Are Mental Disorders Like Physical Diseases?

One of the most important forces in contemporary psychiatry is the drive to understand mental illness on the model of non-infectious physical illness. That is, depression or anorexia are disorders similar to hypertension or arthritis; the former manifest themselves in the mind and the latter in the body, but otherwise all of these conditions are fundamentally similar.

During the second half of the twentieth century the rapid development of drugs that help to control mental disorders helped to strengthen the conviction that such illnesses are in essence no different than physical disorders. It is easy to understand the appeal of this view: Modern medicine has garnered enormous scientific prestige as it has progressively grasped the genesis and effective treatment of a wide range of illnesses. Who wouldn’t want to join this team?

Psychological anthropologists and others who have studied mental illnesses in non-Western cultures have long protested, however, that many mental disorders take significantly different shape in different societies. This would imply that—to take a single example—depression is not the same sort of malady as hypertension, because, unlike depression, hypertension doesn’t significantly vary in presentation cross-culturally.

Eventually, the authors of the DSM—the diagnostic manual used by American psychiatrists—responded to this point by adding a sentence (on page 844 of DSM IV-R) that admits that symptoms of various disorders “are very often influenced by local cultural factors.” This is a step in the right direction, but it doesn’t confront the real problem, namely: Perhaps many mental disorders are not really diseases that may look a little different from place to place. Perhaps instead such disorders are differently constructed in different social environments.

Take anorexia nervosa, for example. In a recent book entitled Crazy Like Us, Ethan Watters points out that wherever we encounter the phenomenon of people endangering their health by ceasing to eat, we label it anorexia. However, in fact this phenomenon can have very different characteristics from place to place. The first anorectics to be described in Hong Kong, in the 1980s, did not have some of the most important characteristics found in American anorectics. For example, the Hong Kong anorectics did not perceive themselves to be overweight and were not avoiding food in an attempt to lose weight.

So, did these people in Hong Kong have an odd version of anorexia? Or did they have a disorder that was actually fundamentally different from anorexia? Watters goes with the latter interpretation and I agree with him. Medical anthropologists have shown that all cultures develop cultural models of both physical and mental disorders. Just as different societies may have different understandings of etiquette or justice, they may have different understandings of what an illness is. Mental disorders are different from place to place because people construct different models of these illnesses depending on many different factors. To take a single example, how people understand a mental disorder has to make sense in terms of their broader assumptions about science, ethics, religion, and so on. Since those broader assumptions vary from place to place, so will the models of illness.

This is important because it turns out that how people understand a mental disorder—their cultural model of the illness—often has considerable influence over the symptoms people experience. People develop the symptoms that make sense in terms of their broader assumptions, and which are similar to the symptoms of other people around them. This process influences some disorders more than others, of course. But this is why mental illnesses, even in our own culture, can appear or disappear in a matter of decades. In Sigmund Freud’s day, hysteria was a widespread mental disorder; it is unknown and unrecognized today. In the past several decades, diagnoses such as anorexia and multiple personality disorder have gone from being extremely rare to commonplace.

Does this mean that mental disorders are utterly different from physical ones? Absolutely not. Mental disorders occur in human bodies, and have physical components. However, it does mean that the assumption that depression is “just like” hypertension is an oversimplification.