Researchers say they may have found a way to diagnose melancholic depression using an imaging technology that allows them to observe levels of certain substances in the brain. Melancholia is a relatively common form of depression marked by insomnia, loss of appetite, and loss of pleasure.
Results of the study show low levels of the inhibitory transmitter GABA and high levels of the excitatory neurotransmitter glutamate in the brain appear to be linked to melancholic depression. Researchers say the findings add to mounting evidence that shows, along with serotonin and norepinepherine systems, both the GABA and glutamate systems also contribute to the mechanism and treatment of mood disorders. They feel that this may ultimately help doctors make more accurate diagnoses that could more effectively guide treatment planning.
In the study, 38 healthy individuals and 33 individuals with major depressive disorder participated. It was found that depressed subjects with melancholic features appear to have the largest and most consistent GABA reductions.
Thus researchers say they hope to explore the usefulness of GABA, glutamate, and other biological markers to identify various types of depression and predict specific treatment responses.