Investigators at Norway's University of Oslo, Institute of Psychiatry investigated the association between cannabis use and neurocognition in 133 patients with bipolar disorder. Researchers reported that subjects who used cannabis performed better than non-users on a series of neurocognitive tests. Authors determined that marijuana use was associated with "statistically significant" improvement in attention, executive function, verbal fluency, logistical memory-learning, and logical memory-recall.

Researchers reported that contrasting results were associated with the use of marijuana among subjects diagnosed with schizophrenia.

Investigators concluded, "The findings suggest that cannabis use may be related to improved neurocognition in bipolar disorder and compromised neurocognition in schizophrenia."

The findings conflict with those of a 2007 study published in the journal Progress in Neuro-Psychopharmacology & Biology Psychiatry that reported that cannabis use was not associated with a decline in cognitive function in schizophrenic patients, and might even improve it.

For more information, please contact Paul Armentano, NORML Deputy Director, at: paul@norml.org.