Chasing the Genetic Ghosts of Mental Illness
For decades, scientists have been making claims about the genetic roots of mental illness, ranging from schizophrenia and depression, to bipolar disorder and attention deficit disorder (ADHD). And for decades, they’ve largely been chasing ghosts.
Eric Kandel, writing for Newsweek, makes the at-least-annual appeal that scientists are making “certain advances in genetics” which give “us new reasons for optimism” in understanding the biological basis for mental illness. As someone who’s been tracking the progress of such genetic advances over the past two decades, I have to say, I remain squarely skeptical.
It doesn’t help that Kandel’s own arguments are exercises in circular logic:
One major advance has been the discovery that there is much more variability in the genome than had been anticipated, and that this takes the form of copy number variation (CNV). These are duplications or deletions of segments of a chromosome, often involving several or tens of genes, that enhance or depress the actions of specific genes. A well-known example of a CNV is the extra copy of chromosome 21 resulting in Down syndrome. It has recently been discovered that this type of variation is extremely common in everyone’s genome.
If there’s “much more variability in the genome,” guess what? That means finding specific meaningful, predictable variations is all the more challenging. If the extra copy of chromosome 21 is “extremely common,” how come Down syndrome isn’t so much more common?
We’ve highlighted previously altered genes that may increase the risk of schizophrenia, for example. But not a year goes by where more such research highlights other genes or other gene variations. I mean, we’ve been talking about this for years. What’s changed recently?
Nothing. If anything, new research shows just how complicated gene research is. If hundreds of gene variations could be indicted in a “simple,” less-serious mental disorder like attention-deficit disorder, imagine the complexity of more debilitating disorders like depression or bipolar disorder.
Kandel also makes this claim you’ve probably heard before:
Scientists are also making progress in finding the biological markers for depression, anxiety, and obsessive-compulsive neurosis. Markers are essential to understanding the anatomical basis of mental disorders, diagnosing them objectively, and following their response to treatment, as well as perhaps preventing psychosis in those at high risk.
Progress? Well, if you call understanding how extraordinarily complex the human genome is, compared to what we thought it was 10 years ago, yeah, I guess you could call that “progress.” But honestly, researchers are not significantly closer to finding genetic markers for depression, anxiety and OCD than they were a decade ago. Think of our understanding of brain disorders and genetics similar to that of unpeeling an onion. The size of a giant watermelon. Or the moon.
But the strangest point made by Kandel is that the effectiveness of psychotherapy is now “proven” because of brain imaging studies which have been called into question:
The most convincing scientific progress in psychiatry in the past decade has had little to do with genomics. It is the rigorous, scientific verification that certain forms of psychotherapy are effective. […] Insofar as psychotherapy works and produces stable, learned changes in behavior, it can cause stable anatomical changes in the brain. We are now beginning to measure such changes with brain imaging.
Who cares? We don’t need brain imaging to understand that psychotherapy works. I guess all those decades of psychology research showing the effectiveness of psychotherapy were for naught until we had the sheer magic of brain imaging.
While I believe understanding human genetics and the neurological basis of mental disorders is important, invaluable work, I think articles like Kandel’s sort of miss the point. This work is slow and arduous, and for every one step forward, we take two steps back. Indeed, we are making progress, but it is not progress one can easily track or summarize in a mainstream news article of this nature.
In the treatment of mental disorders, we have plenty of approaches that work just as well as (and, in fact, work better than) any medical treatment for a medical disease. (Honestly, Kandel should look at the research behind the vast majority of surgical procedures to see the lack of rigorous scientific data that he’s demanding for mental illnesses.)
Genetics may one day hold some sort of key to our understanding of mental disorders. But that’s a line that’s been repeated hundreds of times over the past two decades, and one that seems no truer today than it did in 1989.
Read the full entry: A Biology of Mind
Grohol, J. (2009). Chasing the Genetic Ghosts of Mental Illness. Psych Central. Retrieved on May 28, 2015, from http://psychcentral.com/blog/archives/2009/06/29/chasing-the-genetic-ghosts-of-mental-illness/