Mental Health Expert Dr. Charles Raison Psychiatrist,
Emory University Medical School

Expert answer

The issues you raise, Tony, are so interesting that I am going to devote this week and next week's answer to addressing them. And apologies in advance for using a little more academic language than I normally do.

Modern psychiatry is built around diagnosing psychiatric disorders based on three primary factors: clustering of symptoms, course of symptoms over time and degree of life impairment that results from these symptoms.

Think for a moment about how different this approach is from the way most medical disorders are diagnosed and treated these days. Let's say you develop crushing chest pain and shortness of breath. You go to the ER. Do they make a diagnosis of heart attack (myocardial infarction, or MI) based on your symptoms?

No, they order a blood test that will show whether heart muscle is dying. And they get an electrocardiogram, to measure electrical activity in the heart, which changes in very specific ways in the context of an MI. If these tests are positive, you are admitted and rushed off for other tests and interventions. If the tests are negative, you are told that you are probably having an anxiety problem and referred to a psychiatrist.

We have no blood tests in psychiatry, nothing like an electrocardiogram. All we have are symptoms we can watch over time. In this way, we are in a situation not so different from doctors in other fields of medicine 100 years ago, before organs such as the heart and lungs began yielding their secrets to technology.

I say all this as a prelude to addressing your first question about how similar schizophrenia and bipolar disorder are, and if they are similar, how they can be told apart. It turns out that this question is where modern psychiatry began.

In the 19th century, psychosis was considered to be a single condition characterized by various symptoms consistent with a person being disconnected from reality. It took a gentleman named Emil Kraepelin -- who is often considered the father of biological psychiatry -- to notice around the turn of the 20th century that although psychotic states looked similar to one another, people with psychosis seemed to follow one of two long-term disease courses.

One group of people developed psychosis early in life and had a progressive decline in their ability to think and function that was unremitting and terrible. Reflecting the degeneration that accompanied this state, Kraepelin called this condition "dementia praecox." Today we call this schizophrenia.

Another group of people who developed psychotic symptoms tended to do so a little later in life. Rather than showing a constant decline, these people circulated in and out of madness, and they were always either depressed or elated when they lost touch with reality. To this condition, Kraeplin give the name manic depression -- a term that although still in use, has been supplanted by the category of "bipolar disorder" in official psychiatric nomenclature.

So notice that the essence of the distinction between schizophrenia and bipolar disorder has nothing to do with the type of psychotic symptoms that a patient demonstrates, but rather with the course of the symptoms over time.

This insight got lost for half a century when psychoanalysis reigned supreme, but made a strong comeback in the 1960s and 1970s with the advent of new scientific techniques for studying the brain, and more importantly, the availability for the first time of medications that had profound effects on psychosis and mood disorders.

Especially relevant to the distinction between schizophrenia and manic depression was the discovery that lithium was often a miracle drug for people with bipolar disorder but was generally of little use in schizophrenics. This pharmacological truth seemed to powerfully validate Kraepelin's ideas. From the marriage of Kraepelin, new scientific techniques and new medications was born the modern psychiatric diagnostic guidelines that can be found in the DSM-IV.

So that's a little history. Next week I'll turn to the task of answering your questions directly. But by way of preview I can tell you that the certainties that launched modern diagnostic psychiatry have mostly vanished, and continue to fade with each new scientific discovery. So the short answer to your questions is that schizophrenia and bipolar disorder are increasingly looking more similar than separate.