Epigenetics, the study of how the environment modifies the way the human gene is expressed, is an emerging frontier in science. Diet and exposure to environmental chemicals, among other factors, can cause epigenetic changes that may turn on or off certain genes and make people more or less susceptible to developing Alzheimer’s disease and other disorders. Positive factors, such as physical activity and enriched living conditions, may result in beneficial epigenetic changes such as a longer health span or lowered incidence of chronic diseases. These changes in gene function profoundly influence the behavior of cells and tissues and play a role in neurobiological and cognitive processes, including learning, memory, circadian rhythm, and neurodegeneration.
Until now, little was known about how various epigenetic processes differ across different brain regions, or how the effects of those processes may influence brain activity. NIA-supported researchers investigated DNA methylation, one type of epigenetic modification that can control the level at which a gene is expressed, to produce the first annotated map of patterns of DNA methylation in the brain. Using blood samples and postmortem brain tissue from donors older than age 75 and free of any neuropathology and neuropsychiatric disease, they were able to demonstrate marked differences in methylation in six areas of the brain.
Notably, the investigators at King’s College London, and Baylor College of Medicine, Houston, found increased rates of methylation in regions involved in nervous system development and function and in neurogenesis. Research like this may, one day, result in our ability to investigate epigenetic processes in the brain by studying DNA methylation patterns in readily accessible blood samples.
The data generated in this project are available as a resource to the genomics research community through several avenues, including integration into the Human Epigenome Atlas as part of the regular data release by the NIH Epigenomics Roadmap Initiative .
Reference: Davies, M., et al. Functional annotation of the human brain methylome identifies tissue-specific epigenetic variation across brain and blood. Genome Biology  2012, 13:R43