Are subjective memory complaints indicative of objective cognitive decline or depressive symptoms? Findings from the English Longitudinal Study of Ageing.

Older adults often complain about their memory ability, but it is not clear to what extent subjective memory complaints accurately reflect objective cognitive dysfunctions. The concordance between objective and subjective cognitive performance may be affected by depressive symptoms and by declining insight into cognitive deficits. This study aims to examine longitudinal associations between subjective memory complaints, objective cognitive performance and depressive symptoms. 11,092 participants aged 50 years and above from the English Longitudinal Study of Ageing were followed-up every 2 years over a 6-year period. Two processes latent growth curve models (LGCM) examined associations between levels and changes in several cognitive abilities and subjective memory complaints, unadjusted for depression symptoms. Then three processes LGCM examined associations between levels and changes in depressive symptoms, subjective memory complaints and objective cognitive abilities in the overall sample, and separately among persons with mild cognitive impairment at baseline. More subjective memory complaints were associated with poorer performance in all cognitive domains at baseline. Steeper decline in immediate recall, verbal fluency and processing speed performance was associated increasing subjective memory complaints both in the overall sample and among persons with mild cognitive impairment. Increasing depressive symptoms were associated with both objective and subjective cognitive decline in the overall sample, and only with subjective memory decline among cognitively impaired persons. Self-reported memory complaints may have the potential to identify decline in objective cognitive performance that cannot be explained by depressive symptoms. Among cognitively impaired persons depressive symptoms may amplify subjective but not objective cognitive decline.