Progression of corpus callosum atrophy in Alzheimer disease.
BACKGROUND
Atrophy of the corpus callosum in the absence of primary white matter degeneration reflects loss of intracortical projecting neocortical pyramidal neurons in Alzheimer disease (AD).


OBJECTIVE
To determine individual rates of atrophy progression of the corpus callosum in patients with AD and to correlate rates of atrophy progression with clinical disease severity and subcortical disease.


METHODS
Magnetic resonance imaging-derived measurements of corpus callosum size were studied longitudinally in 21 patients clinically diagnosed as having AD (mean observation time, 17.0 +/- 8.5 months) and 10 age- and sex-matched healthy controls (mean observation time, 24.1 +/- 6.8 months).


RESULTS
Corpus callosum size was significantly reduced in AD patients at baseline. Annual rates of atrophy of total corpus callosum, splenium, and rostrum were significantly larger in AD patients (-7.7%, -12.1%, and -7.3%, respectively) than in controls (-0.9%, -1.5%, and 0.6%, respectively). Rates of atrophy of the corpus callosum splenium were correlated with progression of dementia severity in AD patients (rho = 0.52, P<.02). The load of subcortical lesions at baseline (P<.05) predicted rate of anterior corpus callosum atrophy in healthy controls. Rates of atrophy of corpus callosum areas were independent of white matter hyperintensity load in patients with AD.


CONCLUSIONS
Measurement of corpus callosum size allows in vivo mapping of neocortical neurodegeneration in AD over a wide range of clinical dementia severities and may be used as a surrogate marker for evaluation of drug efficacy.
Teipel
Stefan J
SJ
and Harald Hampel, MD, Dementia and Neuroimaging Section, Department of Psychiatry, Ludwig-Maximilian University, Nussbaumstr 7, 80336 Munich, Germany. stt@psy.med.uni-muenchen.de
Bayer
Wolfram
W
Alexander
Gene E
GE
Zebuhr
York
Y
Teichberg
Diane
D
Kulic
Luka
L
Schapiro
Marc B
MB
Möller
Hans-Jürgen
HJ
Rapoport
Stanley I
SI
Hampel
Harald
H
D000368:Aged; D000544:Alzheimer Disease / Q000150:complications*; D001284:Atrophy; D015415:Biomarkers; D003337:Corpus Callosum / Q000473:pathology*; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D012720:Severity of Illness Index
D015415:Biomarkers