Schizophrenia, "Just the Facts" What we know in 2008. 2. Epidemiology and etiology

University of Florida, 3706 Glin Circle, Tallahassee, FL 32309, United States.
Schizophrenia Research (Impact Factor: 3.92). 08/2008; 102(1-3):1-18. DOI: 10.1016/j.schres.2008.04.011
Source: PubMed


Although we have studied schizophrenia as a major disease entity over the past century, its causes and pathogenesis remain obscure. In this article, we critically review genetic and other epidemiological findings and discuss the insights they provide into the causes of schizophrenia. The annual incidence of schizophrenia averages 15 per 100,000, the point prevalence averages approximately 4.5 per population of 1000, and the risk of developing the illness over one's lifetime averages 0.7%. Schizophrenia runs in families and there are significant variations in the incidence of schizophrenia, with urbanicity, male gender, and a history of migration being associated with a higher risk for developing the illness. Genetic factors and gene-environment interactions together contribute over 80% of the liability for developing schizophrenia and a number of chromosomal regions and genes have been "linked" to the risk for developing the disease. Despite intensive research and spectacular advances in molecular biology, however, no single gene variation has been consistently associated with a greater likelihood of developing the illness and the precise nature of the genetic contribution remains obscure at this time. Environmental factors linked to a higher likelihood of developing schizophrenia include cannabis use, prenatal infection or malnutrition, perinatal complications, and a history of winter birth; the exact relevance or nature of these contributions is, however, unclear. How various genetic and environmental factors interact to cause schizophrenia and via which precise neurobiological mechanisms they mediate this effect is not understood. Etiological heterogeneity, complex patterns of gene-gene and gene-environment interaction, and inadequately elucidated schizophrenia pathophysiology are among the explanations invoked to explain our inadequate understanding of the etio-pathogenesis of schizophrenia. The ability to question some of our basic assumptions about the etiology and nature of schizophrenia and greater rigor in its study appear critical to improving our understanding about its causation.

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Available from: Matcheri Keshavan, Aug 07, 2014
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    • "Common symptoms include positive symptoms (such as disorganization, delusions, or hallucinations) and negative symptoms (anhedonia, decreased emotional expression, impaired concentration , and diminished social engagement) (Van and Kapur 2009). Onset is typically seen in late adolescence with a global lifetime prevalence of about 0.3–0.7 % (Van and Kapur 2009) and average annual incidence of approximately 15 per 100,000 (Tandon et al. 2008). "
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    • "Schizophrenia (SZ) is a severe psychiatric brain disorder that affects about 1% of the population (Harrison, 1999; Insel, 2010; Ripke et al., 2013; Tandon et al., 2008). Symptoms of SZ suggest brain disturbances which affect many systems, and include hallucinations, delusions, disorganized thinking, loss of motivation, cognitive impairment and blunted emotional expression. "
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    • "Genetic and gene–environment interactions account for over 80% susceptibility in the development of schizophrenia (Tandon et al., 2008). De-novo mutations contribute toward the constant replenishment of the pathogenic alleles involved in the disease development (Hatzimanolis et al., 2013). "
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