines and synthesises findings from relevant studies, enhancing understanding of the symptoms and implications of MBI in PD. Nine studies from five separate research institutions were identified. The conceptualisation of MBI varied considerably, affecting the reported prevalence rates of MBI in individuals with early-stage PD. Among PwP, MBI was associated higher education and impaired cognition. Affective dysregulation and impulse control disorders were primary contributors to MBI; abnormal perception was least contributor. This systematic review underscores the specific characteristics and incidence of MBI in early-stage PD. Mood and impulse control disorders are primary concerns associated with MBI. Future longitudinal studies are required to clarify the progression of these symptoms and evaluate MBI’s potential as an indicator for PD-related dementia or increased dependency.