Gray Matter Development, Impulsivity, Tied to Teen Drunkenness

By Marilynn Larkin

December 30, 2019

NEW YORK (Reuters Health) - Among healthy adolescents in Europe, gray matter development and impulsivity were associated, by sex, with an increased frequency of drunkenness, suggesting a brain-based predisposition to alcohol abuse, researchers say.

"There has been continuing debate as to how much alcohol use causes changes in brain structure in adolescents or if there is a path of development in the brain that influences behavior and may put certain adolescents at greater risk of drunkenness," Dr. Gunter Schumann of King's College London, UK, told Reuters Health.

"Our research showed that . . . structural changes in the brain could perhaps be a predictor of alcohol use," he said by email. "This has implications for messaging around teenage drinking, as claims around the effects of alcohol on the brain are often oversimplified and do not reflect the complexity of the interactions between brain development and the environment."

"The research also has implications for identifying risk factors that could ultimately help characterize individuals who are likely to get drunk more often," he noted. "This may be valuable in better understanding what factors contribute to adolescents' getting drunk, and in informing initiatives looking to minimize harm from taking part in risky and impulsive behaviors around drinking."

Dr. Schumann and colleagues analyzed participants of IMAGEN, a multicenter brain imaging study of healthy adolescents in eight European sites in Germany, the UK, Ireland, and France. Analyses were controlled for sex, site, socioeconomic status, family history of alcohol dependency, puberty score, negative life events, personality, cognition, and polygenic risk scores.

Personality and frequency of drunkenness were assessed at age 14 (baseline), 16 (first follow-up), and 19 (second follow-up). Structural brain imaging scans were done at baseline and second follow-up.

As reported in JAMA Psychiatry, 726 white adolescents (58% female) were included in the analysis; 102 (14%) had at least one drunkenness episode.

Drunkenness significantly increased over time and the mean increase in frequency was greater in males compared with females (0.52 vs 0.34). Further, increases in openness and in impulsivity, but not in other traits or in polygenic risk scores, were associated with an increase in drunkenness frequency, particularly in boys.

An increase in drunkenness frequency was associated with accelerated gray matter atrophy in the left posterior temporal cortex (cluster: 6,297 voxels); right posterior temporal cortex (cluster: 2,070 voxels), and left prefrontal cortex (cluster: 10,624 voxels).

Various analyses were used to explore directionality. The results showed directionality from gray matter development to drunkenness increase, rather than the reverse. For example, gray matter volume at age 14 among nondrinkers was associated with a future increase in drunkenness frequency between ages 14 and 19. Conversely, drunkenness frequency at age 14 was not associated with gray matter development between ages 14 and 19.

The authors state, "We found stable directionality from gray matter development (76%) predominantly among female participants (93%) and from impulsivity at age 14 years to increase in drunkenness (94%) predominantly among male participants (99%)."

They conclude that "neurotoxicity-related gray matter atrophy should be interpreted with caution."

Dr. Schumann said, "Future research could investigate adolescents with the most severe decreases in grey matter over time and monitor the onset of substance use disorders and related behaviors such as impulsivity to get a clearer picture of which adolescents may be more at risk."

Pediatrician and addiction specialist Dr. Scott Hadland, Boston Medical Center's Grayken Center for Addiction, commented by email, "There is a large body of research showing that adolescents and young adults who use substances heavily have differences in brain structure and function compared to youth who do not. However, to date, it has not always been clear which came first - the brain changes, which might predispose to substance use, or substance use, which might cause brain changes."

"This study gives some compelling evidence that some of the brain structural changes may have been present to begin with," he told Reuters Health.

"Potential concerns include that this study is only examining one substance, alcohol, and therefore the findings do not necessarily apply to other substances commonly used by youth, including marijuana and nicotine," he noted.

"Also, the authors studied a fairly narrow age range," he said. "It's possible that heavy substance use could indeed cause brain structure and function changes later in adolescence and young adulthood - indeed, there is compelling evidence that this is indeed the case."

Nonetheless, he added, "Clinically, the message remains the same. Regardless of whether brain changes precede or follow heavy substance use, given the clear immediate and long-term harms of excessive drinking, we need to continue to counsel youth that minimizing or eliminating substance use is best for their health."

SOURCE: JAMA Psychiatry, online December 18, 2019.