Alcohol, marijuana worsen white-matter integrity

Chronic alcohol and marijuana consumption during youth is associated with compromised neurocognitive abilities in later adolescence and adulthood, researchers say.

The findings of the new study, in which researchers examined fibre tract integrity affected by adolescent alcohol and marijuana use for 1.5 years, support previous findings of reduced white-matter integrity in these youth.

Chronic use of alcohol and marijuana during youth is associated with poorer neural structure, function, and metabolism, as well as worsened neurocognitive abilities into later adolescence and adulthood.  This may be due to biological and psychosocial transitions occurring during adolescence that impart increased vulnerability to neurotoxic influences.

A study of longitudinal changes in fibre tract integrity associated with adolescent alcohol and marijuana use during 1.5 years supports previous findings of reduced white-matter integrity in these youth.  “Research has shown differences in the brains of teens who use alcohol and marijuana as compared to teens who do not use these drugs or report only very infrequent, minimal use,” Joanna Jacobus, corresponding author of the study from the University of California, San Diego, said.

 “Alcohol and marijuana may have a negative impact by altering important cellular communication in the brain, preventing development of new healthy cells, and/or causing inflammation, which can adversely impact healthy brain development in many ways. For example, the results can lead to changes in brain structure such as volume, and function such as activity.

 She noted that white matter, the “information highway of the brain”, allows for quick and efficient communication between brain regions. Compromised white matter can mean slower cognitive processing and poorer cognitive performance such as memory, attention, and decision-making.

“We found that increasing alcohol use over 1.5 years in late adolescence was related to a decline in white matter health 18 months later, supporting a negative effect of alcohol use on the brain despite potential pre-existing differences.