A study published in the journal Nature Medicine states that severe depression and chronic stress can shrink the brain by blocking the formation of new nerve connections. This thought to contribute to shrinkage of the brain's prefrontal cortex, which is known to occur in MDD sufferers.

For the study, researchers at Yale analyzed tissue of depressed and non-depressed patients who had died  of MDD. They looked for different patterns of gene activation, and found that those in depression exhibited lower levels of expression in genes that are required for the function and structure of brain synapses. 

Evidence pointed to the involvement of a single genetic "switch", or transcription factor - a protein called GATA1. Further studies on rats showed that when GATA1 was switched on, the rodents showed signs of depression.

The findings suggest that loss of brain synapses may be linked to depressive symptoms as well as mental impairment. The researchers hope that these genetic variations in GATA1 may one day help identify people at high risk and help improve treatment methods.

via The Hindu