The findings are based on research abstracts to be presented at Neuroscience 2014, the Society for Neuroscience’s annual meeting in Washington. The research participants consisted of a participant pool of 135 preteen and teenage boys and girls with an average age of 12.6 years. All underwent structural and functional MRI to investigate the connection between brain development and behavior. Questionnaires and tests of neurocognitive functions were used to measure impulsivity and immediate gratification.
One study revealed that adolescents at higher risk of alcoholism have reduced connections in key brain networks; another links impaired brain connections to impulsivity; and two research studies examine impulsivity in relation to sugar intake and intake of DHA, an essential omega-3 fatty acid.
“What this study is attempting to do is identify the differences in the brains of adolescents who go on to misuse alcohol and other drugs,” says VanMeter, one of the lead researchers of the study. “If we know what is different, we may be able to develop strategies that can prevent the behavior.”
The first study examined reduced executive cognitive functioning in the brain’s executive control network, (ECN), in adolescents at risk for developing an alcohol use disorder. Thirty two participants and their parents filled out a Drug Use Screening Inventory questionnaire designed to measure brain connectivity within the ECN, which includes the areas that process emotion, impulsivity and self-control.
The questionnaire was designed to predict future alcohol abuse by examining specific social behavior such as irritability, anger and sadness. The research participants were divided into two groups–16 at high/medium risk for alcohol abuse, based on the test, and 16 at low risk. He then used fMRI scans to look at connectivity in the ECN. He found ECN connectivity was significantly lower in the high/medium risk groups compared to the low risk group.
“We know impaired functioning in the ECN is linked to an earlier age of drinking onset and higher frequency of drinking, but it was unclear whether this dysfunction occurred before drinking or was a consequence of alcohol use,” Clarke says. “Our findings suggest reduced prefrontal cortex development predates alcohol use and may be related to future alcohol use disorders.”
The second study examined the functional connectivity between the insula and anterior cingulate predict impulsivity in adolescents at risk for alcohol misuse by using the Drug Screening Inventory to establish a high/medium risk and a low risk group with 17 participants. The test was administered while the participants underwent fMRI. He found that compared with the low risk group, high/medium risk participants had reduced connectivity between the prefrontal cortex and the insular cortex.
“Less connectivity predicted higher levels of impulsivity,” Stevens said. “Importantly, these effects were observed before the onset of alcohol use. The reduced connectivity between these brain regions could be an important factor in adolescent alcohol use given that reduced inhibitory control has been found to be a factor in alcohol use disorders.”
The third study investigated the association between sugar intake, impulsivity and increased sensitivity to immediate reward, with a food questionnaire and performance on two tests designed to measure impuslivity and ability to delay gratification, while undergoing an fMRI.
“We know that, compared to healthy individuals, adults with alcoholism have a stronger preference for sweet tastes, are more impulsive and are less able to delay gratification,” ssaid Dana Estefan, a former research assistant in VanMeter’s lab who is now a student at New York University. “We wanted to know if this profile fits youth deemed to be at risk for early alcohol use by the Drug Use Screening Inventory.”
The research findings revealed that children with high amounts of added sugar in their diets preferred immediate rewards more than kids with lower levels of added sugar in their diets. The performance tests revealed that individuals with increased sugar intake also showed greater activation in right superior temporal gyrus and right insula, areas linked to impulsivity and emotional affect. Their hypothalamus was also highly activated, which, in adults, is linked to overeating, reward seeking and drug addiction.
The forth study examined the relationship between DHA intake and activation of impulse control circuitry in early adolescents with a food questionnaire and performance tests while the subjects underwent and fMRI.
“My preliminary findings show that while impulsivity levels are the same for kids with high and low levels of DHA in their diets, the brains of kids with low DHA appear to be more active — working harder to compensate — in a region involved in paying attention to the task and a region that participates in executive function,” said Valerie Darcey, a registered dietitian and a graduate student in the Interdisciplinary Program in Neuroscience,. “This tells us that the brains of the kids eating less DHA may not be developing like those eating more DHA.”
Georgetown University Medical Center. “What brain studies reveal about risk of adolescent alcohol use, abuse.” http://www.eurekalert.org/pub_releases/2014-11/gumc-wbs110614.php