Long-Term Effects of Marijuana on the Brain

I posted a while back about how legalizing marijuana may be self-limiting politically as a generation that sees pot smoking as really important are more likely to sit out future elections, unless states move the polling places to pot stores (I should not even suggest that).  This November 10, 2004 Washington Post article about a new study of pot's effects on the brain is doing its best to put a positive spin on it:

Researchers at the Center for Brain Health at the University of Texas in Dallas sought to clear up some of the confusion with a study that looked at a relatively large group of marijuana users and evaluated their brains for a slew of different indicators....

What they found was complex, but the pattern was clear: The brains of marijuana users were different than those of non-marijuana users. The area of the brain responsible for establishing the reward system that helps us survive and also keeps us motivated was smaller in users than in non-marijuana users. But there was also evidence that the brain compensated for this loss of
Relative to other studies, this one had a fairly large sample size; it also excluded participants who had symptoms of psychosis, brain injury or neurological disorders in order to reduce the likelihood that the tests would pick up on other confounding factors. And it looked at three brain characteristics: the volume of the orbitofrontal cortex, how connected that part of the brain was to other areas, and the structural integrity of the white matter.

"We found that while the orbitofrontal cortex was smaller, there was greater functional and structural connectivity," said Filbey. "The white matter seemed to have greater integrity than the [non-marijuana using group]. And the connection between the orbitofrontal cortex and other areas were stronger."

 This November 11, 2014 CNN report points out:

Filbey said the people who regularly used marijuana had IQ's that were five points lower, on average, than the nonusers in the study, although there is no definitive proof that marijuana alone was to blame for the lower IQ.

Just think, a whole nation like Jamaica!  No wonder Democrats like the idea of legalizing pot.

This November 10, 2014 Los Angeles Times article about the study points out:

Researchers noted that the IQ of the marijuana-using group was significantly lower than that of the non-using group--not a finding of the study, but an incidental factor that might be indirectly linked to marijuana use.

and that the brain structure differences, inability to make good decisions, might cause the heavy pot smoking.