Duke University researchers believe they have discovered two distinct brain profiles that appear to be associated with risky sexual activity and problem drinking among young adults.
Researchers say the scans show an imbalance in functions of typically complementary brain regions. They believe the findings may allow clinicians to one day predict how likely young adults are to develop problem drinking or engage in risky sexual behavior in response to stress.
The new research is part of the ongoing Duke Neurogenetics Study (DNS), which began in 2010 to better understand how interactions between the brain, genome and environment shape risky behaviors that can predict mental illnesses including depression, anxiety, and addiction.
“By knowing the biology that predicts risk, we hope to eventually change the biology or at least meet that biology with other forces to stem the risk,” said the senior author of both studies, Ahmad Hariri, Ph.D., professor of psychology and neuroscience at Duke University.
In both studies, the team used non-invasive functional MRI imaging to measure the activity of two brain areas that help shape opposing behaviors crucial for survival: the reward-seeking ventral striatum and the threat-assessing amygdala.
As part of the project, in 2012 researchers evaluated 200 participants and discovered that having both an overactive ventral striatum and an underactive amygdala was associated with problem drinking in response to stress.
The researchers also discovered that the inverse brain pattern — low ventral striatum and high amygdala activity — predicted problem drinking in response to stress both at the time of the scan and three months after.
These results appear in the journal Molecular Psychiatry.
“We now have these two distinct profiles of risk that, in general, reflect imbalance in the function of typically complementary brain areas,” Hariri said.
“If you have high activity in both areas, no problem. If you have low activity in both areas, no problem. It’s when they’re out of whack that individuals may have problems with drinking.”
Interestingly, people with the two different risk profiles may drink for different reasons.
Hariri speculates that those with high ventral striatum activity may be motivated to drink because they are impulsive; combined with a lower danger signal coming from the amygdala, they may be less inclined to reign in their behavior.
In contrast, the participants with low ventral striatum activity usually have lower mood, and an overactive amygdala may make them more sensitive to stress, so they might drink as a coping mechanism.
Balance in the activity of the ventral striatum and the amygdala also predicts sexual behavior, according to the second study, which appears in the Journal of Neuroscience.
In that study, a team led by graduate student Elizabeth Victor asked a subset of DNS participants (70 heterosexual men and women) how many new sexual partners they acquired over an 11-month period.
For men, the same pattern of brain activity linked to problem drinking, high ventral striatum and low amygdala activity, was associated with a greater number of sexual partners compared to those men with more balanced activity of the two brain areas.
But the pattern for more sexually active women was different: They had higher-than-normal activity in both the ventral striatum and the amygdala, indicating both high reward and high threat.
“It’s not really clear why that is,” Hariri said. “One possibility is that this amygdala signal is representing different things in men and women.”
In women, amygdala activity might be driving general awareness, arousal, and responsiveness which, when combined with strong reward-related activity in the ventral striatum, leads to a greater number of partners. In contrast, in men, the amygdala signal could be more focused on detecting danger, Hariri said.
Measuring brain-based predictors of sexual behavior is largely uncharted territory, Victor said. Although a previous study tied higher ventral striatum activity to more sexual partners, no prior studies have accounted for amygdala activity.
Source: Duke University/EurekAlert