Researchers Show Multiple Risk Factors For Teen Alcohol Abuse
Researchers from the Georgetown University Medical Center (GUMC) are taking part in an effort to uncover predictive brain factors in behaviors which could help identify teens who are at heightened risk of alcohol abuse before they ever start drinking. With four abstracts from the Adolescent Development Study set to be presented at Neuroscience 2014, the Society for Neuroscience’s annual meeting, it appears the scientists have zeroed in on a few of these predictive factors.
The Adolescent Development Study is a collaborative effort between the University of Maryland School of Medicine (UMSOM) and GUMC, and seeks to understand how non-fully formed teen brains can lead to risky behaviors including substance use and abuse.
“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 John VanMeter, project director and director of the Center for Functional and Molecular Imaging, and associate professor of neurology at GUMC. “If we know what is different, we may be able to develop strategies that can prevent the behavior.
The studies used a participant pool of 135 preteen and teenage boys and girls with an average age of 12.6 years. All participants underwent structural and functional MRI scans to analyze the link between brain development and behavior. Researchers also used other tests including questionnaires and neurocognitive function testing while adolescents were scanned.
Abstract 1: Evidence of reduced executive cognitive functioning in adolescents at risk for developing an alcohol use disorder
The first study to be presented explores whether lack of connectivity in the brain’s Executive Control Network (ECN) contributes to or is a result of teen alcohol use. Research assistant Tomas Clarke and Stuart Washington, a post-doctoral fellow in VanMeter’s laboratory looked at the link between the Drug Use Screening Inventory questionnaire filled out by the 32 participants’ parents and brain connectivity within the ECN, which includes the areas the process emotion, impulsivity, and self-control.
Rather than assess hereditary links to future alcohol misuse, the questionnaire sought answers about social behaviors in children such as irritability, anger, and sadness.
The researchers split the group into 16 individuals at high/medium risk for alcohol abuse based on the questionnaire and 16 who were at low risk. Then, they underwent fMRI scans focused on the connectivity in the ECN. According to Clarke, they found ECN connectivity was significantly lower in those at high to medium risk of alcohol abuse.
“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.”
Abstract 2: Functional connectivity between the insula and anterior cingulate predict impulsivity in adolescents at risk for alcohol misuse
Another study explored the levels of impulsivity in relation to the connection between executive control in the prefrontal cortex and the insular cortex, which plays a key role in processing emotions.
Benson Stevens, a graduate student in Georgetown’s Interdisciplinary Program in Neuroscience, used the Drug Use Screening Inventory to establish two groups made of 17 participants who were at high/medium risk or low risk. The participants then underwent fMRI while completing the CPT test. Stevens says he found high/medium risk group participants had reduced connectivity between the prefrontal cortex and the insular cortex.
“Less connectivity predicted higher levels of impulsivity,” Stevens says. “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.”
Abstract 3: Relationship between sugar intake, impulsivity and increased sensitivity to immediate rewards in adolescents
The third study assessed the relationship between sugar intake and performance on the Continuous Performance Task (CPT) and Temporal Discounting Task (TD) tests. The CPT evaluates impulsivity and the TD quantifies preference for immediate reward. Researchers based sugar intake on what participants reported in a food questionnaire. The CPT was used while participants underwent fMRI scans.
“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,” explains 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 researchers saw the TD task confirmed the expected finding that those with high amounts of added sugar in their diets had a heightened preference for immediate reward compared to those who ate lower levels of added sugar. The CPT task showed that children with higher sugar intake also had greater activation in right superior temporal gyrus and right insula, areas associated with impulsivity and emotional affect. Estefan also noted the hypothalamus was also highly activated, which is linked to overeating, reward seeking, and drug addiction in adults.
“Our findings could potentially mean a positive correlation between impulsivity and sugar intake in adolescents, but more research needs to be done on this,” she says.
Abstract 4: Relationship between DHA intake and activation of impulse control circuitry in early adolescents
The last study set to be presented examined the relationship between intake of DHA, an essential omega-3 fatty acid, and impulsivity.
Valerie Darcey, a registered dietitian and a graduate student in the Interdisciplinary Program in Neuroscience, asked 81 participants to complete a food questionnaire to measure ingestion of DHA and arachidonic acid (AA), which is an omega-6 fatty acid found in vegetable oil, and many other foods. It is believed AA competes with DHA for a place in cell membranes. This suggests the more AA consumed, the less DHA is used.
Darcey then gave participants the CPT test while they underwent fMRI scanning.
“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,” she says. “This tells us that the brains of the kids eating less DHA may not be developing like those eating more DHA.”