In elderly, 3 cups of coffee per day can reduce Alzheimer's disease risk, reveals study.
A recent study monitoring the memory and thinking processes of people older than 65 found that all those with higher blood caffeine levels avoided the onset of Alzheimer's disease in the two-to-four years of study follow-up.
And coffee appeared to be the major or only source of caffeine for these individuals.
Researchers from the University of South Florida and the University of Miami said the case control study provides the first direct evidence that caffeine/coffee intake is associated with a reduced risk of dementia or delayed onset.
The collaborative study involved 124 people, ages 65 to 88, in Tampa and Miami.
"These intriguing results suggest that older adults with mild memory impairment who drink moderate levels of coffee -- about 3 cups a day -- will not convert to Alzheimer's disease -- or at least will experience a substantial delay before converting to Alzheimer's," said study lead author Dr. Chuanhai Cao, a neuroscientist at the USF College of Pharmacy and the USF Health Byrd Alzheimer's Institute.
"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," Dr. Cao stated.
The study showed this protection probably occurs even in older people with early signs of the disease, called mild cognitive impairment, or MCI.
Patients with MCI already experience some short-term memory loss and initial Alzheimer's pathology in their brains. Each year, about 15 percent of MCI patients progress to full-blown Alzheimer's disease.
The researchers focused on study participants with MCI, because many were destined to develop Alzheimer's within a few years.
Blood caffeine levels at the study's onset were substantially lower (51 percent less) in participants diagnosed with MCI who progressed to dementia during the two-to-four year follow-up than in those whose mild cognitive impairment remained stable over the same period.
No one with MCI who later developed Alzheimer's had initial blood caffeine levels above a critical level of 1200 ng/ml - equivalent to drinking several cups of coffee a few hours before the blood sample was drawn. In contrast, many with stable MCI had blood caffeine levels higher than this critical level.
"We found that 100 percent of the MCI 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," said study co-author Dr. Gary Arendash.
The researchers believe higher blood caffeine levels indicate habitually higher caffeine intake, most probably through coffee. Caffeinated coffee appeared to be the main, if not exclusive, source of caffeine in the memory-protected MCI patients, because they had the same profile of blood immune markers as Alzheimer's mice given caffeinated coffee.
"We are not saying that moderate coffee consumption will completely protect people from Alzheimer's disease. However, we firmly believe that moderate coffee consumption can appreciably reduce your risk of Alzheimer's or delay its onset," Dr. Cao cautioned.
Their findings will appear in the online version of an article to be published June 5 in the Journal of Alzheimer's Disease, published by IOS Press.