Major depression or chronic stress can shrink the brain and decrease brain volume, resulting in emotional and cognitive impairment, according to a new study.

Scientists at Yale University revealed that a single genetic switch was responsible for triggering the loss of brain connection in humans and depression in animal models.

The latest findings, published in the journal Nature Medicine, suggest that the loss in brain mass in the prefrontal cortex of depressed patients could be caused by a genetic switch called the transcription factor, which represses the expression of several genes that are essential for the formation of synaptic connections between brain cells.

"We wanted to test the idea that stress causes a loss of brain synapses in humans," senior author Professor Ronald Duman of the Elizabeth Mears and House Jameson Professor of Psychiatry said in a university new release. "We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated."

Duman and his team had analyzed tissue of depressed and non-depressed patients donated from a brain bank to identify different patterns of gene activation. 

They found that the brains of patients who had been depressed showed lower levels of expression in genes responsible for the function and structure of brain synapses.

Furthermore, lead researcher H.J. Kang found that at least of five of the genes could be regulated by a single transcription factor called GATA1.

Researchers said that rodents displayed depression-like symptoms when the GATA1 transcription factor was activated, suggesting that GATA1 may also be responsible for depression symptoms as well as the loss of connections between neurons.

Researchers believe that the genetic variations in GATA1 may one day help detect people at high risk for major depression or anxiety.

"We hope that by enhancing synaptic connections, either with novel medications or behavioral therapy, we can develop more effective antidepressant therapies," Duman said.