Kendler: Genes, Behavior Intertwine in Mental, Addictive Disorders
Genes and behavior both play a role in how mental and addictive disorders develop, a leading authority on psychiatric and behavioral genetics said Wednesday at the University of Virginia School of Law.
Dr. Kenneth Kendler, the Rachel Brown Banks Distinguished Professor of Psychiatry and a professor of human genetics at Virginia Commonwealth University, appeared at the Law School to deliver the 14th P. Browning Hoffman Memorial Lecture in Law and Psychiatry.
Pinpointing the causes of diseases such as cystic fibrosis or Huntington's disease is relatively straightforward, Kendler said, as they can be traced back to the presence of specific genes.
With psychiatric illnesses, he said, genetic risk often explains only part of the story. Other external factors, such as parenting, substance use, peer deviance or sexual abuse can also play a role.
"Most of us live within two worlds," said Kendler, who directs the Psychiatric Genetics Research Program and the Virginia Institute for Psychiatric and Behavioral Genetics at VCU. "One is the world of atoms bouncing around — mechanistic, scientific explanations, where we understand genes as these conveyors of biological information. They make proteins, the proteins construct cells, the cells influence organs. The other is a world of human agency and volition."
These two worlds are far more intertwined than many might believe, he said.
For example, a parent might influence the expression of a certain genetic trait, such as musical ability, by encouraging the child to take piano lessons. Alternatively, Kendler said, a parent who fails to set clear boundaries for a child with behavioral problems might influence the expression of negative traits.
"Human volitional activity really can influence the expression of our own genes or key behavioral traits," he said.
University of Virginia law professor Richard Bonnie said Kendler is taking on "what may be the most important challenge for modern psychiatry" in seeking to explain the causes of psychiatric disorders and unravel how genes influence vulnerability to those disorders.
"Only with better understanding of the multiple level causal pathways will we be able to make new advances in treatment and prevention," Bonnie said.
Kendler's research, he added, holds implications for the law, notably raising important questions of responsibility.
"The law is replete with special rules predicated on proof of mental illness, typically grounded in principles of responsibility and excuse," Bonnie said. "Do these rules depend on any particular understanding of the etiology of the disorder or even on whether the diagnosis disorder itself is etiologically based? Why does the criminal law recognize a special defense for mental illness and not for other conditions? And why do only some mental disorders count? Or to put it another way, why are some disorders specifically excluded?"
Kendler's talk was sponsored by the Law School and the School of Medicine's Department of Psychiatry and Neurobehavioral Sciences.