Abstract
Schizophrenia is a mental disorder that has no known cause yet. However, some of the proposed causes include genetic factors, biochemical factors, environmental factors, and substance abuse. Although research is still underway to learn more about these causes, this paper discusses some of the existing evidence that proves or disproves environmental factors as causative of schizophrenia. This paper concludes that environmental factors alone do not cause the mental disorder but that they work in conjunction with the genetic factors towards the disorder’s development. This paper then suggests that further research be conducted in order to come up with more conclusive findings regarding the causative effects of these environmental factors.
Introduction
Schizophrenia is a complex psychiatric disorder that affects about 1 percent of the population (King, St-Hilaire & Heidkamp, D., 2010). It is characterized by symptoms such as confused and disorganized thinking, delusions, hallucinations, changed emotions, changed social behaviors, cognitive impairment, poverty of speech, reduced energy and motivation, diminished insight into the illness, and depression (Royal Brisbane and Women’s Hospital).
The real cause of schizophrenia is unknown. However, there are several theories regarding its cause, and these include genetic factors, biochemical factors, environmental factors, and substance abuse (Royal Brisbane and Women’s Hospital, n.d.).
Although further research is still being made concerning these various causes of schizophrenia, this paper provides some of the evidence gathered that either proves or disproves the validity of environmental factors as causes of the mental disorder.
The environmental factors that cause schizophrenia mostly pertain to the psychological and social stressors that people encounter. In particular, some of these stressors can include physical illness, limited personal support, and traumatic life events (Royal Brisbane and Women’s Hospital, n.d.).
In a critical review conducted by Craig Morgan and Helen Fisher (2007), the researchers conducted a meta-analysis of twenty studies that investigated the correlation between childhood trauma and psychotic disorders, as well as five population-based studies of childhood trauma and psychosis. Their findings suggested that childhood trauma caused psychosis (Morgan & Fisher, 2007), although the researchers did acknowledge that there wasn’t a sufficient amount of evidence to support the causal relation. They acknowledged the limitations in the methods used and they also acknowledged that biological mechanisms may also influence the environmental factors (Morgan & Fisher, 2007). This is supported by the metasynthesis conducted by Tsuang, Stone and Faraone (2001), which showed that both genetic factors and environmental factors (i.e. psychosocial factors; pregnancy and delivery complications, and viral infections) cause schizophrenia. They suggested that these two categories or factors may either be interactive or additive. Alternatively, they may be considered from a neurodevelopmental perspective, that is, that the genetic and environmental risk factors have appeared even before or around the time of birth and that both groups of factors interacted well before the development of psychosis.
In the same regard, a systematic review conducted by Leask (2004) investigated the correlation of environmental factors, such as obstetric complications, famine and other stresses, prenatal influenza, substance misuse, immigration, urbanization, and geography of birth, on schizophrenia. His findings showed evidence that the environmental factors that caused schizophrenia were either absent or showed inconsistent small effects, which suggested that there were no clear environmental factors that caused schizophrenia or that there was no single environmental cause of schizophrenia (Leask, 2004). As such, he also suggested that genetic factors be considered along with the environmental factors (Leask 2004) and just like Morgan and Fisher (2007), he also suggested that further research is needed in this area.
Still, the same results were indicated by the findings of Dean and Murray (2005). In a systematic review that they conducted, they also cited that environmental risk factors played a significant role in the development of schizophrenia. In particular, they indicated that the discovery of prenatal and perinatal risk factors made significant contributions to the development of the neurodevelopmental hypothesis (Dean & Murray, 2005). They also placed an emphasis on the interaction between environmental and genetic factors, and they pointed out that the evidence showing environmental factors to be causative of schizophrenia implied that this mental disorder might be preventable.
Similarly, in a systematic review conducted by Van Os and McGuffin (2003) with regards to whether the social environment can cause schizophrenia, the findings showed that the social environment alone cannot be causative of the mental disorder. They asserted that, although the social factors can possibly contribute to the development of schizophrenia among patients with a genetic predisposition, the same cannot be definitively said of patients with no genetic predisposition (Van Os & McGuffin, 2003).
Conclusion
There is no known cause of schizophreniia, although there are several proposed causes, such as genetic factors, biochemical factors, and environmental factors. Research is currently ongoing to determine the real cause of the mental disorder. To this end, this paper discussed the evidence that proved or disproved that environmental factors cause schizophrenia.
It was shown through the studies discussed that most researchers agree that environmental factors, such as the psychosocial and physical stressors, as well as the prenatal and perinatal complications, contribute to the development of schizophrenia. However, all of the researchers also agree that there is no strong evidence to show that environmental factors alone can cause schizophrenia and that, in fact, such evidence is inconsistent. However, they all agree that environmental factors are causative of schizophrenia, along with the genetic factors, and that those with a genetic predisposition are more prone to the environmental risk factors.
Finally, all of the researchers agree that more research needs to be conducted in this area so that conclusive findings may be determined. This would be especially important as knowing the exact causes of the disorder will enable its prevention.
References
Dean, K. & Murray, R.M. (2005). Environmental risk factors for psychosis. Dialogues in
Clinical Neuroscience, 7 (1), 69-80.
King, S., St-Hilaire, A. & Heidkamp, D. (2010). Prenatal factors in schizophrenia. Current
Directions in Psychological Science, 19(4), 209-213.
Leask, S. J. (2004). Environmental influences in schizophrenia: The known and the unknown.
Advances in Psychiatric Treatment, 10, 323-330.
Morgan, C. & Fisher, H. (2007). Environmental factors in schizophrenia: Childhood trauma—A
critical review. Schizophrenia Bulletin, 1, 3-10.
Royal Brisbane and Women’s Hospital. (n.d.). Schizophrenia. Retrieved from
http://www.health.qld.gov.au/rbwh/docs/schizophrenia.pdf.
Tsuang, M.T., Stone, W. S. & Faraone, S. V. (2001). Genes and schizophrenia. British Journal
of Psychiatry, 178 (suppl. 40), s18-s24.
Van Os, J. & McGuffin, P. (2003). Can the social environment cause schizophrenia? British
