Susanna Pilny for redOrbit.com – @PlinyTheShorter
Separate research from the ongoing Duke Neurogenetics Study (DNS) have found that the same two brain areas predict problem drinking and promiscuity.
The ventral striatum (VS) is involved in reward seeking (and plays a role in drug addiction and depression), while the amygdala is important for threat assessment.
After studying 759 undergraduate students (average age of 19), it was found that problem drinking in response to stress was associated with either the amygdala or the ventral striatum being overactive while the other was underactive.
Out of whack brain activity causes problems
“We now have these two distinct profiles of risk that, in general, reflect imbalance in the function of typically complementary brain areas,” Ahmad Hariri, the senior author of both studies, 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.”
As to why these two seemingly opposite brain patterns predict problem drinking, the answer probably lies in what each area does. High VS and low amygdala activity could mean higher impulsivity without high danger alerts from the amygdala. Meanwhile, low VS and high amygdala activity may indicate a lower mood with high stress sensitivity, leading to drinking as a coping mechanism.
As for promiscuity, the same two brain areas were studied in 70 heterosexual men and women, and the results, published in the Journal of Neuroscience, were compared to self-reported numbers of new sexual partners in an 11-month period.
Interestingly, higher numbers of new sexual partners associated with different brain patterns between the sexes. For men, the pattern was high VS and low amygdala activity; for women, both were higher than normal.
“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.”
Hariri suggested that the amygdala may be focusing less on danger and more on general awareness in women. When tied with a strong reward center in the VS, women are more likely to seek out new partners.
For men, the amygdala may be focusing on danger, so low activity means less inhibition when one is reward-seeking.
So what’s next?
By adding in a third brain region—the prefrontal cortex, which is the part of the brain that makes final decisions—researchers hope to predict more accurately which individuals might engage in risky business. (Look out, Tom Cruise.)
This could help those who don’t know they’re at risk—like those who might become alcoholics. “The key is that these are patterns present before problems emerge,” Hariri said. “If we know this about an individual, we can anticipate the problems and anticipate what the nature of those problems will be. This knowledge brings us one step closer to preventing the problems altogether.”
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