The moveable feast of madness

There was an interesting story in the New York Times on Jan 8 called "The Americanization of Mental Illness," that we are just now getting around to blogging about.  It turns out that mental illness varies by time and place. One culture's madness is completely unknown in another.

In some Southeast Asian cultures, men have been known to experience what is called amok, an episode of murderous rage followed by amnesia; men in the region also suffer from koro, which is characterized by the debilitating certainty that their genitals are retracting into their bodies.

Schizophrenia takes a different course in different cultures, being more severe in the US than in other cultures.  The symptoms of what we in the US know as anorexia nervosa -- an obsession with weight and dieting and a view of one's body as fatter than it actually is -- were, until recently, very different in Hong Kong, where anorexic patients primarily complained of bloated stomachs. In the 1990s, however, the symptoms began to mimic the more profound American disease.  And so on.

Thus,

[f]or more than a generation now, we in the West have aggressively spread our modern knowledge of mental illness around the world. We have done this in the name of science, believing that our approaches reveal the biological basis of psychic suffering and dispel prescientific myths and harmful stigma. There is now good evidence to suggest that in the process of teaching the rest of the world to think like us, we’ve been exporting our Western “symptom repertoire” as well. That is, we’ve been changing not only the treatments but also the expression of mental illness in other cultures. Indeed, a handful of mental-health disorders — depression, post-traumatic stress disorder and anorexia among them — now appear to be spreading across cultures with the speed of contagious diseases. These symptom clusters are becoming the lingua franca of human suffering, replacing indigenous forms of mental illness.

And yet, we in the West have been looking for decades for the genes 'for' mental illnesses such as schizophrenia and depression. The searches, as we've written here numerous times, have been essentially fruitless. In part this has been because it has been so difficult to know how to to define the traits so that a study population convincingly has the same disease. But now it seems that much of the difficulty may be that these diseases are products of a particular time in a particular culture, not 'simple' genetic traits like cystic fibrosis or Tay Sachs disease, in which the biological consequences of the causative mutation are clear.

Unless someone wants to argue the unrelenting geneticistic view that Asians have different mental illnesses -- of the extent and type described above -- because they are genetically different. That's possible in principle, though almost impossible to disentangle from culture, geography, and history. However, there are three strong counter arguments, and some supported by actual data. First, there are secular (time) trends in these kinds of traits, that become more common or more rare within lifetimes within a culture.

Second, many classical migrant studies have been done that show that, to a great extent, migrants adopt the characteristics of their new home population. Clearly-genetic traits like facial appearance may not change, and unless largely environmental, cannot change so fast. But culturally-based traits can, and they do. The formal studies largely have to do with disease, but anyone with eyes can see the extent to which second and third generation immigrants adopt all aspects of their local culture that their conservative parents can't prevent.

The third argument is the manifest way in which culture, including in this case ideas of behavioral traits including disease, spreads around the world these days, and so quickly that we know they're not due to genetic change.

There are many profound, if uncomfortable implications. We know what the problem is, but in the absence of a Lone Ranger with a magic silver bullet better idea, we cling to old beliefs or wishful thinking.

For example, does its moveable feast-ness imply that mental illness isn't a biological trait? Not at all. It 'simply' means that there is a much more complex interaction between culture and biology than geneticists are allowing for. And that genetic characteristics are not pre-wiring for specific behaviors, but may be more probabilistically likely to be manifest in various types of environment. This is why most deterministic stories about the genetics of behavior are basically Just-So stories. Once you throw in human culture, all bets about the rules of the game are off. Overall, humans are a constant, relative to variation in culture. But we vary a lot biologically, too.

Biological variation is not a good predictor, in most cases, of specific traits. This is just what the most successful, and thoughtful new GWAS kinds of analysis are also finding about disease -- even without considering the globally varying and changing cultural landscape.