Table 2.
Characteristics and Results of Included Trials (>8-h Treatment, only)
| Citation | Study design | Participants | Usual cannabis use behavior | Treatment | THC dose (mg) | Performance test | Outcomes | Time since last THC use | Effect of THC (compared to placebo unless otherwise stated) |
|---|---|---|---|---|---|---|---|---|---|
| Matheson et al 28 _a (2020) | Randomized; DB; PC (BSD) |
C: 30 (21 M); 22±2 years I: 31 (18 M); 22±2 years |
Weekly–daily | Smoked cannabis cigarettes (562±170 mg; 12.5% THC) (<0.5% CBD) |
70.3±21.3 a | Grooved pegboard task | Time to complete (DH) Time to complete (non-DH) |
24 & 48 h | No significant effect |
| DSST | Number of completed trials Number of correct trials Reaction time |
24 & 48 h | THC ↑ number of correct trials at 48 h | ||||||
| CPT | Percent omission errors Percent commission errors Hit rate Hit rate variability Detectability |
24 & 48 h | No significant effect | ||||||
| HVLT-R | Immediate recall Total recall Learning score Delayed recall Percent retained True positives False positive Discrimination index |
24 & 48 h | No significant effect | ||||||
| Matheson et al 28 _b (2020) | Randomized; DB; PC (BSD) |
C: 30 (21 M); 22±2 years I: 30 (26 M); 22±2 years |
Weekly–daily | Smoked cannabis cigarettes (752±131 mg; 12.5% THC) (<0.5% CBD) |
94.0±16.4 a | Grooved pegboard task | Time to complete (DH) Time to complete (non-DH) |
24 & 48 h | No significant effect |
| DSST | Number of completed trials Number of correct trials Reaction time |
24 & 48 h | THC ↑ number of correct trials at 48 h. | ||||||
| CPT | Percent omission errors Percent commission errors Hit rate Hit rate variability Detectability |
24 & 48 h | No significant effect | ||||||
| HVLT-R | Immediate recall Total recall Learning score Delayed recall Percent retained True positives False positive Discrimination index |
24 & 48 h | No significant effect | ||||||
| Brands et al 29 _a (2019) | Randomized; DB; PC (BSD) |
C: 30 (21 M); 22±2 years I: 31 (18 M); 22±2 years |
Weekly–daily | Smoked cannabis cigarettes (562±170 mg; 12.5% THC) (<0.5% CBD) |
70.3±21.3 a | Simulated driving | SDLP Speed |
24 & 48 h | No significant effect |
| Simulated driving (dual task) | SDLP Speed |
24 & 48 h | No significant effect | ||||||
| Brands et al 29 _b (2019) | Randomized; DB; PC (BSD) |
C: 30 (21 M); 22±2 years I: 30 (26 M); 22±2 years |
Weekly–daily | Smoked cannabis cigarettes (752±131 mg; 12.5% THC) (<0.5% CBD) |
94.0±16.4 a | Simulated driving | SDLP Speed |
24 & 48 h | THC ↓ SDLP at 48 h |
| Simulated driving (dual task) | SDLP Speed |
24 & 48 h | No significant effect | ||||||
| Hartley et al 37 _a (2019) | Randomized; DB; PC (WSD) | 15 M; 22±3 years | Weekly | Smoked cannabis cigarettes (9.8% THC; 1 g tobacco) (<0.1% CBD and CBN) |
10 | Simulated driving | SDLP | 12 & 24 h | No effect b |
| PVT | Reciprocal reaction time | 12 & 24 h | No effect b | ||||||
| Hartley et al 37 _b (2019) | Randomized; DB; PC (WSD) | 15 M; 22±3 years | Weekly | Smoked cannabis cigarettes (9.8% THC; 1 g tobacco) (<0.1% CBD and CBN) |
30 | Simulated driving | SDLP | 12 & 24 h | No effect b |
| PVT | Reciprocal reaction time | 12 & 24 h | No effect b | ||||||
| Hartley et al 37 _c (2019) | Randomized; DB; PC (WSD) | 15 M; 22±3 years | Daily | Smoked cannabis cigarettes (9.8% THC; 1 g tobacco) (<0.1% CBD and CBN) |
10 | Simulated driving | SDLP | 12 & 24 h | No effect b |
| PVT | Reciprocal reaction time | 12 & 24 h | No effect b | ||||||
| Hartley et al 37 _d (2019) | Randomized; DB; PC (WSD) | 15 M; 22±3 years | Daily | Smoked cannabis cigarettes (9.8% THC; 1 g tobacco) (<0.1% CBD and CBN) |
30 | Simulated driving | SDLP | 12 & 24 h | No effect b |
| PVT | Reciprocal reaction time | 12 & 24 h | No effect b | ||||||
| Schoedel et al 25 _a (2018) | Randomized; DB; PC (WSD) c | 43 (31 M) d ; 38±9 years | Infrequent–daily | THC capsules | 10 | Divided attention task | Tracking accuracy | 12 & 24 h | No significant effect |
| HVLT-R | Delayed recall Percent retained |
12 & 24 h | No relevant analysis e | ||||||
| DSST | Number of completed trials Number of incorrect trials |
12 & 24 h | No relevant analysis e | ||||||
| Schoedel et al 25 _b (2018) | Randomized; DB; PC (WSD) c | 43 (31 M) d ; 38±9 years | Infrequent–daily | THC capsules | 30 | Divided attention task | Tracking accuracy | 12 & 24 h | No significant effect |
| HVLT-R | Delayed recall Percent retained |
12 & 24 h | No relevant analysis e | ||||||
| DSST | Number of completed trials Number of incorrect trials |
12 & 24 h | No relevant analysis e | ||||||
| Ronen et al 38 (2008) | DB; PC (WSD) | 14 (10 M); 22±2 years | Monthly–weekly | Smoked THC cigarettes | 17 | Simulated driving | RMS lane position RMS speed Speed RMS steering deviations Reaction time (dual task) |
24 h | No significant effect f |
| Ménétrey et al 26 _a (2005) | Randomized; DB; PC (WSD) | 8 M g ; range: 22–30 years | Unclear | Hemp milk decoction | 16.5 | Road sign test | Time to complete | 10 & 25 h | Ambiguous h |
| Divided attention task | Tracking accuracy Number of errors Reaction time |
10 & 25 h | Ambiguous h | ||||||
| Ménétrey et al 26 _b (2005) | Randomized; DB; PC (WSD) | 8 M g ; range: 22–30 years | Unclear | Hemp milk decoction | 45.7 | Road sign test | Time to complete | 10 & 25 h | Ambiguous h |
| Divided attention task | Tracking accuracy Number of errors Reaction time |
10 & 25 h | Ambiguous h | ||||||
| Ménétrey et al 26 _c (2005) | Randomized; DB; PC (WSD) | 8 M g ; range: 22–30 years | Unclear | THC capsules | 20 | Road sign test | Time to complete | 10 & 25 h | Ambiguous h |
| Divided attention task | Tracking accuracy Number of errors Reaction time |
10 & 25 h | Ambiguous h | ||||||
| Nicholson et al 27 _a (2004) | DB; PC (WSD) | 8 (4 M); range 21–34 years | Current nonusers | Oromucosal spray | 15 | Word memory recall | Immediate recall Delayed recall |
10 h | THC ↓ immediate and delayed recall at 10 h |
| Digit memory recall | Reaction time Number of errors |
10 h | No significant effect | ||||||
| 6-Letter memory recall | Reaction time Number of errors |
10 h | No significant effect | ||||||
| DSST | Number of completed trials | 10 h | No significant effect | ||||||
| Multi-attribute task | System monitoring RT System monitoring RA Communications RT Communications RA Resource management RT Resource management RA Tracking accuracy |
10 h | No significant effect | ||||||
| Choice reaction time task | Reciprocal reaction time Number of errors |
10 h | No significant effect | ||||||
| Sustained attention task | Reaction time Number of errors |
10 h | No significant effect | ||||||
| Nicholson et al 27 _b (2004) | DB; PC (WSD) | 8 (4 M); range 21–34 years | Current nonusers | Oromucosal spray (5 mg CBD) |
5 | Word memory recall | Immediate recall Delayed recall |
10 h | No significant effect |
| Digit memory recall | Reaction time Number of errors |
10 h | THC ↑ reaction time at 10 h | ||||||
| 6-Letter memory recall | Reaction time Number of errors |
10 h | No significant effect | ||||||
| DSST | Number of completed trials | 10 h | No significant effect | ||||||
| Multi-attribute task | System Monitoring RT System Monitoring RA Communications RT Communications RA Resource management RT Resource management RA Tracking accuracy |
10 h | No significant effect | ||||||
| Choice reaction time task | Reciprocal reaction time Number of errors |
10 h | No significant effect | ||||||
| Sustained attention task | Reaction time Number of errors |
10 h | No significant effect | ||||||
| Nicholson et al 27 _c (2004) | DB; PC (WSD) | 8 (4 M); range 21–34 years | Current nonusers | Oromucosal spray (15 mg CBD) |
15 | Word memory recall | Immediate recall Delayed recall |
10 h | No significant effects |
| Digit memory recall | Reaction time Number of errors |
10 h | No significant effects | ||||||
| 6-Letter memory recall | Reaction time Number of errors |
10 h | No significant effect | ||||||
| DSST | Number of completed trials | 10 h | No significant effect | ||||||
| Multi-attribute task | System monitoring RT System monitoring RA Communications RT Communications RA Resource management RT Resource management RA Tracking accuracy |
10 h | No significant effect | ||||||
| Choice reaction time task | Reciprocal reaction time Number of errors |
10 h | No significant effect | ||||||
| Sustained attention task | Reaction time Number of errors |
10 h | No significant effect | ||||||
| Curran et al 34 _a (2002) | Randomized; DB; PC (WSD) | 15 M; 24±2 years | Unclear | THC capsules | 7.5 | Buschkel selective reminding task | Immediate recall Delayed recall |
24 & 48 h | Ambiguous |
| RVIPT | Proportion of hits Reaction time |
24 & 48 h | No significant effect | ||||||
| Baddeley reasoning task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Subtract serial sevens task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Choice reaction time task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Digit cancellation task | Time to complete (ST) Number of errors (ST) Time to complete (DT) Number of errors (DT) |
24 & 48 h | No significant effects | ||||||
| Simple reaction time task | Reaction time | 24 & 48 h | No significant effect | ||||||
| Curran et al 34 _b (2002) | Randomized; DB; PC (WSD) | 15 M; 24±2 years | Unclear | THC capsules | 15 | Buschkel selective reminding task | Immediate recall Delayed recall |
24 & 48 h | Ambiguous |
| RVIPT | Proportion of hits Reaction time |
24 & 48 h | No significant effect | ||||||
| Baddeley reasoning task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Subtract serial sevens task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Choice reaction time task | Reaction time Number of errors |
24 & 48 h | No significant effect | ||||||
| Digit cancellation task | Time to complete (ST) Number of errors (ST) Time to complete (DT) Number of errors (DT) |
24 & 48 h | No significant effect | ||||||
| Simple reaction time task | Reaction time | 24 & 48 h | No significant effect | ||||||
| Fant et al 35 _a (1998) | Randomized; DB; PC (WSD) | 10 M; 27 years, range: 24–31 years |
Monthly–weekly | Smoked cannabis cigarettes (1.8% THC) |
“Eight Puffs” (dose unknown) |
Smooth-pursuit eye movements | Central speed (fixed) Central speed (varied) Peripheral speed (fixed) Peripheral speed (varied) |
23, 24 & 25 h | Ambiguous i |
| Circular lights task | Number of correct responses | 23, 24 & 25 h | No significant effect | ||||||
| Serial addition and subtraction task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Digit recall task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Logical reasoning task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Mannequin task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Fant et al 35 _b (1998) | Randomized; DB; PC (WSD) | 10 M; 27 years, range: 24–31 years |
Monthly–weekly | Smoked cannabis cigarettes (3.6% THC) |
“Eight Puffs” (dose unknown) |
Smooth-pursuit eye movements | Central speed (fixed) Central speed (varied) Peripheral speed (fixed) Peripheral speed (varied) |
23, 24 & 25 h | Ambiguous i |
| Circular lights task | Number of correct responses | 23, 24 & 25 h | No significant effect | ||||||
| Serial addition and subtraction task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Digit recall task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Logical reasoning task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Mannequin task | Number of correct responses Percent correct responses Reaction time |
23, 24 & 25 h | No significant effect | ||||||
| Chait and Perry 30 (1994) | DB; PC (WSD) | 14 (10 M); 25 years, range: 21–34 years |
Monthly–daily | Smoked cannabis cigarettes (3.6% THC) |
“Eight Puffs” (dose unknown) |
Time production task | Time interval (30 sec) Time interval (60 sec) Time interval (120 sec) |
11 & 18 h | No significant effect |
| Standing steadiness task | Standing time | 11 & 18 h | No significant effect | ||||||
| DSST | Number of trials attempted Number of correct trials Percent correct |
11 & 18 h | No significant effect | ||||||
| Backward digit span task | Digit span | 11 & 18 h | No significant effect | ||||||
| Logical reasoning task | NS | 11 & 18 h | No significant effect | ||||||
| Visual divided attention task | Hit rate Reaction time Secondary target errors Number of false alarms |
11 & 18 h | No significant effect | ||||||
| Free recall task | Immediate recall | 11 & 18 h | No significant effect | ||||||
| Leirer et al 40 (1991) | “Blinded” j ; PC (WSD) | 9 (Sex NS); 31 years, range: 24–40 years | Unclear | Smoked cannabis cigarettes | 20 | Simulated flying | Performance score | 24 & 48 h | THC ↓ performance at 24 h |
| Chait 22 (1990) | DB; PC (WSD) | 12 (9 M); 21 years, range: 18–26 years | Weekly–daily | Smoked cannabis cigarettes (800–900 mg; 2.1% THC) |
“Eight Puffs”
k
(dose unknown) |
Time production task | Time interval | 12, 12 & 12 h k | THC ↓ time interval (all days) l,m |
| Simple reaction time task | NS | 12, 12 & 12 h k | No significant effect | ||||||
| Forward digit span task | Digit span | 12, 12 & 12 h k | No significant effect | ||||||
| Visual divided attention task | Reaction time Number of misses Number of false alarms Reaction time variability |
12, 12 & 12 h k | THC ↑ reaction time (all days) l | ||||||
| Choice reaction time task | NS | 12, 12 & 12 h k | No significant effect | ||||||
| Backward digit span task | Digit span | 12, 12 & 12 h k | THC ↓ digit span on day 1 | ||||||
| DSST | NS | 12, 12 & 12 h k | No significant effect | ||||||
| Buschkel selective Reminding task | NS | 12, 12 & 12 h k | No significant effect | ||||||
| Heishman et al 23 _a (1990) | Randomized; DB; PC (WSD) | 3 M; range 27–29 years | Unclear | Smoked cannabis cigarettes (2.57% THC) |
“1×Cigarette” (dose unknown) | Two letter search task | Number of trials attempted Number of correct trials Percent correct |
23, 25, 27, 29 & 31 h | Results not adequately reported |
| Logical reasoning task | Number of trials attempted Number of correct trials Percent correct |
23, 25, 27, 29 & 31 h | Results not adequately reported | ||||||
| Digit recall task | Number of trials attempted Number of correct trials Percent correct |
23, 25, 27, 29 & 31 h | Results not adequately reported | ||||||
| Serial addition and subtraction task | Number of trials attempted Number of correct trials Percent correct |
23, 25, 27, 29 & 31 h | Results not adequately reported | ||||||
| Circular lights task | Number of correct responses | 23, 25, 27, 29 & 31 h | Results not adequately reported | ||||||
| Heishman et al 23 _b (1990) | Randomized; DB; PC (WSD) | 3 M; range 27–29 years | Unclear | Smoked cannabis cigarettes (2.57% THC) |
“2×Cigarette” (dose unknown) n | Two letter search task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported |
| Logical reasoning task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Digit recall task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Serial addition and subtraction task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Circular lights task | Number of correct responses | 19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Heishman et al 23 _c (1990) | Randomized; DB; PC (WSD) | 2 M; range 27–29 years | Unclear | Smoked cannabis cigarettes (2.57% THC) |
“4×Cigarette” (dose unknown) o | Two letter search task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported |
| Logical reasoning task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Digit recall task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Serial addition and subtraction task | Number of trials attempted Number of correct trials Percent correct |
19, 21, 23, 25 & 27 h | Results not adequately reported | ||||||
| Circular lights task | Number of correct responses | 19, 21, 23, 25 & 27 h | Results not adequately reported. | ||||||
| Leirer et al 31 _a (1989) | Randomized; DB; PC (WSD) | 9 (Sex NS); 26 years, range: 18–29 years | Unclear | Smoked cannabis cigarettes | 10 | Simulated flying | Performance score (calm) Performance score (turbulent) |
24 & 48 h | No significant effect |
| Leirer et al 31 _b (1989) | Randomized; DB; PC (WSD) | 9 (Sex NS); 26 years, range: 18–29 years | Unclear | Smoked cannabis cigarettes | 20 | Simulated flying | Performance score (calm) Performance score (turbulent) |
24 & 48 h | No significant effect |
| Leirer et al 31 _c (1989) | Randomized; DB; PC (WSD) | 9 (Sex NS); 38 years, range: 30–48 years | Unclear | Smoked cannabis cigarettes | 10 | Simulated flying | Performance score (calm) Performance score (turbulent) |
24 & 48 h | No significant effect |
| Leirer et al 31 _d (1989) | Randomized; DB; PC (WSD) | 9 (Sex NS); 38 years, range: 30–48 years | Unclear | Smoked cannabis cigarettes | 20 | Simulated flying | Performance score (calm) Performance Score (turbulent) |
24 & 48 h | No significant effect |
| Barnett et al 33 _a (1985) | “Blinded” j ; PC (WSD) | 8 M; range: 22–33 years | Unclear | Smoked cannabis cigarettes (700 mg; 1% THC) |
100 μg·kg−1
(6.8–7.3 mg) |
Visual search task | Reaction time | 10, 12 & 23 h | No effect b |
| Divided attention task | Reaction time Tracking accuracy |
10, 12 & 23 h | No effect b | ||||||
| Critical tracking task | Tracking accuracy | 10, 12 & 23 h | No effect b | ||||||
| Barnett et al 33 _b (1985) | “Blinded” j ; PC (WSD) | 8 M; range: 22–33 years | Unclear | Smoked cannabis cigarettes (700 mg; 1% THC) |
200 μg·kg−1
(14–15 mg) |
Visual search task | Reaction time | 10, 12 & 23 h | No effect b |
| Divided attention task | Reaction time Tracking accuracy |
10, 12 & 23 h | No effect b | ||||||
| Critical tracking task | Tracking accuracy | 10, 12 & 23 h | No effect b | ||||||
| Barnett et al 33 _c (1985) | “Blinded” j ; PC (WSD) | 8 M; range: 22–33 years | Unclear | Smoked cannabis cigarettes (700 mg; 1% THC) |
250 μg·kg−1
(17–18 mg) |
Visual search task | Reaction Time | 10, 12 & 23 h | No effect b |
| Divided attention task | Reaction time Tracking accuracy |
10, 12 & 23 h | No effect b | ||||||
| Critical tracking task | Tracking accuracy | 10, 12 & 23 h | No effect b | ||||||
| Chait et al 24 _a (1985) | “Blinded” j ; PC (WSD) | 13 M; 25 years, range: 21–35 years |
Infrequent–daily | Smoked cannabis cigarettes (1 g; 2.9% THC) |
“Ten Puffs” (dose unknown) |
Card sorting task | Time to complete (simple) Time to complete (suit) |
9.5 h | No significant effect |
| Free recall task | Immediate recall | 9.5 h | No significant effect | ||||||
| DSST | Number of correct trials | 9.5 h | No significant effect | ||||||
| Time production task | Time interval (10 sec) Time interval (30 sec) |
9.5 h | THC ↑ time interval (10 & 30 sec) at 9.5 h compared to target | ||||||
| Chait et al 24 _b (1985) | “Blinded” j ; PC (WSD) | 6 M; age NS | Unclear | Smoked cannabis cigarettes (1 g; 2.9% THC) |
“Five Puffs” (dose unknown) |
Card sorting task | Time to complete (simple) Time to complete (suit) |
9.5 h | Results not reported |
| Free recall task | Immediate recall | 9.5 h | Results not reported | ||||||
| DSST | Number of correct trials | 9.5 h | Results not reported | ||||||
| Time production task | Time interval (10 sec) Time interval (30 sec) |
9.5 h | Results not reported | ||||||
| Yesavage et al 41 (1985) | Pre-/post-trial | 10 (Sex NS); 29 years | Unclear | Smoked cannabis cigarettes | 19 | Simulated flying | Distance off-center on landing Lateral deviation Vertical deviation Aileron (number of changes) Aileron (mean size) Elevations (number of changes) Elevations (mean size) Number of throttle changes |
24 h | THC ↑ distance off-center on landing, lateral deviation, aileron (number of changes), aileron (mean size) and elevations (mean size) at 24 h compared to baseline |
| Rafaelsen et al 39 _a (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
8 | Simulated driving | Brake time Start time Number of gear changes Mean speed |
∼15 h | No significant effect p |
| Rafaelsen et al 39 _b (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
12 | Simulated driving | Brake time Start time Number of gear changes Mean speed |
∼15 h | No significant effect p |
| Rafaelsen et al 39 _c (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
12 | Simulated driving | Brake time Start time Number of gear changes Mean speed |
∼15 h | No significant effect p |
| Rafaelsen et al 39 _d (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
16 | Simulated driving | Brake time Start time Number of gear changes Mean speed |
∼15 h | No significant effect p |
| Rafaelsen et al 36 _a (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
8 | Digit span task (direction NS) | Digit span | ∼15 h | No significant effect p |
| Addition test | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Subtract serial sevens task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Finger labyrinths task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Bourdon's cancellation test | Number of letters scanned Number of errors |
∼15 h | No significant effect p | ||||||
| Rafaelsen et al 36 _b (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
12 | Digit span task (direction NS) | Digit span | ∼15 h | No significant effect p |
| Addition test | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Subtract serial sevens task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Finger labyrinths task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Bourdon's cancellation test | Number of letters scanned Number of errors |
∼15 h | No significant effect p | ||||||
| Rafaelsen et al 36 _c (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
12 | Digit span task (direction NS) | Digit span | ∼15 h | No significant effect p |
| Addition test | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Subtract serial sevens task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Finger labyrinths task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Bourdon's cancellation test | Number of letters scanned Number of errors |
∼15 h | No significant effect p | ||||||
| Rafaelsen et al 36 _d (1973) | Randomized; DB; PC (WSD) | 8 M; range: 21–29 years | Unclear | Oral cannabis (baked into cake) |
16 | Digit span task (direction NS) | Digit span | ∼15 h | No significant effect p |
| Addition test | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Subtract serial sevens task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Finger labyrinths task | Time to complete Number of errors |
∼15 h | No significant effect p | ||||||
| Bourdon's cancellation test | Number of letters scanned Number of errors |
∼15 h | No significant effect p | ||||||
| Kielholz et al 32 _a (1973) | DB; PC (BSD) | 54 q (Sex NS); 34 years | Unclear | THC capsules | 350 μg·kg−1
(∼24.5 mg) r |
Tapping task | Taps (comfortable) (right) Taps (comfortable) (left) Taps (fast) (right) Taps (fast) (left) |
17.5 h | Results not adequately reported |
| Spiral rotor task | NS | 17.5 h | Results not adequately reported | ||||||
| The compensation apparatus | NS | 17.5 h | Results not adequately reported | ||||||
| The tracking apparatus | Reaction time Frequency of pedal pressure |
17.5 h | Results not adequately reported | ||||||
| Kielholz et al 32 _b (1973) | DB; PC (BSD) | 54 q (Sex NS); 34 years | Unclear | THC capsules | 400 μg·kg−1
(∼28 mg) r |
Tapping task | Taps (comfortable) (R) Taps (comfortable) (L) Taps (fast) (R) Taps (fast) (L) |
17.5 h | Results not adequately reported |
| Spiral rotor task | NS | 17.5 h | Results not adequately reported | ||||||
| The compensation apparatus | NS | 17.5 h | Results not adequately reported | ||||||
| The tracking apparatus | Reaction time Frequency of pedal pressure |
17.5 h | Results not adequately reported | ||||||
| Kielholz et al 32 _c (1973) | DB; PC (BSD) | 54 q (Sex NS); 34 years | Unclear | THC capsules | 450 μg·kg−1
(∼31.5 mg) r |
Tapping task | Taps (comfortable) (right) Taps (comfortable) (left) Taps (fast) (right) Taps (fast) (left) |
17.5 h | Results not adequately reported |
| Spiral rotor task | NS | 17.5 h | Results not adequately reported | ||||||
| The compensation apparatus | NS | 17.5 h | Results not adequately reported | ||||||
| The tracking apparatus | Reaction time Frequency of pedal pressure |
17.5 h | Results not adequately reported |
All “Effects of THC” are in comparison to placebo unless otherwise stated; comparisons to baseline are only reported when those to placebo were not conducted or not reported. Significant effects are in bold text.
a
Cigarettes were smoked ad libitum.
b
The authors modeled the “behavioral pharmacokinetics” of THC rather than investigating its effect at specific times post-treatment; however, their modeling still suggests impairment resolves within 8 h.
c
Although “double blinded,” participants had to demonstrate a capacity to distinguish between THC and placebo (in a “Quantification Phase”) to be eligible for inclusion.
d
Only 35 of these participants were included in the analyses investigating THC's effects on cognitive function.
e
Only the “minimum” and “maximum” performance scores were presented and subjected to statistical analysis.
f
Compared to “20 minutes post-placebo” (as performance was not assessed 24 h post-placebo).
g
It is unclear whether six or eight participants completed the cognitive function tests.
h
It is unclear how the time parameter was handled in these statistical analyses (see also ‘ “Next Day” effects of THC’ section).
i
The authors indicate that THC decreased pursuit speeds at 1.75 h, but do not clearly describe its effects at the other time points.
j
The authors do not state whether a single- or double-blind design was used.
k
Participants completed a total of five smoking periods involving “eight puffs” each: (1) 9 PM Friday; (2) 3 PM Saturday; (3) 9 PM Saturday; (4) 3 PM Sunday; and (5) 9 PM Sunday; cognitive function was assessed 12 h after each evening (9 PM) smoking period.
l
Main effect of treatment across all 3 days.
m
This effect is described as “negative” in this article (since any change in time production could indicate “impairment”); however, it is worth noting that participants were closer to the target time on THC than placebo.
n
The first cigarette was administered 4 h before the second.
o
The first two cigarettes were administered 4 h before the second two.
p
We presume these comparisons are against placebo.
q
Total number across all four treatment groups.
r
Value estimated at a body weight of 70 kg.
BSD, between-subject design; C, control group; CBD, cannabidiol; CBN, cannabinol; CPT, continuous performance test; DB, double blind; DH, dominant hand; DSST, digit symbol substitution test; DT, double target; HVLT-R, Hopkins Verbal Learning Test Revised; I, intervention group; L, left; M, male participants; NS, not specified; PC, placebo controlled; PVT, psychomotor vigilance task; R, right; R, correlation coefficient; RA, response accuracy; RT, reaction time; RVIPT, rapid visual information processing task; SB, single blind; SDLP, standard deviation of lane position; ST, single target; WSD, within subject design.