Lead researcher Dr. Shirley Hill, a professor of Psychiatry, says that the size of the right orbitofrontal cortex, an area of the brain that is involved in regulating emotional processing and impulsive behavior, seems to be smaller in teenagers and young adults who have several relatives that are alcohol dependent.
Describing their study in the online edition of the journal Biological Psychiatry, the researchers revealed that they imaged the brains of 107 teens and young adults using magnetic resonance imaging.
The team also said that they examined variation in certain genes of the participants, and administered a well-validated questionnaire to measure the youngsters' tendency to be impulsive.
Sixty-three of the study subjects had multiple alcohol-dependent family members, suggesting a genetic predisposition. The participants also included 44 individuals none of whose relatives were dependent on drugs or alcohol.
The researchers observed that the participants who had several alcohol-dependent relatives were more likely to have reduced volume of the OFC.
Upon looking at the two genes called 5-HTT and BDNF, the researchers found certain variants that led to a reduction in white matter volume in the OFC, and that in turn was associated with greater impulsivity.
"We are beginning to understand how genetic factors can lead to structural brain changes that may make people more vulnerable to alcoholism. These results also support our earlier findings of reduced volume of other brain regions in high-risk kids," Dr. Hill said.
She said that such differences could be observed even before the high-risk offspring started drinking excessively, "leading us to conclude that they are predisposing factors in the cause of this disease, rather than a consequence of it."