In the case of optic neuritis, the optic nerve becomes swollen, and its function is impaired. Inflammation of the optic nerve causes loss of vision because of the swelling and destruction of the protective myelin sheath that covers and insulates the optic nerve.
Various alterations in corresponding genes affect the levels of serotonin or sensitivity to serotonin and may cause behavioral changes. Changes in serotonin level can affect behavior. The level of serotonin is controlled by multiple mechanisms.Any changes in the genes involved may lead to serious consequences.everal genetic alterations in the gene for tryptophan hydroxylase were reported to be associated with suicidal behavior. This enzyme is involved in biosynthesis of serotonin, and therefore its genetic alterations can easily affect the level of this mediator.
Individual behavior also plays a role in health outcomes. For example, if an individual quits smoking, his or her risk of developing heart disease is greatly reduced. Many public health and health care interventions focus on changing individual behaviors such as substance abuse, diet, and physical activity. Positive changes in individual behavior can reduce the rates of chronic disease in this country. Examples of individual behavior determinants of health include: Diet.