It’s the official instruction book for diagnosing and treating mental health conditions in the US, and is used by psychiatrists, medical staff and academic researchers.
The DSM works based on the principle that psychological symptoms can be objectively classified and observed in the same way as physical symptoms, so psychiatric illness can be diagnosed and studied as medical illnesses. Emil Kraepelin, one of the first psychiatrists, pioneered this idea- this is why systems like the DSM are sometimes described as neo-Kraepelinian methods.
In Kraepelin’s time (1883), people were diagnosed haphazardly, based on the most obvious symptoms. Most doctors also believed in Unitary Psychosis, the idea all forms of mental illness were variants of one illness. Kraepelin instead worked by syndromes- patterns and trajectories of symptoms- and wrote an encyclopaedia of psychiatry containing many case histories and promoting his diagnostic system.
So, how does a symptom lead to a diagnosis? The first step is to classify what types of symptoms are a problem, and what sets of symptoms usually appear together. This section in the DSM is known as the Diagnostic Classification.
This is the masterlist of everything currently classified as a disorder or illness by the American Psychological Association (the creators/publishers of the DSM). The APA also decide what disorders cannot be diagnosed together, and what external factors can affect how valid a diagnosis is.
To make a guess at a diagnosis, the psychiatrist will first see which DSM disorder most closely matches the patient’s displayed and volunteered symptoms. After that, the psychiatrist must then make sure the patient’s symptoms can’t be better explained by anything else. For example, if a patient complains of severe anxiety, the psychiatrist might find out that the patient drinks an unsafe amount of coffee; the overload of caffeine could be causing them anxiety, rather than it being due to an anxiety disorder.
What the APA considers a disorder can change over time, due to new information, better research, or social changes. For example, until the DSM-III, being homosexual was considered a mental health issue. After that, homosexuality itself wasn’t a disorder, but if someone was extremely distressed and upset about being homosexual, those feelings would be classified as a disorder instead. This is a similar pattern to being transgender today: some people would see being transgender is a disorder, while others would only consider being very distressed about being transgender as a disorder.
Once a list of disorders has been drawn up, the next part is to make it clear what sets of symptoms relate to each disorder, and what conditions support or prevent a diagnosis of each disorder.
Diagnostic Criteria Sets.
Criteria sets contain the list of symptoms for each disorder, and how many symptoms are usually required for a diagnosis. The DSM-IV criteria list for unipolar depression (otherwise known as Major depression) contains 9 items: to be diagnosed requires experiencing 5 of them, which has to include either the first or second on the list. Severity is based on both how many individual symptoms are present, and their overall impact on the patients life.
Other criteria includes:
- Time limits- a patient needs to have symptoms of Generalised Anxiety Disorder for six months before it can be officially diagnosed.
- Age limits for symptom appearance- ADD can be diagnosed at any age, but some symptoms have to be noticeable before age 7. If all symptoms only appear in adulthood/ late adolescence, it cannot be diagnosed as ADD.
- Age limits for diagnosis, regardless of symptom appearance- Personality disorders cannot be officially diagnosed before age 18, as people’s personalities are seen as too malleable before then.
- Exclusion/ overriding criteria- if someone is diagnosed with unipolar depression, but then has a hypomanic episode, their diagnosis must change to bipolar depression instead.
Each disorder is accompanied by a more descriptive explanation of what a patient may look and sound like, how they might behave when talking to the psychiatrist, and what phrases people with the diagnosis commonly use to describe their experiences. For example, someone with unipolar depression might describe themselves as being in a “fog” or “black cloud”, while someone who has bipolar depression might view their depressive episodes as a “crash” or “hibernation” compared to their previous hypomania.
Descriptive text will also explain what tests could support or go against a diagnosis, and what treatment options are currently seen as most useful. Risk factors, genetic connections (if known) , and prognoses (how well people generally do after being diagnosed), are often included.
Cross-cultural factors and differences are required for some disorders, as people of different cultures (or different genders in the same culture) can explain the same disorder in different ways. For example, people living in Asian cultures are more likely to report unipolar depression and anxiety by their physical symptoms instead of emotional and personal symptoms, due to cultural differences in how mental health issues are perceived.
Finally, the disorders are organised into chapters based on their properties and connections; each version of the DSM will rearrange how disorders are grouped, due to more information on causes and treatments, or data on how the diagnoses have been used and how effective they have been.
Once they have been organised, disorders will then be given a 5-digit code; codes are designed to reflect connections between families of disorders, and variations within families, such as severity and length.
A good way to make sense of DSM codes is to compare it to the Dewey Decimal System used in libraries. A library code, let’s say 513.21, can be translated into different degrees of information about the book. Putting 513.21 into the Dewey Decimal System gives us:
5 = Sciences and maths
51 = maths
513 = arithmetic
513.2 = arithmetic operations
513.21 = basics of arithmetic operations
For books, numbers before the decimal point narrow down the book to its field and subfield, while numbers after the decimal point are used to narrow down the difficulty level, authors, language and other useful information.
DSM codes look the same and often work similarly. Using Mood Disorders as my first example, Mood Disorders mostly occupy number 296 in the DSM.
Numbers after the decimal point are used to specify whether the person’s depression is picked up on for the first time (Single Episode), or long term (Recurrent), as well as its current severity.
They are also used to indicate remission (reduction of symptoms).
For example, the code 296.33 would break down into:
296 = a depressive disorder.
296.3 = major depressive disorder, recurrent type.
296.33 = severe, but without any elements of psychosis.
While 296. 45 would mean:
296 = a depressive disorder.
296.4 = bipolar depression type 1, where the person was most recently hypomanic rather than manic or depressed.
296.45 = in partial remission. (The person has lessened symptoms, usually meaning they are currently on medication).
If things aren’t quite as clear, there are also numbers put in place for that.
For Mood Disorders, 296.9 signifies Mood Disorder Not Otherwise Specified (NOS), aka “we know its some kind of mood disorder, but don’t yet know beyond that”, and 296.8 signifies Bipolar disorder NOS. However, for some reason, Depression NOS is number 311, while Cyclothymia (a chronic but milder version of Bipolar depression) is at 301, along with the Personality disorders.
Ok, maybe the DSM isn’t quite as organised as the Dewey Decimal system…