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Mental disorders
Depression and Manic Depression
Anxiety Disorders

Help Lien : Grow Little Cell Grow! Investigating Neurogenesis Lien : Scientists: Brain cell production may affect depression Lien : Depression Study Eyes Brain Cells
Lien : Newborn brain cells modulate learning and memory
Expérience : Antidepressants promote brain cell growth in rats Expérience : Sustained Use Of Anti-Depressants Increases Cell Growth And Protects Cells In The Brain
Original modules
History Module: The Growth of New Neurons in the Adult Human Brain The Growth of New Neurons in the Adult Human Brain

Neurogenesis and Depression

Some physicians are willing to assert that antidepressants such as Prozac, Zoloft, and Paxil are prescribed too often and too widely. These doctors point out that such medications can cause some far more serious side effects than those acknowledged by the pharmaceutical companies that manufacture them. These side effects include sexual dysfunction, withdrawal symptoms, visual hallucinations, nausea, dizziness, and anxiety.

Even more importantly, these doctors argue, the limited effectiveness of these medications suggests that depression is not just one biological problem among many others, but rather a complex biopsychosocial problem. Moreover, this problem can often be alleviated without drugs, either through psychotherapy or simply through aerobic exercise, such as jogging or dancing.

Lien : BACKLASHOvercoming the Dangers ofProzac, Zoloft, Paxil, andOther Antidepressants withSafe, Effective Alternatives Outil: La gestion du stress

The recent observation that new neurons can form in the hippocampus of the adult human brain has shattered a dogma that had been accepted for nearly 100 years (follow the History module link to the left). Moreover, the discovery that this process of neurogenesis seems to occur extensively in the hippocampus, and especially in the part known as the dentate gyrus, is very exciting for researchers who are trying to understand the beneficial long-term effects of antidepressants that raise serotonin levels, such as Prozac.

Indeed, research on Prozac soon showed that 70% more new neurons form in the hippocampi of rats treated with this drug than in those of normal rats. In other words, serotonin seems to promote neurogenesis in the hippocampus. It was from this observation that a link between depression and neurogenesis was hypothesized.

The idea of such a link did not surprise psychologists, who had long known that intense or prolonged stress can trigger depression. Stress bathes the brain in certain hormones such as glucocorticoids that are known to reduce neurogenesis and even destroy neurons, specifically in the dentate gyrus of the hippocampus.

There thus seems to be at least a correlation between the extent of neurogenesis in a person's hippocampus and the degree to which he or she is or is not depressed. Though scientists cannot prove that depression is caused by a stress-induced deficiency in neurogenesis, some researchers do believe that by stimulating the hippocampus to start growing more neurons again, antidepressants enable patients to construct positive new mental images that restore their confidence in the future.

There thus appear to be more and more facts supporting the hypothesis that a decrease in neurogenesis in the hippocampus is associated with the triggering of depression and that an increase in the rate of new cell formation in the hippocampus is a causal factor in curing it.

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