Psychotic Disorders (cont.)

Except for those psychotic disorders that result from the use of a substance or a medical condition, specific causes for most psychotic disorders are not known. However, an interplay of genetic (familial), biological, environmental, and psychological factors is thought to be involved. We do not yet understand all of the causes and other issues involved, but current research is making steady progress toward elucidating and defining causes of psychosis. For example, schizophrenia and bipolar disorder are thought to have many risk factors in common.

In biological models of psychotic disorders, genetic predisposition, infectious agents, toxins, allergies, and disturbances in metabolism have all been investigated. Psychotic disorders are known to run in families. For example, the risk of illness in an identical twin of a person with schizophrenia is 40%-50%. A child of a parent suffering from schizophrenia has a 10% chance of developing the illness, in contrast to the risk of schizophrenia in the general population being about 1%. Toxins like ketamine or marijuana increase the risk of developing psychosis.

The current concept is that multiple genes are involved in the development of schizophrenia and that risk factors such as prenatal (intrauterine), perinatal (around the time of birth), and nonspecific stressors are involved in creating a disposition or vulnerability to develop the illness. Neurotransmitters (chemicals allowing the communication among nerve cells) have also been implicated in the development of psychotic disorders. The list of neurotransmitters under scrutiny is long, but special attention has been given to dopamine, serotonin, and glutamate.

Also, recent research studies have identified subtle changes in brain structure and function, indicating that, at least in part, schizophrenia could be a disorder of the development of the brain. The fact that autism is a risk factor for developing psychosis during childhood seems to support that theory. Psychosis is more likely to occur in people who have poor medical health in a general sense or who suffer from another mental illness.

Environmental risk factors, like a history of problematic drinking, using tobacco, marijuana or other drugs, have been associated with the development of a psychotic disorder.

There are a number of genetic, medical, psychological, and social risk factors for psychotic disorders. Women who have recently delivered a baby (the postpartum state) are at risk for a number of mental health problems, including postpartum psychosis. More than 25% of mothers with bipolar disorder may develop postpartum psychosis, and more than half of those who have both a personal history of bipolar disorder and a family history of postpartum psychosis may develop the condition. Children of mothers with a psychotic disorder may experience more than the genetic risk of developing a psychotic disorder if their birth or mother's pregnancy with them had problems like infections, high blood pressure, or problems with the placenta.

Psychological risks for developing a psychotic disorder include a history of mood problems and trouble functioning socially or generally. Individuals who tend to be suspicious of others or to have unusual thoughts are also more likely to develop a psychotic disorder. Studies show that women with postpartum psychosis are often victims of domestic violence or abusive childhoods and often have histories of abandonment or substance abuse. Children, teens, or adults who have endured more negative life events, have poor housing, are more ethnically isolated where they live, or otherwise have little in terms of a support group are at higher risk for developing a psychotic disorder.

Source: MedicineNet.com
http://www.medicinenet.com/psychotic_disorders/article.htm