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Dr.T

Two scientists, drawing on their own powers of observation and a creative reading of recent genetic findings, have published a sweeping theory of
brain development that would change the way mental disorders like autism and schizophrenia are understood.
The theory emerged in part from thinking about events other than mutations that can change gene behavior. And it suggests entirely new avenues of research, which, even if they prove the theory to be flawed, are likely to provide new insights into the biology of mental disease.
At a time when the search for the genetic glitches behind brain disorders has become mired in uncertain and complex findings, the new idea provides psychiatry with perhaps its grandest working theory since Freud, and one that is grounded in work at the forefront of science. The two researchers — Bernard Crespi, a biologist at Simon Fraser University in Canada, and Christopher Badcock, a sociologist at the London School of Economics, are both outsiders to the field of behavior genetics.
“The reality, and I think both of the authors would agree, is that many of the details of their theory are going to be wrong; and it is, at this point, just a theory,” said Matthew Belmonte, a neuroscientist at Cornell University. “But the idea is plausible. And it gives researchers a great opportunity for hypothesis generation, which I think can shake up the field in good ways.”
Their idea is, in broad outline, straightforward. Crespi and Badcock propose that an evolutionary tug of war between genes from the father’s sperm and the mother’s egg can, in effect, tip brain development in one of two ways. A strong bias toward the father pushes a developing brain along the autistic spectrum, toward a fascination with objects, patterns, mechanical systems, at the expense of social development.
A bias toward the mother moves the growing brain along what the researchers call the psychotic spectrum, toward hypersensitivity to mood, their own and others’. This, according to the theory, increases a child’s risk of developing schizophrenia later on, as well as mood problems like bipolar disorder and depression.
In short: autism and schizophrenia represent opposite ends of a spectrum that includes most, if not all, psychiatric and developmental brain disorders. “The empirical implications are absolutely huge,” Crespi said. “If you get a gene linked to autism, for instance, you’d want to look at that same gene for schizophrenia; if it’s a social brain gene, then it would be expected to have opposite effects on these disorders, whether gene expression was turned up or turned down.”
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Dr.T