Table 3.
Cognitive effects observed following caffeine consumption.
| Author, year | Dietary intake of caffeine | Population exposed to intervention/total population (percentage) | Quantity ingested/day | Cognitive effects |
|---|---|---|---|---|
| Fischer et al. (50) | Coffee | 1,877/2,622 (71.6%) | ≥115 mg of caffeine/day (≥1 cup of coffee) | Inverse associations (not statistically significant) were observed between higher intake and AD [HR (95% CI) = 0.97 (0.90–1.04); p = 0.338] and memory decline [B (95% CI) = −0.02 (−0.08–0.05); p = 0.241], also in APOE4 carriers [B (95% CI) = 0.11 (−0.06–0.29); p = 0.202] and APOE4 non-carriers [B (95% CI) = −0.04 (−0.11–0.02); p = 0.211] |
| Haller et al. (52) | Coffee | Moderate consumption: 47/145 (32.4%); Heavy consumption: 48/145 (33.1%) | Moderate consumption: 115–230 mg of caffeine/day (1–2 cups of coffee); Heavy consumption: 234–644 mg of caffeine/day (2–6 cups of coffee) | Moderate consumption: better cognitive performance [OR adjusted (95% CI) = 0.447 (0.210–0.952); p = 0.037]; moderate to heavy consumption: better bilateral deep white-matter preservation (p < 0, 05) and cerebral blood-flow in cognitively stable elderly (p < 0.05) in MRI |
| Chocolate | Light consumption: 53/145 (36.6%); Moderate consumption: 46/145 (31.7%); Heavy consumption: 46/145 (31.7%) | Light consumption: 0–4 mg of caffeine/day (0–0.6 serving of chocolate); Moderate consumption: 4–16 mg of caffeine/day (0.7–2.6 servings); Heavy consumption: 16.2–45.2 mg of caffeine/day (2.7–7.5 servings) | Not associated with either cognitive outcomes or MRI parameters | |
| Lin et al. (77) | Coffee | ≥1 cup of coffee/day: 41/1, 105 (4.1%) | ≥115 mg of caffeine/day (≥1 cup of coffee) | Beneficial effects on cognition for drinkers of ≥1 cup of coffee/day [OR unadjusted (95% CI) = 0.20 (0.04–0.98); p < 0.05] |
| Vercambre et al. (68) | Coffee | ≥average consumption (1–2 cups of coffee) | ≥230 mg of caffeine/day (≥2 cups of coffee) | Tendency of beneficial effects on cognitive decline [OR (95% CI) = 0.95 (0.71–1.28); p = 0, 804] but not on functional impairment [OR (95% CI) = 1.12 (0.84–1.50); p = 0.837] |
| Lindsay et al. (57) | Coffee | 2,985/4,019 (74.27%) | ≥115 mg of caffeine/day (≥1 cup of coffee) | Beneficial effects on cognition [OR (95% CI) = 0.69 (0.50–0.96] |
| Paganini-Hill et al. (58) | Coffee/chocolate | <50 mg/day: 156/587 (26.57%a); 50–199 mg/day: 198/587 (33.73%a); >200 mg/day: 138/587 (23.51%a) | Consumers of 50–199 mg of caffeine/day; Consumers of >200 mg of caffeine/day | Beneficial cognitive effects in 50–199 mg/day caffeine users [HR (95% CI) = 0.76 (0, 52–1, 10); p < 0.05] and in >200 mg/day caffeine users [HR (95% CI) = 0.66 (0.43–0.99); p < 0.05] |
AD, Alzheimer's disease; APOE4, E4 allele of the Apolipoprotein E gene; CI, confidence intervals; HR, Hazard Ratio; MRI, magnetic resonance imaging; OR, Odds Ratio; SEE, standard error of estimate. aPossible missing values.