Neuropsychiatric symptoms (NPS) are common in neurodegenerative disorders such as Alzheimer’s disease/Mild Cognitive Impairment (AD/MCI), Parkinson’s disease (PD), Frontotemporal Dementia (FTD), Amyotrophic Lateral Sclerosis (ALS) and in those with Cerebrovascular disease (CVD). The relationship between symptoms, cognition, and function in these cohorts is unclear.
Data was obtained from the Ontario Neurodegenerative Disease Research Initiative study. We used the Neuropsychiatric Inventory Questionnaire‐ severity scale (NPIQ) to measure NPS, Montreal Cognitive Assessment (MoCA) for cognition, and Lawton’s informant based questionnaires to measure basic and instrumental activities of daily living (ADLs/iADLs). Linear regression was performed to investigate the effects of NPS on ADL and iADL function while controlling for age, education and cognition. Results were bootstrapped by resampling residuals (n=1,000) to control for non‐normal sample distribution.
520 participants were enrolled: AD/MCI (n=126), VCD (n=161), PD (n=140), FTD (n=53), and ALS (n=40). There were significant differences between these cohorts on NPIQ scores (AD/MCI=16.77±0.18, VCD=16.94±0.12, PD=16.34±0.17, FTD=21.44±0.15, ALS=14.19±0.22,
p< .001). Across combined cohorts, NPIQ was inversely correlated with MoCA (rs=‐0.15, p=.001), iADLs (rs=‐0.32, p<.001), and ADLs (rs=‐0.34, p<.001). NPIQ (alone) predicted iADLs in FTD, and (together with MoCA) in MCI/AD and PD (Corrected pvalues < .05) but not in CVD or ALS. Further, NPIQ alone predicted ADLs in AD/MCI, FTD and PD (Corrected pvalues < .05) but not in VCD or ALS. Conclusion
NPS burden was different across neurodegenerative disease cohorts. NPS were the main determinants of function in FTD, and in AD/MCI and PD when combined with cognition. However, NPS did not determine function in VCD or ALS. These findings indicate the need for further research into biomarkers of NPS and function, and targets of clinical interventions in neurodegenerative disorders.