The Department of Neurology, Stroke Division, Brigham and Women’s Hospital, Boston, Massachusetts, published on Neurology a study that certified as drinking cocoa, whether rich in flavonoids or not, appears to boost the effect of blood flow on neuronal activity in the brain, known as neurovascular coupling (NVC).
This one shows not only that drinking flavonoid-rich or flavonoid-poor cocoa improves NVC but also that higher NVC is associated with better cognitive performance and greater cerebral white matter structural integrity in elderly patients with vascular risk factors.
As researchers search for ways to detect dementia at the earliest possible stage, the study results could pave the way for using NVC as a biomarker for vascular function in those at high risk for dementia.
Participants were randomly assigned to 2 cups a day of cocoa rich in flavonoids (609 mg per serving) or cocoa with little flavonoids (13 mg per serving). Diets were adjusted to incorporate the cocoa, each cup of which contained 100 calories. Participants were also asked to abstain from eating chocolate.
Researchers measured cerebral blood flow using transcranial Doppler ultrasonography. Among other things, they documented changes in the middle cerebral artery and blood flow velocity at rest and in response to cognitive tasks (NVC).
The study showed that NVC was tightly correlated with cognition; scores significantly better in those with intact NVC.Participants with intact NVC also had significantly better performance on the 2-Back Task, a test for both attention and memory (82% vs 75%; P = .02).
That shows as higher you increase your blood flow during a cognitive task, the better your cognitive performance.
NVC was also correlated with cerebral white matter structural integrity.
These results suggest that NVC could be an important therapeutic target. But before NVC has to be considered a biomarker.
The study found that blood pressure, blood flow, and change in NVC were not significantly different between the 2 cocoa groups.
The authors were surprised at the lack of effect of flavonoids because previous research had indicated a dose-response with respect to cognitive performance. It could be something other than flavonoids in the cocoa, possibly caffeine, that improves NVC, or it could be that the 13 mg in the low-flavonoid cocoa group was enough to have an effect.
In demonstrating a link between NVC and cerebral white matter structural integrity, the study provides an important validation for the association between vascular and cognitive function.