Lead author Dr. Chuanhai Cao, a neuroscientist at the University of South Florida College of Pharmacy and the University of South Florida Health Byrd Alzheimer's Institute and colleagues at the University of Miami said the collaborative study involved 124 people, ages 65-88, in Tampa, Fla., and Miami.
The study participants had mild cognitive impairment -- patients already experienced some short-term memory loss and initial Alzheimer's pathology in their brains. Researchers focused on study participants with mild cognitive impairment because many were destined to develop Alzheimer's within a few years, Cao said.
The study, published in the Journal of Alzheimer's Disease, found 100 percent of the mild cognitive impairment patients with plasma caffeine levels above the critical level experienced no conversion to Alzheimer's disease during the two-to-four year follow-up period, study co-author Dr. Gary Arendash, said.
"These intriguing results suggest that older adults with mild memory impairment who drink moderate levels of coffee -- about three cups a day -- will not convert to Alzheimer's disease, or at least will experience a substantial delay before converting to Alzheimer's," Cao said in a statement. "The results from this study, along with our earlier studies in Alzheimer's mice, are very consistent in indicating that moderate daily caffeine/coffee intake throughout adulthood should appreciably protect against Alzheimer's disease later in life."