Table 4.
Clinical trials investigating the effect of CBD on cognitive and psychomotor function in healthy individuals
| Citation | Study design | Participants | Treatment(s) | Cognitive tasks | Treatment effect |
|---|---|---|---|---|---|
| Karniol et al. (1974) [98] | DB (PC); BSD |
I: 5 M; 21–34 y I: 5 M; 21–34 y I: 5 M; 21–34 y C: 5 M; 21–34 y |
I: Oral 15 mg I: Oral 30 mg I: Oral 60 mg |
Time estimation taska | 15 mg CBD sig. altered the ETI (without FB) at 45 and 95 min. 60 mg CBD sig. altered the ETI (without FB) at 95 and 180 min. No other sig. differences were observed. |
| Dalton et al. (1975) [49] | DB; WSD | 15 M; 21–24 y | Vaporised 150 μg·kg-1 |
Wobble board Pursuit meter Delayed auditory feedback “Pegs” |
Standing steadiness, hand-eye coordination, cognition and manual coordination were unchanged from baseline 5–85 min post-tx |
| Leweke et al. (2000) [111] | SB; WSD | 9 M; 26–35 y | Oral 200 mg | Binocular depth inversion | Depth inversion scores were unchanged from baseline 1, 2, 3, 4, 5, 6 and 24 h post-tx. |
| Bogwardt et al. (2008) [22] | DB (PC); WSD | 15 M; 27 ± 6 y | Oral 600 mg | Go/No-Go Task | Reaction time and accuracy were unaffected between ~1 and 2 h post-tx. |
| Bhattacharyya et al. (2009) [17] | DB (PC); WSD | 15 M; 27 ± 6 y | Oral 600 mg | Verbal memory task | Word recall was unaffected ~1–2 h post-tx. |
| Palo Fusar-Poli et al. (2009) [67] | DB (PC); WSD | 15 M; 27 ± 6 y | Oral 600 mg | Facial emotion recognition | Reaction time and accuracy were unaffected ~1–2 h post-tx. |
| Hindocha et al. (2015) [86] | DB (PC); WSD | 48 (34 M); ~22 y | Vaporised 16 mg | Facial emotion recognition | CBD sig. improved emotion recognition at 60% intensity 10 min post-tx. Recognition at 20, 40, 80 and 100% intensity were unaffected. |
| Hundal et al. (2017) [90] | DB (PC); BSD |
I: 16 (8 M); 26 ± 9 y C: 18 (8 M); 25 ± 8 y |
Oral 600 mg |
Symbol coding Digit span (forward and reverse) Verbal learning task |
Digit-symbol recoding, forward digit span, reverse digit span, immediate recall and delayed recall were unaffected 135 min post-tx. |
| Arndt & de Wit (2017) [8] | DB (PC); WSD | 38 (19 M); 24 ± 4 y |
Oral 300, 600 and 900 mg |
Emotional stroop Facial emotion recognition Attentional bias task |
Reaction time, emotion recognition and attentional bias were unaffected 3–4 h post-tx. |
| Birnbaum et al. (In Press) [19] | No blind; WSD | 8 (6 M); 49 y | Oral 300 mg |
Phonemic and semantic fluency Digit span Trail making test (A & B) Symbol–digit modality task |
Test scores were unchanged from baseline 2.5 h post-tx (test outcomes not specified) |
| Spindle et al. (In Press) [160] | DB (PC); WSD | 18 (9 M); 31 ± 6 y | Oral 100 mg and Vaporised 100 mg |
Digit symbol substitution Divided attention task Paced serial addition task |
Speed and accuracy of digit symbol substitution and paced serial addition, as well as speed, accuracy and tracking on the divided attention task were unaffected between 0.5 and 8 h post-tx. |
BSD between-subject design, C control group, CBD cannabidiol, DB double-blind, ETI estimated time interval, FB feedback, I intervention group, M male subjects, PC placebo-controlled, SB single-blind, Tx treatment, WSD within-subject design
The “Treatment effects” described are in comparison to a placebo condition, unless otherwise stated
aTime estimation task: participants were asked to produce a 60 s interval 10 times. The first 5 estimations were without feedback and the remaining 5 were with feedback. This task was repeated 45, 95. and 180 min post-treatment