Curcumin is a bright yellow plant extract obtained from turmeric, the dried root powder — commonly used in curries — of the Curcuma longa plant, a member of the ginger family.
A mainstay of traditional Chinese and Indian herbal medicines, curcumin is a polyphenol that is thought to have anti-inflammatory and anti-oxidant effects.
Curcumin and Alzheimer’s disease
Inflammation and oxidative stress are known to contribute to Alzheimer’s disease. Oxidative stress occurs when there is an imbalance between the body’s production of potentially harmful free radicals and its ability to neutralize them.
Curcumin has been shown to improve Alzheimer’s disease-like symptoms in mice.
Other animal studies have suggested that curcumin can reduce tau protein clumping in the brain, slowing cognitive deterioration. Scientists have linked the clumping of tau protein to Alzheimer’s disease in humans.
Curcumin also may help protect brain cells, yet other animal studies have shown.
However, despite the evidence that curcumin can combat Alzheimer’s in animals, it has yet to demonstrate such effects in humans. Scientists say that simply eating more curcumin-based curries is unlikely to alleviate Alzheimer’s disease because of the spice’s limited bioavailability in the brain. Bioavailability is the extent to which a therapy is available where it is needed.
The liver and intestines modify curcumin in a way that leads the kidneys to quickly flush it from the body. This leaves little of the polyphenol to work in the brain.
Curcumin in clinical trials
A 24-week Phase 2 clinical trial (NCT00099710) showed that Curcumin C3 Complex failed to generate cognitive improvements in 36 people with mild to moderate Alzheimer’s disease. Most participants tolerated the compound well, but three had to withdraw from the trial due to gastrointestinal problems.
Chinese researchers conducted a six-month-long Phase 1/2 trial (NCT00164749), which showed that a combination of curcumin and gingko extract did not reduce amyloid beta protein levels in the blood of Alzheimer’s patients, or improve their cognition.
An ongoing Phase 2 clinical trial (NCT01811381) is investigating the combined benefits of curcumin and yoga in people with mild cognitive impairment. In the first six months of the study, patients receive either a daily dose of curcumin or a placebo. In the next six months, they continue taking curcumin or a placebo but also engage in aerobic or yoga training.
The trial’s objectives are to see whether curcumin plus exercise can have an effect on blood biomarkers, brain images, and cognitive scores of people with Alzheimer’s. The trial is still recruiting participants in California. It is expected to be completed in December 2019.
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