Impairment due to cannabis and ethanol: clinical signs and additive effects

Abstract

This study demonstrates that cannabis impairs driving ability in a concentration-related manner. The effect is smaller than for ethanol. The effect of ethanol and cannabis taken simultaneously is additive. Conjunctival injection, dilated pupils and slow pupil reaction are among the few signs to reveal THC influence.

The relationship between observed signs of impairment and THC concentration in oral fluid

“…This finding is in line with previous experimental and epidemiological studies showing that cannabis impairs driving performance in a concentration-related manner Ramaekers et al, 2004Ramaekers et al, , 2006. Considering the results obtained by Bramness et al (2010) in particular, the present results strengthen the hypothesis that a similar distribution of drug concentration exists in OF and whole blood in a population related by the prevalence of signs of impairment Verstraete, 2010, 2011).…”

“…The group under the influence of only alcohol was compared to the groups under the influence of THC (THC alone and alcohol + THC) to prove the reliability of the signs test for determining impairment (Koski et al, 2005;Bramness et al, 2010). According to the Spanish legal limits for DUI of alcohol and many European countries (European Commission, 2014), two alcohol concentration levels were considered (0.01-0.25 mg/l and >0.25 mg/l).…”

“…Moreover, OF sampling seems to be better accepted by people than urine or blood sampling, and samples can be taken by the police officers themselves, simplifying the enforcement procedure (Verstraete, 2005;Gjerde and Verstraete, 2011). However, OF is not yet the best matrix for the detection and confirmation of the presence of drugs in drivers, and most studies showing that cannabis impairs driving performance in a concentration-related manner use blood as the matrix (Ramaekers et al, 2004;Laumon et al, 2005;Bramness et al, 2010).…”

Impact of age at onset of cannabis use on cannabis dependence and driving under the influence in the United States

“…Although it has been proposed that cannabis impaired subjects may compensate for their impairment by reducing driving speed, it appears likely that cannabis and alcohol have additive deleterious effects on driving ability (Bramness et al, 2010). As mentioned above, cannabis use has been associated with a threefold increased in responsible fatal traffic crashes (Laumon et al, 2005).…”

Effekter av cannabis varer lenger enn antatt

“…Vi har vist at det er god overensstemmelse mellom utfall på kognitive og psykomotoriske ferdigheter og konsentrasjonen av THC i blodet (14)(15)(16)…”