Published: Dec. 15, 2014 By

Teen with head in arms

Researchers find clues about why some adolescents abuse alcohol and engage in risky sex for a limited time, while in others, the habits linger

Beleaguered moms often say their child is “just going through a phase,” knowing full well that the kid will eventually outgrow troubling behavior, but now scientists may be close to using brain imaging to take motherly instinct out of the equation.

A team of researchers at the University of Colorado Boulder has used neuroimaging techniques to understand associations between brain function and risky behavior, moving one step closer to definitively diagnosing dangerous predispositions to risk-taking.

Specifically, researchers have identified a region of the brain that may yield insight into why some adolescents engage in heavy drinking and risky sex for a limited time, while others continue the pattern throughout life.

"We were really interested in, and continue to be, this broad question of what we can do, essentially, to reduce risky behavior.”

In a study conducted earlier this year, the scientists found relationships between alcohol use, sexual behavior and various networks of the adolescent brain, concluding that the level of activity in a specific network of the brain, the default dorsal mode network—or dDMN—may be a useful indicator for future patterns of risky behavior.

Two-hundred-thirty-nine kids between the ages of 14 and 18 were recruited from juvenile justice diversion programs in the southwestern United States to take part in the study. During “resting state scans,” images of test subjects’ brains were taken as they rested in a magnetic resonance imaging (MRI) machine.

Scanning during this idle state allowed researchers to observe functional connectivity strength throughout the brain, which is essentially a correlation of activity and blood flow in different neural networks and regions.

The two networks studied were the default dorsal mode network (dDMN) and the executive control network (ECN). The former is associated with introspection and things like daydreaming, becoming active during moments when individuals are not focusing on any task in particular. The latter is associated with the regulation of mental processes and has also been studied in the context of change over time with alcohol use.

In addition to the MRI session, participants answered questions about how often they had sex, how often they used protection, how often they drank alcohol and how often alcohol was involved in sexual encounters.

Responses about sexual behavior were then transformed into a single composite score of “riskiness” by multiplying frequency of sex in past three months by how often protection was used. The Alcohol Use Disorders Identification Test was applied to determine potentially harmful levels of alcohol consumption.

Following the baseline data collection, the same kids reported on their risk behavior every three months for a year.

The results

As predicted, statistical analyses revealed a correlation between alcohol use and risky sexual behavior. Higher levels of alcohol use often went hand in hand with high levels of risky sexual behaviors.

MRI scans revealed that the adolescents who had higher levels of functional connectivity in the dDMN also generally had higher self-reported levels of alcohol consumption.

Researchers suspected that higher levels of activity in the dDMN, which is the network underlying processes like sensitivity to internal states, meant that individuals felt greater levels of pleasure when consuming alcohol. These increased feelings of pleasure paired with the exciting newness of alcohol may encourage an adolescent to drink more.

Rachel Thayer“For a lot of teenagers, as they are just beginning to be exposed to alcohol, it’s a new experience, new bodily sensations, and that might be related to their increasing alcohol use,” says Rachel Thayer, a doctoral student in clinical psychology and first author on an article reporting the research in the journal Current HIV Research.

The key observation came while exploring the relationship between the brain and alcohol use over time. Rather than alcohol use increasing compared to those with lower activity in the same region of the brain, as one might expect, it decreased.

Researchers then reconsidered their hypothesis about dDMN’s relationship to risky behavior. While sensory pleasure may be supported by a high-functioning dDMN, the perception of negative side effects (like nausea) is also likely increased. This heightened sensitivity likely encourages an individual to decrease their alcohol consumption over the long run.

The Implications

These findings are helpful, as Thayer says, because they identify ways researchers could better treat or understand harmful behaviors: “We were really interested in, and continue to be, this broad question of what we can do, essentially, to reduce risky behavior. Applying some of these neuroimaging approaches to adolescents can be interesting because there is ongoing brain development in adolescence, and using drugs or alcohol while the brain is still developing may have long-term impacts.”

A nuanced understanding of the various trajectories for risk-taking during adolescence might open up the possibility for accurately determining which teens are going through a typical phase of risky behavior, as opposed to teens who might be predisposed to long-term problematic behaviors.

However, it is important to realize the potential limitations to using brain imaging to predict behaviors. Only having been invented in the mid-1990s, functional magnetic resonance imaging is just a baby in the world of science. The fledgling field was catapulted to widespread popularity and acceptance during the start of the 21st century due to growing interest in the brain and provocative headlines like “This is your brain on politics.”

But this popular brand of science has critics. Critiques of fMRI often center on the inability of current technology to precisely pinpoint areas of the brain and conclusively relate them to behaviors.

In a 2012 article in the New Yorker, cognitive scientist Gary Marcus said that current fMRI technology might merely be “the magnifying glass that leads us to the microscope we really need.”

Other critics note that scanner noise and the sheer complexity of the human variables involved means that analyzing fMRI studies may be akin to trying to make sense out of random data, a criticism which is backed up in part by the numerous disagreements in the scientific community on which areas of the brain are responsible for certain behaviors.

Writing in The New York Times, psychiatrist Sally Satel says, “this logically suspect approach is called ‘reverse inference,’ and when crudely applied it functions much like a high-tech Rorschach test, inviting interpreters to read what they want into largely ambiguous findings.”

Despite these potential shortcomings, however, improvements in experimental design and data sharing continue to strengthen our understanding of the brain and how it shapes behavior, says Thayer. “It speaks to how careful we need to be as researchers, and the more data available, the more likely we are to be able to reach a coherent picture.”

Of course, the bigger challenge lies not really with the science itself, but with providing context and commentary. One of the most important considerations in interpreting research is recognizing limitations and thinking critically about the results. Studies like Thayer’s are a starting point for creating future hypotheses that should open new possibilities, not a finishing line for drawing simple conclusions.

Robert Stein is a CU-Boulder senior majoring in English and an intern for Colorado Arts & Sciences Magazine.