Epigenetic and Dementia

Epigenetic is a process where so-called "dormant" genes are switched on or off in response to specific chemical triggers. The best example we have in aging is the increasing differentiation of identical twins—twins that developed from a single egg. In the 2005 proceedings at the National Academy of Science where a group of Spanish, Swedish, Danish, English, and American investigators report their study conclusions, it was reported that whereas young identical twin pairs are essentially indistinguishable in their epigenetic markings, older identical twin pairs show substantial variations. Resulting in increasing differences between the pair. This has been termed as “epigenetic drift” which is associated with aging.

Differences in gene expression among older twin pairs were some four times greater than those observed in young twin pairs. And the environment plays a significant role in this differentiation.  The more different the twins' upbringing, the greater the difference in their epigenetic makeup and observable differences between the two twins.  In some cases there is enough of a difference so that one twin gets dementia and the other does not. Although some genes have been identified for some early-onset forms of Alzheimer's disease, genes only explain 10-5% of diagnosed Alzheimer's disease, the rest remain unexplained and epigenetics might hold the answer.

Paul Coleman, from Sun Health Research Institute, in Arizona, looked at one set of identical twins—one who died of Alzheimer's disease, while the other twin died without Alzheimer’s disease. Coleman and his colleagues found that the twin that died from Alzheimer's disease not only had the characteristic disease in the brain but he also had less epigenetic activity (DNA methylation) indicating that this might be the reason for getting the disease in the first place. The twins attended the same schools and both worked as chemical engineers. However in their adult life, the one that died from Alzheimer's disease at the age of 76 was exposed to extensive pesticides at work, while the healthier twin worked in a different environment and died of prostate cancer at age 79.

Because there are so many factors involved in daily living, there is an issue in saying that the environment switches on/off specific genes that causes changes in the brain. However, emerging new results in dementia, are exposing examples where people with the disease—plaques and tangles throughout the brain—are escaping the expression of dementia. The only feasible answer is the possibility of epigenetic influences.

Epigenetic process has also been shown why certain diseases promote the expression of dementia A study by Jun Wang and her colleagues from New York Mount Sinai Hospital demonstrated that diabetes may bring about epigenetic changes. Having diabetes switches on a disease mechanism in the brain that makes the diabetic patient more prone to dementia. For the first time there is a study that shows why diabetic patients are at an increased risk of developing dementia. This new evidence, that diabetes might be the trigger to dementia, is a more likely cause given that approximately 60 percent of Alzheimer's disease patients have at least one serious medical condition associated with diabetes.
Epigenetics might hold the key in consolidating research findings that we could not explain before, while at the same time  provide a theoretical explanation of how environmental and external factors contribute to the expression of dementia.

© USA Copyrighted 2013 Mario D. Garrett