Longitudinal neuroimaging correlates of subjective memory impairment: 4-year prospective community study.

BACKGROUND Complaints about memory are common in older people but their relationship with underlying brain changes is controversial. AIMS To investigate the relationship between subjective memory impairment and previous or subsequent changes in white matter lesions and brain volumes. METHOD In a community cohort study of 1336 people without dementia, 4-year changes in brain magnetic resonance imaging measures were investigated as correlates of subjective memory impairment at baseline and follow-up. RESULTS Subjective memory impairment at baseline was associated with subsequent change in hippocampal volume and at follow-up impairment was associated with previous change in hippocampal, cerebrospinal fluid and grey matter volume and with subcortical white matter lesion increases. All associations with volume changes were U-shaped with significant quadratic terms - associations between least decline and subjective memory impairment were potentially explained by lower baseline hippocampal volumes in the groups with least volume change. Associations between hippocampal volume change and subjective memory impairment at follow-up were independent of cognitive decline and depressive symptoms, they were stronger in participants with the apolipoprotein E (APOE) ε4 allele and in those without baseline subjective memory impairment. CONCLUSIONS Complaints of poor memory by older people, particularly when new, may be a realistic subjective appraisal of recent brain changes independent of observed cognitive decline.