AMHERST, Mass. – Neuroscientist Heather Richardson and colleagues at the University of Massachusetts Amherst have received a $400,000 grant to study how binge drinking during adolescence affects development in the prefrontal cortex, an area that directs decision-making and controls emotions, and one of the last brain regions to mature.
Richardson, doctoral student Wanette Vargas, and others at UMass Amherst’s Neurobiology of Stress and Addiction Laboratory use an adolescent rat model to reflect the typical teen experience with alcohol, which includes individual variability and intermittent exposure. A two-year grant from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) at the National Institutes of Health, plus support from the UMass Amherst College of Natural Sciences, will fund a series of studies to advance understanding of how risky drinking among teens may change the development of neural circuits and cause potentially long-lasting mental health consequences.
“We use adolescent animals that are not predisposed to drink and we try as much as possible to mimic the typical teenager’s experience with alcohol. This means the experiments include individual variability because the animals voluntarily choose to binge when alcohol is available. But, like teenagers, at times they have no access to alcohol so they can’t drink at all,” Richardson explains.
She adds that alcohol is the most common substance of abuse during adolescence, a time when both female and male teens engage in episodes of heavy, binge drinking. With this work, Richardson and colleagues hope to fill a significant knowledge gap regarding the effects of voluntary drinking early in adolescence on the developing prefrontal cortex.
Specifically, the researchers are investigating how alcohol affects myelin, a fatty insulating layer that coats axons, nerve fibers, and helps brain cells communicate with one another quickly and efficiently. Myelin is still forming around axons in the prefrontal cortex of 28- to 56-day-old adolescent rats. In humans, Richardson says, there is some evidence of an association between reduced myelin in the brain with alcohol use, but it’s not clear whether this is a result of drinking or whether people with less myelin are predisposed to drinking.
In her group’s laboratory studies, animals have intermittent access to alcohol, so they sometimes can press a lever to be rewarded with a sweetened alcohol drink and other times do not have access to the lever. Food and water are always available so alcohol consumption is completely voluntary. Most animals will drink enough alcohol to reach the binge level at least a few times over the exposure period.
Binge drinking is defined by NIAAA as drinking enough alcohol within two hours to reach a blood alcohol level of 0.08. The experiments use sweetened alcohol because teenagers commonly drink sugary alcoholic beverages and because adolescent rats will voluntarily binge drink sweetened alcohol in the laboratory.
A control group will receive sweetened water without alcohol. Groups will be allowed to consume equal amounts of the mixtures on average, and the researchers will track both individual and group differences to look for relationships between drinking behavior and quantitative variables related to myelination in the brain.
If alcohol causes a change in myelinated axons within the prefrontal cortex, the next important step will be to establish whether males and females have different sensitivity to these effects, Richardson says. She also plans follow-up studies to determine whether there is a threshold below which alcohol consumption is not associated with brain changes.
“If drinking a beer or two intermittently through early adolescence causes brain changes, that is something we need to know. Overall, we hypothesize that drinking early in development affects the brain’s ability to function normally. If it does, our ultimate goal will be to uncover possible mechanisms and determine ways in which we can reverse these effects,” she adds.
Richardson’s successful grant proposal was aided by support of the UMass Amherst Center for Research on Families Research Scholars Program.