Bipolar Disorder Essay Example | Topics and Well Written Essays - 1500 words

Bipolar Disorder - Essay Example Genetic factors are considered to be the leading contributor to the disease, accounting for up to 80% of the risk of having the illness. The heritability index was calculated to be around 0.7 (Edvardsen 2008). Despite having been restricted to a relatively low number of samples, twin studies have revealed a considerable genetic component, together with a clear environmental impact. Extensive studies over the last years have consistently estimated the concordance rate for bipolar I disorder to be around 5% in fraternal twins, in comparison to over 40% in  identical  twins (Barnett & Smoller 2009). Studies have also identified certain physiological processes underlying the bipolar disorder. For instance, by means of magnetic resonance imaging researchers have noted the differences in the volume and density of various brain zones between the healthy individuals and patients with BD. Specifically, the analysis of structural MRI findings provided evidence of the increased volume of the pale body and lateral ventricles (Arnone et al 2009). Simultaneously, functional MRI scans indicated the impaired coordination between the limbic corpus amygdaloideum and prefrontal region (Srakowski et al 2012). According to another theory, when genetically predisposed people are exposed to stress, their stress threshold at which behavioral changes happen lowers. After a number of such exposures, the episodes may start spontaneously. In support of the theory, Alloy and Bender (2011) report of the correlation between stressful situations and malfunction of the  hypothalamic-pituitary-adrenal axis. Stress factors cause hypothalamic hyperactivation, which may eventually result in disease. Some researchers imply the major contribution of the environmental factors to the development of bipolar disorder. Evidence suggests that broken interpersonal relationships and hurtful early-life events may increase the risk of onsets and induce