New Perspectives on the Biology of Depression

"A New Culprit in Depression? Multi-University Study Finds Surprising Differences in Gene Activity in Brains of Depressed People" :

ANN ARBOR, Mich., Oct. 14 (AScribe Newswire) -- The brains of people with severe depression have lower levels of several related molecules that are key to the development, organization, growth and repair of the brain than the brains of people without the disease, or those with the bipolar form of depression, a new study finds.

The discovery, which surprised researchers in the multi-university consortium that made it, suggests a whole new direction for understanding depression and developing new depression treatments. It may even help scientists understand how some antidepressant medications work in the brain to ease symptoms, and why there is wide variation in how depressed people respond to different antidepressants.

... In the current paper, the researchers report what they found when they zeroed in on a group of six kinds of related mRNA that had the most coordinated differences between the samples from depressed brains, the non-depressed brains and the bipolar brains.

These turned out to be mRNAs for four different FGF molecules and two receptors that bind to FGF and are key to their function. Levels of all of the mRNAs encoding these proteins were lower in the brains of people with major depression. Lower mRNA levels mean the brain may not produce enough protein to carry out normal function.

... Akil notes that the brains of bipolar people in the study did not show the decreased FGF gene activity. "This was all the more remarkable since both groups of individuals were severely depressed at the time of death," she says. "This is yet another indication that bipolar illness, though classified with depression as a mood disorder, is biologically a very different disease.