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Impairment due to cannabis and ethanol: clinical signs and additive effects.
Addiction. 2010 Jun; 105(6):1080-7.A

Abstract

AIMS

Studies have shown that the impairing effects of Delta-9-tetrahydrocannabinol (THC) are dose-related. Cannabis intake increases the risk of traffic accidents. The purpose of this study was to see how different clinical tests and observations were related to blood THC concentrations and to determine whether the combined influence of THC and ethanol was different from either drug alone.

DESIGN

A retrospective cross-sectional forensic database study.

SETTING

Drivers apprehended by the police suspected of driving under the influence of alcohol and other drugs.

PARTICIPANTS

We investigated 589 cases positive for THC only. In addition, 894 cases with THC and ethanol were included. A comparison was made with 3480 drivers with only ethanol in their blood and 79 drivers who tested negative.

MEASUREMENTS

Data were analytical results of blood samples and the 27 clinical tests and observations included in the Norwegian clinical test for impairment (CTI).

FINDINGS

No relationship was found between blood THC concentration and most of the CTI tests. Blood THC concentration was, however, related to conjunctival injection, pupil dilation and reaction to light and to the overall risk of being judged impaired. When THC and ethanol were detected together the risk of being judged impaired was increased markedly.

CONCLUSIONS

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.

Authors+Show Affiliations

Norwegian Centre for Addiction Research, University of Oslo, Oslo, Norway. j.g.bramness@medisin.uio.noNo affiliation info availableNo affiliation info available

Pub Type(s)

Evaluation Study
Journal Article

Language

eng

PubMed ID

20331551

Citation

Bramness, Jørgen G., et al. "Impairment Due to Cannabis and Ethanol: Clinical Signs and Additive Effects." Addiction (Abingdon, England), vol. 105, no. 6, 2010, pp. 1080-7.
Bramness JG, Khiabani HZ, Mørland J. Impairment due to cannabis and ethanol: clinical signs and additive effects. Addiction. 2010;105(6):1080-7.
Bramness, J. G., Khiabani, H. Z., & Mørland, J. (2010). Impairment due to cannabis and ethanol: clinical signs and additive effects. Addiction (Abingdon, England), 105(6), 1080-7. https://doi.org/10.1111/j.1360-0443.2010.02911.x
Bramness JG, Khiabani HZ, Mørland J. Impairment Due to Cannabis and Ethanol: Clinical Signs and Additive Effects. Addiction. 2010;105(6):1080-7. PubMed PMID: 20331551.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Impairment due to cannabis and ethanol: clinical signs and additive effects. AU - Bramness,Jørgen G, AU - Khiabani,Hassan Zaré, AU - Mørland,Jørg, Y1 - 2010/03/10/ PY - 2010/3/25/entrez PY - 2010/3/25/pubmed PY - 2011/1/22/medline SP - 1080 EP - 7 JF - Addiction (Abingdon, England) JO - Addiction VL - 105 IS - 6 N2 - AIMS: Studies have shown that the impairing effects of Delta-9-tetrahydrocannabinol (THC) are dose-related. Cannabis intake increases the risk of traffic accidents. The purpose of this study was to see how different clinical tests and observations were related to blood THC concentrations and to determine whether the combined influence of THC and ethanol was different from either drug alone. DESIGN: A retrospective cross-sectional forensic database study. SETTING: Drivers apprehended by the police suspected of driving under the influence of alcohol and other drugs. PARTICIPANTS: We investigated 589 cases positive for THC only. In addition, 894 cases with THC and ethanol were included. A comparison was made with 3480 drivers with only ethanol in their blood and 79 drivers who tested negative. MEASUREMENTS: Data were analytical results of blood samples and the 27 clinical tests and observations included in the Norwegian clinical test for impairment (CTI). FINDINGS: No relationship was found between blood THC concentration and most of the CTI tests. Blood THC concentration was, however, related to conjunctival injection, pupil dilation and reaction to light and to the overall risk of being judged impaired. When THC and ethanol were detected together the risk of being judged impaired was increased markedly. CONCLUSIONS: 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. SN - 1360-0443 UR - https://www.unboundmedicine.com/medline/citation/20331551/Impairment_due_to_cannabis_and_ethanol:_clinical_signs_and_additive_effects_ L2 - https://doi.org/10.1111/j.1360-0443.2010.02911.x DB - PRIME DP - Unbound Medicine ER -