Overlap in frontotemporal atrophy between normal aging and patients with frontotemporal dementias.
Normal aging leads to frontocortical atrophy. The degree to which this complicates the use of frontotemporal atrophy as a diagnostic criterion for the frontotemporal dementias (FTDs) has not been reported. The present case-control study compared frontotemporal volumes delineated with semi-automatic brain region extraction [n=30 controls vs. 16 behavioral variant FTD (bvFTD) vs. 14 primary progressive aphasia]. Logistic regression identified those regions least helpful for distinguishing bvFTD and primary progressive aphasia from controls. Linear regression tested the correlation of duration of illness to atrophy severity. The control group showed high variance in volumes. Controls had right frontal lobe volumes that overlapped considerably with bvFTD volumes, but, as anticipated, the left anterior temporal volumes of interest showed 91% accuracy in distinguishing the aphasic subgroup from controls. Left-sided and not right-sided atrophy in the medial middle frontal region distinguished the bvFTD group from controls. The relegation of structural imaging to a supportive criterion for diagnosis is reasonable in the context of the range of atrophy due to normal aging. While volumetry identified left-sided atrophy as useful for identifying FTD cases, future studies should determine whether clinicians could make these distinctions on viewing routine diagnostic magnetic resonance imaging scans.
Chow
Tiffany W
TW
Division of Neurology, Department of Medicine, University of Toronto, Toronto, Canada. tchow@rotman-baycrest.on.ca
Binns
Malcolm A
MA
Freedman
Morris
M
Stuss
Donald T
DT
Ramirez
Joel
J
Scott
Chris J M
CJ
Black
Sandra
S
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D001284:Atrophy / Q000209:etiology / Q000473:pathology; D016022:Case-Control Studies; D003704:Dementia / Q000473:pathology*; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012372:ROC Curve