To further evaluate robustness of our findings, we conducted stratified analyses by follow-up time (<50th percentile vs ≥50th percentile of follow-up time) and age (20-65 vs ≥65 years). Because NHANES does not provide data on temporality of health conditions and medications, we developed an alternative propensity score with more than 650 non–central nervous system (CNS) medications excluded (ie, cardiovascular, metabolic, and anti-infective medications) and repeated all analyses after limiting medications in our propensity scores to only those used to treat chronic CNS disorders. All analyses were performed using SAS, version 4.2 (SAS Institute Inc). All P values were from 2-sided tests and results were deemed statistically significant at P < .05.
