Marijuana's long-term effects on the brain: do you want the good news or the bad news? (STA BREAKING NEWS and ARCHIVES)

by Theresa , Tuesday, January 06, 2015, 12:55

A study by University of Texas scientists has found that chronic marijuana users have a smaller orbitofrontal cortex (OFC), but increased brain connectivity.

In Proceedings of the National Academy of Sciences, the researchers describe how they compared adult marijuana users and gender- and age-matched non-users, accounting for potential biases such as gender, age and ethnicity.

On average, the marijuana users who participated in the study consumed the drug three times per day. Cognitive tests show that chronic marijuana users had lower IQ compared to age-and gender-matched controls but the differences do not seem to be related to the brain abnormalities as no direct correlation can be drawn between IQ deficits and OFC volume decrease.

"What's unique about this work is that it combines three different MRI techniques to evaluate different brain characteristics," said study author Sina Aslan. "The results suggest increases in connectivity, both structural and functional that may be compensating for gray matter losses. Eventually, however, the structural connectivity or 'wiring' of the brain starts degrading with prolonged marijuana use."

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