It is widely believed that the brain is biologically affected and altered by stress, but it is very difficult to “see into the brain” to identify the processes and pinpoint the effects. In new research at Johns Hopkins University, a team of scientists led by 2009 NARSAD Young Investigator Grantee Richard S. Lee, Ph.D., found that in an animal model of stress, changes to DNA detected in blood samples were mirrored in brain tissue. The finding, proving a long-held but previously unconfirmed concept, could significantly aid in identification and treatment of mental illnesses.
To study this, the researchers treated mice with different doses of cortisol, the primary stress hormone, over a four-week period. They took blood samples weekly to measure genetic alterations and then dissected the brains at the end of the month to see if the genetic alterations were also found in the brain tissue. They were looking in particular at changes to a gene called FKBP5 that has been implicated in depression, bipolar disorder and post-traumatic stress disorder. They report, in a paper reported online in advance of June publication in Psychoneuroendocrinology, that epigenetic changes—lasting alterations in how a gene is expressed and functions without an alteration to the underlying DNA sequence—detectable in the blood mirrored alterations in brain tissue linked to underlying psychiatric diseases.
"Many human studies rely on the assumption that disease-relevant epigenetic changes that occur in the brain—which is largely inaccessible and difficult to test—also occur in the blood, which is easily accessible," said Dr. Lee, an instructor in the Department of Psychiatry and Behavioral Sciences. "This research on mice suggests that the blood can legitimately tell us what is going on in the brain, which is something we were just assuming before, and could lead us to better detection and treatment of mental disorders and a more empirical way to test whether medications are working."