What are your chances of developing a mental disorder at some point in your life?

Most of us worry about the possibility of getting physically sick at some time in our life and that is why insurance coverage of medical diseases is so common. However, how many of us even think about developing a psychological illness let alone get insurance coverage for it?

Yet a recent and very reliable survey in the United States (US) concluded that about half of the population will experience a mental disorder of some kind, at some time in their life (Kessler et al, 2005; Appendix).

Although the probability of developing a mental illness approximates that of developing a physical illness, most of us fail to even consider that possibility. The purpose of this post is to provide information about the most prevalent mental disorders: the more prevalent a mental disorder the greater is your chance of developing it.

There are two ways of considering the prevalences of mental illness or disorders. The first is by classes of mental disorders grouped according to some broad distinguishing feature. The general class of mental disorder is given in Table 1, column 1, the distinguishing figure in column 2. The second is way of describing mental illnesses is using specific diagnostic categories and this is illustrated by the variety of mental disorders provided in Table 1, column 3.

The prevalence of mental illness and in particular the ranking of the various kinds of mental illness varies according to whether one considers the broad classification or the specific diagnostic types.

Using the former, the top four general classes of mental disorders in order of decreasing lifetime prevalence were anxiety disorder (28.8 %); impulse control disorders (24.8%); mood disorders (20.8%); and finally substance use disorders (14.6%)(Kessler et al, 2005). (For more detailed discussion of these results please see the previous post “How common is mental illness and what types are most prevalent?”). However if the specific diagnostic categories are used then the prevalences and ranking are quite different as illustrated in Tables 2 and 3.

Table 1. Prevalences of top four classes of mental disorders in a recent US survey (Kessler et al, 2005)

Table 2. The prevalence of top ten diagnostic categories of mental disorders (Kessler et al, 2005)

DSM-IV/WMH-CIDI specific disorders ranked by lifetime prevalence Lifetime prevalence (%) Major depression 16.6 Alcohol abuse 13.2 Specific phobia 12.5 Social phobia 12.1 Conduct disorder 9.5 Oppositional-defiant disorder 8.5 Attention-deficit/hyperactivity disorder (ADHD) 8.1 Drug abuse e.g. cocaine 7.9 Post traumatic stress disorder (PTSD) 6.8 Generalized anxiety 5.7

What is the ranking of mental disorders in Asia and how does it compare to the US?

At the present time there are no epidemiological statistics on mental disorders in Asia directly comparable to the Kessler study in the United States.

However there is a yet-to-be published similar study, the Singapore Mental Health Study (SMHS; 2011), conducted by the Institute of Mental Health (IMH) of Singapore of over 6600 persons. Using the preliminary figures published in a media release by IMH, the top three mental disorders are displayed in Table 3.

The most prevalent mental disorder in both the US and Singaporean studies was major depressive disorder while the second most prevalent was alcohol abuse. Thus there is good general agreement between the two studies with respect to the ranking of mental disorders and it is likely that the ranking of the top ten in Singapore will resemble that reported in the US study.

The lifetime prevalences of mental disorders were substantially lower in the Singaporean sample compared to the US sample being only about one third that in the US study.

One possible explanation for this difference is that Singaporeans were more reluctant to admit to having had a mental disorder to those conducting the survey due to the greater stigmatization of mental illness in Singapore compared to the United States. This may also explain why the Singaporean study found that “The majority of the people with mental illness were not seeking help.” And if they did seek help it was only after years of delay.

Table 3. Top three mental health disorders in a nationwide sample of Singaporeans

DSM-IV/WMH-CIDI specific disorders ranked by lifetime prevalence Lifetime prevalence (%) Major depression 16.6 Alcohol abuse 13.2 Specific phobia 12.5

What is the prevalence of borderline personality disorder and co-dependency?

Although little could be found for the prevalence of co-dependency there was information for the more severe form of this condition which is called borderline personality disorder BPD). In a study of 34,653 US adults the prevalence of BPD was 5.9% (Zanarini et al 2011). This would put BPD as the tenth most common diagnosis instead of generalized anxiety disorder as shown in Table 2.

Concluding Remarks

The purpose of this post is to provide information about the prevalence of mental disorders and the types that one is most likely to develop.

Although relatively comprehensive data is presently available for only a US sample, preliminary results from the Singapore Mental Health Study suggest a similar ranking of mental disorders in Singapore and perhaps Asia in general.

In both the US and Singapore the most likely disorder that we will develop at some point in our life is depression while the second most likely is alcohol abuse. Fortunately effective prevention strategies exist for many of the mental disorders including depression and alcohol abuse which are the top two diagnoses.

There also is a variety of effective treatments available for these psychological problems. It is hoped that this information will open the way for you to educate yourself so that you will be better prepared if yourself or a loved one develops a psychological disorder.

References

Kessler, Ronald C., Berglund, Patricia, Demler, Olga, Jin, Robert, Merikangas, K. R., Walters, Ellen E., (2005). Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV Disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, Vol. 62(6), 593-602, doi:10.1001/archpsyc.62.6.593

The Singapore Mental Health Study (SMHS)(2011). Institute of Mental Health. Media Release. 18 November 2011. http://www.imh.com.sg/downloads/newsroom/2011/SMHS%20news%20release.pdf

Zanarini, Mary C., Horwood, Jeremy, Wolke, Dieter, Waylen, Andrea, Fitzmaurice, Garrett, Grant, Bridget F., (2011). Prevalence of DSM-IV borderline personality disorder in two community samples: 6,300 English 11-year-olds and 34,653 American adults. Journal of Personality Disorders, Vol 25(5), 607-619, doi:10.1521/pedi.2011.25.5.607

Appendix

The survey itself is referred to as the National Comorbidity Survey Replication (NCS-R) and was carried out between 2001 and 2003. The disorders were diagnosed based on both the Diagnostic and Statistical Manual, Fourth Revision and the World Mental Health Survey Initiative Version of the World Health Organization (WHO) Composite International Diagnostic Interview (WMH-CIDI).

