RSNA: Gene Variation Associated with Brain Atrophy in Mild Cognitive Impairment

Oak Brook, Ill. (PRWEB) January 13, 2014

The presence of a gene variant in people with mild cognitive impairment (MCI) is associated with accelerated rates of brain atrophy, according to a new study published online in the journal Radiology.

The study focused on the gene apolipoprotein E (APOE), the most important genetic factor known in non-familial Alzheimers disease (AD). APOE has different alleles, or gene variations, said the studys senior author, Jeffrey R. Petrella, M.D., associate professor of radiology at Duke University School of Medicine in Durham, N.C.

We all carry two APOE alleles, and most people have at least one copy of the APOE epsilon 3 (3) variant, which is considered neutral with respect to Alzheimers risk, Dr. Petrella said.

The less common epsilon 4 (4) allele, in contrast, is associated with a higher risk for development of AD, earlier age of onset, and faster progression in those affected, as compared with the other APOE alleles.

Dr. Petrella and colleagues recently analyzed data from the Alzheimers Disease Neuroimaging Initiative (ADNI) involving 237 patients, mean age 79.9, with MCI, a slight but noticeable decline in cognitive ability that is tied to a higher risk of AD. The researchers used MRI to measure brain atrophy rates in these patients over a 12- to 48-month period.

The 4 carriers in the study group exhibited markedly greater atrophy rates than 3 carriers in 13 of 15 brain regions hypothesized to be key components of the cognitive networks disrupted in AD.

The results showed atrophy in brain regions we know are affected by AD, in a population of patients who do not have AD, but are at risk for it, Dr. Petrella said. This suggests the possibility of a genotype-specific network of related brain regions that undergo faster atrophy in MCI and potentially underlies the observed cognitive decline.

The researchers did not explore why APOE 4 might accelerate atrophy, but the affect is likely due to a combination of factors, noted Dr. Petrella.

The protein has a broad role in the transport and normal metabolism of lipids and a protective function on behalf of brain cells, including its role in the breakdown of beta-amyloid, one of the proteins implicated in the pathophysiology of AD, he said.

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RSNA: Gene Variation Associated with Brain Atrophy in Mild Cognitive Impairment