Alcohol and THC Together Affect Drivers More Severely

The combination of alcohol and THC-containing foods significantly impairs driving ability, with effects stronger than those of either substance taken alone, according to a study by Johns Hopkins university School of Medicine researchers published in JAMA Network Open.

The researchers examined the effects of alcohol, THC and their combination on driving ability, level of intoxication and the results of standard sobriety tests. They found that the effects of both substances are mutually reinforcing rather than a simple sum of their individual actions.

THC, the main psychoactive substance in cannabis, affects concentration, reaction time and motor coordination. In countries where cannabis is legal, it is also sold in food products such as sweets, drinks and baked goods.

Study participants consumed brownies containing 10 or 25 mg of THC or a placebo, after which they were given an alcoholic or non-alcoholic drink. Alcohol doses were set to reach blood alcohol levels of 0.05% or 0.08%.

Participants then underwent simulator driving, psychomotor tests and standard sobriety tests, repeating the measurements over seven hours.

The results showed that the combination of alcohol and THC caused more severe and longer-lasting impairment of driving ability. The researchers also noted that standard police sobriety tests often fail to fully detect this condition.

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