According to the World Health Organization, depression, anxiety and other mood disorders are the most prevalent causes of chronic illness in the world. A mood disorder can be debilitating and emotionally painful. Fortunately, there are medical and therapeutic treatments available for these conditions, and most people respond well to one or the other of these approaches. Researchers continue to look for improved treatment options by examining the brain abnormalities related to depression.
Shrinking Brain
People who are at risk for developing depression have a 28 percent shrinking of the right hemisphere, the half of the brain that is highly specialized for creativity and social and emotional processing, reports Columbia University child psychiatrist Bradley Peterson. This is about the same amount of loss as is found in patients with Alzheimer's and schizophrenia. The thinning of the hemisphere could be detrimental to a person's abilities to pick up on social and emotional cues from other people, resulting in social failure. This, in turn, could be the immediate trigger of the disease, adds Dr. Petersen.
Lack of Pleasure
After the onset of depression, activity in brain regions associated with positive emotions starts to drop, says University of Wisconsin at Madison brain researcher Aaron Heller. The implicated regions are reward areas in the brain's frontal lobe. When there is a failure of activity in the reward areas regardless of the nature of the incoming stimulus, the condition is referred to as "anhedonia," the inability to experience pleasure. Heller and his team used brain imagining to examine the reward areas in 27 depressed patients and 19 controls. The study did not show whether depression is the trigger or the result of the brain abnormalities.
A Hyperactive Brain
Depressed people's movement and behaviors are often slow and inhibited. But their brains may be working overtime, say researchers from the National Institute of Mental Health. The scientists found an overactive emotional circuit running through the front and center of the brain of patients in remission, regardless of whether they had psychological symptoms. The brain abnormality, which involves orbitofrontal cortex, thalamus, anterior cingulate and ventral striatum, does not correlate with any psychological feeling of depression. The researchers believe that the circuit may be a trait marker that makes people vulnerable for developing depression.
Beyond Serotonin
A chemical implicated in major depression is serotonin. But researchers have now identified a different neurotransmitter that appears to be significantly linked to depression, reports a research team in the March 2010 issue of "Biological Psychiatry." The chemical is gamma-aminobutyric acid (GABA), a natural inhibitor of extreme brain activity. In many cases of depression, it's not serotonin or dopamine imbalances that are the culprits but an overactive brain that spirals down a negative path, the scientists explain. The new findings could offer insight into a new way to treat patients with depression who don't respond to the standard-variety mood enhancers, say the scientists.
Link between Anxiety and Depression
Researchers have known for some time that depression, anxiety and stress are related. But they were not exactly sure how. Depression often co-occurs with anxiety and stress, and the symptoms can be hard to distinguish. But researchers at the University of Western Ontario have now discovered a link between the three conditions that explain their co-occurrence. Stress is significantly correlated with corticotropin releasing factor receptor 1 (CRFR1), which increases the expression of stress hormone and anxiety symptoms. But CRFR1 also increases the number of serotonin receptors (5-HTRs), which leads to depression. So, CRFR1 is a common cause of all three conditions.
References
- Science Daily: Early Brain Marker For Familial Form Of Depression: Structural Changes In Brain's Cortex
- Science Daily: Depression Saps Endurance of the Brain's Reward Circuitry
- Science Daily: Depression Traced To Overactive Brain Circuit
- Science Daily: Critical Brain Chemical Shown to Play Role in Severe Depression
- Science Daily: Biological Link Between Stress, Anxiety and Depression Identified
