Introduction
Methods
Search Strategy
Eligibility Criteria
Results
Evidence at a Glance
Study | Type of study | Study sample | Cannabinoids investigated | Cognitive domain investigated |
---|---|---|---|---|
Wade et al. 2003 [57] | Randomized, double-blind, cross-over, behavioral study | Patients with neurological disorders | Δ9-THC, Δ9-THC + CBD, CBD | Attention |
Roser et al. 2008 [54] | Double-blind, cross-over, EEG study | Healthy participants | Δ9-THC, Δ9-THC + CBD | Attention, processing speed |
Morgan et al. 2010 [51] | Naturalistic, behavioral study | Cannabis users | Δ9-THC + CBD | Verbal memory, episodic memory, executive function |
Bhattacharyya et al. 2010 [58••] | Randomized, double-blind, cross-over fMRI study | Healthy participants | Δ9-THC, CBD | Verbal memory, emotional processing, executive function, visual and auditory processing |
Schoedel et al. 2011 [55] | Randomized, double-blind, cross-over, behavioral study | Recreational cannabis users | Δ9-THC, Δ9-THC + CBD | Attention, processing speed, working memory |
Winton-Brown et al. 2011 [59] | Pseudo-randomized, double-blind, cross-over, fMRI study | Healthy participants | Δ9-THC, CBD | Visual and auditory processing |
Bhattacharyya et al. 2012 [60] | Randomized, double-blind, cross-over, fMRI study | Healthy participants | Δ9-THC, CBD | Attentional salience processing |
Morgan et al. 2012 [50] | Naturalistic, behavioral study | Cannabis users | Δ9-THC + CBD | Verbal memory, episodic memory, recognition memory |
Englund et al. 2013 [52••] | Randomized, double-blind, behavioral study | Healthy participants | Δ9-THC, Δ9-THC + CBD | Verbal memory, working memory, executive function |
Bhattacharyya et al. 2015 [61••] | Randomized, double-blind, cross-over, fMRI study | Healthy participants | Δ9-THC, CBD | Attentional salience processing |
Hindocha et al. 2015 [53••] | Randomized, double-blind, cross-over, behavioral study | Cannabis users | Δ9-THC, Δ9-THC + CBD, CBD | Emotional processing |
Gruber et al. 2016 [56] | Longitudinal, behavioral study | Patients certified for medical cannabis | Δ9-THC + CBD | Executive function, processing speed |
Englund et al. 2016 [62] | Double-blind, cross-over, behavioral study | Healthy participants | Δ9-THC, Δ9-THC + Δ9-THCV | Verbal memory, working memory |
Study | Aim of study | Population |
n; age (years) | Cannabinoid concentration | Exposure | Placebo controlled | Behavioral results | Neuroimaging results |
---|---|---|---|---|---|---|---|---|
Wade et al. 2003 [57] | Effects of Δ9-THC, CBD, and their combination on attention | Patients with multiple sclerosis (n = 18), spinal cord injury (n = 4), brachial plexus damage (n = 1), and amputation (n = 1) | 24; 48 | 1. 2.5 mg Δ9-THC 2. 2.5 mg Δ9-THC +2.5 mg CBD 3. 2.5 mg CBD | Acute challenge with titrated sl. Δ9-THC, CBD, or Δ9-THC + CBD | ✓ | 1. ↓ attention
2. NS 3. NS | NA |
Roser et al. 2008 [54] | Effects of Δ9-THC and Δ9-THC + CBD on attention and processing speed | Healthy subjects | 20 (10 M, 10 F); 28.2 ± 3.1 | 1. 10 mg Δ9-THC 2. 10 mg Δ9-THC +5.4 mg CBD | Acute challenge with 4 po. Δ9-THC or Δ9-THC + CBD cps. over 3 weeks | ✓ | 1. NS 2. NS 1. vs. 2. NS | 1. ↓ P300 wave amplitudes
2. ↓ P300 wave amplitudes
|
Morgan et al. 2010 [51] | Effects of cannabis CBD content on verbal memory, episodic memory, and executive function | Cannabis-using subjects with different patterns of cannabis use (low CBD, n = 22, cannabis use = 17.1 ± 11.2 days per month; high CBD, n = 22, cannabis use = 13.3 ± 11.9 days per month) | 44; 21.4 ± 2.0 and 21.55 ± 1.8 | <0.14% (low) CBD cannabis vs. >0.75% (high) CBD cannabis (in front of NS different Δ9-THC contents) | a. Unintoxicated state b. Chosen strain smk. during study | ✕ | a. NS b. high CBD > low CBD in verbal memory, NS other domains | NA |
Bhattacharyya et al. 2010 [58••] | Effects of Δ9-THC and CBD on verbal memory, emotional processing, executive function, and visual and auditory processing | Healthy subjects with lifetime cannabis use <15 times | 15 (15 M); 26.7 ± 5.7 | 1. 10 mg Δ9-THC 2. 600 mg CBD | Acute challenge with po. singles doses of Δ9-THC or CBD | ✓ | 1. NS 2. NS |
1. vs. 2. Opposite effects of Δ9-THC and CBD on brain activity related to verbal memory, emotional processing, executive function, and visual and auditory processing
|
Schoedel et al. 2011 [55] | Effects of increasing dosages of Δ9-THC and Δ9-THC + CBD on attention, processing speed, and working memory | Frequent recreational cannabis-using subjects | 23 (19 M, 4 F); 19–45 | 1. 20 or 40 mg Δ9-THC 2. 10.8 mg Δ9-THC + 10 mg CBD, 21.6 mg Δ9-THC + 20 mg CBD, 43.2 Δ9-THC + 40 mg CBD | Acute challenge with om. Δ9-THC or Δ9-THC + CBD at different concentrations | ✓ | 1. ↓ working memory, NS other domains 2. NS | NA |
Winton-Brown et al. 2011 [59] | Effects of Δ9-THC and CBD on visual and auditory processing | Healthy subjects with lifetime cannabis use <15 times | 14 (14 M); 26.7 ± 5.7 | 1. 10 mg Δ9-THC 2. 600 mg CBD | Acute challenge with po. single doses of Δ9-THC or CBD | ✓ | NA |
1. vs. 2. Opposite effects of Δ9-THC and CBD on brain activity related to visual and auditory processing
|
Bhattacharyya et al. 2012 [60] | Effects of Δ9-THC and CBD on attentional salience processing | Healthy subjects with lifetime cannabis use <15 times | 15 (15 M); 26.7 ± 5.7 | 1. 10 mg Δ9-THC 2. 600 mg CBD | Acute challenge with po. single doses of Δ9-THC or CBD | ✓ | 1. NS, however Δ9-THC-induced striatal deactivation correlated with response latency
2. NS |
1. vs. 2. Opposite effects of Δ9-THC and CBD on brain activity related to attentional salience
|
Morgan et al. 2012 [50] | Effects of cannabis Δ9-THC and CBD contents on verbal memory, episodic memory, and recognition memory | Cannabis-using subjects with different patterns of cannabis use (recreational use, n = 54, cannabis use ≤25 days per month; daily use, n = 66, cannabis use ≥25 days per month) | 120 (89 M, 31 F); 16–23 | 1. Low CBD vs. high CBD cannabis 2. Low Δ9-THC cannabis vs. high Δ9-THC cannabis (Δ9-THC and CBD contents tested in hair samples) | Unintoxicated state | ✕ | 1. high CBD > low CBD in recognition memory, independently of frequency of use 2. daily high Δ9-THC < low Δ9-THC in verbal and episodic memory
| NA |
Englund et al. 2013 [52••] | Effects of CBD pretreatment prior to Δ9-THC challenge on verbal memory, working memory, and executive function | Healthy subjects (lifetime cannabis use PLB group: 118 ± 218 episodes; lifetime cannabis use CBD group: 137 ± 234 episodes) | 48 (27 M, 21 F); 21–50 | 1. 1.5 mg Δ9-THC 2. 600 mg CBD pretreatment prior to 1.5 mg Δ9-THC | Acute challenge with single doses of iv. Δ9-THC or iv. Δ9-THC + po. CBD | ✓ | 1. ↓ working memory
2. Δ9-THC + CBD > Δ9-THC in verbal memory and some working memory components
NS other domains | NA |
Bhattacharyya et al. 2015 [61••] | Effects of Δ9-THC and CBD on attentional salience processing | Healthy subjects with lifetime cannabis use <15 times | 15 (15 M); 26.7 ± 5.7 | 1. 10 mg Δ9-THC 2. 600 mg CBD | Acute challenge with po. single doses of Δ9-THC or CBD | ✓ | 1. NS, however Δ9-THC-induced reduction of fronto-striatal connectivity correlated with response latency
2. NS |
1. vs. 2. Opposite effects of Δ9-THC and CBD on brain connectivity related to attentional salience
|
Hindocha et al. 2015 [53••] | Effects of Δ9-THC, CBD and their combination on emotional processing | Cannabis-using subjects with different patterns of cannabis use (light use, n = 24, cannabis use ≤25 days per month; heavy use, n = 24, cannabis use ≥25 days per month) | 48 (34 M, 14 F); 21 < mean < 23 | 1. 8 mg Δ9-THC 2. 8 mg Δ9-THC +16 mg CBD 3. 16 mg CBD | Acute challenge with inh. Δ9-THC, CBD, or Δ9-THC + CBD | ✓ | 1. ↓ emotional processing, independently of frequency of use and schizotypy traits 2. Δ9-THC + CBD > Δ9-THC in emotional processing
3. ↑ emotional processing, independently of frequency of use and schizotypy traits | NA |
Gruber et al. 2016 [56] | Effects of MMJ on executive function and processing speed | MMJ certified patients with anxiety (n = 5), depression (n = 3), chronic pain (n = 7), sleep (n = 5), and other conditions (n = 6); MMJ use: 9.3 ± 8.8 episodes per week | 11 (6 M; 5 F); 48.9 ± 15.1 | Δ9-THC + CBD at unspecified dosages | 3-month treatment | ✕ |
↑ executive function and processing speed
| NA |
Englund et al. 2016 [62] | Effects of Δ9-THCV pretreatment prior to Δ9-THC challenge on verbal memory and working memory | Healthy subjects with lifetime cannabis use (<25 times) | 10 (10 M); 23.8 | 1. 1 mg Δ9-THC 2. 50 mg Δ9-THCV pretreatment prior to 1.5 mg Δ9-THC | Acute challenge with a single dose of iv. Δ9-THC or a single dose of iv. Δ9-THC + 5 days of po. Δ9-THCV | ✓ | 1. ↓ verbal memory, NS on other domains 2. Δ9-THC + Δ9-THCV > Δ9-THC in some verbal memory components but < in others
| NA |