Subjective memory complaints: Prevalence, associated factors and sex differences in the ELSI-Brazil study.

Background: Subjective memory complaints (SMCs) are a possible prodrome of cognitive decline but are understudied in low- and middle-income countries (LMIC). We aimed to estimate the prevalence of SMCs in a large, nationally representative sample of older adults from Brazil and to identify sociodemographic and health-related factors that are associated with SMCs independently of objective memory.

Methods: Baseline data (n = 7831) from the ELSI-Brazil study, a national representative sample of adults aged 50 and over. They were asked to rate their memory and then divided into two groups - having or not having SMCs. Logistic regression models were used to estimate the association of demographic characteristics, health related factors, objective memory performance and disability in basic (b-ADL), instrumental (i-ADL), and advanced (a-ADL) activities of daily living associated with SMCs. Whether sex was an effect modifier of the association between age and objective memory performance and SMCs was also tested.

Results: Of the sample, 42% (95% CI; 39.9-43.9) had SMCs, and it was higher among women (46.9%) than men (35.9%). SMC prevalence decreased with age among women and increased among men, and for both it decreased with better cognitive performance. Fully adjusted logistic regression model showed that older age, higher education, higher b-ADL scores, and better cognitive performance were associated with decreased SMCs, while being female, with higher number of chronic conditions, higher i-ADL scores, worst self-rated health, and an increased number of depressive symptoms were associated with increased SMCs. However, the interaction test (p < 0.001) confirmed that increased age was associated with decreased SMCs only among women, and that better objective memory performance was associated with decreased SMCs only among men.

Conclusions: SMCs are common in the Brazilian older population and are associated with health and sociodemographic factors, with different patterns between men and women. There is a need for future studies looking at the cognitive trajectory and dementia risk in older adults with subjective cognitive complaints.