Subjective Memory Impairment in the General Adult Population: Associations With Early-Life Cognition, Concurrent...

Subjective memory impairment (SMI) is used as a proxy for objective memory, although their relationship remains unclear. Moreover, SMI is suggested to be a risk factor for dementia. This study investigated associations between SMI and (1) concurrent objective memory performance, (2) early-life general cognitive abilities (GCA), and (3) if SMI and objective memory scores were associated with distinct or overlapping sociodemographic, health, and lifestyle risk factors for dementia.

2690 participants between 30 and 90 years from the general, geographical population study HUNT4 were included. SMI scores were from the Meta-Memory-Questionnaire. Verbal, spatial, and ability to differentiate between similar representations (pattern separation) were tested concurrently. GCA was from conscription at age 18. We implemented multiple imputation and inverse probability weighting from the entire population to account for selection bias.

Higher SMI scores were associated with verbal memory and GCA, but not spatial or pattern separation memory. There was an interaction between sex and verbal memory on SMI, with men reporting higher SMI than women at similar lower verbal memory performance. Higher SMI scores were associated with higher age, blood pressure, depression, sleep, fatigue, and chronic pain, but not APOE4 or lifestyle variables. All memory tests were positively associated with each other and negatively with age. Diabetes was associated with verbal memory.

In the general population, SMI was weakly linked to concurrent verbal memory and GCA in adolescence. Health, in particular mental health, was highly associated with SMI but not objective memory performance. Thus, SMI is a complement to memory testing, not a proxy.