The body's manufacture of CoQ10 begins to drop after the age of about 20, leading to its investigation in age-related disease. It has been shown to help prevent Parkinson's and is also thought to prevent skin ageing, significantly boosting demand in recent years to more than $200m (€162m) across the US alone.
The new study, by researchers from Hamdard University in India, John Hopkins University and the Pediatrics Medical University of South Carolina in the US, looked at the effect of CoQ10 supplementation on rats with forced brain impairment and oxidative damage.
Although the mechanism of Alzheimer's is not clear, more support is gathering for the build-up of plaque from amyloid deposits. The deposits are associated with an increase in brain cell damage and death from oxidative stress.
It is against the oxidative stress that CoQ10 appear to offer protection.
"CoQ10 supplementation improves learning and memory deficits possibly by inhibiting the oxidative stress and improving levels of ATP," wrote lead author Tauheed Ishrat in the journal Behavioural Brain Research (doi: 10.1016/j.bbr.2006.03.009).
One-year old male rats were divided into four groups, with ten animals in each group. The first group was used as the control, the second group received a daily supplement of CoQ10 in corn oil (10 mg per kg body weight), the third group received an injection into the brain of streptozotocin (STZ) to induce Alzheimer-type damage and no diet supplementation, and the fourth group was injected with STZ and received a daily supplement of CoQ10.
After three weeks, the researchers found that animals in the third group (STZ treated with no CoQ10 supplement) showed a loss of cognitive performance. However, the STZ treated rats that received the CoQ10 supplements performed comparably with rats in group 2 (CoQ10 supplement only) and group 1 (control).
Biochemical analysis of the brain tissues showed that adenosine triphosphate (ATP) - the main energy vehicle in energy transfer - was significantly reduced in the STZ treated group, but not in the three other groups, leading the researchers to suggest that CoQ10 has an important role in intracellular electron transport for ATP production.
"CoQ10 significantly reversed the impact of oxidative alterations seen in STZ rats; this shows the antioxidant potential of CoQ10," concluded the researchers.
It is not clear if such studies can be directly extended to humans and significant further study is required.
Public demand for CoQ10-containing products has seen the market grow. In the United States most new CoQ10 products have been supplements, with fewer skin care products hitting the market.
In Europe, meanwhile, CoQ10 has proved more popular in skin care formulations than in supplements, thanks to its anti-aging antioxidant properties.
Conservative estimates put worldwide sales of CoQ10 at around $350 million in 2004.
These new results add to earlier research linking CoQ10 to reduced risk of Parkinson's disease and appear in-keeping with the cognitive benefits of the coenzyme.
Alzheimer's disease is the most common form of dementia and currently affects over 13 million people worldwide. The direct and indirect cost of Alzheimer care is over $100bn (€81bn) in the US alone. The direct cost of Alzheimer care in the UK was estimated at £15bn (€22bn).