Article

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: 4.43). 08/2008; 102(1-3):1-18. DOI: 10.1016/j.schres.2008.04.011
Source: PubMed

ABSTRACT 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.

Download full-text

Full-text

Available from: Matcheri Keshavan, Aug 07, 2014
2 Followers
 · 
227 Views
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Schizophrenia is a severe psychiatric disorder with lifetime prevalence of ~ 1% worldwide. A genotyping study was conducted using a custom panel of Illumina 1536 SNPs in 840 schizophrenia cases and 876 controls (351 patients and 385 controls from North India; and 436 patients, 401 controls and 143 familial samples with 53 probands containing 37 complete and 16 incomplete trios from South India). Meta-analysis of this population of Indo-European and Dravidian ancestry identified three strongly associated variants with schizophrenia: STT3A (rs548181, p = 1.47 × 10− 5), NRG1 (rs17603876, p = 8.66 × 10− 5) and GRM7 (rs3864075, p = 4.06 × 10− 3). Finally, a meta-analysis was conducted comparing our data with data from the Schizophrenia Psychiatric Genome-Wide Association Study Consortium (PGC-SCZ) that supported rs548181 (p = 1.39 × 10− 7). In addition, combined analysis of sporadic case–control association and a transmission disequilibrium test in familial samples from South Indian population identified three associations: rs1062613 (p = 3.12 × 10− 3), a functional promoter variant of HTR3A; rs6710782 (p = 3.50 × 10− 3), an intronic variant of ERBB4; and rs891903 (p = 1.05 × 10− 2), an intronic variant of EBF1. The results support the risk variants observed in the earlier published work and suggest a potential role of neurodevelopmental genes in the schizophrenia pathogenesis.
    Schizophrenia Research 01/2015; 162(1-3). DOI:10.1016/j.schres.2014.12.031 · 4.43 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Many aspects of spiritual experience are similar in form and content to symptoms of psychosis. Both spiritually advanced people and patients suffering from psychopathology experience alterations in their sense of 'self.' Psychotic experiences originate from derangement of the personality, whereas spiritual experiences involve systematic thinning out of the selfish ego, allowing individual consciousness to merge into universal consciousness. Documented instances and case studies suggest possible confusion between the spiritually advanced and schizophrenia patients. Clinical practice contains no clear guidelines on how to distinguish them. Here we use a case presentation to help tabulate clinically useful points distinguishing spiritually advanced persons from schizophrenia patients. A 34-year-old unmarried male reported to our clinic with four main complaints: lack of sense of self since childhood; repeated thoughts questioning whether he existed or not; social withdrawal; and inability to continue in any occupation. Qualitative case analysis and discussions using descriptions from ancient texts and modern psychology led to the diagnosis of schizophrenia rather than spiritual advancement.
    Journal of Religion and Health 12/2014; 53(6). DOI:10.1007/s10943-014-9994-0 · 1.02 Impact Factor
  • Source
    • "Mental disorders in general and psychosis in particular are commonly associated with psychosocial risk factors (Rössler et al., 2005; Tandon et al., 2008). This is what we also found concerning sub-clinical psychosis , albeit with differences between odd beliefs/behavior and anomalous perceptions. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Several studies have demonstrated that expression of a psychosis phenotype can be observed below the threshold of its clinical detection. To date, however, no conceptual certainty has been reported for the validity and reliability of sub-clinical psychosis. Our main objectives were to assess the prevalence rates and severity of various psychosis symptoms in a representative community sample. Furthermore, we wanted to analyze which latent factors are depicted by several currently used psychosis questionnaires. We also examined how those latent factors for sub-clinical psychosis are linked to psychosocial factors, normal personality traits, and coping abilities related to chronic stress. Most of the eight subscales from the Paranoia Checklist and the Structured Interview for Assessing Perceptual Anomalies had a very similar type of distribution, i.e., an inverse Gaussian (Wald) distribution. This supported the notion of a continuity of psychotic symptoms, which we would expect to find for continuously distributed symptoms within the general population. Sub-clinical psychosis can be reduced to two different factors - one representing odd beliefs about the world and odd behavior, and the other one representing anomalous perceptions (such as hallucinations). Persons with odd beliefs and behavior are under greater burden and more susceptible to psychosocial risks than are persons with anomalous perceptions. These sub-clinical psychosis syndromes are also related to stable personality traits. In conclusion, we obtained strong support for the notion that there is no natural cut-off separating psychotic illness from good health. Sub-clinical psychosis of any kind is not trivial because it is associated with various types of social disability. Copyright © 2014 Elsevier B.V. All rights reserved.
    Schizophrenia Research 12/2014; 161(2-3). DOI:10.1016/j.schres.2014.11.033 · 4.43 Impact Factor
Show more