Since the incidence in children and adolescents, clinical features and the high familial prevalence of the disease have been determined, it has become inevitable to examine the genetic aspect of the disease. There are debates on etiology. Genetic, environmental factors, neurobiologic, hormonal and neurochemical factors are mentioned and research is being conducted on them.
Genetic Infrastructure of Bipolar Disorder (BD);
Even if the results of the studies are contradictory about the regions that can be held responsible in the genome, the common result of all studies is that genetic transmission is effective in BB in a way that cannot be ignored. The high prevalence of the disease in the children of adults with bipolar disorder and in the parents and relatives of children with BD points to the importance of genetic etiology.
In studies conducted, the incidence of BD in children of individuals with the disease was found to be 7 times higher than in healthy children. This risk is not only for GC. Children of individuals with depression, conduct disorder, disruptive behavior disorder and anxiety disorders have also been found to have a higher incidence of GI compared to healthy children. The prevalence rate of the disease in children of individuals with PDD was found to be 5.7%.
Twin Studies
In addition to familial genetic transmission studies, twin studies have been an important source of data on the genetic transmission of all diseases in medicine; it is one of the only sources we have in determining how effective genetic factors are compared to environmental factors. If we think that genetics plays an important role in the basis of a disease, high concordance (co-morbidity) in monozygote studies is an expected situation. When BB is taken into consideration , theconcordance of the disease in monozygotic twins is 70-90%, while the rate is 16-35% in fraternal twins.
Imaging Studies
Many scientific studies have begun to reveal very important data about the process of the development of GC. For example, functional magnetic resonance (IMR) studies, a brain imaging method, have shown decreased metabolic activity in some brain regions (especially in the dorsolateral prefrontal cortex) and increased metabolic activity in some regions (right cerebellar hemisphere) in individuals with GC (DelBello et al., 2003). Structural magnetic resonance imaging (MRI) studies have also shown differences in some brain regions (especially subcortical white matter hyperintensity) in BB cases (Pillai et al., 2002).
Molecular Genetic Studies
Some differences in brain biochemistry have also been found in patients with BB. In particular, changes in the levels of neurotransmitters such as dopa-min, noradrenaline, serotonin and sometimes hormones such as thyroid hormones or melatonin have been found to be important in the formation of BB. In addition, the role of secondary messenger systems within the nerve cell in the process of BB formation has come to the fore in recent years.
