Objective: To assess the relationship between individual items from the Neuropsychiatric Inventory and five cognitive domains in patients with Parkinson’s disease (PD) and normal cognitive functioning, mild cognitive impairment, and dementia.

Background: A variety of psychiatric symptoms have been reported in patients with PD. Significant neuropsychiatric symptoms contribute to the quality of life in PD patients. However, there are few studies assessing the relationship between neuropsychiatric symptoms and cognitive impairment in PD.

Method: 119 PD participants received clinical and neuropsychological evaluations and were classified into cognitive groups using Movement Disorder Society Task Force criteria (cognitively normal [PD-NC], n=42; mild cognitive impairment [PD-MCI], n=51; dementia [PDD], n=26). Patients and their caregivers were interviewed with the Neuropsychiatric Interview (NPI). The NPI assesses the presence of delusions, hallucinations, agitation, depression, anxiety, elation, apathy, disinhibition, irritability, motor disturbance, nighttime behaviors, and appetite. The neuropsychological evaluation consisted of tests representing five cognitive domains (attention/working memory, executive function, memory, language, visuospatial function). Raw scores were transformed to z scores on the basis of normative data at our center. Cognitive domain scores were calculated by averaging z scores for neuropsychological tests within each of the specific domains. A linear regression analysis was conducted using a recursive modeling technique.

Results: Using linear modeling with cognitive diagnosis as the outcome and age, PD duration, and NPI scores as predictors, a significant model was obtained (F = 9.680[7,111], p < 0.0005), with age (F = 16.339[1,117], p < 0.0005, followed by PD duration (F = 11.194[1,117], p = 0.001), followed by NPI Delusions (F = 8.188 [1,117], p = 0.005), followed by NPI Irritability (F = 6.888 [1,117], p = 0.01). No other NPI items were significant predictors.

Conclusion: After accounting for PD duration and age, NPI Delusions and Irritability items predicted normal cognitive functioning, mild cognitive impairment, and dementia in patients with PD. Although psychiatric symptoms are reported to be common in PD patients with mild cognitive impairment and dementia, the current findings highlight the comorbidities of delusions and irritability.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-relationship-of-neuropsychiatric-symptoms-and-cognitive-impairment-in-parkinsons-disease/