The researchers studied data on the health and diet of patients over 70 years old with mild cognitive impairment or in the early stages of Alzheimer's disease. The participants were divided into two groups depending on the amount of caffeine consumed. It turned out that people who consumed less caffeine had a significantly increased risk of memory impairment and other cognitive functions. The probability of developing Alzheimer's disease in this group was 2.5 times higher compared to those who consumed more caffeine.

Additionally, the scientists analyzed the composition of the cerebrospinal fluid of the participants. It was found that people who consumed little caffeine had a decrease in the concentration of beta-amyloid proteins in the cerebrospinal fluid. The researchers explained that this could serve as a biological marker of neurodegeneration characteristic of Alzheimer's disease. The less toxic proteins the cerebrospinal fluid "removes", the more they remain in the brain.