Classifications of Mental Illness—A History

From the lecture series: Psychology of Human Behavior

By David W. Martin, Ph.D., North Carolina State University

It would be nice if we could follow the medical model in psychology and know exactly what the treatment is for a mental illness once we have made a diagnosis, but that does not always happen…

Doctor talking to patient for diagnosing mental illness
(Image: By Chinnapong/Shutterstock)

Diagnosis and Classification of Mental Illness

Sometimes the therapy is more determined by the training of the therapist than by the particular diagnosis. The hope is that the diagnosis would tell you something about what therapies might be brought to bear to try to correct the condition.

That is one reason—and probably the major one—to have a classification system for mental illnesses, but there are other reasons as well. The real impetus for a classification system in the United States came out of a clerical reason.

This is a transcript from the video series Psychology of Human Behavior. Watch it now, on Wondrium.

After the Second World War, when people were being released from the military, the clerks had to classify what a person’s condition was, and they often did not have a box to check to say what their mental condition was because there wasn’t a very good classification system at that point. So around 1952 came the first official classification system from the American Psychiatric Association, and that was partly driven by the necessity of this clerical task of putting people into the box.

After the Second World War, when people were being released from the military, the clerks had to classify what a person’s condition was, and they often did not have a box to check to say what their mental condition was because there wasn’t a very good classification system at that point.

Today there is a clerical duty that is even greater than that, the insurance companies and the third-party payers for people with mental illnesses. They want to know what the classification of the person is. If you are a therapist and dealing with a particular patient, one of the first things you have to do is make a diagnosis and write down the number from the classification system that says what category this person fits into.

Then the insurance company says that you can do certain things, you can have a certain number of sessions of therapy if the person has this particular classification; but it is very different for another classification. Again, it is a clerical matter.

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Problems with Classification Systems of Mental Illness

Engraving of Hippocrates by Peter Paul Rubens, 1638
Hippocrates classified mental illnesses into three categories: mania, melancholia, and phrenitis (Image: By Paulus Pontius – Courtesy of the National Library of Medicine/Public Domain)

Of course there are some problems with classification systems, such as self-fulfilling prophecies. Once you have classified somebody in a particular way, the label tells people something about their behavior and people expect to be that way. But that doesn’t always wind up being the case, and it can still be very difficult to get rid of the label.

What is the history of the classification systems? People have dealt with mental illness for a long time. The first case of trying to classify mental illness comes from Hippocrates, who lived from 460–377 B.C. Hippocrates is considered the father of medicine, and the Hippocratic Oath that doctors take is named after him. He classified mental illnesses into three categories: mania, melancholia, and phrenitis, which was a brain fever of some sort.

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Mania is probably what we call psychotic today; a person who is running around out of control. Melancholia is probably what we call depression today. So he had these three different classification systems, and he had certain theories about why this was, including bodily fluids and bile and other things that were happening.

1980 "Avicenna" stamp of Algeria
Avicenna, from Arabia added a couple of mental illness classifications including epilepsy and hysteria (Image: By Algeria post/Public Domain)

Then in the Islamic tradition, Avicenna, from Arabia, 980–1037 B.C., added a couple of classifications including epilepsy and hysteria. Many of Freud’s early patients were categorized as having hysteria—which we now call conversion disorder—where you have part of the body that does not work quite properly and it has a psychological root cause to it. So, Avicenna added those two categories more than 1,000 years ago.

Then not much happened after that for many hundreds of years, partly because people totally misunderstood mental illness. They thought that mental illness was caused by demons for the most part, and that it was a religious experience. If it is just demons, how do you classify a demon? A demon can do almost anything a demon wants to. So there wasn’t much in the way of classification at that point.

Diagnostic and Statistical Manual of Mental Disorders

Finally in the 20th century there came the Second World War, and the American Psychiatric Association decided that they would start an official classification system at that point. They used some of the classifications that had sort of been left over from history as a starting point, along with psychoanalytic theory because it provided a theoretical context for many of these mental illnesses.

In 1952 they came up with what is called the Diagnostic and Statistical Manual of Mental Disorders, commonly referred to as the “DSM.” The first one that came out we now call DSM-I, because there have been subsequent DSMs. 

It took them about 15 years to come up with the second version, the DSM-II, and then the times got shorter and shorter; and whereby they are coming out with a new official one about every seven or eight years now, and there is often a revision in the middle of that process too-—DSM-II, DSM-III, DSM-III-R. We are currently on DSM-IV, and before that we were on DSM-TR, which is another revision called “Text Revision,” which is what TR stands for. Supposedly, as we learn more, we change this diagnostic and statistical manual, and it gets thicker and thicker as the number of classifications become larger and larger.

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Over the years, this has changed in a number of ways. The original one had a lot to do with the theoretical underpinnings of psychoanalysis and psychoanalytic theory. They got rid of that between DSM-II and DSM-III. DSM-II had about seven different classifications in it and then DSM-III had a whole bunch more classifications, because under DSM-II for example, you had neurosis as a category, and then were a number of different kinds of anxiety disorders under that, and it was all in a psychoanalytic model.

Then they broke all of that out in DSM-III. The DSM-III tried very hard to become atheoretical and to get rid of this sort of underlying psychoanalytic structure that had propped up DSM-II. The DSM-III also made quite a breakthrough in that they were far more concerned with specifying the exact sort of symptoms a person had to have. Now, in DSM-IV, you get lists indicating that you have to have, for example, three out of the following five things in order to be diagnosed with this particular disorder.

So, it is very much more driven by observing the person. There is still some subjectivity, but because of the emphasis on symptoms, they have been able to make the system far more reliable. Reliability means that if you have one person who is doing the diagnosis in a particular case and gives a classification to it, then it is likely that a second clinician would give the same classification.

The DSM-II was very unreliable and people disagreed quite a bit, even with themselves. If you asked them at a particular time to diagnose a particular condition, and then asked them a year later, giving them the same symptoms, people could not even agree with themselves because the descriptions of the classifications was so nebulous, so ambiguous.

Learn more about anxiety—once called neurosis—and mood disorders

So one thing that has been achieved with DSM-IV is much more reliability. As for validity, that is harder to be sure about. How do you know for sure what a person has? Validity means that you have classified it correctly; that it indeed is the disorder you have just called it. We do know that if it is not reliable, it is not going to be very valid. That does not say whether it is the correct thing.

They had a good list of diagnostic criteria for whether or not somebody was a witch a number of centuries ago. They were quite reliable about it, but were they valid? We do not think so today, because we do not think that there are witches today. So validity is a bit of a different concept, and we are not quite as sure about that, even with today’s fairly sophisticated systems.

Common Questions About Classifications of Mental Illness

Q: Is there a cause for mental illness?

Mental illness is usually caused by a combination of ailments including the environmental stresses one experiences along with genetics and chemical imbalances.

Q: Are there any first signals of a person going crazy?

Going crazy is an imprecise diagnosis, but mental illness can be predicted somewhat by prolonged social withdrawal, anxiety, irrational fears, and dramatic changes in behavior or hallucinations.

Q: Are people born mentally ill?

In the same way people are born with Down’s syndrome, people can be born with a proclivity toward mental illness and potentially with some symptoms that would describe mental illness.

Q: Does mental illness start at a certain age?

The age at which mental illness begins is different for all, but statistically at the age of 14, around 50% mental illness manifests.

This article was updated on 12/29/2019

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