At least 25% with a mental health problem is a conservative estimateBMJ 2012; 344 doi: http://dx.doi.org/10.1136/bmj.e1776 (Published 14 March 2012) Cite this as: BMJ 2012;344:e1776
- 1Institute of Psychiatry, London SE21 7HJ, UK
- 2Mental Health Research Team, College of Human and Health Sciences and College of Medicine, Swansea University, Swansea SA2 8PP, UK
There are enormous problems in deciding what counts as a mental disorder,1 but most epidemiologists use an official classification such as the international classification of diseases.
We were responsible for providing evidence that the one year prevalence of mental disorders in community samples is about 250/1000.2 We obtained this figure by combining figures for cross sectional prevalence with admittedly speculative estimates of annual inceptions, so that a cross sectional rate of 180/1000 was inflated by assuming that about a third of that number would develop a new episode during the next year. Even at that time, we had excellent evidence that most episodes are of short duration (fewer than three months). Since then, surveys have asked people to remember their health over the previous year. By 2002 it was shown that survey results were yielding slight underestimates: the rate for the UK was then revised upwards to 270/1000, also taking into account rates reported by the Office for National Statistics.3
These rates did not include severe mental disorders, such as schizophrenia, bipolar disorder, or dementia, and neither did they include alcohol and drug dependence. These are annual rates, not lifetime rates—the concept of lifetime prevalence is necessary for studies of the genetics of mental disorders, but it is a highly questionable concept where common mental disorders are concerned. This is because it assumes that people not only can, but will, reveal information about minor disorders that occurred many years ago that they might have forgotten or suppressed. For this reason, we have never quoted figures for lifetime rates.
However, for those who like to think in these terms, “at least 25%” is almost certainly a conservative estimate.
Cite this as: BMJ 2012;344:e1776
Competing interests: None declared.