If your family doctor wants to know if you have an infection, they’ll order a blood test. To check for a broken bone, they’ll do an X-ray. For heart problems, maybe an electrocardiogram makes sense. What test can diagnose someone with major depression? With obsessive-compulsive disorder? Posttraumatic stress disorder?
Some people are surprised to find out that there are no laboratory tests to diagnose a mental illness. No blood tests, CT scans, or anything else. Instead, a diagnosis is based on your symptoms. You describe symptoms while giving your history and answering questions from your health provider. Their observations, and sometimes those of family and friends, also help establish the diagnosis.
With no tests to diagnose it, some people believe mental illness is not real. They are wrong. Mental illness is very real. Many physical illnesses are also diagnosed solely from their symptoms. Most syndromes (Wikipedia lists over 1,400) fit that category, e.g., irritable bowel syndrome or post-concussion syndrome. Other illnesses now have tests that didn’t exist in the past. Genetic tests identify mutations associated with some illnesses, while advanced imaging can see brain changes characteristic of other ailments. Perhaps someday researchers will identify tests for specific mental illnesses.
To make a diagnosis, your doctor evaluates your symptoms against a set of criteria for a certain illness. If the doctor feels you meet those criteria, then you have that illness. Think of it like taking a test that you’d rather not pass.
What do the criteria for a mental illness look like? Here’s an example for binge-eating disorder. Note the specifics on duration and impact.
Recurrent episodes of binge eating. An episode is characterized by both of the following:
The binge-eating episodes are associated with three (or more) of the following:
Marked distress regarding binge eating is present.
The binge eating occurs, on average, at least once a week for 3 months.
The binge eating is not associated with the recurrent use of inappropriate compensatory behaviour as in bulimia nervosa and does not occur exclusively during the course of bulimia nervosa or anorexia nervosa.
The criteria for every mental illness come from a thick book called the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published by the American Psychiatric Association. New versions are the product of years of meetings and debates by experts in all areas of mental health.
The DSM-5 reflects the current mainstream understanding of different mental illnesses. It highlights the clinically relevant symptoms that identify each illness and helps providers differentiate between them. It gives mental health professionals a common language to communicate with one another.
The DSM-5 has much more on each illness than just the list of criteria, including diagnostic features, prevalence, development, course, risk factors, culture- and gender-related issues, differential diagnosis, and comorbidity.
The DSM-5 is nicknamed the “bible” of psychiatry. But it was written by people, some with vested interests, and is not infallible. There are heated disagreements about issues large and small. How are illnesses categorized? How relevant are certain symptoms? What should or should not be considered a disorder? The DSM evolves over time, alongside the theory and practice of mental health care. Think of it as a guidebook and judge it by how well it helps guide people back to health.
Many people, for a variety of reasons, are skeptical of psychiatry. They believe that the mental health system medicalizes normal human emotion. They fear that every thought and feeling will eventually be evidence of some disease. These people ignore that symptoms have to significantly interfere with your life to suggest an illness. You certainly wouldn’t choose to treat it otherwise.
You saw earlier that mental illnesses are organized into about 20 categories in the DSM-5. These categories can be convenient, but it’s the specific illness that matters when you want to treat it. It’s useful to talk about depressive disorders versus anxiety disorders, but a category isn’t a diagnosis.
One category that generates a lot of confusion and misunderstanding is personality disorders. Personality disorders are diagnosed when people have significant and longstanding difficulty coping with life events. They have unhealthy or inflexible coping strategies that cause tension in relationships with others. Here are two examples:
Imagine you are someone who is very distressed by uncertainty. You may cope by trying to control everything around you. If this has a large enough impact on your life, you may be diagnosed with obsessive-compulsive personality disorder.
Imagine a friend tells you they are unavailable to have coffee with you. Most people would see this as a minor disappointment. But you might decide they cancelled because they hate you. As a result, you might feel abandoned and become so distressed you engage in self-harm such as cutting. These are hallmarks of borderline personality disorder, one of the most stigma-laden mental illnesses.
Personality disorders are difficult to diagnose and often misdiagnosed. They’re present even during long periods when mood, anxiety, etc. are not problematic. They tend to occur in direct response to life events. Other disorders are not always as strongly tied to life events. Providers need a thorough, long-term history to correctly diagnose a personality disorder.
Personality disorders don’t respond as well to some short-term treatments or medications used for other illnesses. At best, these temporarily reduce impulsive, unhealthy coping behaviours. Without specific therapy, people with personality disorders often bounce from one crisis to another without getting better. The hospital emergency room can get them past the crisis but isn’t the right setting to treat people with personality disorders.
If diagnosis is as simple as using a checklist of criteria, can anyone do it? Can you diagnose yourself? Can you diagnose one of your relatives? Making an accurate mental health diagnosis is not that simple.
First, you’d need to be familiar with the hundreds of different disorders in the DSM-5. You’d need to know what symptoms to look for, how to identify them, and be able to rule out other diagnoses. It’s too easy to focus on one or two things and miss many others. Having an incomplete picture of what’s going on with someone is a recipe for misdiagnosis.
You may have identified all relevant symptoms and know the criteria. It’s still a skill to know how to interpret those criteria—how severe the symptoms have to be, for example.
Many mental health symptoms can also be symptoms of other illnesses. That makes a general knowledge of medicine essential. Often, the first signs of a brain tumour are changes in behaviour. You don’t want to quickly pass that off as some mild mental illness.
Making an accurate diagnosis requires substantial knowledge, skill, and experience. Being able to do it well is an art. It also explains why psychiatrists complete five or more years of theoretical and practical training after undergraduate and medical school. They are taught to diagnose and treat the full range of mental illnesses. Yes, your psychiatrist is a real doctor. At one time, they helped deliver babies, performed surgery, and did spinal taps.
People other than psychiatrists frequently diagnose and treat mental illness. Family doctors have comprehensive health knowledge including training in mental health. Psychologists may have more mental health training, though lack the medical background. Their diagnosis may come with the caveat that they can’t exclude other physical illnesses.
If something seems unusual or if the standard treatment isn’t working, they may recommend a psychiatrist. These are hints that something else may be going on, and getting a fresh look, including reviewing your diagnosis, may help.
You may have people in your life now who are telling you what’s wrong with you or insisting that nothing is wrong. How much should you depend on what they say?
Does the exact mental health diagnosis really matter that much?
If you have chest pain, you want to know whether it’s from a heart attack, pneumonia, acid reflux, or a pulled muscle. You really want to know before someone decides to crack your chest open to perform surgery.
As with physical health, the same symptoms can suggest different illnesses. Someone with frequent suicidal thoughts may be suffering from a form of depression. They may have an entirely different illness such as borderline personality disorder. The two are treated very differently. Poor concentration may be a symptom of depression or anxiety. It could be due to attention-deficit hyperactivity disorder, low iron levels, or other things. Treating the wrong problem is not likely to be helpful. An antidepressant won’t fix poor concentration due to ADHD. Cognitive behavioural therapy for anxiety will not address an iron deficiency.
To complicate matters, having two or more (comorbid) mental illnesses at the same time is common. Some of your symptoms may be explained by one illness and other symptoms by another. Sometimes there will be overlap. It’s also common to have a mental illness with a comorbid physical illness. In fact, if you have certain physical illnesses, you have a much greater chance of also having some mental illnesses.
At the same time, it’s easy to get too carried away with specific details. Will it really matter if a major depressive disorder is classified as severe versus moderate? Probably not. Don’t get too worked up over it. Sometimes it makes sense to label your illness “Herbert,” and get on with it!
As another example, say the criteria for an illness requires you to have six of twelve symptoms. You may only have five, but those five are causing you significant distress. Yes, you don’t technically have the illness. But it also may not hurt to treat you as if you fully met the criteria. The same thinking applies when you may have all the symptoms, but one is not quite severe enough.
Sometimes patients with comorbid illnesses get hung up on their diagnoses a bit too much. They obsess about whether something they did was because of their anxiety or their ADHD. A diagnosis is just a tool, valuable only as long as it’s useful in helping you become well.
As with many physical illnesses, there are no laboratory investigations yet that definitively diagnose a mental illness.
Each mental illness is defined by a set of specific criteria, but there are usually multiple ways to meet criteria for an illness; comorbid mental illnesses (more than one at a time) are also common.
The DSM-5 defines the criteria and provides a great deal of additional information on each illness. Specific training and expertise are needed to interpret and apply this information.
A mental illness is only diagnosed when symptoms are severe enough to have a significant impact on functioning.
Now Available! A MSP-supported live course for BC residents based on the book. [Mar/2023]
While you can read it for free online, there are conditions on sharing it with others (see below). You can also still purchase copies in paperback or e-book (PDF, Kindle, Kobo, etc.).
Now Available! A MSP-supported live course for BC residents based on the book.
