The association between motor subtypes and psychopathology in Parkinson's disease

Abstract

Background: In Parkinson's disease (PD) it has been suggested that various motor subtypes are also characterized by a different prevalence and severity of specific non-motor symptoms such as cognitive deterioration, depression, apathy and hallucinations. The aim of this study was to investigate the association between motor subtypes and psychopathology in PD.

Methods: An exploratory and confirmatory cluster analysis of motor and psychopathological symptoms was performed with a randomized sample of 173 patients each, stemming from two research databases: one from Stavanger University Hospital and one from Maastricht University Hospital. These databases contained data of standardized assessments of patients with the Unified Parkinson's Disease Rating Scale, the Montgomery-Asberg Depression Rating Scale, and the Mini-Mental State Examination.

Results: PD patients can be accurately and reliably classified into four different subtypes: rapid disease progression subtype, young-onset subtype, non-tremor-dominant subtype with psychopathology and a tremor-dominant subtype. Cognitive deterioration, depressive and apathetic symptoms, and hallucinations all cluster within the non-tremor-dominant motor subtype, that is characterized by hypokinesia, rigidity, postural instability and gait disorder.

Conclusions: This study shows that non-tremor-dominant PD is associated with cognitive deterioration, depression, apathy, and hallucinations, which has implications for future research into the pathophysiology of psychopathology in PD.