Table 2.
Results from the hierarchal regression analyses examining 2-way interactions between 5-HTTLPR and BDNF (top), 5-HTTLPR and COMT (middle) and COMT and BDNF (bottom).
| Variable | F | (Δ)R2 | Beta | SE | t | P-value |
|---|---|---|---|---|---|---|
| Step 1 | 1.20 | .046 | .31 | |||
| (Constant) | 4.20 | .77 | 5.46 | .00 | ||
| Age | −.02 | .01 | −2.18 | .03 | ||
| Caucasian | −.70 | .76 | −.92 | .36 | ||
| African American | −.97 | .97 | −1.00 | .32 | ||
| Asian | −.54 | .79 | −.69 | .49 | ||
| Hispanic | −.68 | .78 | −.87 | .39 | ||
| Native American | −.78 | 1.30 | −.60 | .55 | ||
|
| ||||||
| Step 2 | 1.71 | .022 | .18 | |||
| 5-HTTLPR | .23 | .13 | 1.84 | .07 | ||
| BDNF | −.03 | .15 | −.17 | .87 | ||
|
| ||||||
| Step 3 | 4.40 | .027 | .04 | |||
| 5-HTTLPR x BDNF | .43 | .21 | 2.10 | .04 | ||
|
| ||||||
| Step 2 | 1.89 | .023 | .15 | |||
| 5-HTTLPR | .23 | .12 | 1.94 | .05 | ||
| COMT | −.03 | .12 | −.21 | .83 | ||
|
| ||||||
| Step 3 | .26 | .002 | .61 | |||
| 5-HTTLPR x COMT | .09 | .17 | .51 | .61 | ||
|
| ||||||
| Step 2 | .02 | .000 | .98 | |||
| BDNF | −.03 | .15 | −.19 | .85 | ||
| COMT | −.01 | .13 | −.06 | .96 | ||
|
| ||||||
| Step 3 | .44 | .003 | .51 | |||
| BDNF x COMT | .15 | .23 | .66 | .51 | ||
Notes. Betas presented above are unstandardized, and p-values are two-tailed. Since each regression analysis was intended to test a distinct hypothesis, these analyses were conducted separately to preserve degrees of freedom. However, the results from Step 1 are presented only once given that all of the predictors in this step were the same across all three of these analyses.