Neuropsychiatric Symptoms in Parkinson's Disease Dementia Are More Similar to Alzheimer's Disease than Dementia with Lewy Bodies: A Case-Control Study

Background and purpose Previous studies on the clinical and pathological manifestations of Parkinson's disease dementia (PDD) have reported findings more similar to dementia with Lewy bodies (DLB) than to Alzheimer's disease (AD). The aim of this study was to investigate the neuropsychiatric symptoms of PDD compared to DLB and AD. Methods We conducted a retrospective case-control study on 125 newly diagnosed consecutive PDD patients and age-and dementia stage-matched controls with either DLB (N = 250) or AD (N = 500) who visited the same hospital over the same period. For each case and control, neuropsychiatric symptoms were assessed using the Neuropsychiatric Inventory (NPI). Results Overall, 513 (58.6%) patients were female and 362 (41.4%) were male. Comparisons of clinical data revealed that the PDD group, similar to the AD group, had a lower NPI total score, NPI caregiver burden score, and rate of antipsychotic use (all p < 0.001) than the DLB group. One or more psychiatric symptoms were reported in 95.2% of the PDD, 99.2% of the DLB, and 96.8% of the AD patients. The PDD group had lower subscores in the items of delusions, hallucinations, agitation, anxiety, irritation, aberrant motor behavior compared to the DLB group. Severe neuropsychiatric symptoms among all dementia patients were associated with younger age, more advanced stage, and a diagnosis of DLB. Conclusion Neuropsychiatric symptoms in PDD were more like those in AD than in DLB. Severe neuropsychiatric symptoms in degenerative dementia were associated with younger age, more advanced stage of dementia, and a diagnosis of DLB.