Driving and Cannabis

After hearing some ridiculous responses on a recent radio chat programme, I thought it worthwhile to post these pieces about research into driving and cannabis. They're taken from the Bulletins of the International Association for Cannabis as Medicine.

Researchers at the University of Maryland found the use of cannabis was not associated with the risk of causing a traffic accident. The records of 6,581 drivers who were hospitalized at a shock trauma center in the years 1997 through 2001 were analysed. Results on the presence of alcohol and illegal drugs were linked to police crash reports. Crash culpability was strongly associated with alcohol use, but no association was found between crash culpability and driving with cannabis in the system (as detected in urine).
(Source cited: Soderstrom CA, et al. Annu Proc Assoc Adv Automot Med 2005;49:315-30.)

The effects of the synthetic cannabinoid nabilone on driving ability was investigated in six patients with multiple sclerosis and spasticity. In a crossover design they received either 2 mg nabilone/day or placebo. No indication was found of a deterioration of any of the five investigated neuropsychological functions (reaction time, working memory, divided attention, psychomotor speed and mental flexibility)
during the four-week treatment period with nabilone. Nabilone shows similar effects as THC, 1 mg of nabilone comparing to about 10 mg THC.
(Source cited: Kurzthaler I, et al. Hum Psychopharmacol 2005 Apr 18; [Electronic publication ahead of print])