Pubdate: Tue, 12 Jan 2016
Source: London Free Press (CN ON)
Copyright: 2016 The London Free Press
Author: Jonathan Sher
Page: A1


Turns out getting stoned on marijuana can carry much more dire 
consequences for teenagers than for adults - at least if you're a rat 
and part of a study released Monday by researchers in London.

Researchers at Western University's Schulich School of Medicine & 
Dentistry have published a study that shows that a key psychoactive 
component of marijuana harms adolescent rats, producing changes 
similar to what is found in schizophrenia.

"Adolescence is a critical period of brain development and the 
adolescent brain is particularly vulnerable," said Steven Laviolette, 
a professor in the departments of anatomy and cell biology, and psychiatry.

His research, published in the January issue of Cerebral Cortex, 
comes as a critical time.

Justin Trudeau's Liberal government has promised to legalize pot, 
regulate its sale and remove possession of small amounts as a crime - 
but has not unveiled details about how such changes would be implemented.

That left a researcher like Laviolette some room to affect the public 
debate, and though some longtime pot smokers were quick to criticize 
his work, the London scientist actually supports legalization.

If the goal is to keep pot out of the hands of teens, Canada has 
failed - teenage usage rates here are among the highest in the 
industrialized world, he said. Taking pot out of the hands of 
criminal dealers may help reduce access by teens, he said.

"Clearly, criminalization doesn't work," he said.

Researchers have long known the harm that can be caused by the 
psychoactive component that produces a "high" - 
delta-9-tetrahydrocannabinol or THC for short. But Laviolette pushed 
that knowledge further, showing how, at the molecular level, THC 
affects the developing brain of adolescent rats.

His research team found neuronal and molecular changes identical to 
neuropsychiatric conditions such as schizophrenia. Adolescent rodents 
given THC were socially withdrawn and had increased anxiety, elevated 
levels of dopamine and an inability to filter out unnecessary 
information, all factors in schizophrenia. Changes persisted into adulthood.

"Health policy makers need to ensure that marijuana, especially 
marijuana strains with high THC levels, stays out of the hands of 
teenagers. In contrast, our findings suggest that adult use of 
marijuana does not pose substantial risk," Laviolette said.

Adult rodents showed no harmful long-term effects, though both 
adolescents and adults experienced deficits in social cognition and memory.

"With the (rise) in adolescent cannabis use and (increasing) THC 
content in newer cannabis strains, it is critically important to 
highlight (risk) factors (with) exposure to marijuana, particularly 
during adolescence," lead author Justine Renard said.

Asked about the study, Federal Health Minister Jane Philpott agreed 
the current system doesn't work with teen use here the highest in the 
developed world.

"Our government's commitment to legalize, regulate, and restrict 
access to marijuana will not only keep profits out of the illicit 
drug trade, it will ensure marijuana stays out of the hands of 
children and teens," she wrote in an email to The Free Press.

About half of the people who seek help at the First Episode Mood and 
Anxiety Program at London Health Sciences Centre used marijuana, said 
its medical director, Dr. Elizabeth Osuch.

"It's brilliant research," she said of the study. Earlier research 
showed that adolescents who used marijuana had significantly lower 
IQs compared to non-users of those who started using pot after age 18.
- ---
MAP posted-by: Jay Bergstrom