At the start of the study, 18 of the 60 participants had impaired neurovascular coupling. By the end of the study, it had improved by 8.3%.
These participants also improved their scores on a working memory speed test. At the start of the study, it took them 167 seconds to complete the test, while at the end they did it in 116 seconds.
In participants with regular neurovascular coupling at the start of the study, there was no change either in blood flow measures or working memory.
A subset of 24 participants also underwent MRI scans to look for tiny areas of damage in the white matter of the brain. These can occur when there is a restriction in blood flow.
The MRI scans showed that the participants with impaired neurovascular coupling were the ones most likely to have these tiny areas of brain damage.
There was no difference between the participants who drank flavanol-rich cocoa and the ones who drank flavanol-poor cocoa.