Don't take stress or depression lightly, they can actually shrink the brain and contribute to both emotional and mental degradation, according to a US study.
Now researchers have discovered one reason why this occurs - a single genetic switch that triggers loss of brain connections in humans and depression in animal models.
The findings show that 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, which in turn could contribute to loss of brain mass, the journal Nature Medicine reports.
"We wanted to test the idea that stress causes a loss of brain synapses (junctions of nerve cells) in humans," said senior study author Ronald Duman, professor of psychiatry, neurobiology and pharmacology at Yale University.
"We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated," he added.
The research team analysed tissue of depressed and non-depressed patients donated from a brain bank and looked for different patterns of gene activation, according to a statement from Yale.
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.