Antidepressant effects on neurogenesis

Recent studies have shown that neurogenesis continues into adulthood and that the central nervous system (CNS) has the capability for self repair. The function of these newly generated cells is not well known and prompts for further study. This ties into the concept of depression given that it has been found that the hippocampus of the patient shows signs of atrophy and neural loss, this part of the brain being largely responsible for long term memory.

Neurogenesis primarily occurs within two parts of the brain, the dentate gyrus (largely responsible for learning, memory, and spatial coding) and the subventricular zone and neurogenesis is required for the behavioral effects of antidepressants. Though the role of adult neurogenesis and its relation to depression is still heavily debated upon.

Depression is a large issue that exists worldwide. Major depressive disorder affects approximately 14.8 million American adults, or about 6.7 percent of the U.S. population age 18 and older, in a given year. (Archives of General Psychiatry, 2005).

To aide these issues selective serotonin reuptake inhibitors like fluoxetine, monoamine oxidase inhibitors, like tranylcypromine, specific norepinephrine reuptake inhibitors , like reboxetine and phosphodiesterase-IV inhibitors, like rolipram, will alleviate the symptoms of depression. It is believed that an imbalance in serotonin and noradrenaline pathways may underlie the development of certain depressive disorders.

There is increasing evidence that the hippocampus is involved in the regulation of emotional responses, in particular depression being one of these many. Clinical magnetic resonance imaging and post-mortem studies in depression patients, as well as in animal studies, which have revealed that chronic stress and depression result in neural atrophy in the hippocampus, and that these effects can be reversed by antidepressants, which is what makes them so vital to the recovery of the brain when dealing with depression.

This may suggest that neurogenesis can be the underlying factor in the hippocampus link to depression. In support of this idea, glucocorticoids which are stress-related hormones induce neural atrophy and decrease neurogenesis. On the contrary, antidepressants like fluoxetine, promote neurogenesis. Investigators have continued exploring the effects of stress and depression on neurogenesis, but all that is known for now is that such neurological disorder and detrimental to our health. It is important for those who endure such ailments to receive treatment. Because just like a physical illness we are unable to recover and maintain good health if we ignore the condition of our health and resist treatment.

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