Depression and manic depression
Depression is one of the most prevalent disorders in the Western world, and, according to the World Health Organization, it will even be the No. 1 disorder in 2020. Ten to 15 per cent of the population − from all levels of society − experience depression during their lifetime; and about 5% has to contend with manic depression. Despite the high socio-economic costs and mortality rate, the causes of these psychiatric disorders are not yet known. However, scientists are in agreement that the origin of depression can be attributed to a combination of hereditary and environmental factors such as stress.
The role of serotonin
The hormone serotonin plays an important role in our brain chemistry. The amount of serotonin in the brain has a large influence on our thinking, emotions and behavior. Because antidepressants affect the level of serotonin in the brain, it has long been suspected that serotonin plays a role in the development of psychiatric disorders. So, the amount of serotonin that you produce and keep under control appears to be crucial in the fight against (manic) depression. Because the TPH2 protein is instrumental in regulating the serotonin level, scientists suspect that TPH2 plays a role in the development of psychiatric disorders.
Ann Van Den Bogaert and her colleagues from the research group of Jurgen Del-Favero have also been studying the role of TPH2 in the development of depression and manic depression. They have conducted a genetic study in which they compared the variation in the TPH2 gene between patients with depression and healthy individuals. The DNA of two random individuals are 99.9% identical − the 0.1% that is different contains the genetic variation that can originate disorders.
In collaboration with the Swedish research group under the direction of Rolf Adolfsson and Karl-Fredrik Norrback, the researchers studied the DNA of hundreds of Swedish patients with depression and manic depression and that of healthy control subjects. By comparing the genetic variations between the patients and healthy individuals, they have shown that in this Swedish population TPH2 is involved in the development of depression and manic depression.
Thus, their research brings us a step closer to a better understanding of these psychiatric disorders.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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