Table 1.
Studies included in meta-analysis.
| Current Cannabis User Studies | fMRI activation task | CU M/F | NU M/F | Age of CU (years) |
Age of NU (years) |
Quantity of cannabis used by CU | Time between scan and last smoke * | Age of onset of cannabis use for CU (years) | Average years of cannabis use by CU | Task condition | Results whole brain analysis | Task Performance results | Number of task comparisons | Tesla |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Abdullaev et al., 2010 | Attention Network Task | 10/4 | 10/4 | 19.5 (0.8) (SD) |
19.7 (1.4) (SD) |
71-196 days per year | 48 | 12-16 | N/A | Executive task; Alerting task; Orienting task. | CU > NU R-LPFC, supplementary motor cortex, Lateral parietal cortex; No difference for alerting & orientation task. | Longer reaction time for CU. More errors made for executive task. | 3 | 3T |
| Use Generation Task | 5/2 | 5/2 | 19.6 (0.9) (SD) |
20 (0.2) (SD) |
71-196 days per year | 48 | 12-16 | N/A | Generating nouns versus reading nouns; difficult words versus easy words. | CU > NU R-VPFC NU > CU Bi -ACG to L-PFC, L- TPC; CU > NU R - ACC, R FOC, L frontal pole & L precuneus. | N/A | 2 | 3T | |
| Smith et al., 2011 | Go/NoGo Task | 6/4 | 9/5 | 19-21 | 19-21 | > 1 joints per week | 3 | N/A | 4.55 years |
Press all but X; Press X | No significant differences in both tasks after including covariates. | No Significant difference | 2 | 1.5T |
| Chang et al., 2006 | Visual- Attention Task | 9/3 | 11/8 | 27.91 6 3.13 (SEM) |
30.57 6 1.83 (SEM) |
≥5 days per week | 4 | 9–20 | 36–448 months | Visual attention | CU > NU small clusters of L precuneus, L-LG & L limbic uncus. NU > CU R-FC, Bi- dorsal parietal and R cerebella. | No Significant difference | 1 | 4T |
| Cousijn et al., 2012 | Iowa Gambling Task | 21/11 | 26/15 | 21.4 (2.3) (SD) |
22.2 (2.4) (SD) |
> 10 days per month | 38.4 | N/A | 2.5 (1.9) (SD) |
Win > Loss; Loss > Win | CU > NU R-OFC, R insula, L-STG; No activation difference. | No Significant difference | 2 | 3T |
| Gruber, Rogowska and Yurgelun-Todd, 2009 | Facial effect task | 14/1 | 14/1 | 25 (±8.8) | 26 (±9.0) | 4-7 days per week | 12 | 14.9 (±2.50) | N/A | Viewing Angry; Viewing Happy | CU > NU R-IFG, R-precuneus, R-paracetral lobe, L-SFG, cerebellar, R-MiTG, NU > CU L-SPL, interhemispheric precuneus, L- CG ; CU > NU cerebella, NU > CU L -STG & sub.lobular space. | No Performance data | 2 | 3T |
| Heitzeg et al., 2015 | Emotional arousal word task | 12/8 | 14/6 | 19.84 (1.45) (SD) |
20.51 (1.26) (SD) |
>100 time (average 618.12) | 48 | N/A | 13.4 (2.7) (SD) |
Negative words; Positive words. | NU > CU R- MiFG, R- DLSFG, R- MiTG, R-STG, R calcarine fissure, R- L, insula CU > NU R Dorsolateral SFG, NU > CU R-IPL. | No Significant difference | 2 | 3T |
| King et al., 2011 | Checker-board task | 16/14 | 16/14 | M = 21 F = 22.5 |
M = 23 F= 24.5 |
6-7 days per week | 12 | M = 14.5 F = 16 (years) |
M = 78 F = 63 (months) |
2HZ frequency; 4HZ frequency | CU > NU SFG, NU > CU LG & cuneus; L- postcentral gyrus, Bi- MiFG, R-SPG, R- frontal pole, NU > CU R- postcentral gyrus, R- precentral gyrus & L- LG. | None Taken | 2 | 3T |
| Kanayama et al., 2004 | Spacial working memory Task | 10/2 | 6/4 | 37.9 (7.4) (SD) |
27.8 (7.9) (SD) |
5100-54000 life time use | 21 | N/A | >5000 lifetime use | Short- delay task minus perception task. | CU > NU R-SFG, L-MiFG, IFG, R-STG, Bi. ACG. R. precentral gyrus, Bi -caudate & R-putamen. NU > CU Bi -MiFC. | No Significant difference | 1 | 1.5T |
| Wesley, Hanlon and Porrino, 2011 | Iowa Gambling Task | 9/7 | 6/10 | 26.4 (3.6) (SD) |
26.6 (6.1) (SD) |
Mean 29.4 days per month | 12 | 16.3 (2.1) (SD) |
9.6 (4.1) (SD) |
Win; Lose | No difference in Win; NU > CU Bi. MFG, R ACC, R-Precuneus & R- SPL, L declive. |
More loss events for CU | 2 | 1.5T |
| Adolescent Current Cannabis Users | Task | CU M/F | NU M/F | Age of CU (years) |
Age of NU (years) |
Quantity of cannabis used by CU | Time between scan and last smoke * | Age of onset of cannabis use for CU (years) | Average years of cannabis use by CU | Trials | Results whole brain analysis | Task Performance results | Number of task comparisons | Tesla |
| Acheson et al., 2015 | Win/Lose Gambling Task | 11/3 | 11/3 | 17.3 (1.3) (SEM) |
17.6 (1.0) (SEM) |
>5 uses per week | 12 | N/A | N/A | Win ; Loss | CU > NU Bi- MiFG, caudate claustrum; CU > NU R- MiFG, R- PCC R- ACC, L-Insula, Bi. claustrum Bi- declive. | Not Reported | 2 | 3T |
| Behan et al., 2014 | Go/NoGo Task | 16/1 | 17/1 | 16.5 (0.2) (SEM) |
16.1 (0.4) (SEM) |
42.9 mean joints per week | 12 | 13 (0.2) (SEM) |
N/A | Successful inhibition | NU > CU Bi. white matter adjacent to ACC. | CU significantly worse at inhibition task. | 1 | 3T |
| Lopez-Larson et al., 2012 | Finger Tapping | 22/12 | 17/7 | 18.2 (0.7) (SD) |
18.0 (1.9) (SD) |
Mean use of 10.3 joints per week | 24 | 15.3 (1.4) (SD) |
N/A | Finger taping | NU > CU R- CG | Not Reported | 1 | 3T |
| Abstinent Cannabis User Studies |
Task | CU M/F | NU M/F | Age of CU (years) |
Age of NU (years) |
Quantity of cannabis used by CU | Time between scan and last smoke * | Age of onset of cannabis use for CU (years) | Average years of cannabis use by CU | Trials | Results whole brain analysis | Task Performance results | Number of task comparisons | Tesla |
| Schweins-burg et al., 2011 | Verbal Encoding Task | 27/9 | 29/9 | 18.1 (0.9) 18.0 (1.0) (SD) |
17.6 (0.8) 18.1 (0.7) (SD) |
480.7 (277.2 SD) life time use | 600 | 14.5 (2.5) 14.9 (3.4) (SD) |
N/A | Novel encoding | No significant difference. | No Significant Difference | 1 | 3T |
| Schweins-burg et al., 2008 | Spacial working memory Task | 11/4 | 12/5 | 18.1 (0.7) (SD) |
17.9 (1.0) (SD) |
480.7 (277.2 SD) life time use | 672 | N/A | 4.0 (1.6) (SD) |
SWM> Viligance; Viligance> SWM. |
CU > NU R- SPL NU > CU R- DLPFC; CU > NU R - Inferior cuneus. |
No Significant Difference | 2 | 1.5T |
| Tapert, et al, 2007 | Go/NoGo Task | 12/4 | 12/5 | 18.1 (0.7) (SD) |
17.9 (1.0) (SD) |
>60 times | 672 | 14.0 (1.6) (SD) |
N/A | Inhibition; Go | CU > NU Bi- SFG, Bi- MiFG, R-Insula, L- MPFC, Bi- PPC, R- LG, CU > NU R-IFG, R- insula, R-SFG, R-SPL, R-IPL, R medial precuneus. | No Significant Difference | 2 | 1.5T |
*Time between scan and last smoke reported here as the mean or median estimate (number of hours) reported in the manuscript, or based on the inclusion/exclusion criterion related to minimum period of abstinence reported in the manuscript.
CU = Cannabis users NU = Non-using controls, R = Right, L = Left, Bi = Bilateral, LPFC = Lateral Prefrontal Cortex, VPFC = Ventrolateral Prefrontal Cortex, DLPFC = Dorsolateral Prefrontal Cortex, MPFC = Medial Prefrontal Cortex, PFC = Prefrontal Cortex, OFC = Orbitofrontal Cortex, FC = Frontal Cortex, MFG = Medial Frontal Cortex, MiFG = Middle Frontal Gyrus, SFG = Superior Frontal Gyrus, DLSFG = Dorsolateral Superior Frontal Gyrus, FOC = Frontal Orbital Cortex, IFG = Inferior Frontal Gyrus, PPC = Posterior Parietal Cortex, IPL = Inferior Parietal Lobe, TPC = Temporo-Parietal Cortex, SPL = Superior Parietal Lobe, SPG = Superior Parietal Gyrus, MTG = Medial Temporal Gyrus, MiTG = Middle Temporal Gyrus, STG = Superior Temporal Gyrus, LG = Lingual Gyrus, CG = Cingulate Gyrus, ACC = Anterior Cingulate Cortex, ACG = Anterior Cingulate Gyrus.