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For many people, the day doesn’t truly begin until they’ve had their first sip of coffee. But if you have a loved one living with Alzheimer’s disease — or you’re worried about your own risk — you may wonder what effect drinking coffee has on the brain over time. So, does coffee cause Alzheimer’s?
Scientists have been studying the connection between caffeine and Alzheimer’s disease for years. Despite all the research, the answer isn’t yet fully clear. In this article, we’ll cover everything researchers have learned so far about the link between Alzheimer’s disease and caffeine, and what it could mean for you and your loved ones.
Over the past few decades, scientists have done many studies to understand how coffee consumption and caffeine intake relate to Alzheimer’s disease and other types of age-related cognitive decline (problems with memory and thinking). So far, results have been mixed. However, some studies suggest that moderate coffee intake may be linked to a lower risk of developing dementia later in life.
A 2023 meta-analysis — a study that combines data from several large studies — explored this link. It found that people who drank one to four cups of coffee per day had a reduced risk of Alzheimer’s compared to those who rarely drank it. People who drank one to two cups per day had the lowest risk of Alzheimer’s. Drinking more than four cups, however, didn’t add any beneficial effects and might even be linked to a slightly higher risk.
It’s important to remember that these findings show correlation, not cause and effect. This means that researchers found a pattern between coffee drinking and a lower risk of Alzheimer’s disease, but it doesn’t mean that caffeine directly prevents it. Other factors — such as diet, exercise, or overall health — could also play a role.
Still, not every study has found the same connection. Some long-term observational studies haven’t shown a clear link between coffee consumption and cognitive decline. A few have even reported similar or higher rates of dementia among coffee drinkers.
Some neuroscience (brain science) studies have explored how caffeine might affect people who already have Alzheimer’s disease or cognitive impairment. The results suggest that moderate caffeine intake may also help to slow cognitive decline. People who drank two to three cups of coffee per day showed slower changes in memory and thinking. However, this effect may depend on a person’s genes and daily habits.
Caffeine is a stimulant found in coffee, tea, chocolate, and some sodas. It works mainly by blocking a chemical in the brain called adenosine, which helps regulate sleep and alertness. When adenosine is blocked, neurons (nerve cells) become more active, making you feel more awake and focused.
Scientists are studying several ways that caffeine might help support cognitive function (thinking ability) or even protect the brain from decline.
Caffeine can cross the blood-brain barrier, which means it can act directly inside the brain. Once it’s in the brain, it blocks a certain type of adenosine receptor called the A2A receptor. Research shows that in Alzheimer’s disease, these receptors can become overactive. This may contribute to more neuroinflammation (brain inflammation), cell damage, and memory loss. It seems that by blocking A2A receptors, caffeine calms overactive brain cells. In turn, this may lower inflammation and slow memory decline.
Animal studies have shown that caffeine may help limit the buildup of amyloid beta in the brain. Amyloid beta is a sticky protein that forms plaques (protein clumps) in the brains of people with Alzheimer’s disease. However, further studies in humans are needed to confirm these results.
Caffeine also acts as an antioxidant. This means it helps reduce the effects of oxidative stress — damage caused by unstable molecules in the brain. Studies suggest caffeine may boost the brain’s defense systems, helping cells stay healthier longer.
Laboratory research shows that caffeine may also help protect neurons in other ways. For instance, caffeine may activate a specific protein in the brain that helps neurons use energy more efficiently and boosts the activity of key antioxidants.
Caffeine may also strengthen the action of a protein that turns on genes involved in fighting inflammation and repairing cell damage. Some studies suggest that caffeine could also help balance levels of glutamate, a brain chemical involved in learning and memory. Together, these positive effects could make brain cells more resistant to the stress and inflammation linked to Alzheimer’s disease and other types of dementia, but more studies are needed to confirm these findings.
If caffeine is thought to help the brain, does that mean only regular coffee offers benefits? Maybe not. Some research suggests that decaffeinated coffee may also support brain health. In animal studies using models of Alzheimer’s disease, extracts of both regular and decaffeinated coffee protected brain cells by reducing damage caused by toxic proteins.
This finding hints that coffee’s helpful effects may come from more than caffeine alone. Coffee beans contain many natural plant compounds called polyphenols. These compounds act as powerful antioxidants that help protect brain cells from damage and inflammation. Even after caffeine is removed from coffee, these compounds remain. This may explain why decaffeinated coffee may still offer some of the same brain health benefits as regular coffee.
While moderate coffee intake may support brain health, too much caffeine can have downsides. High amounts may cause anxiety, trouble sleeping, and heart problems. Older adults may also be more sensitive to caffeine, which increases the risk of these problems. People with heart disease, high blood pressure, anxiety, or sleep problems should be especially careful.
Research shows that drinking more than six cups of coffee a day may actually increase the risk of dementia by as much as 53 percent. This risk was similar for both regular and decaffeinated coffee. In a large study of about 400,000 people, those who drank the most coffee also had smaller brain volume — especially in the hippocampus, a key area for memory.
Scientists don’t yet know why this happens. One theory is that it may be linked to natural coffee oils that can raise cholesterol. For now, doctors generally agree that enjoying coffee in moderation is likely safe and even neuroprotective (protects the brain) for most healthy adults.
Current research doesn’t show that caffeine causes memory loss. In fact, most studies suggest the opposite. Moderate caffeine intake may help protect memory and thinking skills, especially as people age. However, drinking too much caffeine can interfere with sleep. Over time, poor sleep can harm memory.
According to the U.S. Food and Drug Administration (FDA), up to 400 milligrams of caffeine a day is generally considered safe for most healthy adults. That’s roughly the amount found in about two to three cups of coffee. Consuming more than 1,200 milligrams in a short period can cause serious symptoms, such as seizures.
Even after years of study, researchers still have many unanswered questions about caffeine and Alzheimer’s disease. So far, most findings show patterns, not proof. Many studies rely on self-reported coffee intake, which can be unreliable. In addition, their methods and follow-up times vary, making results hard to compare.
Scientists are still working to understand how much caffeine — or which compounds in coffee — matter most. It’s also unclear whether caffeine protects the brain directly or works indirectly by interacting with lifestyle factors like mood, energy, or metabolism. More long-term, controlled studies in humans are needed to determine exactly how caffeine affects brain health and what amounts are truly safe or beneficial.
Caffeine may play a small role in supporting brain health, but it’s only one piece of the puzzle. Genetic risk and lifestyle factors have an impact, too. Research consistently shows that the following habits help protect the aging brain:
Together, these habits have a far greater impact on long-term cognitive function than any single food or drink.
On myALZteam, people share their experiences with Alzheimer’s disease, get advice, and find support from others who understand.
How many cups of coffee do you usually have per day? Let others know in the comments below.
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