Mental illness as a term refers to a wide spectrum of disorders, including anxiety disorders, addiction disorders, eating disorders, gender or sexual disorders, and somatoform disorders. Despite the amount of research done pertaining to mental illness, much remains to be discovered. Thus, the etiology of mental illness is not fully known. Based on the information uncovered so far though, researchers suspect that mental illness is caused by various factors.
Chemical imbalance is an exemplar of a biological factor involved in the etiology of mental illness. Specifically, when there is imbalance in brain neurotransmitters, nerve cells cannot adequately communicate, brain messages are insufficiently processed, and mental illness can occur. Substance abuse that occurs over an extended period of time can alter brain chemistry and cause mental illness. Inadequate nutrition, lack of absorption of vitamins and minerals, or exposure to environmental toxins such as lead could result in changes in brain chemistry which can predispose mental illness.
Genetics is another biological factor in the etiology of mental illness. Having a genetic susceptibility does not necessarily mean a person will have a mental illness. Whether the person eventually has mental illness depends on the presence of exacerbating factors such as abuse, stress, or the presence of traumatic events.
Injury to the brain is another factor that has biological impact and which is involved in the etiology of mental illness. The brain injury may occur when a person is older or even during the gestation period or birth. Other biological factors in mental illness include previously existing health conditions. For example, the health condition called pediatric autoimmune neuropsychiatric disorder (PANDA), which is caused by a streptococcus bacteria infection, is reportedly a possible cause of mental illness in children.
Psychological factors involved in the etiology of mental illness include severe or traumatic experiences suffered during childhood. For example, physical, sexual, or emotional abuse could lead to mental illness. Parental neglect or loss of a parent could also be one of the factors in mental illness.
Environmental factors involved in mental illness can include various experiences which, if they occur excessively, can be problematic. The presence of excessive stress alters brain chemistry and that can predispose a person to experiencing mental illness. Experiences such as loss of loved ones and coping with poverty and feelings such as anxiety and anger could predispose one to mental illness. Additionally, changing schools or jobs, social rejection, or a dysfunctional family climate are all experiences which can be factors in mental illness if the experience is prolonged or extreme enough.