Thursday, October 24, 2013

Nonreplication and despair in psychiatric genetics

Jay Joseph, whose critical work on genetics in psychiatry I’ve discussed here previously, published a piece the other day at Mad in America in which he describes the refusal of Genome-wide Complex Trait Analysis (GCTA) to conform to the insistent claims of psychiatric geneticists.

I was struck by the public statements of some of the proponents of biogenetic psychiatry, who saw in GCTA the method that would, despite decades of “failure to identify genes for psychiatric disorders,” finally prove them right:
Although the GCTA method was developed as a means of solving the “missing heritability” problem, like GWA studies and other methods it is based on assuming the validity of heritability estimates for human behavioral traits, as well as assuming that twin and adoption studies have established the genetic basis of psychiatric disorders. The validity of each of these assumptions, however, is very questionable.5 And yet, leading behavioral geneticists such as Robert Plomin and Eric Turkheimer have embraced GCTA, seeing it as a way out of the missing heritability conundrum.6 Turkheimer even saw it as the ultimate refutation of the arguments of twin research critics, writing that “the new paradigm” has put criticism of the assumptions of family and twin studies “to rest.” Turkheimer believed that the GCTA method “should drive a stake through the heart of a classical line of argument against classical behavioral genetics and its attendant statistical assumptions.”7

...Although in 2011 Turkheimer believed that the GCTA method would “drive a stake through the heart of” criticism of behavioral genetic theories and methods, and would finally put criticism of twin studies “to rest,” the opposite scenario appears to be playing out before us, as leading behavioral genetic researchers struggle to prevent negative GCTA findings, and the obvious false assumptions underlying twin research, from driving a stake through the heart of twin studies themselves.
Once again, this isn’t how science works. You don’t get to respond to valid criticisms of existing research or assumptions by arguing that future research will retroactively justify them. These people sound more like mad scientists, shouting vainly to a skeptical world from their mountaintop labs – “You just wait! My next experiment will show all of you that I was right all along!” (Or at least that’s how they would sound if people didn’t keep reflexively granting their statements respectability.)

They’re doing research without doing science. Science depends on an honest reckoning with the existing evidence, including a critical evaluation of research and the conclusions drawn from it. It involves humility concerning the quality and findings of the research base as a whole, and if that research base is plagued with nonreplicability that has to factor into the evaluation of any individual study and should lead to the broader questioning of theories (and I use the term loosely in this context), assumptions, and methods. If research doesn’t lead to this sort of questioning, you’re not doing science.

What’s led the field to stray so far from basic scientific standards? Another remark by Joseph caught my eye:
As Faraone candidly posed the question, “Nonreplication had been the curse of molecular psychiatric genetics for decades. Has it returned in a new guise?”12

The answer to Faraone’s question probably is yes, because due to major problems and false assumptions underlying previous family, twin, and adoption studies, in addition to the questionable validity and reliability of psychiatric disorders in general,13 the “curse” Faraone referred to is merely the scientific likelihood that genes for the major psychiatric disorders do not exist. This is a cause for celebration, not despair, as society can now part ways with genetic diversions and focus on environmental causes, interventions, and prevention. [my emphasis]
I have to wonder why this does seem to be a cause of despair and denial for these researchers. To be sure, even when scientific integrity demands it, people are generally reluctant to acknowledge that the paradigm that has guided their work is false. (On the other hand, by accepting it, those working in false paradigms are freed to pursue more promising scientific projects.) Also probably at work is the belief that finding biogenetic causes is necessary to developing effective treatments or cures, though this is plainly nonsensical: useful interventions are not going to emerge from a misunderstanding of the problem.

But there seems to be an attachment to biogenetic psychiatry that goes beyond these concerns. Why are so many people, in the field and in the general population, so attached to this notion? Why does the genetic model of human behavior and “mental illness” have such a hold that people are led to try to ignore and explain away contradictory findings, looking desperately to every new technique to at last provide it a scientific basis? Why is it so difficult for them to abandon? Given the dark political history of this model, these questions need answers.

No comments:

Post a Comment