Compounds in Cinnamon Might Hold the Key to AD Prevention
By: Sai Srihaas Potu
Alzheimer's disease (AD), the most common form of dementia, is a complex disease characterized by an accumulation of β-amyloid plaques and neurofibrillary tangles composed of tau amyloid fibrils associated with synapse loss and neurodegeneration leading to memory impairment and other cognitive problems.
There is currently no known treatment that slows the progression of this disorder. According to the 2018 World Alzheimer report, there are an estimated 50.6 million people worldwide living with dementia at a total cost of more than US$600 billion in 2018, and the incidence of AD throughout the world is expected to double in the next 20 years. There is a pressing need to find biomarkers to both predict future clinical decline and for use as outcome measures in clinical trials of disease-modifying agents.
For years, researchers have known that cinnamon contains many herbal elements and compounds that can help heal the body. However, in a new study, they have found out that cinnamon might hold a clue that can help cure AD. In light of this claim, one important question about its validity comes up: can the red-brown spice with the unmistakable fragrance and variety of uses offer an important benefit? The common baking spice might hold the key to delaying the onset of the effects of Alzheimer’s disease. That is, according to Roshni George and Donald Graves, scientists at UC Santa Barbara.
Alzheimer’s disease is the most common form of dementia, a neurodegenerative disease that progressively worsens over time as it kills brain cells. No cure has yet been found, nor has the major cause of Alzheimer’s been identified.
However, two compounds found in cinnamon, cinnamaldehyde and epicatechin, are showing some promise in the effort to fight the disease. According to George and Graves, the compounds have been shown to prevent the development of the filamentous tangles found in the brain cells that characterize Alzheimer’s. Responsible for the assembly of microtubules in a cell, a protein called tau plays a large role in the structure of the neurons, as well as their function.
The problem with tau in Alzheimer’s is that it starts aggregating. When the protein does not bind properly to the microtubules that form the cell’s structure, it tends to clump together forming insoluble fibers in the neuron. The older we get the more susceptible we are to these twists and tangles; Alzheimer’s patients develop them more often and in larger amounts.
The use of cinnamaldehyde, the compound responsible for the bright, sweet smell of cinnamon, has proven effective in preventing the tau knots. By protecting tau from oxidative stress, the compound, an oil, could inhibit the protein’s aggregation. To do this, cinnamaldehyde binds to two residues of an amino acid called cysteine on the tau protein. The cysteine residues are vulnerable to modifications, a factor that contributes to the development of Alzheimer’s.
Oxidative stress is a major factor to consider in the health of cells in general. Through normal cellular processes, free radical-generating substances like peroxides are formed, but antioxidants in the cell work to neutralize them and prevent oxidation. Under some conditions, however, the scales are tipped, with increased production of peroxides and free radicals, and decreased amounts of antioxidants, leading to oxidative stress.
Epicatechin, which is also present in other foods, such as blueberries, chocolate, and red wine, has proven to be a powerful antioxidant. Not only does it quench the burn of oxidation, but it is also activated by oxidation so the compound can interact with the cysteines on the tau protein in a way similar to the protective action of cinnamaldehyde. The researchers claim that cell membranes that are oxidized also produce reactive derivatives, such as acrolein, that can damage the cysteines. Epicatechin also sequesters those byproducts.
Studies indicate that there is a high correlation between Type 2 diabetes and the incidence of Alzheimer’s disease. The elevated glucose levels typical of diabetes lead to the overproduction of reactive oxygen species, resulting in oxidative stress, which is a common factor in both diabetes and Alzheimer’s disease. Other research has shown cinnamon’s beneficial effects in managing blood glucose and other problems associated with diabetes.
Since tau is vulnerable to oxidative stress, the researchers decided to study whether Alzheimer’s disease could benefit from cinnamon, especially looking at the potential of small compounds. Although this research shows promise, the researchers believe that they are still a long way from knowing whether this will work in human beings. The researchers caution against ingesting more than the typical amounts of cinnamon already used in cooking.
If cinnamon and its compounds do live up to their promise, it could be a significant step in the ongoing battle against Alzheimer’s. A major risk factor for the disease, age, is uncontrollable. In the United States, Alzheimer’s presents a particular problem as the population lives longer and the Baby Boom generation turns gray, leading to a steep rise in the prevalence of the disease. It is a phenomenon that threatens to overwhelm the U.S. health care system. According to the Alzheimer’s Association, in 2019, Alzheimer’s disease will cost the nation $150 billion.
Worldwide, approximately 50 million people are living with dementia, with Alzheimer’s disease (AD) comprising 60–70% of cases. AD is a progressive, neurodegenerative disease characterized clinically by cognitive decline and behavioral disturbances. In the future, researchers need to continue to research AD in order to understand the impact that certain biomarkers have on the development of AD and to identify new treatment options for patients with the disease.
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