In this video I describe the DSM-5, the Diagnostic and Statistical Manual of Mental Disorders – 5th edition, which is used to diagnose mental illness in the United States. The DSM-5 was released in 2013 and describe the symptoms, prevalence, and comorbidity of mental illnesses. I also discuss the changes from previous editions of the DSM, such as the abandonment of the axial system and greater focus on objective symptoms of disorder.

See the ICD-11 here: http://www.who.int/classifications/icd/en/

Video Transcript

Hi, I’m Michael Corayer and this is Psych Exam Review. In this video we’re going to talk about the DSM the Diagnostic and Statistical Manual of Mental Disorders which is in its fifth edition released in 2013. Now if you’re familiar with earlier editions of the DSM you might have noticed that the dsm-5 switched to using the Arabic numeral 5 rather than the Roman numeral, and the reason for this is that the plan is that there will be more frequent updates to the DSM and these will be labeled like software updates so we’ll have the DSM 5.1 5.2 etc. and of course it’s rather clunky to try to do that with Roman numerals.

Now the DSM is the most commonly used manual for diagnosing mental illness in the United States but it’s not the only manual in use and in Europe it’s more common for psychiatrists to use the ICD. This is the International Statistical Classification of Diseases and related health problems. And this is in its 11th edition released just a few months ago in 2018.

Now in the DSM-5 one of the changes was greater focus on objective symptoms of mental illness and this refers to symptoms that are observable symptoms, that are reliable, and symptoms that can be easily counted and this sounds like a good thing to have more objective criteria for the symptoms of mental illness but in practice this is very difficult to do. And this relates to some of the problems that I’ve talked about in previous videos and one of these is that diagnosis is often dependent on how patients describe their symptoms to a psychiatrist. And what this means is that patients might not be able to do this, they might lack the insight that’s necessary in order to determine which thoughts, feelings, and behaviors are relevant and which might be symptoms of mental illness. And even if they do recognize which aspects of their thoughts or behaviors might indicate symptoms of mental illness, they might not be able to accurately explain those symptoms to a psychiatrist.

This is especially true if we think about more severe mental illnesses. So if you have somebody who’s suffering from a severe case of schizophrenia then it’s unlikely this person will be able to clearly and accurately describe their experience to a psychiatrist. And this is going to make the diagnosis rather difficult. It’s also the case that patients might misrepresent some of their symptoms. They might emphasize certain aspects of their thoughts or behaviors or they might downplay other aspects and they might do this intentionally or unintentionally, and it might influence their diagnosis. So we could imagine two patients who have exactly the same symptoms but if they differ and how they can understand or explain those symptoms to a psychiatrist, then they might end up getting different diagnoses.

Now another related idea is the idea of the assumption of monism. this is something I talked about in one of the first videos in this course. This is the assumption that everything is physiology; that all of our thoughts, feelings, emotions, behaviors, these all have physiological activity associated with them. Now we often adopt this assumption when it comes to thinking about mental illness. We think that there must be some physiological explanation for all symptoms of mental illness. But it’s important remember that doesn’t mean that there’s a biological defect that’s responsible. And what I mean by that is it doesn’t mean there has to be something wrong with your brain or something wrong with your physiology in order for you to manifest certain symptoms of mental illness. And another way of saying this is that functional biology can still lead to abnormal behavior. In other words, you can have a perfectly functioning brain, let’s say or, or any other aspect of your physiology, and yet you could still have symptoms of mental illness. And this is part of the reason why we don’t have physiological tests for psychological disorders . We don’t necessarily know that there are defects associated with certain mental illnesses.

Now sometimes we hear popular discussion of mental illnesses and we see this in media, we see this in advertisements, and we see descriptions of what sound like physiological explanations for the disorders. And yet these physiological explanations are not actually part of the diagnosis. And so a prime example of this is the discussion of chemical imbalance for depression. You see this in advertisements for antidepressants. You hear people talk about depression as being related to some chemical imbalance, and this might lead you to believe that there’s some sort of measurement of chemicals that occurs in the diagnosis of depression, and that’s not the case. There are no chemical measurements that are used to confirm a diagnosis of depression. We don’t have ways to measure neurotransmitters in a living human brain. And so it’s also the case that there’s no description of what an appropriate chemical balance would be. So when we talk about a chemical imbalance it’s not very useful because we don’t like to know what the appropriate balance would be. So to talk about an imbalance doesn’t make much sense.

Now this means that there is necessarily a subjective or interpretive component to diagnosis because we don’t have these clear biological markers of mental illness. And this means this subjective component means that different psychiatrists might see the same symptoms and they might not give the same diagnosis and this is a problem that has plagued psychiatry for decades. In 1962 Aaron Beck and colleagues did a study where they had 153 patients and these patients were seen by pairs of psychiatrists and then the psychiatrists each gave independent diagnosis of the patients. And rather startlingly, what Beck and colleagues found was that these independent diagnoses were only in agreement 54% of the time.

Now a similar study by John Cooper in 1972 considered the role of culture in diagnosis. What Cooper and colleagues did was they wondered whether psychiatrists in different areas would give different diagnoses for the same patients. And so they conducted clinical interviews with patients and these were videotaped and the videos were then given to psychiatrists in New York and psychiatrists in London. And what Cooper and colleagues found was that the psychiatrists in New York were twice as likely to give a diagnosis of schizophrenia while psychiatrists in London were twice as likely to give a diagnosis of an affective disorder. So again we have the same interview, the same expression of symptoms, being interpreted differently by different psychiatrists and that is leading to different diagnoses. And of course both of these studies are several decades old and the DSM has been updated since then and this is part of the reason for this push for greater objectivity, to try to reduce these problems.

In the DSM-5 one of the major changes was the abandonment of the axial system that was used in previous editions of the DSM. The axial system was a way of assessing relevant medical illnesses, other risk factors, that might be associated with disorders and considering these in the diagnosis. This was deemed to be rather subjective and this is why it was abandoned. So other risk factors like poverty or social support used to be considered in diagnosis in the DSM-IV but that’s no longer part of the DSM-5. Some critics of the DSM-5 have suggested that this reduces emphasis on psychological and social factors that are actually important for understanding illness and so there’s some disagreement here on whether or not this push for greater objectivity is a good thing or whether it’s causing us to ignore some of the subjective components that are actually important for understanding disorders.

Now in the DSM-5 we also have mention of the prevalence for each disorder. So what prevalence refers to is the frequency of occurrence of a disorder and you can think about prevalence in different ways; there’s different types of prevalence. We can talk about the lifetime prevalence and that refers to the frequency of occurrence over the course of a lifetime. Or we can talk about the point prevalence, and that refers to the frequency of occurrence over a certain period of time like a year. This distinction between lifetime prevalence and point prevalence can be seen in something like an eating disorder like bulimia nervosa or anorexia nervosa. And so if we have a woman who’s 40 years old, her risk of developing an eating disorder is very low and the reason for that is that eating disorders, while they do affect women much more than men, they affect women who are in their teens and twenties much more than women at other ages. And so what that means is the prevalence, the point prevalence is going to be different for a woman who’s twenty years old compared to a woman who’s 40 years old. Now in the DSM-5 the prevalence that’s given is usually a 12-month prevalence, so this refers to the percentage of the population with that diagnosis over a one-year period; so what percent of the population has this diagnosis during a year.

Now it’s important remember that the prevalence here in this case, this 12-month prevalence, refers to how widespread the illness is, not the risk of contracting it. So what I mean by that is if you look at a particular disorder and you see it has a 12-month prevalence of 10% what that indicates is that 10% of the population has that diagnosis over the course a year, but that doesn’t mean that you have a 10% risk of contracting that disorder.

It’s also important to separate prevalence from incidence, because incidence refers to the number of new cases over a particular time period. So the incidence over the course of a year, it might be very different from the prevalence. One way you could think about that is if you imagine an infection. So let’s say we have some outbreak of this infection that affects many people and so they all, there’s a very high incidence they all get diagnosed in the same year. They’re all new cases of this infection. Now let’s say a year later many of them still have this infection but it’s not infecting new people. So we’d have high prevalence that second year; there’s still a large percentage of the population that has the infection, but low incidence because there aren’t any new cases being reported. So that’s a way you can think about the difference between prevalence and incidence and it’s important to remember in the DSM that we’re talking about prevalence we’re not talking about new cases each year.

And lastly we have mention of the comorbidity of illnesses in the DSM-5. So I mentioned comorbidity in a previous video and this refers to illnesses or disorders that are diagnosed at the same time in the same patient. So the DSM-5 lists disorders that are frequently diagnosed together. So if you’re reading about an eating disorder in the DSM-5 it might mention that it’s comorbid with something like depression and this is the reason why prevalence rates are not additive. What I mean by that is if you looked at ten different disorders and you said okay each of these ten disorders has a 12-month prevalence of 10 percent, meaning 10 percent of the population has that diagnosis over the course of a year, then you might think well that means everybody must have a mental illness, right? If there’s 10 disorders and they each have 10 percent prevalence, then it sounds like everybody has a disorder. But of course that’s not how prevalence rates work. They’re not additive that way and the reason is comorbidities. Because what we see is that mental illnesses tend to be concentrated amongst a smaller number of people who each have several disorders.

So when we talk about the fact that eating disorders are frequently comorbid with depression or that anxiety and depression or comorbid or PTSD and depression or comorbid then what we’re seeing that same patient is being counted in the prevalence rate for multiple disorders. So a person who has anorexia nervosa and depression is going to be counted in the prevalence rates of both of those disorders even though it’s only one patient. Okay so those are some of the basic ideas in the DSM-5. I hope you found this helpful, if so, please like the video and subscribe to the channel for more. Thanks for watching!