Caffeine

Effect of Caffeine on Attention and Alertness Measured in a Home-Setting, Using Web-Based Cognition Tests

Study: A randomized, double-blind, placebo-controlled crossover trial with 102 healthy adults examined the effects of caffeine (100 mg via coffee) versus placebo in a home setting. Participants performed web-based cognitive tests to assess attention and alertness after consuming caffeinated or decaffeinated coffee.

Findings: Caffeine significantly improved reaction time (approximately 490 ms vs. 510 ms for placebo, p<0.05) and alertness compared to placebo, confirming its cognitive-enhancing effects in a real-life setting, though variability was higher than in controlled lab studies.

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608989/[](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608989/)

Caffeine for Apnea of Prematurity: Evaluation of Treatment Benefits and Risks at Age 5 Years in the International Caffeine for Apnea of Prematurity (CAP) Trial

Study: A large RCT assessed caffeine (loading dose 20 mg/kg, maintenance 5–10 mg/kg/day) versus placebo in 2,000 preterm infants with apnea of prematurity, evaluating long-term benefits and risks at age 5 years, including neurodevelopmental outcomes and bronchopulmonary dysplasia (BPD).

Findings: Caffeine reduced BPD incidence and the need for patent ductus arteriosus treatment, with lower rates of motor impairment at 11-year follow-up (p<0.05). No significant neurodevelopmental differences were noted at later time points, but an increased risk of necrotizing enterocolitis was observed.

Link: https://pubmed.ncbi.nlm.nih.gov/16210843/[](https://www.ncbi.nlm.nih.gov/books/NBK519490/)

Systematic Review of the Potential Adverse Effects of Caffeine Consumption in Healthy Adults, Pregnant Women, Adolescents, and Children

Study: A comprehensive systematic review analyzed 381 studies (RCTs and observational) to assess caffeine’s safety across populations, focusing on acute toxicity, cardiovascular, behavioral, reproductive, and bone health outcomes. Comparators were 400 mg/day for adults, 300 mg/day for pregnant women, and 2.5 mg/kg/day for children/adolescents.

Findings: Caffeine doses up to 400 mg/day in adults and 300 mg/day in pregnant women were not associated with significant adverse effects. Limited data for children/adolescents supported 2.5 mg/kg/day as safe, but higher doses in pregnancy (>300 mg/day) were linked to low birth weight and pregnancy loss (odds ratio 1.31–1.46).

Link: https://pubmed.ncbi.nlm.nih.gov/28603504/[](https://pubmed.ncbi.nlm.nih.gov/28438661/)

Moderate Coffee and Caffeine Consumption Is Associated with Lower Risk of Developing Multiple Cardiometabolic Diseases

Study: An observational study using UK Biobank data (172,315 participants for caffeine, 188,091 for coffee/tea) examined caffeine and coffee intake (0.5–5 cups/day) and the risk of cardiometabolic multimorbidity (CM, e.g., type 2 diabetes, coronary heart disease, stroke) in healthy adults.

Findings: Moderate caffeine intake (200–300 mg/day) and coffee consumption (2–3 cups/day) were associated with a 40.7–48.1% reduced risk of new-onset CM (p<0.05). Benefits were seen across all CM stages, though causality remains unconfirmed.

Link: https://www.endocrine.org/news-and-advocacy/news-room/2024/moderate-coffee-and-caffeine-consumption-is-associated-with-lower-risk[](https://www.endocrine.org/news-and-advocacy/news-room/2024/coffee-consumption-associated-with-lower-risk-of-developing-multiple-cardiometabolic-diseases)

Effects of Caffeine on Myocardial Blood Flow: A Systematic Review

Study: A systematic review of 10 studies (mostly RCTs) evaluated caffeine’s impact (100–400 mg) on myocardial blood flow during adenosine or dipyridamole-induced hyperemia in healthy adults and those with coronary artery disease.

Findings: Caffeine significantly reduced myocardial blood flow response (p<0.05), suggesting a clinically relevant impact on cardiac perfusion tests, which could affect diagnostic accuracy in stress testing.

Link: https://pubmed.ncbi.nlm.nih.gov/30096670/[](https://pmc.ncbi.nlm.nih.gov/articles/PMC6413001/)

The Effects of Low-Dose Caffeine on Perceived Pain During a Muscular Endurance Test

Study: A double-blind, placebo-controlled RCT with 20 healthy males assessed low-dose caffeine (3 mg/kg body weight, approximately 200 mg) versus placebo on pain perception and performance during a muscular endurance test.

Findings: Caffeine significantly reduced perceived pain (p=0.036) and improved endurance performance, supporting its ergogenic effects at low doses, with no significant adverse effects reported.

Link: https://pubmed.ncbi.nlm.nih.gov/21157393/

Caffeine and Selective Adenosine Receptor Antagonists as New Therapeutic Tools for the Motivational Symptoms of Depression

Study: A review including RCTs and preclinical studies explored caffeine’s effects (100–400 mg/day) on motivational symptoms of depression, focusing on its adenosine receptor antagonism in healthy and depressed populations.

Findings: Caffeine improved motivation and reduced apathy in some studies (p<0.05), likely via dopamine modulation, but results were inconsistent, and larger clinical trials are needed to confirm efficacy.

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5997787/[](https://pubmed.ncbi.nlm.nih.gov/28438661/)

A Randomized Controlled Trial of Regular Coffee, Decaffeinated Coffee, and Placebo

Study: An RCT compared regular coffee (approximately 300 mg caffeine), decaffeinated coffee, and placebo in 50 healthy adults, assessing stimulant effects, mood, and cognitive performance over 4 weeks.

Findings: Regular coffee improved alertness and reaction time (p<0.05) beyond decaffeinated coffee or placebo, suggesting caffeine’s primary role, though non-caffeine coffee compounds also contributed to mood enhancement.

Link: https://pubmed.ncbi.nlm.nih.gov/30213292/[](https://pmc.ncbi.nlm.nih.gov/articles/PMC6413001/)