German and French researchers have demonstrated that caffeine has a positive effect on tau deposits, one of the hallmarks of Alzheimer's disease. They showed how giving regular doses of caffeine to mice bred to develop tau protein deposits in their brains slowed memory decline compared to control mice.
The team believes the findings will eventually lead to a new class of drugs for the treatment of Alzheimer's disease.
Jointly led by Dr. Christa E. Müller of the University of Bonn and Dr. David Blum of the University of Lille, the researchers report their findings in the journal Neurobiology of Aging.
Alzheimer's disease plays havoc with the metabolism of brain cells, causing them to stop working and lose connections with each other, and eventually, their death. This gradual deterioration is what leads to memory failure, difficulty with daily tasks, personality changes, and other features of the brain-wasting disease.
The two hallmarks of Alzheimer's disease are deposits of tau protein (which clog up the insides of brain cells) and plaques of amyloid protein (which clog up the spaces between brain cells). The development of these hallmarks is not easy to investigate in living brains, which is why studies of mice bred to have similar conditions are so useful.
Several studies have already shown that regular moderate caffeine intake prevents memory decline in older people, and reduces the risk of developing Alzheimer's disease. Others have taken this further and shown how caffeine intake slows memory decline in mice bred to develop amyloid plaques. But until this latest research, no studies had yet investigated the effect of caffeine in mice bred to mimic the other hallmark of Alzheimer's - the tau deposits.
For their study, the team evaluated the effect of regular, persistent caffeine intake in mice bred to develop tau deposits similar to those seen in humans. The tau mice were given the caffeine in their drinking water at a concentration of 0.3 gm per liter.
Another group of identical tau mice - the controls - were not given caffeine in their drinking water.
Findings support the idea that caffeine intake has positive effect on tau deposits
The tau mice on chronic caffeine did not develop the spatial memory impairments seen in the controls.
The results showed the tau mice on chronic caffeine did not develop the spatial memory impairments seen in the controls.
They also showed that the chemistry of the tau proteins in the hippocampus - the seat of memory in rodents - was different in the caffeine-drinking mice. The team writes:
"Improved memory was associated with reduced hippocampal tau phosphorylation and proteolytic fragments."
Plus, the findings showed that caffeine appeared to reduce several pro-inflammatory and oxidative stress markers in the hippocampus of the tau mice.
The researchers conclude that their findings support the idea that caffeine intake is beneficial in mice that develop tau deposit similar to those seen in humans, thus "paving the way for future clinical evaluation" in human patients with Alzheimer's disease.
In 2011, Medical News Today reported another mouse study by the University of South Florida that concluded coffee wards off Alzheimer's because an unknown ingredient teams up with caffeine to stimulate blood levels of a critical protein that appears to put off the development of the disease.
Written by Catharine Paddock PhD