Middle-aged people who drink moderate amounts of coffee significantly reduce their risk of developing Alzheimer's disease, a study by Finnish and Swedish researchers showed Thursday.

"Middle-aged people who drank between three and five cups of coffee a day lowered their risk of developing dementia and Alzheimer's disease by between 60 and 65 per cent later in life," said lead researcher on the project, Miia Kivipelto, a professor at the University of Kuopio in Finland and at the Karolinska Institute in Stockholm.

The study, which was also conducted in cooperation with the National Public Health Institute in Helsinki and which was published in the Journal of Alzheimer's Disease this month, was based on repeated interviews with 1,409 people in Finland over more than two decades.

They were first asked about their coffee-drinking habits when they were in their 50s and their memory functions were tested again in 1998, when they were between 65 and 79 years of age.

A total of 61 people had by then developed dementia, 48 of whom had Alzheimer's, the researchers said.