Demographic and baseline data.

<p>Results are mean ± SD. The p values are for correlation with the gene score.</p

Gene scores in relation to learning and plasticity.

<p>AIC is a measure of goodness of fit, where lower numbers indicate a better fit. P-values are for the gene score*drug interaction term. The unweighted gene score assumed equal contribution from each polymorphism, while the weighted gene score used weights for each polymorphism that were derived from the motor learning task.</p

Effect of L-Dopa on skilled motor learning varied with gene score.

<p>Below gene score = 2, L-Dopa provides better learning, and above gene score = 2, Placebo provides better learning. Values are derived from the mixed-effects model and reflect the percent improvement from the reference condition of gene score = 0 during the placebo week, using the average value for all covariates.</p

The Marble Navigation Task used to measure skilled motor learning.

<p>(A) Participants view the computer screen to see where to move the marble. (B) The MNT board used for week 1. (C) A novel version of the same MNT board was used for week 2.</p

Summary of polymorphisms and classification for gene score.

<p>The five polymorphisms related to brain dopamine neurotransmission are listed. Each was in Hardy-Weinberg equilibrium.</p

The experimental protocol.

<p>The experimental protocol.</p

Results of the mixed-effects model in relation to skilled motor learning.

<p>Estimates of the β values for the fixed effects in the model predicting the expected time to completion of the marble game [E(TTC)], with lower times indicating greater motor skill. This model controlled for learning effects across week 1 and 2 by including week, day, and their interaction. The model also controlled for age, gender, weight and ethnicity.</p

Adjusted association between dopamine score and depressive symptoms.

<p>Cell entries are beta coefficients, standard errors (s.e.), p-values and 95% confidence intervals (CI). The HS model controlled for race/ethnicity. The STAR*D model contained controls for age (continuous), sex (0 = male; 1 = female); marital status (0 = married/cohabiting; 1 = never married; 2 = divorced, widowed, or separated); and five principle components for genetic ancestry/population stratification. The GSP model controlled for age (continuous), sex (0 = male; 1 = female), and four principle components for genetic ancestry/population stratification. Depressive symptoms were measured by 3 scales: CES-D (HS), HAM-D (STAR*D), POMS short form (GSP).</p

Summary of polymorphisms and classification for the genetic risk score.

<p>Summary of polymorphisms and classification for the genetic risk score.</p

Adjusted association between individual dopamine variants and depressive symptoms.

<p>Cell entries are beta coefficients, standard errors (s.e.), p-values and 95% confidence intervals (CI). The HS model controlled for race/ethnicity.</p