12 April 2011

Clear Genetic Links to Poor Impulse Control, Drug Dependency

University of Michigan medical researchers have identified genetic links to aberrant brain function leading to alcohol and drug dependencies.
The results, published online April 12 in Molecular Psychiatry, suggest that variations in the GABRA2 gene contribute to the risk of alcoholism by influencing impulsive behaviors, at least in part through a portion of the cerebral cortex known as the insula, says study senior author Margit Burmeister, Ph.D., research professor at U-M's Molecular and Behavioral Neuroscience Institute.

...Individuals under distress who also have the risky genetic variant tend to act impulsively, a behavior that may lead to the development of alcohol problems, says lead author Sandra Villafuerte, Ph.D., a research investigator at U-M's Molecular and Behavioral Neuroscience Institute and Department of Psychiatry.

"Developing deeper understandings of the various genetic and environmental factors involved in risky behaviors may guide prevention and treatment efforts in the future," Villafuerte says.

The study included 449 people, who came from 173 families – 129 of whom had at least one member diagnosed with alcohol dependence or abuse. Those with certain variations in the GABRA2 gene were more likely to have alcohol dependence symptoms and higher measures of impulsiveness in response to distress, the study found. Stronger associations were found in women than in men.

...Researchers also used functional magnetic resonance imaging (fMRI) to observe changes of blood flow in the brains of 44 young adults from these families as they performed a task in which they anticipated winning or losing money.

"The neuroimaging allowed us to see for the first time how these genetic variants create differences in how the brain responds in certain situations," says Mary M. Heitzeg, Ph.D., a research assistant professor in U-M's Department of Psychiatry and U-M's Addiction Research Center.

They found that individuals with one form of the GABRA2 gene associated with alcoholism showed significantly higher activation in the insula when anticipating rewards and losses than those with other combinations. This higher activation was also related to a greater level of impulsiveness in response to distress.

..."We believe these results suggest GABRA2 exerts an influence on an underlying neural system that impacts early risk factors and, later, alcohol dependency," says Burmeister, also a professor of psychiatry and human genetics at the U-M Medical School. "In the future, we hope to further examine the effects of family environment and other behavioral and environmental factors." _PO
Genetic influences on behaviours are too numerous to count, yet are extremely difficult to pin down with specificity. That is because multiple causes at several different levels are influencing the events which we observe. It will take many years to sort the many levels of causation -- many of them circular (incorporating feedbacks) in nature.

Persons who are indoctrinated into the religion of political correctness tend to eschew all discussion of genetic influences on behaviour. Funding for research can be difficult to obtain if highly indoctrinated "ethicists" feel that the valid findings of the research may be misconstrued in a way as to contradict politically correct dogma.

But such a PC approach only dooms persons who suffer from genetic disadvantages of behaviour to lifetimes of suffering. Much better to learn everything we can about these phenomena, so as to be able to compensate for these genetically based behavioural and cognitive disadvantages on as many levels as possible.

One approach to compensating for genetic defects in brain functioning is to run a low level dc current through the skull into the brain.

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