The study, which appeared in the journal Archives of Neurology, focused on 1,393 elderly people with no history of cognitive problems and on 482 others with mild cognitive impairment, a condition of mental decline that may be a precursor to Alzheimer’s or other types of dementia.
The subjects, whose average age was 77, were then each assigned to one of three groups depending on whether they were weak, moderate or strong adherents of a Mediterranean diet, which is characterized by consuming little meat, few dairy products, moderate amounts of alcohol and large quantities of fish, vegetables, fruits and olive oil. It was assumed that each participant, as an elderly person with long-set habits, had been following his or her diet for many years.
After almost five years, some 275 members of the healthy group developed mild cognitive impairment. Strong followers of a Mediterranean diet had a 28 percent lower risk of slipping into cognitive impairment, compared with the weak followers. The moderate Mediterranean diet adherents had a 17 percent lower risk than the weak group.
A Mediterranean diet also seemed to have a protective effect on those with mild cognitive impairment. Of the 482 patients with mild cognitive impairment at the start of the study, 106 developed Alzheimer’s disease some four years later. But the strong Mediterranean diet followers had a 48 percent lower risk of Alzheimer’s. And even the moderate adherents of the diet enjoyed a 45 percent lower risk.
The results of the study are not definitive proof of the value of a Mediterranean diet, because it wasn’t a controlled clinical experiment. But the researchers said it would still be valuable to pursue a Mediterranean diet because it’s been proven to be good for heart health – and may provide a brain health bonus.
“We know it’s a healthy diet for other reasons,” said lead author Nikolaos Scarmeas, assistant professor of neurology at Columbia University Medical Center. “It makes sense for people to eat in a healthy way as soon as they can and for the longest they possibly can.”