Background Understanding the prevalence of schizophrenia has important implications for both health service planning and risk factor epidemiology. The aims of this review are to systematically identify and collate studies describing the prevalence of schizophrenia, to summarize the findings of these studies, and to explore selected factors that may influence prevalence estimates. Methods and Findings Studies with original data related to the prevalence of schizophrenia (published 1965–2002) were identified via searching electronic databases, reviewing citations, and writing to authors. These studies were divided into ‘‘core’’ studies, ‘‘migrant’’ studies, and studies based on ‘‘other special groups.’’ Between- and within-study filters were applied in order to identify discrete prevalence estimates. Cumulative plots of prevalence estimates were made and the distributions described when the underlying estimates were sorted according to prevalence type (point, period, lifetime, and lifetime morbid risk). Based on combined prevalence estimates, the influence of selected key variables was examined (sex, urbanicity, migrant status, country economic index, and study quality). A total of 1,721 prevalence estimates from 188 studies were identified. These estimates were drawn from 46 countries, and were based on an estimated 154,140 potentially overlapping prevalent cases. We identified 132 core studies, 15 migrant studies, and 41 studies based on other special groups. The median values per 1,000 persons (10%–90% quantiles) for the distributions for point, period, lifetime, and lifetime morbid risk were 4.6 (1.9–10.0), 3.3 (1.3– 8.2), 4.0 (1.6–12.1), and 7.2 (3.1–27.1), respectively. Based on combined prevalence estimates, we found no significant difference (a) between males and females, or (b) between urban, rural, and mixed sites. The prevalence of schizophrenia in migrants was higher compared to nativeborn individuals: the migrant-to-native-born ratio median (10%–90% quantile) was 1.8 (0.9–6.4). When sites were grouped by economic status, prevalence estimates from ‘‘least developed’’ countries were significantly lower than those from both ‘‘emerging’’ and ‘‘developed’’ sites (p = 0.04). Studies that scored higher on a quality score had significantly higher prevalence estimates ( p= 0.02).

https://espace.library.uq.edu.au/view/UQ:75868/UQ_PV_75868.pdf

A systematic review of the prevalence of schizophrenia.

Over 70 prevalence studies of schizophrenia published since 1948 are reviewed. Despite problems of method, the studies suggest that there may be significant differences in prevalence among different populations and that prevalence may change over time. Further research is needed on how much differences in diagnosis or the course of schizophrenia contribute to the variable prevalence rates. The paper suggests the following as areas for additional enquiry: a possible north-south gradient, special populations (e.g. American Hutterites, northern Swedes, western Irish, castes in India) and ongoing case registers in areas of suspected high and low prevalence.

Prevalence studies in schizophrenia.

A meta-analysis of 13 psychiatric epidemiological studies consisting of 33572 persons in 6550 families yielded an estimate prevalence rate of 58.2 per thousand population. Organic psychosis (prevalence rate 0.4), schizophrenia (2.7), affective disorders (12.3) contributed a rate of 15.4 for psychoses. The prevalence rate for mental retardation (6.9), epilepsy (4.4), neurotic disorders (20.7), alcohol/drug addiction (6.9; and miscellaneous group (3.9) were estimated. Higher prevalence for urban sector, females, age group of 35-44, married/widowers/divorced, lower socioeconomic status, and nuclear family members were confirmed. Epilepsy and hysteria were found significantly high in rural communities. Manic affective psychosis, mental retardation, alcohol/ drug addiction and personality disorders were significantly high in males. The findings indicated that there are 1.5 crore people suffering from severe mental disorders (psychoses) in India, and that severe diseases have higher representation at specialized as well as general hospital clinics. Among other things, the results aid in conducting morbidity surveys by more methodological approach.

Prevalence of Mental and Behavioural Disorders in India : A Meta-Analysis

Substance use patterns are notorious for their ability to change over time. Both licit and illicit substance use cause serious public health problems and evidence for the same is now available in our country. National level prevalence has been calculated for many substances of abuse, but regional variations are quite evident. Rapid assessment surveys have facilitated the understanding of changing patterns of use. Substance use among women and children are increasing causes of concern. Preliminary neurobiological research has focused on identifying individuals at high risk for alcohol dependence. Clinical research in the area has focused primarily on alcohol and substance related comorbidity. There is disappointingly little research on pharmacological and psychosocial interventions. Course and outcome studies emphasize the need for better follow-up in this group. While lack of a comprehensive policy has been repeatedly highlighted and various suggestions made to address the range of problems caused by substance use, much remains to be done on the ground to prevent and address these problems. It is anticipated that substance related research publications in the Indian Journal of Psychiatry will increase following the journal having acquired an 'indexed' status.

Substance use and addiction research in India

Epidemiological studies report prevalence rates for psychiatric disorders from 9.5 to 370/1000 populations in India. This review critically evaluates the prevalence rate of mental disorders as reported in Indian epidemiological studies. Extensive search of PubMed, NeuroMed and MEDLARS using search terms "psychiatry" and "epidemiology" was done. Manual search of literature was also done. Retrieved articles were systematically selected using inclusion and exclusion criteria. Only sixteen prevalence studies fulfilled the study criteria. Most of the epidemiological studies done in India neglected anxiety disorders, substance dependence disorders, co-morbidity and dual diagnosis. The use of poor sensitive screening instruments, single informant and systematic underreporting has added to the discrepancy in the prevalence rate. The prevalence of mental disorders reported in epidemiological surveys can be considered lower estimates rather than accurate reflections of the true prevalence in the population. Researchers have focused on broad non-specific, non-modifiable risk factors, such as age, gender and social class. Future research focused on the general population, longitudinal (prospective), multi-centre, co-morbid studies, assessment of disability, functioning, family burden and quality of life studies involving a clinical service providing approach, is required.

Psychiatric epidemiology in India

A study to assess the nature and extent of mental disorders in a rural community was undertaken in three paras of Nasibpur village in West Bengal The high prevalence rate of 27 per 1,000 population was found, with significant variations in the rates and diagnostic patterns of mental disorders in the three population groups The planning of an adequate mental health programme is regarded as a national priority

M. N. Rao

Papers

Mental health in an Indian rural community.