Table 3. Adjusted odds ratio (95% CI) of depressive symptoms according to caffeine intake in elderly Japanese women (n = 1,992).
| Caffeine intake (n = 1,992) | |||||
| Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | Trend Pa | |
| (n = 498) | (n = 498) | (n = 498) | (n = 498) | ||
| Median caffeine intake, mg/1,000 kcal | 76.5 (0–119.2) | 150.2 (119.3–173.0) | 203.7 (173.3–234.8) | 284.5 (234.9–758.0) | |
| Depressive symptoms, % | 24.9 | 22.7 | 21.1 | 19.5 | |
| Crude OR (95% CI) | 1.00 (Reference) | 0.89 (0.66–1.19) | 0.81 (0.60–1.08) | 0.73 (0.54–0.99) | 0.03 |
| Age adjusted OR (95% CI) | 1.00 (Reference) | 0.89 (0.67–1.20) | 0.83 (0.62–1.12) | 0.76 (0.56–1.03) | 0.07 |
| Model 1b OR (95% CI) | 1.00 (Reference) | 0.91 (0.68–1.23) | 0.86 (0.63–1.16) | 0.74 (0.54–1.01) | 0.052 |
| Model 2c OR (95% CI) | 1.00 (Reference) | 0.99 (0.73–1.33) | 0.91 (0.67–1.24) | 0.75 (0.55–1.02) | 0.058 |
BMI, body mass index; CES-D, Center for Epidemiologic Studies Depression Scale; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; METs, metabolic equivalent hours.
Participants with depressive symptoms were defined as a CES-D score ≥16.
Caffeine intake calculated from green tea, black tea and Chinese tea, coffee and cola.
Caffeine intake, EPA + DHA intake and folate intake were energy-adjusted according to the density method.
aTrend P values were based on linear regression analysis for continuous variables with ordinal numbers 0–3 assigned to caffeine intake categories.
bModel 1: adjusted for age (years, continuous) and residential block (Hokkaido and Tohoku, Kanto, Hokuriku and Tokai, Kinki, Chugoku and Shikoku, and Kyushu), living status (alone or not alone), current smoking (yes or no), alcohol drinking (yes or no), marital status (married or unmarried), physical activity level (total metabolic equivalents hours/day: METs, continuous), size of residential area (city with a population ≥1 million, city with a population <1 million, and town and village), BMI (kg/m2, continuous), and education (junior high school, high school junior college, and university and higher).
cModel 2: adjusted for variables in model 1 with EPA + DHA intake (mg/1,000 kcal, continuous), folate intake (µg/1,000 kcal, continuous), and dietary supplement use (yes or no).