Table 3.
Unadjusted and adjusted association between cumulative exposure to cannabis and hippocampal volume, fractional anisotropy (FA) and cerebral blood flow (CBF) at Year 30. 648 CARDIA participants at the Year 30 MRI sub-study excluding participants with a history of stroke or TIA.
| NEVER TOBACCO SMOKING | Standardized difference in MRI measures (95% CI)a | ||
|---|---|---|---|
| Unadjusted | Demographic adjusted | Fully adjusted | |
| Hippocampus volume (mm3) | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | −61.16 (−146.35–24.04) | −97.01 (−185.69 to −8.33) | −85.55 (−180.59–9.49) |
| -0.5 to < 2 cannabis years | −20.31 (−128.66–88.03) | −49.72 (−160.50–61.07) | −39.67 (−159.80–80.46) |
| ->2 cannabis years | −29.15 (−162.25–103.96) | −85.42 (−227.52–56.69) | −37.99 (−201.08–125.09) |
| P-value for trendb / R2 | 0.5/ 0.44 | 0.18/ 0.46 | 0.3/ 0.48 |
| Fornix FA | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | −0.0098 (−0.0193 to −0.0002) | −0.0073 (−0.0168–0.0021) | −0.0052 (−0.0155–0.0051) |
| ->2 cannabis years | −0.0144 (−0.0144–0.0097) | −0.0067 (−0.0217–0.0084) | −0.0013 (−0.0189–0.0164) |
| P-value for trendb/ R2 | 0.09/ 0.02 | 0.18/ 0.13 | 0.3/ 0.15 |
| Hippocampus CBF (ml/100 g/min) | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | −0.61 (−4.03–2.82) | 0.77 (−2.82–4.36) | 0.49 (−3.39–4.36) |
| -0.5 to < 2 cannabis years | −3.99 (−8.44–0.45) | −1.46 (−6.05–3.12) | −1.43 (−6.49–3.62) |
| ->2 cannabis years | −1.61 (−6.42–3.21) | 1.29 (−3.81–6.39) | −0.40 (−6.60–5.80) |
| P-value for trendb/ R2 | 0.3/ 0.02 | 0.6/ 0.11 | 0.8/ 0.14 |
| EVER TOBACCO SMOKING | Standardized difference in MRI measures (95% CI)a | ||
| Unadjusted | Demographic adjusted | Fully adjusted | |
| Hippocampus volume (mm3) | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | −67.11 (−218.17–83.96) | −114.15 (−268.91–40.61) | −125.11 (−284.78–34.56) |
| -0.5 to < 2 cannabis years | −53.48 (−206.41–99.44) | −106.85 (−265.78–52.08) | −141.34 (−306.00–23.32) |
| ->2 cannabis years | −105.82 (−260.84–49.20) | −139.86 (−300.75–21.03) | −152.20 (−323.60–19.20) |
| P-value for trendb/ R2 | 0.5/ 0.44 | 0.4/ 0.46 | 0.4/ 0.51 |
| Fornix FA | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | 0.0023 (−0.0158–0.0203) | −0.0012 (−0.0190–0.0165) | 0.0010 (−0.0178–0.0198) |
| ->2 cannabis years | −0.0011 (−0.0194–0.0172) | 0.0004 (−0.0180–0.0188) | 0.0052 (−0.0150–0.0255) |
| P-value for trendb/ R2 | 0.06/ 0.02 | 0.09/ 0.15 | 0.18/ 0.17 |
| Hippocampus CBF (ml/100 g/min) | |||
| -Never user | Reference | Reference | Reference |
| -1 day to 0.5 cannabis years | −2.76 (−8.10–2.58) | −0.33 (−5.43–4.78) | 1.98(−3.13–7.08) |
| -0.5 to < 2 cannabis years | −4.32 (−9.74–1.11) | −1.30 (−6.63–4.03) | 0.97(−4.48–6.41) |
| ->2 cannabis years | −1.90 (−7.41–3.61) | 2.37 (−3.13–7.86) | 5.11 (−0.68–10.90) |
| P-value for trendb/ R2 | 0.4/ 0.02 | 0.2/ 0.24 | 0.10/ 0.41 |
Stratified by ever tobacco smoking.
FA fractional anisotropy, CBF cerebral blood flow, CARDIA coronary artery risk development in young adults study, N number of participants; 95% CI 95% confidence interval.
*Results from multivariable adjusted linear regression models. First unadjusted (only hippocampal volume adjusted for total intracerebral volume in unadjusted models), then adjusted for demographics (sex, race, age, education years, study center) and finally, current and cumulative alcohol use, cumulative cigarette smoking, self-reported lifetime illicit drug use (amphetamines, methamphetamines, cocaine, heroin), depression and BMI.
aLinear regression models determined the association between MRI scores and self-reported cumulative exposure to cannabis use. Negative standardized scores indicate smaller Volume, lower FA or lower CBF.
b P-values from a Wald test. All P-values two sided.