Measurements of the amygdala and hippocampus in pathologically confirmed Alzheimer disease and frontotemporal lobar degeneration.
BACKGROUND
Differentiating between Alzheimer disease (AD) and frontotemporal lobar degeneration (FTLD) can be difficult, particularly in the earliest stages of the diseases. Patterns of atrophy on magnetic resonance imaging may help distinguish these diseases and aid diagnosis.


OBJECTIVE
To assess the diagnostic utility of magnetic resonance imaging-derived amygdala and hippocampal volumes from patients with pathologically proved AD and FTLD.


METHODS
Cross-sectional volumetric magnetic resonance imaging study of the hippocampus and amygdala.


METHODS
Specialist cognitive disorders clinic. Subjects Thirty-seven subjects, including 10 patients with pathologically proved AD, 17 patients with pathologically proved FTLD, and 10 age-matched control subjects.


METHODS
Hippocampal and amygdala volumes.


RESULTS
Geometric mean amygdala and hippocampal volumes were, respectively, 15.0% (95% confidence interval [CI], 4.2%-24.5%) and 16.4% (95% CI, 5.9%-25.6%) lower in the AD than in the control group. In FTLD, the equivalent differences were 43.1% (95% CI, 31.9%-52.6%) in the amygdala and 36.1% (95% CI, 27.5%-43.7%) in the hippocampus. Volumes were significantly lower in the FTLD than in the AD group (P<.01 in both regions). Within the FTLD clinical subgroups, there was evidence of a difference in pattern of atrophy with greater asymmetry (left smaller than right) in semantic dementia compared with frontal variant FTLD (P<.001). On average, the left hippocampus was 14% smaller in semantic dementia than in frontal variant FTLD, whereas the right hippocampus was 37% larger. On average, the left amygdala was 39% smaller in semantic dementia than in frontal variant FTLD, whereas the right amygdala was only 1% smaller.


CONCLUSIONS
Hippocampal atrophy is not specific to AD or FTLD. However, severe or asymmetrical amygdala atrophy should suggest FTLD. Atrophy patterns follow clinical syndromes rather than pathology.
Barnes
Josephine
J
Dementia Research Centre, University College London, Institute of Neurology, London, England. j.barnes@dementia.ion.ucl.ac.uk
Whitwell
Jennifer L
JL
Frost
Chris
C
Josephs
Keith A
KA
Rossor
Martin
M
Fox
Nick C
NC
D000328:Adult; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000503:physiopathology; D000679:Amygdala / Q000473:pathology* / Q000503:physiopathology; D001284:Atrophy / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D015331:Cohort Studies; D003704:Dementia / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests