Age-associated memory impairment and early Alzheimer's disease. Only time will tell the difference

A reliable and early diagnosis of incipient Alzheimer's disease (AD) is one of the obligatory requirements for timely and potentially successful therapeutic intervention. The potential diagnostic significance of mild cognitive impairment and subjective memory complaints was examined. Groups of patients with age-associated memory impairment (AAMI) and with AD were examined prospectively and their subjective complaints, cognitive performance and neuroimaging findings were compared with those of healthy elderly controls. Subjective complaints were most severe in the AD group. Both, memory complaints and depressive disturbances had high loadings on one underlying principal component. There was no statistical correlation between a global score of cognitive performance and subjective complaints in the patient groups, but the correlation between performance and brain atrophy was statistically significant. The degree of brain atrophy, but not subjective complaints (or the diagnostic distinction between AAMI and AD) were associated with the severity of cognitive deterioration during a 2-year follow-up period. This, and the observation of an increased frequency of the apolipoprotein E allele 4 in the AD and AAMI groups, suggest that biological risk markers will be of greater significance for the early diagnosis of AD than the patient's subjective complaints. Patients satisfying criteria for AAMI need to be followed-up, because no reliable diagnostic markers for the earliest or preclinical stages of AD are available to date.