Scientists have known that stress and depression can cause the brain to retract or lose volume, a condition associated with both emotional and cognitive impairment. Now, a new study discovers why this occurs.
Yale scientists have found that the deactivation of a single genetic switch can instigate a cascading loss of brain connections in humans and depression in animal models.
Researchers say the genetic switch, known as a transcription factor, represses the expression of several genes that are necessary for the formation of synaptic connections between brain cells. The loss of connections, in turn, can contribute to loss of brain mass in the prefrontal cortex, say the scientists.
“We wanted to test the idea that stress causes a loss of brain synapses in humans,” said senior author Ronald Duman, Ph.D. “We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated.”
In the study, the research team analyzed tissue of depressed and non-depressed patients donated from a brain bank and looked for different patterns of gene activation.
The brains of patients who had been depressed exhibited lower levels of expression in genes that are required for the function and structure of brain synapses.
Lead author and postdoctoral researcher H.J. Kang, Ph.D., discovered that at least five of these genes could be regulated by a single transcription factor called GATA1.
When the transcription factor was activated in animal models, rodents exhibited depressive-like symptoms, suggesting GATA1 plays a role not only in the loss of connections between neurons but also in symptoms of depression.
This finding of genetic variations in GATA1 may help researchers identify people at high risk for major depression or sensitivity to stress.
“We hope that by enhancing synaptic connections, either with novel medications or behavioral therapy, we can develop more effective antidepressant therapies,” Duman said.
Source: Yale University