Summary: Researchers say teens who start drinking prior to age 15 and who also binge drink are more likely to have memory problems as adults. Additionally, early binge drinking may indicate later risk for developing alcoholism.
Source: Columbia University.
A new study from researchers at Columbia University Irving Medical Center found that binge drinking impairs working memory in the adolescent brain. The study, in mice, explains why teenagers who binge drink are 15 times more likely to become alcoholics during adulthood.
The study was published on July 4th in the Journal of Neuroscience.
“The brains of young teens are at a stage of development that makes them more vulnerable to being switched on to alcohol addiction,” says Neil Harrison, PhD, professor of anesthesiology and pharmacology at Columbia University Vagelos College of Physicians and Surgeons (VP&S) who researches the effects of alcohol on the brain. “The question we’re asking is, can we find those switches in the adolescent binge drinker so that we can turn it off?”
Other researchers have looked at the neuroscience of binge drinking–by getting mice intoxicated through vapor inhalation or alcohol injection. Michael Salling, PhD, assistant professor of anesthesiology at VP&S, and his team are taking a different approach, allowing the mice to drink voluntarily.
“Short cuts are useful in getting animals to drink, but these models don’t resemble how drinking develops in humans,” Harrison says. In Salling’s approach, mice are given access to alcohol every other day during a period in their development that’s equivalent to human adolescence. “Some of the mice drink avidly and some very little–which parallels the human experience.”
The consequences of binge drinking in adolescent mice are also similar to the effects in humans. As the mice become young adults, those that drank heavily in their youth adopt drinking patterns often seen in people.
“Often the mice will drink robustly as soon as the alcohol is provided,” says Salling. “This so-called front-loading behavior is frequently present in people who later develop an alcohol use disorder.”
The most striking changes the researchers saw appeared in neurons within the mouse equivalent of the human prefrontal cortex (PFC), which is involved in planning actions by suppressing inappropriate responses and maintaining working memory (which governs very short-term memory) and attention. The area does not completely mature in people until their 20s.
In the binge-drinking mice, certain PFC neurons were less able to generate persistent activity, and these changes appear to impair working memory. This finding is consistent with imaging studies that show decreased resting activity in the PFC of alcoholics and binge drinkers.
“These findings may help explain why human adolescent binge drinkers have memory problems,” Salling says, “but they also suggest that there are ways to intervene.”
Harrison and Salling found that binge drinking altered neuron excitability by interfering with channels that allow ions to flow into the neurons.
“Targeting these channels may restore normal patterns of activity in the PFC and improve working memory,” says Harrison, who adds that neurobiological studies such as this are needed to develop new treatments for alcohol use disorders.
“Most adults with alcohol use disorders begin their excessive drinking as teenagers. If we hope to find ways to prevent or treat these disorders, it’s critical that we understand not only the social and environmental factors that contribute to early binge drinking, but also the changes that occur in the brain that lead to alcohol addiction.”
Funding: The study was funded by grants from the National Institutes of Health (5F32AA022028-02 and 5R01AA023531-04).
Source: Helen Garey – Columbia University
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to Columbia University Irving Medical Center.
Original Research: Abstract for “Alcohol Consumption during Adolescence in a Mouse Model of Binge Drinking Alters the Intrinsic Excitability and Function of the Prefrontal Cortex through a Reduction in the Hyperpolarization-Activated Cation Current” by Michael C. Salling, Mary Jane Skelly, Elizabeth Avegno, Samantha Regan, Tamara Zeric, Elcoma Nichols and Neil L. Harrison in Journal of Neuroscience. Published July 4 2018.
Alcohol Consumption during Adolescence in a Mouse Model of Binge Drinking Alters the Intrinsic Excitability and Function of the Prefrontal Cortex through a Reduction in the Hyperpolarization-Activated Cation Current
Periodic episodes of excessive alcohol consumption (“binge drinking”) occur frequently among adolescents, and early binge drinking is associated with an increased risk of alcohol use disorders later in life. The PFC undergoes significant development during adolescence and hence may be especially susceptible to the effects of binge drinking. In humans and in animal models, adolescent alcohol exposure is known to alter PFC neuronal activity and produce deficits in PFC-dependent behaviors, such as decision making, response inhibition, and working memory. Using a voluntary intermittent access to alcohol (IA EtOH) procedure in male mice, we demonstrate that binge-level alcohol consumption during adolescence leads to altered drinking patterns and working memory deficits in young adulthood, two outcomes that suggest medial PFC dysfunction. We recorded from pyramidal neurons (PNs) in the prelimbic subregion of the medial PFC in slices obtained from mice that had IA EtOH and found that they display altered excitability, including a hyperpolarization of the resting membrane potential and reductions in the hyperpolarization-activated cation current (Ih) and in intrinsic persistent activity (a mode of neuronal firing that is dependent on Ih). Many of these effects on intrinsic excitability were sustained following abstinence and observed in mice that showed working memory deficits. In addition, we found that resting membrane potential and the Ih-dependent voltage “sag” in prelimbic PFC PNs are developmentally regulated during adolescence, suggesting that adolescent alcohol exposure may compromise PFC function by arresting the normal developmental trajectory of PN intrinsic excitability.
SIGNIFICANCE STATEMENT Binge alcohol drinking during adolescence has negative consequences for the function of the developing PFC. Using a mouse model of voluntary binge drinking during adolescence, we found that this behavior leads to working memory deficits and altered drinking behavior in adulthood. In addition, we found that adolescent drinking is associated with specific changes to the intrinsic excitability of pyramidal neurons in the PFC, reducing the ability of these neurons to generate intrinsic persistent activity, a phenomenon thought to be important for working memory. These findings may help explain why human adolescent binge drinkers show performance deficits on tasks mediated by the PFC.