Schizophrenia Q 64
The family of a schizophrenic client asks the nurse if there is a genetic cause of this disorder. To answer the family, which fact would the nurse cite?
A. Conclusive evidence indicates a specific gene transmits the disorder.
B. Incidence of this disorder is variable in all families.
C. There is a little evidence that genes play a role in transmission.
D. Genetic factors can increase the vulnerability for this disorder.
Correct Answer: D. Genetic factors can increase the vulnerability for this disorder.
Research shows that family history statistically increases the risk for the development of schizophrenia. Genetics also play a fundamental role – there is a 46% concordance rate in monozygotic twins and a 40% risk of developing schizophrenia if both parents are affected. The gene neuregulin (NGR1) which is involved in glutamate signaling and brain development has been implicated, alongside dysbindin (DTNBP1) which helps glutamate release, and catecholamine O-methyltransferase (COMT) polymorphism, which regulates dopamine function.
Option A: However, no single gene has yet been identified. Several studies postulate that the development of schizophrenia results from abnormalities in multiple neurotransmitters, such as dopaminergic, serotonergic, and alpha-adrenergic hyperactivity or glutaminergic and GABA hypoactivity.
Option B: This is incorrect because genetics plays a role in the etiology of schizophrenia. The incidence is also up to ten times greater in children of African and Caribbean migrants compared to Caucasians according to a study conducted in Britain. The association between cannabis use and psychosis has been widely studied, with recent longitudinal studies suggesting a 40% increased risk, while also suggesting a dose-effect relationship between the use of the drug and the risk of developing schizophrenia.
Option C: The neurochemical abnormality hypothesis argues that an imbalance of dopamine, serotonin, glutamate, and GABA results in the psychiatric manifestations of the disease. It postulates that four main dopaminergic pathways are involved in the development of schizophrenia. This dopamine hypothesis attributes the positive symptoms of the illness to excessive activation of D2 receptors via the mesolimbic pathway, while low levels of dopamine in the nigrostriatal pathway are theorized to cause motor symptoms through their effect on the extrapyramidal system. Low mesocortical dopamine levels resulting from the mesocortical pathway are thought to elicit the negative symptoms of the disease.