There have been several studies reported in the media about cinnamon and its potential benefits in preventing the development of Alzheimer's disease. However, all of the studies that these reports are based on were performed in the lab, and used chemicals extracted from cinnamon rather than the spice itself.
The amount of cinnamon that you would have to consume in order to reach the levels of the chemicals used in these studies would be toxic. More research is needed into these chemicals but, if beneficial, they will need to be provided in a drug form rather than in cinnamon.
The common spice cinnamon has been reported to have anti-viral, anti-microbial, anti-inflammatory and anti-oxidant effects. Researchers have specifically looked into the effects of cinnamon extracts on some of the hallmarks of Alzheimer's disease. For example, cinnamon bark extracts have been shown to prevent and even reverse Alzheimer's disease in mouse and fruit fly models of the disease.
Can it prevent the developement of tau protein tangles?
Other extracts have also been shown to have potential for future treatments. Lab studies have shown that cinnemaldehyde and epicatectin, both found in cinnamon, can prevent the development of 'tangles' of tau protein similar to those seen in people with Alzheimer's disease. Most experiments so far have been conducted in cells grown in the lab so it is unclear if the same effects will be seen in animal models or humans, or if there will be any impact on the function of brain cells.
Though some of the extracts of cinnamon may warrant investigation to try and establish new treatments, cinnamon itself is not a treatment for Alzheimer's disease. The levels of cinnamon a person would have to eat to replicate the results of many of these experiments would actually be toxic.