Adolescent brains are insensitive to alcohol for a short time, but at great cost

October 24, 2006

Whereas brain development during adolescence may initially serve to "safeguard" youth from certain effects of alcohol such as intoxication and hangover, it will also likely make them more vulnerable to the longer-term effects of alcohol. A first-of-its-kind study uses rodents to examine development of acute tolerance to alcohol-induced social impairment among adolescents and adults. Findings show that younger rodents have nervous systems that quickly adapt to alcohol's effects - called tolerance - which permits heavy drinking at an early age. Results are published in the November issue of Alcoholism: Clinical & Experimental Research.

"Adolescence is a time of rapid changes of the brain," said Elena I. Varlinskaya, a research professor at Binghamton University and the study's corresponding author, "particularly in the prefrontal cortex and limbic and mesolimbic brain systems of human adolescents. Adolescent rodents show similarities with human adolescents in terms of dramatic age-related remodeling of the brain. Using animal models, researchers have shown that unpleasant physical symptoms associated with alcohol intoxication and hangover, which make adults stop drinking, are not experienced to the same degree by adolescents."

"There are several potential implications of having a brain that is less sensitive to alcohol," said Marisa M. Silveri, assistant professor of psychiatry at Harvard Medical School, "such as a disconnect between the behavioral and the physiological effects of alcohol use. Adults may not be aware of the level of intoxication in teens, given that they demonstrate significantly less motor impairment and sedation than adults do given the same amount of alcohol. Thus, a lack of overt signs of intoxication may mask the more potentially damaging effects of alcohol on neural systems involved in learning and memory."

Varlinskaya added that adolescent insensitivity to alcohol may also be related to an ability to rapidly counteract different effects of alcohol with compensatory responses such as acute tolerance. "Acute tolerance is characterized by a more rapid decline in alcohol-induced impairment than in blood or brain alcohol levels following a single alcohol dose," she said. "We know that social behavior is sensitive to low-to-moderate doses of alcohol. Therefore, this study examined development of acute tolerance to alcohol-induced impairment of social behavior among adolescent and adult rats."

Researchers used Sprague-Dawley rats. Social activity was examined after the animals were administered alcohol, after a five- or 30-minute interval: on postnatal day (P) 28, the equivalent of early adolescence; P35, mid adolescence; P42, late adolescence; or P70, the equivalent of young adulthood. Brain alcohol concentrations were also measured in the animals.

"We found greater acute tolerance in adolescent than adult animals at alcohol levels comparable to human binge drinking," said Varlinskaya. "In other words, both adolescents and adults showed the same degree of social impairment when tested immediately after or five minutes following alcohol exposure. However, the social behavior of adult animals was still severely suppressed 30 minutes after alcohol administration, whereas the social behavior of adolescents was almost similar to that of animals not exposed to alcohol."

"This study extends previous findings that adolescents are generally less impaired by alcohol's effects to now include alcohol's effects on social inhibition," said Silveri. "These findings support the notion that the adolescent brain functions quite differently than the adult brain, particularly in its response to alcohol. Even though the adolescent brain has the capacity to adapt to an alcohol challenge, this will likely come at great cost as valuable cerebral resources are redirected from the important role of brain development to instead adapting to an alcohol challenge, and then restoring the system back to status quo once alcohol is eliminated or the challenge is removed."

Varlinskaya concurs. "This ability of adolescents to rapidly counteract some unpleasant alcohol effects by developing acute tolerance may allow them to have more drinks per occasion," she said. "This binge pattern of drinking, being unsafe in general, might be extremely dangerous for adolescents, given that their brain is especially vulnerable to alcohol-related damage."

"Social behavior is an understudied area, particularly with regard to adolescence and alcohol's effects," added Silveri. "The choice of this dependent variable is timely in that human neuroimaging studies are beginning to examine developmental changes in brain function that are commensurate with the development of emotional intelligence and social behavior. In addition, this is one of the first studies to document tolerance to alcohol's effect on social behavior, which occurs in an age-dependent manner."

"Human adolescents are confronted with a variety of potentially stressful challenges, and they often use alcohol to control stress and cope with problems," said Varlinskaya. Her future work will therefore focus on the impact of stress on the effects of alcohol on social behavior of adolescent and adult rodents.
-end-
Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. The co-author of the ACER paper, "Ontogeny of Acute Tolerance to Ethanol-Induced Social Inhibition in Sprague-Dawley Rats," was Linda P. Spear of the Department of Psychology at Binghamton University. The study was funded by the National Institute on Alcohol Abuse and Alcoholism

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
Brightsurf.com 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 Amazon.com.