Friday, July 10, 2009

Hypertrophy May Be the Key to Silent Alzheimer's Disease

Neuronal hypertrophy more common in those with asymptomatic form of disease

THURSDAY, July 9 (HealthDay News) -- The brain cells of people with asymptomatic Alzheimer's disease undergo significant hypertrophy, which may be a compensatory mechanism to prevent cognitive impairment, according to a study published online July 8 in Neurology.

Diego Iacono, M.D., of Johns Hopkins University in Baltimore, Md., and colleagues measured the volumes of neuronal cell bodies, nuclei and nucleoli in the CA1 region of the hippocampus of four groups of subjects: 10 with asymptomatic Alzheimer's disease, five with mild cognitive impairment, 10 with Alzheimer's disease, and 13 age-matched controls. They also compared the linguistic ability of all groups in early life.

Among the subjects with asymptomatic Alzheimer's disease, there were significantly greater degrees of hypertrophy compared to the subjects with mild cognitive impairment, at 44.9 percent more for cell bodies, 59.7 percent for nuclei, and 80.2 percent for nucleoli, the investigators found. Subjects in the control and asymptomatic Alzheimer's disease groups also had significantly higher idea density scores than their counterparts in the mild cognitive impairment and Alzheimer's disease groups.

"The major finding of the present study is the significant hypertrophy of cell bodies, nuclei and nucleoli in CA1 neurons of asymptomatic Alzheimer's disease subjects compared with the mild cognitive impairment and age-matched controls groups," the authors write. "Neuronal hypertrophy may constitute an early cellular response to Alzheimer's disease pathology or reflect compensatory mechanisms that prevent cognitive impairment despite substantial Alzheimer's disease lesions."

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