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Coffee vs tea for dementia prevention? What a 43-year study found
Coffee vs tea for dementia prevention? What a 43-year study found
Health Team
••3 min read•Wellness
A large Harvard-led study tracking 131,000 people for up to 43 years found moderate caffeinated coffee and tea intake linked to lower dementia risk, while decaf showed no association.
FOUR DECADES OF DATA POINT TO CAFFEINE, NOT DECAF, IN DEMENTIA RISK STUDY
People taking part in two health studies in the United States have been sending back the same forms, about what they eat for a long time. These forms have lists of foods. Ask how many cups of each food they have every day and how often they have had them over the past year. The people have been sending these forms back for years and years. The forms have been adding up. So has the amount of coffee people have been drinking. The coffee people have been drinking has really added up over time.
People who study health have looked at information from 131,821 men and women who took part in the Nurses’ Health Study and the Health Professionals Follow-Up Study. What they found out which is now in JAMA is that drinking amounts of coffee and tea that have caffeine in them is connected to a lower chance of getting dementia over a long period of time. The coffee and tea that people drank had an impact on their health so the coffee and tea are really important, in this study.
THE COHORTS AND THE DATA
The groups of people started in 1976 and 1986. These people did not have cancer Parkinson’s disease or dementia when they joined. The researchers looked at what the people in the groups ate every two to four years. They used questionnaires that they knew would give them the right information. This way the researchers could see what the people, in the groups normally ate over time not what they ate once.
People drank coffee and tea for 37 years and we saw what happened. There were 11,033 cases of dementia. The people who drank the coffee with caffeine had a lower risk of dementia about 18% lower compared to the people who drank the least. People who drank tea had a risk too about 14% lower. Coffee with caffeine and tea seemed to make a difference. Coffee, with caffeine was linked to a risk of dementia and so was tea.
DOSE AND DIFFERENCE
The strongest signal showed up when people drank an amount of coffee. About two to three cups of coffee per day or one to two cups of tea per day. Drinking coffee or tea did not make the connection, between coffee and the signal any stronger. The coffee and tea people drank every day was the key and coffee and tea were the things that mattered.
Decaffeinated coffee does not seem to have a connection, to the risk of dementia. The tests that people took to check their brain function also did not show any difference.. When we look at the women who drank coffee with caffeine we see that they did a little better on some tests that they took over the phone. The key thing to remember here is that the difference is small. Decaffeinated coffee and caffeinated coffee are two things and we are talking about caffeinated coffee. The women who drank caffeinated coffee did a little better but only a little.
FACTORS AND CONTROLS
The caffeine signal gets our attention for a reason. The people who did this study thought about a lot of things that could affect the results like how old people're if they smoke how much they exercise, how much alcohol they drink their weight, what they eat and if they have been sick before. They also thought about if people are more likely to get Alzheimers disease because of their genes.. What they found was that the connections they saw were pretty much the same for people who are, at high risk and those who are not. The caffeine signal is interesting because of this.
LIMITATIONS IN THE DATA
The data does not show how people prepare their coffee and tea. The questionnaires did not ask if people drink espresso or filter coffee or if they like tea or black tea. They also did not ask about how people like their coffee or tea or if they add milk and sugar. The thing is, the amount of caffeine and polyphenol in coffee and tea can be very different depending on how people make it which means we are not really sure, about some things. The data cannot capture the preparation detail of coffee and tea.
Dementia outcomes were found out when doctors made a diagnosis and when people died. This way of doing things has some problems: death certificates can get it wrong when it comes to decline and people with mild Dementia may never even get a diagnosis. We are talking about eleven thousand Dementia cases over four decades which's a lot.. It is not certain if this shows the whole problem, with Dementia.
The thing with causation is that it is still something we worry about. When people have a trouble thinking it can change the way they do things every day and this can happen years before they even know what is wrong with them. The people studying this tried to make it fair by not looking at the people who got sick early and, by doing checks. They found that the connection was still there. They cannot say for sure that it is really true. Reverse causation is still a problem that they cannot get rid of.
The study has some limitations. We only did testing on the women and we did it over the phone. This was a solution because we had to do it on a large scale. We do not have the kind of test results, for the men. This is a problem that affects the conclusions we drew from the testing and the study. The female cohort had testing but the male cohort did not have the same testing.
THE BROADER CONTEXT
Dementia is a problem all over the world and it is getting worse. Alzheimers disease is the reason for this. It affects than six million people in the United States. By 2050 this number is expected to go up to 13 million people. We do not have good treatments, for Alzheimers disease that can actually change the course of the disease. So we really need to focus on finding ways to prevent Alzheimers disease and dementia.
WHAT THE STUDY DOES — AND DOES NOT — SHOW
This study shows that people who drink beverages for a long time might have a lower risk of getting dementia. The study does not say that drinking beverages is the reason for this lower risk. It also does not mean that coffee is a treatment, for dementia.
For habitual drinkers, two cups may sit in a different category from none — beyond that, the evidence narrows to what long-running questionnaires can and cannot see.
Health Team
