Loughborough, UK: Scientists have found that drinking two to three cups of coffee a day may significantly reduce the risk of developing dementia, but drinking more coffee does not further protect the brain.

One large study followed 131,821 American nurses and health care professionals for up to 43 years, starting when they were in their early 40s. During this period, 11,033 people (about 8%) developed dementia. But people who drank moderate amounts of caffeinated coffee or tea were significantly less likely to be among them.

The protective effect was strongest in people under 75, where consuming about 250 mg to 300 mg of caffeine (about 2 to 3 cups of coffee) daily reduced the risk of dementia by 35%. The important thing is that drinking more than this will not give you any additional effects.

Women in the study reported drinking about four and a half cups of coffee or tea a day at the time of their participation, while men reported drinking about two and a half cups. People who drank more caffeinated coffee tended to be younger, but they also drank more alcohol, smoked more and ate more calories, all factors that have been found to increase the risk of dementia.

Interestingly, people who drank more decaf coffee had faster memory decline. Researchers believe this is probably because people switched to decaf after developing sleep problems, increased blood pressure, or heart rhythm disturbances. All of these are themselves associated with cognitive decline and dementia.