The rates of regional brain loss and cognitive decline caused by aging and the early stages of Alzheimer's disease (AD) are higher for women and for people with a key genetic risk factor for AD, say researchers at the University of California, San Diego School of Medicine in a study published online July 4 in the American Journal of Neuroradiology.
The linkage between APOE ε4 which codes for a protein involved in binding lipids or fats in the lymphatic and circulatory systems was already documented as the strongest known genetic risk factor for sporadic AD, the most common form of the disease. But the connection between the sex of a person and AD has been less-well recognized, according to the UC San Diego scientists.
"APOE ε4 has been known to lower the age of onset and increase the risk of getting the disease," said the study's first author Dominic Holland, PhD, a researcher in the Department of Neurosciences at UC San Diego School of Medicine. "Previously we showed that the lower the age, the higher the rates of decline in AD. So it was important to examine the differential effects of age and APOE ε4 on rates of decline, and to do this across the diagnostic spectrum for multiple clinical measures and brain regions, which had not been done before."
The scientists evaluated 688 men and women over the age of 65 participating in the Alzheimer's Disease Neuroimaging Initiative, a longitudinal, multi-institution study to track the progression of AD and its effects upon the structures and functions of the brain. They found that women with mild cognitive impairment (a condition precursory to AD diagnosis) experienced higher rates of cognitive decline than men; and that all women, regardless of whether or not they showed signs of dementia, experienced greater regional brain loss over time than did men. The magnitude of the sex effect was as large as that of the APOE ε4 allele.
"Assuming larger populatio
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University of California - San Diego