Figure 1.

Odds ratios for Parkinson disease according to joint categories of baseline caffeine intake and smoking status, National Institutes of Health-AARP Diet and Health Study, 1995–2006. Caffeine intake was defined as low (first quintile), moderate (second and third quintiles), or high (fourth and fifth quintiles). Smoking status was defined as never smoker (striped bars), past smoker who had smoked for 1–29 years (gray bars), or past smoker who had smoked for ≥30 years/current smoker (dotted bars). Specific odds ratios appear above the bars.