"2 to 3 Cups of Coffee a Day May Lower Dementia Risk," Harvard Study Finds

Harvard Medical Team Publishes Findings in JAMA
Study Analyzes 40 Years of Data from Over 130,000 Participants
"2?3 Cups of Coffee and 1?2 Cups of Tea Help Cognitive Function"

A study has found that drinking 2 to 3 cups of caffeinated coffee a day, or 1 to 2 cups of tea, helps slow cognitive decline and reduce the risk of dementia.

A study found that drinking 2 to 3 cups of caffeinated coffee a day helps slow cognitive decline and reduce the risk of dementia. Photo to help readers understand the article.

According to Yonhap News on the 10th, a team led by Professor Daniel Wang of Harvard Medical School in the United States reported in the Journal of the American Medical Association (JAMA) that "by analyzing 40 years of follow-up data on more than 130,000 participants in the Nurses' Health Study and the Health Professionals Follow-up Study, we confirmed that caffeine intake can reduce the risk of dementia."

The researchers used data from 131,821 participants in the U.S. Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS) to analyze how caffeinated coffee, tea, and decaffeinated coffee affect dementia risk and cognitive health. In particular, using food frequency questionnaire data collected every 2 to 4 years, they divided participants into four groups (high, medium-high, medium-low, and low) according to their caffeine intake, and compared dementia diagnoses, subjective cognitive decline, and objective cognitive function test results over a period of up to 43 years.

During the follow-up period, a total of 11,033 people were diagnosed with dementia. The analysis showed that the dementia incidence rate in the top 25% group for caffeine intake was 141 cases per 100,000 person-years (one person-year is defined as observing one person for one year), which was associated with an 18% lower risk of dementia compared with the bottom 25% group for caffeine intake, which had 330 cases per 100,000 person-years. People who drank caffeinated coffee also had a lower prevalence of subjective cognitive decline and, on some measures, performed better on objective cognitive function tests.

Photo to help readers understand the article.

The researchers stated, "Similar results were observed among those with higher tea consumption, but this association was not seen with decaffeinated coffee," adding that this "suggests that caffeine may be the main factor behind the neuroprotective effect." They went on to explain, "The cognitive benefits were most pronounced in participants who consumed 2 to 3 cups of caffeinated coffee a day and 1 to 2 cups of tea a day, and even among those with higher caffeine intake, the negative effects suggested in some previous studies were not observed."

Dementia currently has only limited treatment options, which mainly alleviate or delay symptoms, making early prevention particularly important. Many researchers have therefore focused on studying how lifestyle factors such as diet affect dementia risk for prevention. Among these, coffee and tea contain bioactive substances such as polyphenols and caffeine, which have drawn attention as neuroprotective factors that can reduce inflammation and cellular damage and help prevent cognitive decline.

Professor Wang, who led the research team, said, "There are many ways to protect cognitive function during the aging process," and added, "This study suggests that consuming caffeinated coffee or tea may be one piece of the puzzle in protecting cognitive function." However, he also noted, "Further research is needed to determine which specific components act through which mechanisms."