Prevalence
and incidence of mental health problems
Introduction
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
Anxiety 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.
Mood disorders
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 .
Schizophrenia
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).
Personality disorders
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.
In India
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.
References
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.
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