Table 3.
Multilevel linear models predicting depressive symptoms
| Fixed effects | All months (n = 15,336 person months among 773 individuals) | Alcohol-use months (n = 11,921 person months among 755 individuals) | Months in which both alcohol and marijuana used (n = 4,553 person months among 545 individuals) | |||
|---|---|---|---|---|---|---|
|
| ||||||
| B | 95% CI | B | 95% CI | B | 95% CI | |
| Between person | ||||||
| Intercept | 1.74 | (1.44,2.03) | 1.82 | (1.47,2.18) | 1.12 | (0.82,1.42) |
| Female | 0.29 | (0.14,0.44) | 0.28 | (0.13,0.44) | 0.20 | (−0.01,0.41) |
| Race/ethnicity | ||||||
| Non-Hispanic White (reference) | ref. | ref. | ref. | ref. | ref. | ref. |
| Non-Hispanic Asian | −0.02 | (−0.22,0.17) | −0.02 | (−0.23,0.18) | −0.01 | (−0.29,0.26) |
| Non-Hispanic White Other | −0.02 | (−0.22,0.19) | −0.03 | (−0.24,0.18) | 0.04 | (−0.23,0.32) |
| Hispanic | −0.02 | (−0.28,0.25) | 0.00 | (−0.28,0.27) | 0.04 | (−0.33,0.40) |
| Age in years | 0.01 | (−0.03,0.06) | 0.02 | (−0.02,0.07) | 0.01 | (−0.04,0.07) |
| Proportion of all months | ||||||
| Alcohol use | −0.85 | (−1.26,−0.44) | ||||
| Both alcohol and marijuana use | −0.13 | (−0.54,0.29) | ||||
| Person average substance use | ||||||
| Alcohol use quantity/frequency | 0.11 | (−0.04,0.26) | −0.03 | (−0.20,0.14) | ||
| Marijuana use occasions | 0.13 | (0.03,0.23) | ||||
| Proportion of all months | ||||||
| Neither alcohol nor marijuana | ref. | ref. | ||||
| Alcohol-only | −0.56 | (−0.91,−0.22) | ||||
| Marijuana-only | 0.26 | (−0.76,1.28) | ||||
| CAM | −0.48 | (−0.99,0.03) | ||||
| SAM | −0.03 | (−0.41,0.36) | ||||
| Proportion of alcohol-use months | ||||||
| Alcohol-only | ref. | ref. | ||||
| CAM | 0.27 | (−0.13,0.67) | ||||
| SAM | 0.39 | (0.10,0.69) | ||||
| Proportion of alcohol and marijuana months | ||||||
| CAM | ref. | ref. | ||||
| SAM | −0.29 | (−0.65,0.08) | ||||
| Within-person (time-varying) | ||||||
| Month of study (in years) | −0.08 | (−0.14,−0.03) | −0.06 | (−0.12,0.00) | 0.01 | (−0.07,0.10) |
| Quantity/frequency of alcohol use | 0.02 | (−0.03,0.06) | 0.09 | (0.02,0.15) | ||
| Marijuana use occasions | 0.03 | (−0.02,0.07) | ||||
| Pattern of substance use | ||||||
| Neither alcohol nor marijuana | ref. | ref. | ||||
| Alcohol-only | −0.12 | (−0.19,−0.04) | ref. | ref. | ||
| Marijuana-only | 0.12 | (−0.05,0.29) | ||||
| CAM | −0.05 | (−0.16,0.06) | 0.05 | (−0.03,0.13) | ref. | ref. |
| SAM | −0.03 | (−0.13,0.08) | 0.09 | (0.01,0.17) | 0.05 | (−0.04,0.15) |
| Random effects | ||||||
|
| ||||||
| Intercept variance | 1.01 | 1.01 | 1.04 | |||
| Within-person variance | 1.14 | 1.06 | 1.09 | |||
Note. SAM=simultaneous alcohol and marijuana; CAM=concurrent alcohol and marijuana but not simultaneous use. Bold typeface indicates fixed effect p<.05