Genetic Link to Disorders Discovered

Chromosome variant could affect a person's susceptibility to alcoholism or depression, research shows

SUNDAY, July 15, 2001 (HealthDayNews) -- U.S. scientists have pinpointed an area on a particular chromosome that could make some people susceptible to alcoholism and others prone to depression, says a new study.

The finding may some day make it easier to predict whether a person is likely to have these disorders and could lead to new drug treatments down the line.

"We found an area on chromosome 1 that appears to be related to a vulnerability to alcoholism or affective disorders," says lead author Dr. John I. Nurnberger, director of the Institute of Psychiatric Research at Indiana University Medical Center.

That means, he says, that "within families, some people with a gene variant in this area may develop alcoholism and other people with that variant may develop depression."

Chromosomes are rod-shaped structures within the nucleus of cells containing genetic information that determine a person's inherited characteristics.

Although the gene or genes identified by Nurnberger's team don't actually cause alcoholism or depression, they do increase the risk, he says.

"The outcome has to be determined by a multitude of factors, some of which are genetic and some of which are environmental," Nurnberger says.

The study was published in a recent issue of the American Journal of Psychiatry.

Nurnberger and his fellow researchers analyzed data collected through the Collaborative Study of the Genetics of Alcoholism. It's an ongoing study at six American research centers, which has gathered clinical and biological data of 987 people from families where there is a high risk of alcoholism.

Although Nurnberger says his research is an important advance in better understanding alcoholism and depression, he stresses that much more work has to be done.

"What we need to do is find out the exact nature of the gene or genes in that area, and that's what we're working on now," he says.

The research also could lead to more effective drug treatments or tests to identify people who are vulnerable to alcoholism or depression.

"We think there are things we can do about it, but we don't know yet how to design the treatments because we don't know the exact biochemical pathways involved," Nurnberger says.

This is just one example of overlap in genetic vulnerability, Nurnberger adds.

''That's something we're discovering as we do more and more of these studies -- that the genetic vulnerability may overlap between categories or that categories are not neatly defined,'' he notes.

"There are other instances like that where you have the same area that appears to be involved in multiple illnesses," Nurnberger says. "The flip side of that is you have the same illness, which may be related to many different chromosomal areas. So it's a complex picture."

Mental-health experts say Nurnberger's research is potentially significant.

"I think this is very exciting because what we've known clinically for some time is that many people who are prone to abuse alcohol also are vulnerable to depression. And now we've got some reinforcing genetic information that corroborates our clinical impressions," says Dr. Richard T. Suchinsky, of the U.S. Department of Veterans Affairs who is also chairman of the American Psychiatric Association's Council on Addiction Psychiatry.

He agrees Nurnberger's research could lead to better treatments for depression and alcoholism.

''We're a ways away from there, but at least it's a big step down the road,'' Suchinsky says.

What To Do

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) says 13.8 million Americans who are 18 or older have a drinking problem and 8.1 million of them are alcoholics. The American Psychiatric Association says depression affects about 17 million Americans each year.

For more information on depression, go to the National Institute of Mental Health. To learn more about alcohol-related issues, go to the NIAAA.

SOURCES: Interviews with John I. Nurnberger, M.D., Ph.D., director, Institute of Psychiatric Research, Indiana University Medical Center, Indianopolis; Richard T. Suchinsky, M.D., associate director for addictive disorders, Mental Health and Behavioral Sciences Service, U.S. Department of Veterans Affairs, Washington, D.C.; May 2001 American Journal of Psychiatry Consumer News