Medial temporal lobe
atrophy (
MTA) is a recognized marker of
Alzheimer's disease (AD), however, it can be prominent in
frontotemporal lobar degeneration (
FTLD). There is an increasing awareness that posterior
atrophy (PA) is important in AD and may aid the differentiation of AD from
FTLD. Visual rating scales are a convenient way of assessing
atrophy in a clinical setting. In this study, 2 visual rating scales measuring
MTA and PA were used to compare
atrophy patterns in 62 pathologically-confirmed AD and 40
FTLD patients. Anatomical correspondence of
MTA and PA was assessed using manually-delineated regions of the hippocampus and posterior cingulate gyrus, respectively. Both
MTA and PA scales showed good inter- and intrarater reliabilities (kappa > 0.8).
MTA scores showed a good correspondence with manual hippocampal volumes. Thirty percent of the AD patients showed PA in the absence of
MTA. Adding the PA to the
MTA scale improved discrimination of AD from
FTLD, and early-onset AD from normal aging. These results underline the importance of considering PA in AD diagnosis, particularly in younger patients where medial temporal
atrophy may be less conspicuous.