Prevalence and incidence of mental health problems
Prevalence and incidence are both terms that are commonly used to refer to measurements of disease frequency.
The prevalence of a disease is the proportion of a population that is affected by the disease at a specific time.
Incidence is a measure of the risk of developing some new condition within a specified period of time.
The prevalence of mental disorders has been studied around the world, providing estimates on how conmnon mental disorders. Different criteria or thresholds of severity have sometimes been used.
In the World
The World Health Organization undertaking a global survey of 26 countries in all regions of the world, based on ICD and DSM criteria. The first published figures on the 14 country surveys completed to date, indicate that, of those disorders assessed, anxiety disorders are the most common in all but I country (prevalence in the prior 12-month period of 2.4% to 18.2%) and mood disorders next most common in all but 2 countries (12 month prevalence of 0.8% to 9.6%), while substance disorders (0. I %- 6.4%) and impulse-control disorders (0.00/0- 6.80/0) were consistently less prevalent.
Specific mental disorders
A review that pooled surveys in different countries up to 2004 found overall average prevalence estimates for any anxiety disorder of 10.6% (in the 12 months prior to assessment) and 16.6% (in lifetime prior to assessment), but that rates for individual disorders varied widely.
A review that pooled surveys of mood disorders in different countries up to 2000 found 12-month prevalence rates of 4.1% for major depressive disorders (MDD), 2% for dysthymic disorder and 0.72% for bipolar I disorder. The average lifetime prevalence found was 6.7% for MDD (with a relatively low lifetime prevalence rate in higher-quality studies, compared to the rates typically highlighted of 50/0- 12% for men and 1 00/0- 250/0 for and rates of 3.6% for dysthymia and 0.8% for Bipolar I .
A 2005 review of prior surveys in 46 countries on the prevalence of' schizophrenic disorders, including a prior 1 0-c.ountry WHO survey, found an average (median) figure of 0.4% for lifetime prevalence up to the point of assessment and 0.3% in the 12-month period prior to assessment. A lifetime morbid risk, reported to be to develop schizophrenia at any point in life regardless of time of assessment, was found to be "about seven to eight individuals per I (0.7/0.80/0). The prevalence of schizophrenia was consistently lower in poorer countries than in richer countries, but the prevalence did not differ between urban/rural areas or men/women (although incidence did).
Norwegian survey found a similar overall prevalence of almost I in 7 (13.4%), based on meeting personality criteria over the prior five-year period. Rates for specific disorders ranged from 0.8% to 2.8%, with rates differing across countries, and by gender, educational level and other factors. A US survey that incidentally screened for personality disorder found an overall rate of 14.79%.
Child psychiatric disorders
Approximately 7% of a preschool pediatric sample was given a psychiatric diagnosis in one clinical study, and approximately 10% of l - and 2-year-olds receiving developmental screening have been assessed as having significant emotional/behavioral problems based on parent and pediatrician reports.
Epidemiological studies report prevalence rates for psychiatric disorders varying from 9.5 to 370/1000 population in India. Despite variations in the design of studies, available data from the Indian studies suggests that about 20% of the adult population in the community is affected with one or the other psychiatric disorder.
A meta-analysis of 13 epidemiological studies consisting of 33,572 persons reported that a prevalence rate of psychiatric disorders is 58.2 per 1000 population.
· Organic psychosis (prevalence rate 0.4/1000),
· Schizophrenia (2.7/1000),
· Affective disorders (12.3/1000)
· Psychoses -(15.4/1000)
· Mental retardation (6.9/1000),
· Epilepsy (4.4/1000),
· Neurotic disorders (20.7/1000),
· Alcohol/drug addiction (6.9/1000; and miscellaneous group (3.9/1000) were estimated.
l . Bada Math Suresh, Srinivasraju R. Indian Psychiatric epidemiological studies: Learning from the past. Indian Journal of Psychiatry. 2010 January; 52(Suppl l): S95- S 103.
2.Reddy mv, chandrashekar CR. Prevalence of mental and behavioural disorders in india : a metaanalysis. Indian J. Psychial, 1998, 40 (2), 149-157.
3.Available from: http://en.wikipedia.org/wiki/Prevalence of rnental disorders.
4.Ganguli I IC.Epidemiological findings on prevalence of mental disorders in India. Indian Journal of Vol 42. Jan 2000.