Posted on February 5, 2016 in Adolescents

Teen Drinking Leads to Lasting Deficits in Memory, Ability to Learn

New findings from a team of American researchers indicate that teenagers who engage in regular, intermittent drinking can unwittingly trigger lasting dysfunction in the hippocampus, a part of the brain responsible for learning and memory.

Doctors, researchers and public health officials are well aware that teenagers who drink alcohol can experience disruptions in the normal process of brain growth and development. In a study published in April 2015 in the journal Alcoholism: Clinical & Experimental Research, researchers from two U.S. universities used laboratory experiments on rats to explore the impact that regular, periodic adolescent drinking has on the function of the brain’s hippocampus. The researchers concluded that teens who maintain a recurring, intermittent pattern of alcohol consumption can develop significant changes in hippocampus function and structural composition that persist into adulthood.

Teens and Alcohol

Alcohol intake is declining in both younger and older American teenagers, according to 2014 data compiled by the National Institute on Drug Abuse and the University of Michigan. Despite this fact, 41 percent of all eighth graders, 10th graders and 12th graders consume at least some alcohol throughout the year. Unfortunately, substantial numbers of teens qualify as binge drinkers by rapidly consuming enough alcohol to merit an assessment of legal drunkenness on a blood-alcohol screening. The federal Centers for Disease Control and Prevention estimate that binge drinking accounts for more than 90 percent of the total number of alcohol servings consumed by American adolescents. A smaller but still significant number of teenagers qualify as heavy drinkers by regularly exceeding the gender-specific daily or weekly standards for moderate alcohol intake.

Alcohol is a toxic substance known for its ability to disrupt the normal process of growth and development in a teenager or younger child. Teens who drink may unknowingly alter their brains in several ways and therefore may never reach full brain maturation in early adulthood. Broadly speaking, risks for growth and development problems are highest for those adolescents who binge drink, although non-binging adolescent alcohol consumers also increase their odds of experiencing significant and potentially lasting damage.

The Hippocampus

The hippocampus is a brain structure known for its seahorse-like shape. It forms part of a larger brain network known as the limbic system and plays an essential role in the formation, storage and use of short-term memories and long-term memories. The hippocampus also plays a critical part in the normal learning process and helps regulate emotional states by funneling memory data to a connected brain structure known as the amygdala. Damage or malfunction in the hippocampus can alter any stage of learning or memory processing. In addition to a general decline in learning and memory skills, problems in the structure are associated with specific ailments that include Alzheimer’s disease and various forms of amnesia.

Impact of Intermittent Teen Drinking

In the study published in Alcoholism: Clinical & Experimental Research, researchers from Duke University Medical Center and Vanderbilt University periodically gave a group of adolescent rats access to enough alcohol to get drunk, but not enough alcohol to pass out. This access to alcohol was terminated as the rats progressed from adolescence to adulthood. The researchers looked at several aspects of hippocampus structure and function in the adult rats previously exposed to regular, intermittent alcohol intake. These aspects included the ability of nerve cells in the hippocampus to increase their rate of baseline level of activity when necessary in order to support learning and memory processing.

The researchers found that the adult rats with an adolescent drinking history experienced hyperactivity in the hippocampus cells responsible for supporting learning and memory. Somewhat counterintuitively, this hyperactive state actually decreases learning and memory capacity by triggering periodic halts in normal hippocampus function. In addition, the researchers found that the adult rats with a teen drinking history had an unusually high number of immature cell structures inside the hippocampus. The researchers also found that the rats had unusually low levels of two key hippocampus proteins.

Overall, the study’s authors concluded that a teenager who maintains an intermittent pattern of alcohol intake can produce damaging alterations in the function of his or her hippocampus, as well as damaging alterations in hippocampus structure. They believe that hippocampus damage acquired during adolescence may help explain the deficits in memory and learning observed in some adults, even when those adults no longer consume alcohol.

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