This result showed that there was no association between schizophrenics and the 14 candidate genes that were previously identified genes (DTNB1, DISC1, RGS4, STX7, NRG1, DRD2, DAOA, CHRNA7, ARVCF, COMT, PPP3CC, TAAR6, DAOA, and AKT1). Only chance variation was seen in the distribution of the data from the study. Environmental factors in the onset of schizophrenia

In the research of the environmental factors that influence the onset and development of schizophrenia, researcher not only look at the dwelling of a person (house and neighborhood) but also look at other environmental aspects such as their nutrition, social life, chemical and hormonal environment as relates to development during pregnancy and other dynamics such as education, drug abuse, use of supplements, etc.

Research has shown that children who are born during the months of winter i.e. January to about April have a risk that is 10% higher than average of developing schizophrenia. Those children who are born in urban areas have a risk that is 50% higher than average. Similarly, if the mother of the child has previously suffered from certain diseases such as rubella, influenza and polio, they have an increased risk of schizophrenia. This risk for rubella is at 500% above normal. Above all, other risk factors include cases of famine and hunger during the period of development, pre-eclampsia during pregnancy, Rhesus factor incompatibility and family history Conklin & Iacono, 2002()

Another study puts the risk of birth during winter at between 5-8% higher than normal which is quite similar to the results of the study described above. This study also showed that geographical variations also play a role in the onset and development of schizophrenia. Schizophrenia is known to have greater incidence in developing countries including the Caribbean. This study also established the rate of urban children developing schizophrenia to be at about 47-48% above normal. This is also similar to the results of the study above. Other environmental risk factors that were established by this study include the misuse of drugs and substances especially for those who self-medicate with the various drugs. These drugs include alcohol, which has a 34% rate of risk, cannabis with an 88% rate of risk, and cigarettes with a 90% risk of schizophrenia...

Researchers agree that the development of schizophrenia is known to be as a result of some kind of genetic predisposition e.g. during pregnancy and early childhood which leads to subtle brain alterations that cause the susceptibility to schizophrenia. Environmental factors on the other hand usually develop during early childhood and the period of adolescence and can lead to brain damage and therefore further increase the risk of developing schizophrenia. By looking at schizophrenia using the biopsychosocial model is it easier to understand the path to schizophrenia and thus device ways to treat and prevent the disease.
References

Conklin, H.M., & Iacono, W.G. (2002). Schizophrenia: A Neurodevelopmental Perspective. Current Directions in Psychological Science, 11(1), 33-37.

Gaser, C., Nenadic, I., Buchsbaum, B.R., Hazlett, E.A., & Buchsbaum, M.S. (2004). Ventricular enlargement in schizophrenia related to volume reduction of the thalamus, striatum, and superior temporal cortex. The American Journal of Psychiatry, 161(1), 151-156.

Harrison, P.J., & Owen, M.J. (2003). Genes for schizophrenia? Recent findings and their pathophysiological implications. The Lancet, 361(9355), 417-419.

Leask, S.J. (2004). Environmental influences in schizophrenia: the known and the unknown. Advances in Psychiatric Treatment, 10(1), 323-330.

McCarley, R., Faux, S., Shenton, M., LeMay, M., Cane, M., Ballinger, R., & Duffy, F. (1989 ). CT abnormalities in schizophrenia. A preliminary study of their correlations with P300/P200 electrophysiological features and positive/negative symptoms. Arch Gen Psychiatry, 46(8), 698-708.

Owen, M.J., Craddock, N., & O'Donovan, M.C. (2005). Schizophrenia: genes at last? Trends in Genetics, 21(9), 518-525. doi: 10.1016/j.tig.2005.06.011

Rajarethinam, R., Prasad, K., & Keshavan, M.S. (2005). The Nature of Brain Abnormalities in Schizophrenia: What Do We Really Know? Current Psychosis & Therapeutics Reports, 2005(3), 48-52.

Riley, B., & Kendler, K.S. (2005). Molecular genetic studies of schizophrenia. European Journal of Human Genetics, 14(6), 669-680.