Epidemiology of schizophrenia: the global burden of disease and disability

Abstract

Evidence from nearly a century of epidemiological research indicates that schizophrenia occurs in all populations with a prevalence in the range of 1.4 to 4.6 per 1000 and incidence rates in the range of 0.16-0.42 per 1000 population. Multi-centre studies conducted by the World Health Organization have highlighted important differences between 'Western' and 'Third World' populations as regards the course and outcome of the disorder, with a significantly better prognosis in the developing countries. The factors underlying the better outcome of schizophrenia in developing countries remain essentially unknown but are likely to involve interactions between genetic variation and specific aspects of the environment. These features place schizophrenia, along with diabetes, cancer and hypertension, into the group of genetically complex diseases which are characterised by polygenic transmission, locus heterogeneity and environmental contribution to causation. The emerging pattern of risk factors and antecedents of schizophrenia suggests multiple, mainly quantitative deviations from the average developmental trajectory, primarily in the areas of early neurodevelopment, cognitive ability and social behaviour. These deviations are compatible with the notion of non-specific background factors facilitating the operation of genetically determined causal pathways. Research likely to result in new insights should focus on the population distribution and behavioural effects of potential risk factors and markers suggested by biological and genetic research.

The Prevalence and Correlates of Nonaffective Psychosis in the National Comorbidity Survey Replication (NCS-R)

“…One way to finesse this problem would be to change the focus to a more tractable research task, as in the Study on Low Prevalence (i.e., psychotic) Disorders (SLPD) carried out in conjunction with the Australian National Survey of Mental Health and Wellbeing. The SLPD carried out a screen for psychosis among all patients in treatment for mental health problems in four areas of Australia in a specified month and then carried out an in-depth assessment of NAP with screened positives (Jablensky 2000). An exercise of this sort is tractable and useful in estimating demand for treatment of psychosis even if it does not estimate unmet need for such treatment.…”

“…These include the findings that NAP has a median age-of-onset in the late teens or early twenties that is somewhat earlier among men than women (Jablensky et al 1992), that NAP is significantly related to disadvantaged social status (Jablensky 2000), that NAP is highly comorbid with a wide range of other mental disorders and substance use disorders (Murray et al 2002), that NAP is associated with substantial impairment in all areas of life (Jablensky et al 1980), and that the vast majority of people with NAP are in contact with the treatment system (Sartorius et al 1986). We also found a somewhat higher relative-odds of NAP among men than women (1.6), which is consistent with a modest, but statistically significant, elevation among men compared to women found in meta-analysis of incidence studies (McGrath et al 2004).…”

Altered Interhemispheric and Temporal Lobe White Matter Microstructural Organization in Severe Chronic Schizophrenia

“…Schizophrenia is a chronic and disabling mental disorder (Jablensky, 2000) associated with gray matter (GM) and white matter (WM) abnormalities. Recent meta-analyses of voxel-based imaging studies showed widespread clusters of GM volume reductions with no regions of volume increases, and widespread WM deficity in schizophrenia (Bora et al, 2011).…”

Acute Serotonin and Dopamine Depletion Improves Attentional Control: Findings from the Stroop Task

“…Schizophrenia is a severe, chronic and disabling psychiatric disorder prevalent in approximately 0.4-1% of the world's population (Bhugra, 2005;Jablensky, 2000). In addition to the positive and negative symptoms, patients also often experience severe disturbances in cognitive functioning (Abi-Dargham, 2004;Gold and Weinberger, 1995;Keefe et al, 2006).…”