Four cups of coffee a day marks brain‑health tipping point, study shows

Researchers from Australia and the United States presented a study at the 2024 Alzheimer's Association International Conference that linked high coffee intake to accelerated decline in fluid intelligence, a key component of brain function. The analysis of about 8,500 participants aged over 60 found that drinking four or more cups of coffee daily was associated with a faster loss of logical reasoning and pattern‑recognition abilities, whereas moderate consumption of one to three cups showed no adverse effect and may even be protective.

The same reports noted that tea consumption, especially in larger amounts, correlated with better performance on fluid‑intelligence tests, suggesting a contrasting effect to coffee. Separate research on German medical students published in 2026 indicated that a moderate intake of one to two cups per day was linked to higher exam scores, while both zero and excessive consumption (three or more cups) were associated with lower performance. Overall, the findings emphasize that coffee’s benefits are dose‑dependent, with a critical threshold around four cups per day where potential harms to cognitive health emerge.