Coffee and Alzheimer's: What Observational Studies Have Found

Among the most unwelcome effects of aging is cognitive decline, and there are few things scarier than dementia and Alzheimer’s Disease. Dementia starts in old age or later middle age and is characterized by memory loss over time, confusion, personality and mood changes and impaired thinking and even physical function.

Of people who develop dementia, 60–65% of them have Alzheimer’s Disease, affecting tens of millions of people worldwide. The disease is characterized by the death of brain cells, neurofibrillary tangles, and the build up of a plaque called beta amyloid in a patient’s brain. Because of how it destroys the memory, the disease creates a heavy emotional and practical burden for the patients who suffer from it as well as their loved ones who must provide care. It is the sixth leading cause of death in the United States today. Its causes are not understood very well, and 90% of cases are sporadic and not linked to a family history. Its greatest risk factor is age.

Once Alzheimer’s begins to kill off brain cells, the process cannot be stopped or reversed by any therapies that have yet been discovered. Primary prevention--doing everything possible to keep the disease from developing in the first place--is the most important thing to do in order to make sure you never have to suffer from this tragic disease.

Several observational studies have examined whether mid-life coffee drinking is associated with later dementia risk.

"We are not saying that moderate coffee consumption will completely protect people from Alzheimer's disease. However, we firmly believe that moderate coffee consumption can appreciably reduce your risk of Alzheimer's or delay its onset." -- Chuanhai Cao, a neuroscientist at the USF

There is evidence that both caffeine as well as coffee’s other properties (such as polyphenols/CGAs) may play a part in improving cognitive function.

On one hand, a 2016 Journals of Gerontology analysis reported lower dementia incidence among older women with higher caffeine intake. In the study, middle-aged women who reported having about five to six eight ounce cups of coffee or black tea every day were 36% less likely to develop Alzheimer’s. Since the results were the same for both those drinking tea and coffee, the study correlated the results to the effects of caffeine. Proponents of coffee for the prevention of Alzheimer’s disease have pointed specifically to caffeine’s effects on the central nervous system and its ability to cross the blood-brain barrier.

A 2013 laboratory experiment by Jang et al. showed that the beneficial effects of coffee were a result of more than just caffeine, however. In this study, rats who had been given scopolamine (a drug that causes cognitive impairment) were then given instant decaffeinated coffee. They then were judged against a control group on their ability to complete a water maze. The results of the test showed that the group that was given decaffeinated coffee had better cognitive function than the one that wasn’t. As many other coffee and health related studies have demonstrated, coffee’s health benefits are about more than just caffeine. An earlier laboratory study had also tied both caffeic acid and chlorogenic acid--the CGAs that are found in coffee--to neuroprotective qualities. Researchers did note that caffeic acid’s protective properties were the stronger of the two but chlorogenic acid made a difference as well.

The unfortunate news is that antioxidant therapies for Alzheimer’s Disease alone have not been shown to be effective in stopping the progression of the disease once it has started. Though scopolamine is a good tool for simulating cognitive difficulties, there are differences in rodent and human brains that have not yet been bridged in experiments. Rats do not develop the same beta amyloid deposits that are characteristic of Alzheimer’s Disease.

The good news is that a lifelong coffee habit can improve your chances of never developing Alzheimer’s in the first place. Eskelinen concluded in a 2010 analysis of multiple epidemiological studies that a 3–5 cup of coffee per day habit at mid-life predicted a 65% lower risk of Alzheimer’s and dementia in late life.

As a bonus, short term benefits of coffee include better memory, mood, vigilance, and overall cognitive function.