Caffeinated coffee linked to lower dementia rates in long-term study

• Among those who consumed more caffeinated coffee, there were 141 cases of dementia per 100,000 people per year, compared with 330 among those who drank it rarely or not at all.
• The most favorable associations were seen with two to three cups of coffee or one to two cups of tea per day; consuming more than these amounts offered no clear additional benefit.
• The study found associations, rather than proving that caffeine prevents dementia; the caffeine content of the tea was not specified.

Long-term follow-up linked caffeinated coffee with measures of cognitive health

Regular consumption of caffeinated coffee was associated with a lower incidence of dementia and more favorable measures of cognitive health with age in a long-term study of U.S. adults. Participants were followed for up to 43 years, allowing researchers to compare their habits with later outcomes over an extended period. However, the length of the follow-up does not turn the observed association into proof that coffee directly protects the brain.

Researchers found the strongest positive associations among those who drank two to three cups of caffeinated coffee a day. Participants with higher consumption were less likely to have diagnosed dementia than people who drank very little of this type of coffee or avoided it altogether. The report also noted that the association held regardless of participants’ genetic risk. This finding does not mean that heredity no longer affects the likelihood of developing the disease.

Dementia refers to a group of conditions that gradually impair memory, thinking, reasoning, and the ability to manage everyday activities. Alzheimer’s disease is the most common cause of dementia, but other brain disorders can also lead to it. Occasional forgetfulness can accompany aging, whereas with dementia, cognitive difficulties become serious enough to interfere with daily life. That is why identifying habits associated with risk is important for the study of aging.

Difference in the recorded rate of dementia

Among people who drank more caffeinated coffee, researchers recorded 141 cases of dementia per year for every 100,000 people. Among those who rarely or never drank the beverage, the rate was 330 cases per 100,000 people annually. This comparison shows a notable difference between the groups in the observations, but it does not show that coffee caused it. Based on the data presented, the influence of other differences between participants cannot be ruled out.

In addition to dementia cases, researchers tracked subjective cognitive decline: a person's sense that their memory or thinking had worsened. Such changes were reported by 7.8% of participants who drank more caffeinated coffee and 9.5% of those who drank it rarely or not at all. This is a self-assessment, not necessarily an impairment confirmed by formal cognitive testing. These complaints alone do not mean that a person has dementia.

People with subjective complaints may notice that they find it harder to recall information, concentrate, or find the right words. These experiences are not the same as a diagnosis and do not automatically confirm an illness, but they help describe how participants themselves perceive age-related changes in cognitive abilities. The lower proportion of such reports among those who drank more caffeinated coffee adds to the overall picture of associations, but does not establish a mechanism or cause for the differences.

The most favorable associations were seen with moderate consumption

When comparing the amount of coffee consumed with the outcomes, the most favorable association for coffee was observed at two to three cups a day. The authors also note that drinking more was not accompanied by any obvious additional protection. Therefore, the results do not support the simple assumption that the more coffee you drink, the better your cognitive performance. This is a range associated with the most favorable outcomes in the study, not a proven recommendation for everyone.

The association between coffee consumption and measures of brain health was also observed among participants with different genetic risks of dementia. Genetic risk refers to the influence of inherited DNA variants that may increase or decrease the likelihood of certain conditions. The authors emphasize that genetics is only part of a broader picture that includes age, overall health, and lifestyle. The results presented do not allow us to conclude that coffee offsets inherited predisposition.

Tea was also associated with a lower incidence of dementia and better cognitive measures. The most favorable associations were observed among participants who drank one to two cups of tea a day; drinking more did not show any additional benefit. However, the study did not distinguish between caffeinated and decaffeinated tea. Therefore, the findings on tea cannot determine whether caffeine played a role in the observed association or whether it was explained by other characteristics of the drink or the participants themselves.

Association does not mean proven prevention

Comparing regular and decaffeinated coffee offered a separate clue: caffeinated coffee was associated with favorable outcomes, while decaffeinated coffee did not show the same benefits. Caffeine is a natural stimulant found in coffee and tea, among other things; it affects the central nervous system, temporarily increasing alertness and reducing feelings of fatigue. But the long-term effects of caffeine on the brain are a separate question that these observations do not answer.

The difference between regular and decaffeinated coffee makes the possible role of caffeine a subject for further study, but does not prove that caffeine itself explains the results. Observational data may also reflect other differences between people who choose different drinks. The original report does not provide information that would allow the possible effect of caffeine to be separated from all related factors. Therefore, a conclusion that coffee directly prevents dementia would go beyond what the results presented can support.

The practical significance of the study is limited to identifying associations, not establishing a way to prevent dementia. The most favorable results were associated with two to three cups of coffee a day and one to two cups of tea; exceeding these amounts showed no further benefit. It is unknown whether the association between caffeine, tea, and cognitive outcomes is due to a causal effect or to other characteristics of the participants. The report also provides no basis for treating the results as individual medical advice.

Source: ScienceDaily