Parkinson’s Disease and Parkinson-Plus Syndromes

Abstract

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder characterized by motor symptoms arising from the loss of dopamine-producing neurons in the midbrain. It is also associated with non-motor symptoms, including in cognition and mood, related to pathology elsewhere in the brain, from lower brainstem to cortex; some present well before the motor symptoms. The diagnosis of PD is based on history and clinical examination, and the cause remains unknown. The Parkinson-plus syndromes (dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration) are less common than idiopathic PD. Differential diagnosis is challenging due to substantial heterogeneity in the presentation of PD, which comprises motor subtypes, and the Parkinson-plus syndromes. Treatment is symptomatic and focuses primarily on dopamine replacement and the relief of motor symptoms, although efforts are underway to also treat the debilitating non-motor symptoms through behavioral and pharmacological interventions. Neuropsychological assessment is of value in identifying and tracking changes in cognition, with the earliest and most common problems being in attention and executive function. Research on biomarkers for PD and the Parkinson-plus syndromes is increasing in regard to genetic factors, neuroimaging, and fluid markers. Moving beyond the traditional view of PD and the Parkinson-plus syndromes as motor disorders and considering the full spectrum of symptoms will be an important step toward identifying biomarkers in the prodromal phase, as well as enhancing understanding of the course of the diseases in regard to brain and behavior, which ultimately should lead to improved care on the path to cure.