A commercially available nutraceutical supplement composed of, among other ingredients, green tea and blueberries led to modest improvements in cognitive processing speed in older, cognitively healthy adults, according to results of a randomized, placebo-controlled trial.
This finding is "noteworthy" given that processing speed is "most often affected early on in the course of cognitive aging, and successful performance on these tasks often underlies more complex cognitive outcomes, such as memory and verbal ability," the researchers write.
The study was published in Rejuvenation Research.
The nutraceutical NT-020 contains a proprietary formulation of blueberry, carnosine, green tea, vitamin D3, and Biovin. It was patented by the University of South Florida (USF) in partnership with the James A. Haley Veterans' Hospital and licensed to Natura Therapeutics, Inc. The supplement is commercially available as NutraStem.
The study team randomly assigned 113 healthy adults aged 65 to 85 years to NT-020 (2 pills daily) or matching placebo for 2 months. Eight people dropped out (6 in the NT-020 group and 2 in the placebo group), most indicating that they no longer had time to participate, leaving 105 to complete the study.
At baseline and after 2 months, participants underwent a battery of cognitive performance tests of episodic memory, processing speed, verbal ability, working memory, executive functioning, and complex speed.
The researchers note that adults taking NT-020 "improved significantly" from baseline on 2 measures of processing speed, namely, the identical pictures test (P = .021) and the number comparison task (P = .012). The placebo group had no change on the identical pictures test and a slight decline on the number comparison task.
None of the other cognitive ability measures were related to intervention group. NT-020 was well tolerated.
Co–principal investigator Brent Small, PhD, of the School of Aging Studies at USF, in Tampa, told Medscape Medical News that it is "somewhat unclear" whether the improvement in processing speed is clinically meaningful, mainly due to the study population.
"Gains of the magnitude that we saw here are positive, but it is hard to say if they are clinically meaningful because we are dealing with a population that is not clinically impaired," said Dr. Small. "Currently, we are seeking funding for additional studies that will focus on persons with mild cognitive impairment," he added.
In prior preclinical studies, the researchers gave aging laboratory rats NT-020 and found that it promoted the growth of stem cells in the brain, produced an overall rejuvenating effect, benefited animals with simulated stroke, and led to better cognitive performance.
"NT-020 is 95% polyphenols," study co–principal investigator Paula C. Bickford, PhD, of the Department of Neurosurgery and Brain Repair, USF Health Morsani College of Medicine, and senior research career scientist at the James A. Haley Veterans' Hospital in Tampa, said in a statement.
"The basis for the use of polyphenol-rich nutritional supplements as a moderator of age-related cognitive decline is the age-related increase in oxidative stress and inflammation. Nonvitamin polyphenols are the most abundant modulators of oxidative stress and inflammation in our diet," she explained.
Reached for comment, Robert Krikorian, PhD, of the Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati Academic Health Center in Ohio, said the current study "appears to have been designed well, and the discussion concerning the modest positive findings and the limitations of the study seem thorough."
"In particular," said Dr. Krikorian, "as the authors noted, the relatively high preintervention level of functioning may have been a factor mitigating ability to measure benefit from the supplementation. That is, there may have been a ceiling effect."
"Also, the time frame of the intervention was briefer than many of our natural products studies. On the other hand, showing improvement in processing speed is impressive, as diminished speed of processing with aging is a well-established observation," Dr. Krikorian noted.
Although the team's observations "need to be corroborated, it provides a basis for further investigation of this product, perhaps with a sample of individuals with mild cognitive decline," he said.
In his own research, Dr. Krikorian has found that blueberry juice may boost memory in older adults with early memory decline, as previously reported by Medscape Medical News.
The current study was supported by a grant from the USF Neuroscience Collaborative. Dr. Small has disclosed no relevant financial relationships. Two of the authors are cofounders of Natura Therapeutics, which developed and markets NT-020. Dr. Krikorian has disclosed no relevant financial relationships.
Rejuvenation Res. Published online October 17, 2013. Abstract
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Cite this: Green Tea, Blueberry Supplement May Improve Cognition - Medscape - Feb 13, 2014.