FRIDAY, Dec. 14 (HealthDay News) -- Teens who are heavily into drinking and smoking pot may show signs of breakdown in the brain's wiring system, a small study suggests.
Using brain scans of 92 teenagers, researchers found that kids who regularly drank and used marijuana showed negative changes in the brain's "white matter" over 18 months.
The brain has two broad types of tissue, known as gray matter and white matter. The gray matter can be seen as the brain's information-processing centers, while the white matter is like the wiring connecting those centers.
It's not clear what the current findings could mean for teens' everyday brain function. And it's not even certain that it's the substance abuse causing the white matter changes.
But researchers say the results offer a cautionary message about heavy drinking and pot smoking.
"White matter is the information highway. It allows the brain to communicate quickly and efficiently," said the study's lead researcher, Joanna Jacobus, a postdoctoral fellow at the University of California, San Diego.
If white matter is "less healthy," she explained, there could be subtle effects on a person's memory, attention and mental processing speed.
Dr. Duncan Clark, a researcher at the University of Pittsburgh School of Medicine who studies teen substance abuse, also weighed in on the study.
"We are concerned that alcohol, marijuana or other substance use may cause delays or deficits in teen brain development," Clark said. "This study adds to those concerns."
Other studies have found signs of white-matter "disorganization" in kids who drink or smoke pot. What's different here is that the researchers followed kids over time to see whether substance abuse itself was linked to brain changes, said Clark, who was not involved in the study.
The findings, reported online Dec. 14 in the journal Alcoholism: Clin
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