Table 5.
Summarized effects of cannabis and alcohol on simulated and on-road driving.
| Outcome measurea | Cannabis intake historyb | Simulator studies showing THC impairment | Simulator studies not showing THC impairment | On-road studies showing THC impairment | On-road studies not showing THC impairment | Studies showing cannabis–alcohol interaction | Studies not showing cannabis–alcohol interaction |
|---|---|---|---|---|---|---|---|
| RT | O | Ronen et al. (10), Rafaelsen et al. (64) | Anderson et al. (55) | — | — | — | — |
| NS | Lenné et al. (53), Liguori et al. (57) | Liguori et al. (65) | — | Robbe (59) | Robbe (59), Ramaekers et al. (67) | Lenné et al. (53), Liguori et al. (65) | |
| Headway maintenance | NS | Lenné et al. (53) | — | — | Robbe (59) | — | Lenné et al. (53), Robbe (59), Ramaekers et al. (67) |
| Headway variability | NS | Lenné et al. (53) | — | Robbe (59), Ramaekers et al. (67) | — | Robbe (59), Ramaekers et al. (67) | Lenné et al. (53) |
| Road tracking, SDLP | O | Ronen et al. (10) | Ronen et al. (3), Anderson et al. (55) | — | — | Ronen et al. (3) | — |
| NS | Lenné et al. (53) | — | Robbe (59), Ramaekers et al. (67) | — | Robbe (59), Ramaekers et al. (67) | Lenné et al. (53) | |
| Road tracking, Other | O | Ménétrey et al. (60) | — | — | — | — | — |
| NS | Papafotiou et al. (66) | Liguori et al. (57) | — | Robbe (59), Ramaekers et al. (67) | Robbe (59), Ramaekers et al. (67) | — | |
| Speed | O | Ronen et al. (3), Ronen et al. (10), Anderson et al. (55) | Liguori et al. (57) | — | — | Ronen et al. (3) | — |
| NS | Lenné et al. (53) | — | — | Robbe (59) | — | Lenné et al. (53) | |
| Speed variability | O | Ronen et al. (10), Rafaelsen et al. (64) | Ronen et al. (3), Anderson et al. (55) | — | — | — | Ronen et al. (3) |
| NS | Lenné et al. (53) | Liguori et al. (57) | — | Robbe (59) | — | Lenné et al. (53) | |
| Divided attention | O | Anderson et al. (55) | — | — | — | — | — |
| NS | Lenné et al. (53) | — | — | — | — | Lenné et al. (53) | |
| Visual search/processing speed/short-term memory | O | Ménétrey et al. (60) | — | — | Lamers et al. (4) | Lamers et al. (4) | — |
| Collisionsc | O | Ronen et al. (3), Ronen et al. (10) | — | — | — | Ronen et al. (3) | — |
a
See Table D in the online Data Supplement for specific outcome measures, THC doses, study details, and results.
b
O (occasional) denotes <12 times per month. NS (not specified) denotes history not given, or various (see Table D in the online Data Supplement for specific cannabis history).
c
Collisions in the studies were too few for statistical analysis; data are reported as studywide number of collisions.