As little as one cup of coffee a day could have a protective effect against Alzheimer’s disease, the most common form of dementia, according to new research published today.

A daily dose of caffeine blocks the disruptive effects of high cholesterol that scientists have linked to the disease, a study has found.

The findings, in the Journal of Neuroinflammation, were based on research by scientists at the University of North Dakota School of Medicine and Health Sciences.

In the study, researchers gave rabbits 3mg of caffeine each day, the equivalent of a daily cup of coffee for an average-sized person. The rabbits were fed a cholesterol-enriched diet during this time. After 12 weeks, a number of laboratory tests showed that the blood brain barrier - which protects the central nervous system from the rest of the body’s circulation - was "significantly” more intact in rabbits receiving a daily dose of caffeine.

Previous studies have shown that high levels of cholesterol break down the blood brain barrier which can then no longer protect the central nervous system from the damage caused by blood-borne contamination.

Leakage in the blood brain barrier occurs in a number of neurological disorders, such as Alzheimer’s disease.

Jonathan Geiger, of the University of North Dakota School of Medicine and Health Sciences, said: “Caffeine appears to block several of the disruptive effects of cholesterol that make the blood-brain barrier leaky. High levels of cholesterol are a risk factor for Alzheimer’s disease, perhaps by compromising the protective nature of the blood-brain barrier. For the first time we have shown that chronic ingestion of caffeine protects the blood brain barrier from cholesterol-induced leakage.”

He added: “Caffeine is a safe and readily available drug and its ability to stabilise the blood-brain barrier means it could have an important part to play in therapies against neurological disorders.”

The research confirms earlier studies showing that caffeine intake protects against memory loss in ageing and in Alzheimer’s disease.

Dr Susanne Sorensen, head of research at the Alzheimer’s Society, said: “This is the best evidence yet that caffeine equivalent to one cup of coffee can help protect the brain against cholesterol. It sheds important light on why previous research has shown drinking coffee may reducing the risk of dementia.

“In addition to its effect on the vascular system, elevated cholesterol levels also cause problems with the blood brain barrier. This barrier, which protects the brain from toxins and infections, is less efficient prior to brain damage caused by Alzheimer’s disease or strokes.

“This research in animals shows that caffeine can help keep the blood brain barrier in good order, even with a diet rich in cholesterol. More research is now needed to determine whether drinking coffee has the same impact on the blood brain barrier in people and can help protect people against dementia.”

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