A COMMENT ON AGE AT ONSET AS A SUBTYPE OF ALZHEIMER-DISEASE

Subtypes of Alzheimer disease (AD) can be approached from different wa ys. An intuitive and commonly proposed subtype relates to the age at o nset of disease. Research on age at onset as a subtype has yielded con flicting results that may, in part, reflect different measurement appr oaches. Refinement of the measurement of change in AD should yield a c learer picture of subtypes, as would closer ties between neuropatholog ic and clinical work. Thus, it is suggested that future research shoul d use measurement techniques that more closely characterize AD than do current approaches. In addition, progress would likely be through att empts to link clinical findings regarding rates of change to neuropath ologic findings.