Coffee Reduces Risk of Alzheimer's Disease: Direct Evidence
It would be too bold a move at this point to say that drinking coffee prevents Alzheimer's disease. However, the results of a new study indicate that older adults with mild memory problems who drink a moderate amount of coffee each day will not progress to Alzheimer's disease or at least will have a significant delay before converting to this most common type of dementia.
The good news about coffee and caffeine
One of the first things to point out about this study is that it involved the use of caffeinated coffee--not decaf. In fact, the investigators measured levels of caffeine in the study participants' blood and from there determined that about three cups of coffee daily was the "magic" number needed to achieve the benefits observed in the study.
Here's what the investigators discovered among the 124 individuals ages 65 to 88 who participated in the study. The researchers focused on people with early signs of Alzheimer's disease, a condition called mild cognitive impairment (MCI), as about 15% of people with MCI progress to full-blown Alzheimer's disease each year.
- Blood caffeine levels at the beginning of the study were 51% lower in participants who had MCI that progressed to dementia during the two-to-four year follow-up than those whose MCI remained stable during the same time period
- None of the participants with MCI who later developed Alzheimer's had a starting blood caffeine level greater than 1,200 ng/mL, which is the equivalent of drinking several cups of caffeinated coffee a few hours before the blood sample was taken
- All of the participants with MCI who had blood caffeine levels greater than 1,200 ng/mL did not progress to Alzheimer's disease during the follow-up period
- Therefore, caffeine appears to protect individuals who already have MCI
Lead author Dr. Chuanhai Cao, a neuroscientists at the University of South Florida (USF) College of Pharmacy and the USF Health Byrd Alzheimer's Institute, called the results "intriguing" and noted that these findings, "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."
Other health benefits of coffee and caffeine
The most recent study showing the health benefits of drinking coffee was published in the New England Journal of Medicine and reported on the risk of dying among a population of more than 400,000 men and women aged 50 to 71 at baseline. After a 13-year follow-up, the investigators concluded that drinking coffee was associated with a reduced risk of death due to heart disease, stroke, respiratory disease, injuries and accidents, diabetes, and infections, but not cancer.
Another study, however, did see a reduced risk of cancer associated with coffee consumption. Swedish researchers found that women who drank more than five cups of coffee daily could significantly reduce their risk of developing anti-estrogen-resistant, estrogen-receptor breast cancer.
Other studies have suggested coffee consumption may reduce the risk of endometrial cancer, prostate cancer, and uterine cancer. Controlled clinical trials are needed to determine if these findings and others are valid.
Why coffee is important for Alzheimer's disease
A study from the Johns Hopkins Bloomberg School of Public Health reported that more than 26 million people around the world were estimated to be living with Alzheimer's disease in 2006. By 2050, the number is expected to reach more than 106 million.
The need for effective preventive and treatment measures for Alzheimer's disease is clear, and this latest study from the University of South Florida and the University of Miami is one example of that effort.
Dr. Cao noted that although he and his fellow researchers are not saying that drinking several cups of coffee every day will completely protect them from developing Alzheimer's disease, "we firmly believe that moderate coffee consumption can appreciably reduce your risk of Alzheimer's or delay its onset."
Therefore, the take-home message is that "Moderate daily consumption of caffeinated coffee appears to be the best dietary option for long-term protection against Alzheimer's memory loss," concluded co-author Dr. Gary W. Arendash, USF department of cell biology, microbiology and molecular biology.
Cao C et al. High blood caffeine levels in MCI linked to lack of progression to dementia. Journal of Alzheimer's Disease 2012; 30(3): 559-72
Freedman ND et al. Association of coffee drinking with total and cause-specific mortality. New England Journal of Medicine 2012 May 17; 366(20): 1891-904