In an article published online today by Scientific American, author Gary Stix points to two apparently conflicting scientific studies regarding a specific variant of the gene encoding ‘cholesteryl ester transfer protein’, CETP I405V. One of these studies, published in early 2011 by researchers at the Albert Einstein College of Medicine, found that individuals who carry two copies of this CETP variant within their DNA appear to have a lower risk of dementia and cognitive decline, and of heart disease. It could potentially be surmised from this study that CETP I405V contributes in some way to healthy aging and longevity.
However, a more recent study conducted at Rush University Medical Center in Chicago has found that CETP I405V may instead correspond to an increased risk of Alzheimer’s. In an attempt to replicate results from the Albert Einstein study, the Rush researchers observed a more rapid rate of cognitive decline in study participants having this CETP variant. Additionally, post-mortem studies of the brains of deceased participants with CETP I405V revealed greater densities of the type of plaque that is characteristic of Alzheimer’s disease.
While startling, these conflicting results are perhaps not surprising, per Mr. Stix:
"Welcome to the wild-and-wooly world of gene-association studies that attempt to tie DNA to disease. Unless the link between a gene and a disease or phenotype is a very strong one, researchers who try to follow up on initial studies often get different results the second or third time around."
Perhaps the differing results in the two CETP I405V studies is due to demographic differences between participants in the two studies, or perhaps these were due to chance rather than genetics. Alternately, perhaps CETP I405V in and of itself has a relatively weak effect on an individual’s cognitive abilities. It’s simply impossible to say at this point in time.
A number of CETP inhibitors are currently in clinical trials for use against cardiovascular disease. Based on the disparate results of the Albert Einstein and Rush studies, one must wonder how these may – or may not – ultimately bear on an individual’s cognitive health.