This article summarizes the underlying biology and current diagnostic and treatment strategies for the cognitive and neuropsychiatric features of Parkinson disease (PD) and dementia with Lewy bodies (DLB).
Cognitive impairment and neuropsychiatric symptoms have been increasingly recognized in PD and DLB, leading to improved diagnosis and treatment strategies. While PD is most associated with and diagnosed by the presence of motor symptoms, nonmotor symptoms can often be the most debilitating for patients. Neuropsychiatric symptoms are highly prevalent nonmotor features and include cognitive impairment, depression, anxiety, psychosis, impulse control disorders, and apathy. Neuropsychiatric symptoms can be difficult to recognize and diagnose in patients with PD, in part because of comorbidity and symptom overlap with core PD features. Treatment strategies are a combination of pharmacologic and nonpharmacologic interventions used in the general population and those specific to PD. DLB is a clinical dementia syndrome, often with similar cognitive, behavioral, autonomic, and motor features as PD. Moreover, DLB has shared underlying pathophysiology with PD, as both are associated with postmortem findings of α-synuclein neuropathology at autopsy and have shared genetic risk and prodromal symptoms. DLB is clinically differentiated from PD by the presenting features of cognitive impairment in DLB, compared with the variable onset of cognitive impairment occurring 1 year or more after established motor onset in PD. Thus, diagnosis and treatment of cognitive impairment and neuropsychiatric symptoms in DLB are similar to that of PD and have important implications for maintaining patient independence and providing support for caregivers because motor, cognitive, and neuropsychiatric symptoms have an additive effect on patient functional disability.
A careful history and physical examination are often needed to accurately diagnose and treat the heterogeneous cognitive and behavioral symptoms of PD and DLB. Accurate diagnosis and treatment of neuropsychiatric symptoms and cognitive impairment in PD and DLB are important, as these are a considerable source of patient disability and caregiver burden.