Substance use in teens leads to altered brain structure: US study

New Delhi: A study of teenagers in the US has revealed distinct differences in brain structures between those resorting to substance use, including alcohol and cannabis, before turning 15 and those not.

The researchers, including those from Washington University in St. Louis, US, also found that many of these differences such as a bigger brain and a thinner prefrontal cortex were possibly present before the teenagers started substance use.

This suggested that these aspects may be involved in the risk of initiating substance use later in life, along with other factors, including genetic and environmental ones, the researchers said.

The prefrontal cortex is part of the cortex -- the outermost layer of the brain and known to help one perform higher-level functions such as planning, decision-making and achieving goals.

Some of the brain differences observed between the two groups of teenagers also appeared unique to the type of substance used, the team said.

The findings are published in The Journal of the American Medical Association (JAMA) Network Open.

However, the researchers said that more work is needed to discern how these structural differences translate into brain function or behaviours.

"This (study) adds to some emerging evidence that an individual's brain structure, alongside their unique genetics, environmental exposures and interactions among these factors, may impact their level of risk and resilience for substance use and addiction," said US' National Institute on Drug Abuse Director Nora Volkow.

"Understanding the complex interplay between the factors that contribute and that protect against drug use is crucial for informing effective prevention interventions and providing support for those who may be most vulnerable," Volkow said.

The team also said that the study's findings should not be used for diagnosing, as brain structure alone cannot predict substance use.

For the analysis, the researchers looked at MRI scans of 9,804 children across the US when they were 9-11 years of age. The participants were followed over a period of three years -- 3,460 reported substance initiation before age 15, while the others did not.

Between the two groups, five structural differences pertained to the brain in general, while an additional 39 pertained to specific regions -- 22 of which were related to the thickness of cortex.

"We identified neuroanatomical features associated with substance use initiation that were present before substance exposure," the authors wrote.

The participants were recruited from the ongoing Adolescent Brain Cognitive Development (ABCD) Study, examining brain development and mental health in nearly 12,000 youth in the US starting at age nine and following them into early adulthood.