A new neuroimaging study has found that individuals who consumed their first alcoholic drink before the age of 18 had weaker connections in the brain’s cognitive control network compared those who consumed their first alcoholic drink after the age of 18. This suggests that starting to drink alcohol at a young age might make this brain network less effective. The study was published in Psychiatry Research: Neuroimaging.
Although the adverse effects of alcohol consumption and related long-term health risks are well known, it is estimated that 30% of youth in the United States use alcohol by the eighth grade. 62% of adolescents report drinking their first alcoholic drink by the time they graduate from high school, around 18 years of age.
Studies have found that individuals who start using alcohol earlier are more likely to develop alcohol-related problems later in life. Individuals who drink their first alcoholic drink earlier are also more likely to get drunk for the first time at an earlier age. They are also more likely to participate in binge drinking i.e., to consume more than 5 standard drinks for men or more than 4 for women on a single occasion.
Binge drinking is a risk factor for developing alcohol use disorder, and people with alcohol use disorder are more likely to suffer from major depressive disorder too. In short, there are many negative consequences associated with early alcohol drinking, which is why scientists are interested in understanding how it affects the brain.
Study author Maci M. Jacobson and her colleagues were specifically interested in how alcohol use during adolescence, when the brain is still developing, might impact the cognitive control network, which includes the dorsolateral prefrontal cortex, dorsal anterior cingulate cortex, and dorsal parietal cortex regions. They theorized that alcohol might interfere with the maturation of neurons in the brain, leading to long-term issues with the network’s functioning.
The researchers hypothesized that alcohol use during adolescence, a time when the brain is still developing, might adversely affect the maturation of neurons, resulting in worse functioning of this network later in life. The plausibility of this idea is supported by findings that alcohol use during adolescence is associated with decreased volume in the hippocampus, prefrontal cortex, and cerebellum regions of the brain and with decreased brain white matter integrity.
To investigate this, the researchers used a type of brain scan called functional magnetic resonance imaging (fMRI). They compared brain scans of 96 young adults, some of whom started drinking before 18 and others who started after.
Participants completed the Diagnostic Interview for Genetic Studies, a clinician-administered interview that assess participant’s psychiatric health and functioning. This interview also provides data on the age when the interviewee first drank alcohol (“How old were you when you had your first drink of alcohol?”) and if/when he/she got drunk for the first time. Participants also completed several tasks that assessed cognitive control.
The results showed that the average age of first drink for early drinkers was 15.5 years. Proportions of males and females that had their first alcoholic drink before 18 years of age were similar. Early drinkers were more likely to use tobacco and cannabis compared to late drinkers. Late drinkers were more likely to have never smoked tobacco or cannabis. 73% of them never smoked tobacco and 82% never smoked cannabis. 21% of early drinkers were daily cannabis smokers. There were no daily cannabis smokers among late drinkers.
Functional magnetic resonance imaging results showed that early drinkers had significantly lower connectivity of regions of the cognitive control network including the dorsolateral prefrontal cortex on both sides of the brain compared to late drinkers.
“We identified lower cognitive control network connectivity to be associated with an earlier age of onset of alcohol use, independent of whether individuals had experienced major depressive disorder before,” the researchers concluded. “These results suggest that individuals who begin drinking alcohol earlier in life may have alterations in the development of the cognitive control network; however, longitudinal research is necessary to determine whether lower connectivity precedes or follows early alcohol use, and any other relevant factors.”
While this study provides valuable insights into the effects of alcohol use on the brain, it has some limitations. The number of participants was relatively small, and the researchers didn’t have detailed information about the participants’ alcohol use. Additionally, since this was an observational study, it can’t establish a cause-and-effect relationship between early alcohol use and changes in brain connectivity.
The study, “Reduced connectivity of the cognitive control neural network at rest in young adults who had their first drink of alcohol prior to age 18”, was authored by Maci M. Jacobson, Lisanne M. Jenkins, Daniel A. Feldman, Natania A. Crane, and Scott A. Langenecker.