The latest edition of the psychologist bible was released in March.
The Diagnostic and Statistical Manual (the DSM) published by the American Psychiatric Association is the most influential document in worldwide mental health. It is released about every 10-15 years, and a revised edition is released every 5-8 years. The March edition, the DSM-V-TR, is a revision – this means no major changes, business as usual.
A simple answer to the question “how many psychological disorders are there?” is “about 300”. There are nearly 300 entries for unique disorders in the DSM-V-TR. That’s a lot to bear in mind! I’m sometimes asked, “how do you remember all of these conditions?”
The honest truth is that I, like most mental health professionals, don’t keep all 300 in mind. Instead, we tend to think a lot about the commonly diagnosed disorders (see my list of them here), and relatively little about the obscure disorders. Most clients meet criteria of one of the top 10 disorders.
But even these 10 disorders could be boiled down to fewer syndromes, by looking into genetic clusters of risk factors.
A recent study by the University of Colorado in Boulder analysed the genes correlated with 11 common disorders. The researchers used data from several large gene banks to look for genetic inter-linkages between these disorders. The disorders investigated were: schizophrenia, bipolar disorder, major depressive disorder, anxiety disorder, anorexia nervosa, obsessive-compulsive disorder, Tourette syndrome, post-traumatic stress disorder, problematic alcohol use, ADHD and autism
The authors found that schizophrenia and bipolar disorder shared a significant amount of genetic signal (up to 70%). Although these two disorders share the symptoms of delusions and depressive-type deficits, they are thought of as separate categories of disorders.
Another key finding was that Anorexia Nervosa and Obsessive-Compulsive Disorder have strong genetic overlap. I have previously written about other research that has come to a similar conclusion about the link between these two disorders. These two disorders share symptoms related to behavioural over-control.
Research such as this demonstrates that there is a huge crossover amongst the psychological disorders. When the next DSM comes out (the DSM-VI) it will be interesting to see if the greater knowledge of genetics will lead to a streamlined system. Or whether we will persist in having 300 diagnoses.