TABLE 3.
Association of age of initiation of cannabis use with IQ changes among cannabis users (n = 2028).
| Unadjusted | Model 1 a | Model 2 b | Model 3 c | Model 4 d | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| b [95% CI] e | R 2 | p value | b [95% CI] e | R 2 | p value | b [95% CI] e | R 2 | p value | b [95% CI] e | R 2 | p value | b [95% CI] e | R 2 | p value | |
| Age of initiation of cannabis use | 0.003 | 0.219 | 0.226 | 0.223 | 0.229 | ||||||||||
| > 25 years (n = 109) | Ref. | — | Ref. | — | Ref. | — | Ref. | — | Ref. | — | |||||
| 18–25 years (n = 883) | −0.08 [−2.05, 1.88] | 0.933 | 0.61 [−1.14, 2.36] | 0.491 | 0.52 [−1.22, 2.27] | 0.558 | 0.54 [−1.20, 2.29] | 0.542 | 0.45 [−1.30, 2.19] | 0.613 | |||||
| < 18 years (n = 1036) | 1.14 [−0.81, 3.09] | 0.250 | 1.16 [−0.58, 2.89] | 0.191 | 1.00 [−0.75, 2.75] | 0.263 | 1.16 [−0.57, 2.89] | 0.187 | 0.95 [−0.79, 2.70] | 0.285 | |||||
a
Model 1: Age at follow‐up, retest interval, IQ at conscription, years of education.
b
Model 2: Age at follow‐up, retest interval, IQ at conscription, years of education, years of weekly extreme binge drinking, use of other illicit drugs, smoking.
c
Model 3: Age at follow‐up, retest interval, IQ at conscription, years of education, psychiatric disorders, CCI.
d
Model 4: Fully adjusted model.
e
Positive numbers indicate less change in IQ scores from baseline to follow‐up compared to the change observed in the reference group, while negative numbers indicate a larger change in IQ scores compared to the reference group.