Researchers from Mass General Brigham tracked more than 130,000 people for over four decades
and found that those who regularly consumed moderate amounts of caffeinated coffee or tea had an 18 percent lower risk of developing dementia compared to those who rarely touched the stuff.

Caffeine swiggers also scored better on some cognitive tests and were less likely to complain about memory slips, according to the study. 
The apparent benefits weren't tied to heroic levels of caffeine intake,
just to steady, mid-range consumption
– roughly two to three cups a day
– suggesting that consistency matters most
https://www.theregister.com/2026/03/21/turns_out_your_coffee_addiction/