The eyes have it: Seeking expressions of the genetic risk for developing alcoholism

October 15, 2002

Genetic factors play a key role in the development of alcoholism. A family history of alcoholism does not, however, guarantee that individual offspring will develop the disease. In an effort to discover identifying "markers" of those at risk for alcoholism, researchers in the October issue of Alcoholism: Clinical & Experimental Research evaluate the influence of a family history of alcoholism on the response of saccadic eye movements to alcohol.

Saccades are high-velocity eye movements made from one point to another, as in reading. Their main function is to bring the image of a target from the visual periphery onto the fovea centralis (center of the retina), where vision is most acute. The saccadic control system is sensitive to alcohol, and saccadic parameters provide reliable measures of alcohol's effects in a dose-dependent manner.

"The premise of our research is that the brain's response to alcohol is related to a genetically influenced risk for alcoholism," said Sean O'Connor, professor of psychiatry at Indiana University School of Medicine and corresponding author for the study. "We used a familial history of alcoholism as a proxy for genetic influence, since specific genes cannot yet be identified. Saccadic eye-movements fulfilled all the criteria for a good measure of the brain's response to alcohol: they are known to be genetically influenced; they are a very reliable measure of brain function as most people will execute these movements in the same way day after day; they are quite sensitive to alcohol; and a lot is known about the systems of neurons that control the movements." O'Connor explained that associating response of saccades to alcohol with the genetic risk for alcoholism is the first step in seeking specific genes increasing that risk.

Researchers evaluated saccadic performance in 54 adults (27 males, 27 females) with a family history of alcoholism, and 49 adults (24 males, 25 females) without a family history of alcoholism. Participants were given alcohol and a placebo in a counter-balanced order. The alcohol was administered intravenously in order to achieve a breath alcohol concentration of 60 mg% in 20 minutes and to maintain it for 160 minutes. Saccadic eye movement was tested before each session (called baseline), and twice during the maintained level of intoxication.

The two groups showed significant overall differences in operational characteristics of the saccadic control system, both at baseline and when the brain was exposed to alcohol. Subjects with a family history of alcoholism were slightly but consistently slower than subjects without a history throughout the sessions, and appeared to "recover" baseline measures despite prolonged and constant exposure to alcohol.

"A key finding of our study is that the adaptive response of saccades to alcohol is associated with a family-history status known to be associated with a genetic influence on the risk for alcoholism," said O'Connor. In other words, brain function among those with a family history of alcoholism returned towards "normal" despite continued exposure to alcohol.

"We are still trying to learn what is actually inherited that affects the risk of alcoholism," said David Crabb, professor of medicine and of biochemistry and molecular biology at Indiana University School of Medicine. "In other words, is the inherited risk related to brain control functions? to the inability to control drinking? to the euphoria of drinking? We need to know this in order to devise therapies that address the actions of alcohol on the brain." He called the study's identification of brain functions (the control of eye movement at a subconscious level) that are both influenced by genetic factors (the family history of alcoholism) and show responses to alcohol "an incremental yet important step toward understanding genetic influences on alcohol's effects on the brain."

Crabb said these findings may one day have practical applications, such as developing a battery of easy-to-use measures of risk. "We could test children of alcoholics," he said. "Perhaps combining the results of the eye movement tests in young people with other measures would predict their risk of alcoholism or other alcohol problems. If we could accurately tell people if they are at a higher or lower risk of alcoholism based on their test results, this could influence some people to reduce their drinking."

O'Connor said it's important for the field of alcohol research to continue to examine the question: "What does alcohol have to do with an increased risk for alcoholism?" His own research plans include quantifying the degree to which genes influence responses to alcohol, examining how other brain functions respond to alcohol, and expanding those studies to include experimental control of how quickly alcohol reaches and leaves the brain.
Co-authors of the Alcoholism: Clinical & Experimental Research paper included: T. Blekher and R.D. Yee of the Department of Ophthalmology; V.A. Ramchandani and T.-K. Li of the Department of Medicine; L. Flury and T. Foroud of the Department of Medical & Molecular Genetics; and D.A. Kareken of the Department of Psychiatry - all at Indiana University School of Medicine. The study was funded by the National Institute on Alcohol Abuse and Alcoholism, and Research to Prevent Blindness.

Alcoholism: Clinical & Experimental Research

Related Alcohol Articles from Brightsurf:

Alcohol use changed right after COVID-19 lockdown
One in four adults reported a change in alcohol use almost immediately after stay-at-home orders were issued: 14% reported drinking more alcohol and reported higher levels of stress and anxiety than those who did not drink and those whose use stayed the same.

Changes in hospitalizations for alcohol use disorder in US
Changes over nearly two decades in the rate of hospitalizations and in-hospital deaths from alcohol use disorder in the US were examined in this study.

Associations of alcohol consumption, alcohol-induced passing out with risk of dementia
The risk of future dementia associated with overall alcohol consumption and alcohol-induced loss of consciousness in a population of current drinkers was examined in this observational study with more than 131,000 adults.

New alcohol genes uncovered
Do you have what is known as problematic alcohol use?

Does estrogen influence alcohol use disorder?
A new study from researchers at the University of Illinois at Chicago shows that high estrogen levels may make alcohol more rewarding to female mice.

Sobering new data on drinking and driving: 15% of US alcohol-related motor vehicle fatalities involve alcohol under the legal limit
A new study in the American Journal of Preventive Medicine, published by Elsevier, found that motor vehicle crashes involving drivers with blood alcohol concentrations (BACs) below the legal limit of 0.08 percent accounted for 15% of alcohol-involved crash deaths in the United States.

Alcohol-induced deaths in US
National vital statistics data from 2000 to 2016 were used to examine how rates of alcohol-induced deaths (defined as those deaths due to alcohol consumption that could be avoided if alcohol weren't involved) have changed in the US and to compare the results by demographic groups including sex, race/ethnicity, age, socioeconomic status and geographic location.

Cuts in alcohol duty linked to 2000 more alcohol-related deaths in England
Government cuts to alcohol taxes have had dramatic consequences for public health, including nearly 2000 more alcohol-related deaths in England since 2012, according to new research from the University of Sheffield's School of Health and Related Research (ScHARR).

Integrated stepped alcohol treatment for people in HIV care improves both HIV & alcohol outcomes
Increasing the intensity of treatment for alcohol use disorder (AUD) over time improves alcohol-related outcomes among people with HIV, according to new clinical research supported by the National Institutes of Health.

The Lancet:Targets to reduce harmful alcohol use are likely to be missed as global alcohol intake increases
Increasing rates of alcohol use suggest that the world is not on track to achieve targets against harmful alcohol use, according to a study of 189 countries' alcohol intake between 1990-2017 and estimated intake up to 2030, published in The Lancet.

Read More: Alcohol News and Alcohol Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to