Symptom clusters of subjective cognitive decline amongst cognitively normal older persons and their utilities in...

Prior literature on subjective cognitive decline (SCD) has mostly focused on memory complaints. It is uncertain whether the other non-memory complaints are equally relevant and can be used, alongside memory complaints, to identify populations at high risk of cognitive impairment. How the memory and non-memory complaints of SCD cluster with each other amongst community-dwelling individuals was investigated, and the differential utility of the symptom clusters of SCD in predicting objective cognitive performance was evaluated.

This study included 736 participants who were ≥60 years and had normal cognition, using the baseline data of an ongoing cohort study. Participants completed baseline assessments which comprised an SCD scale, a global cognitive measure and neuropsychological tests. Symptom clusters of SCD - as identified from exploratory and confirmatory factor analyses - were included in structural equation models to predict baseline changes in neuropsychological tests.

The symptoms of SCD were split into two distinct factors, of which factor 1 was reported much more frequently than factor 2. Each standard deviation (SD) increment in factor 1 led to a 0.16-0.50 SD increase in global cognition, immediate memory, visuospatial abilities, language, attention and delayed memory (P < 0.05). In contrast, each SD increment in factor 2 worsened some of the cognitive domains by 0.18-0.37 SD.

The various complaints of SCD can have different implications amongst cognitively normal older persons and may possibly be classified into age-related symptoms and pathological symptoms. The findings highlight the need for caution when selecting SCD measures, and illustrate the potential utility of SCD subtypes to inform on the underlying neurobiology.