Callosal microstructural abnormalities in Alzheimer's disease and alcoholism: same phenotype, different mechanisms.
Magnetic resonance (MRI) and diffusion tensor imaging (DTI) data were acquired in 13 Alzheimer's disease (AD) patients, 15 elderly alcoholics, and 32 elderly controls. Midsagittal area, length, dorsoventral height, fractional anisotropy (FA), and mean diffusivity (MD) of the total corpus callosum and volume of the lateral ventricles were measured; area, FA, and MD were also determined for the callosal genu, body, and splenium. On DTI, both patient groups had lower FA and higher MD than controls in all callosal regions. On MRI, both patient groups had smaller genu than controls; additional size deficits were present in the alcoholism group's callosal body and the AD group's splenium. The callosal arch was higher in the AD but not the alcoholic group compared with controls. The two patient groups had larger ventricles than controls, and the AD group had larger ventricles than the alcoholic group. Callosal area correlated with its height, and callosal FA and MD correlated with ventricular volume in AD, whereas callosal area correlated only with FA in alcoholics. In AD, the disruption of the callosal integrity, which was associated with distorted callosal shape, was related to ventricular dilation, which has been shown in twin studies to be under a multitude of genetic, polygenetic, and environmental influences. Conversely, in alcoholism, disruption of callosal microstructural integrity was related to shrinkage of the corpus callosum itself.
Pitel
Anne-Lise
AL
Department of Psychiatry and Behavioral Sciences and Neuroscience Program, Stanford University School of Medicine, Stanford, CA 94305, USA.
Chanraud
Sandra
S
Sullivan
Edith V
EV
Pfefferbaum
Adolf
A
D000368:Aged; D000369:Aged, 80 and over; D000437:Alcoholism / Q000473:pathology*; D000544:Alzheimer Disease / Q000473:pathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D002552:Cerebral Ventricles / Q000473:pathology; D003337:Corpus Callosum / Q000473:pathology* / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011569:Psychiatric Status Rating Scales; D013223:Statistics as Topic