Table 4.
Parameter estimates for models testing indirect effects of white matter fractional anisotropy on the association between motivation to abstain and alcohol problem severity
| B | SE | t | p | ||
|---|---|---|---|---|---|
|
|
|||||
| A path | “mediator”=prefrontal | 0.00 | 0.00 | −2.38 | .03 |
| B path | −194.68 | 75.59 | −2.57 | .02 | |
| C path | 0.36 | 0.46 | 0.77 | .45 | |
| C′ path | −0.21 | 0.46 | −0.46 | .65 | |
| Controls | Gender | −2.53 | 2.97 | −0.85 | .40 |
| Age | −0.79 | 1.27 | −0.62 | .54 | |
| Days alcohol use | 1.24 | 0.49 | 2.54 | .02 | |
| Treatment days | 0.16 | 0.18 | 0.89 | .38 | |
| Conduct disorder | 6.65 | 3.32 | 2.00 | .06 | |
| Model summary: R2=0.65, F(7, 18)=4.75, p=.004 | |||||
| A path | “mediator”=OF | 0.00 | 0.00 | −2.50 | .02 |
| B path | −110.92 | 56.35 | −1.97 | .06 | |
| C path | 0.36 | 0.46 | 0.77 | .45 | |
| C′ path | −0.13 | 0.50 | −0.26 | .80 | |
| Controls | Gender | −2.93 | 3.14 | −0.93 | .36 |
| Age | −0.78 | 1.35 | −0.57 | .57 | |
| Days alcohol use | 1.22 | 0.52 | 2.36 | .03 | |
| Treatment days | 0.01 | 0.19 | 0.06 | .95 | |
| Conduct Disorder | 6.72 | 3.56 | 1.89 | .07 | |
| Model summary: R2=0.60, F(7, 18)=3.93, p=.01 | |||||
| A path | “mediator”=temporal | 0.00 | 0.00 | −2.68 | .01 |
| B path | −210.99 | 67.29 | −3.13 | .006 | |
| C path | 0.36 | 0.46 | 0.77 | .45 | |
| C′ path | −0.38 | 0.45 | −0.84 | .41 | |
| Controls | Gender | −1.27 | 2.89 | −0.44 | .66 |
| Age | −0.91 | 1.20 | −0.76 | .45 | |
| Days alcohol use | 1.28 | 0.46 | 2.80 | .01 | |
| Treatment days | 0.19 | 0.17 | 1.08 | .29 | |
| Conduct disorder | 8.08 | 3.06 | 2.64 | .02 | |
| Model summary: R2=0.69, F(7, 18)=5.71, p=.001 | |||||
Notes: n=26 (in addition to the 4 participants not followed at 6-months, 2 participants who reported no alcohol use in the past 6 months at baseline left the “motivation to abstain from alcohol” item blank, which was coded as “missing” data), B = unstandardized coefficient, SE=standard error. “Mediator”=intervening variable being tested. OF=orbitofrontal. Days alcohol use=Number of drinking days in the 30 days prior to scan. Treatment days=Number of treatment days attended from the start of intensive outpatient treatment to the scan. Conduct disorder (0=no, 1=yes)=current conduct disorder diagnosis at baseline A path (see Figure): independent variable (baseline motivation to abstain from alcohol) to intervening variable (fractional anisotropy). B path: direct effect of intervening variable (fractional anisotropy) on dependent variable (6-month Rutgers alcohol problems inventory score). C path: Total effect of independent variable (baseline motivation to abstain from alcohol) on dependent variable (6-month Rutgers alcohol problems inventory score). C′ path: Direct effect of independent variable (baseline motivation to abstain from alcohol) on dependent variable (6-month Rutgers alcohol problems inventory score), after controlling for the intervening variable (white matter integrity). Controls: partial effect of control variables on dependent variable.