Subjective cognitive and olfactory impairments predict different prospective dementia outcomes

Area of Science:

• Neuroscience
• Gerontology
• Public Health

Background:

• Self-reported measures are increasingly recognized for their potential in early disease detection.
• Dementia, including Alzheimer's disease (AD) and Parkinson's disease (PD), poses a significant public health challenge.
• Early identification of individuals at risk is crucial for timely intervention and management.

Purpose of the Study:

• To investigate the predictive value of various self-reported measures for different dementia subtypes.
• To assess the risk of progression to Alzheimer's disease (AD) dementia, Parkinson's disease (PD) dementia, or other-cause dementia.
• To determine the utility of subjective cognitive decline (SCD), subjective olfactory impairment (SOI), subjective taste impairment (STI), and self-reported poor health (SPH) in dementia risk prediction.

Main Methods:

• Utilized data from 6,028 cognitively unimpaired individuals in the 8th wave of the English Longitudinal Study of Ageing (ELSA) as a baseline.
• Included a 2-year follow-up sample of 5,297 individuals from the 9th wave of ELSA.
• Employed logistic regression models to analyze the association between self-rated measures and dementia outcomes, controlling for age.

Main Results:

• Subjective cognitive decline (SCD) based on memory complaints significantly predicted progression to AD dementia (OR=11.145) and other-cause dementia (OR=4.448).
• Subjective olfactory impairment (SOI) significantly predicted progression to PD dementia (OR=7.440).
• Older age was a significant predictor across all dementia outcomes, and non-memory cognitive complaints also predicted other-cause dementia.

Conclusions:

• Self-reported measures, particularly SCD and SOI, are valuable and accessible tools for identifying individuals at risk of specific dementia types.
• These subjective assessments, combined with demographic factors like age, can aid in early dementia screening within the general population.
• Different subjective complaints are specifically associated with distinct dementia outcomes, highlighting their targeted predictive potential.