Researchers have found evidence of change on the molecular level in the brains of women who suffered from major depressive disorder.
Women are twice as likely as men to develop major depressive disorder (MDD) and more likely to experience recurring episodes. According to the results of a study published online last week in the journal Molecular Psychiatry, the brains of women who suffer from MDD show clear evidence of change on the molecular level.
In the study, researchers looked at post-mortem brain tissue samples of 21 women who had MDD and 21 women who had no history of depression. They found that in the depressed women, tissue from the amygdala, a part of the brain involved in sensing emotion, bore evidence of reduced expression of genes including the one for brain-derived neurotrophic factor (BDNF) and of genes present in certain subtypes of neurons that express the neurotransmitter gamma-aminobutyric acid (GABA).
The researchers then engineered a number of different mutations of the BDNF gene in mice to see what effect they would have on the GABA neurons. They found two mutations that led to the same reduced expression of the GABA subtype and also mirrored other changes seen in the depressed human brains.
The researchers note that it has long been suspected that low levels of BDNF and reduced GABA function are involved in the development of depression. “Our work ties these two concepts together because we first show that BDNF is indeed low in depression and second that low BDNF can influence specific GABA cells in a way that reproduces the biological profile we have observed in the depressed brain,” said the study’s lead author, Etienne Sibille, associate professor of psychiatry at the University of Pittsburgh School of Medicine, in a press release.