Drinking two cups of hot chocolate a day may help older people keep their brains healthy and their thinking skills sharp, according to a new study. US researchers studied 60 people with an average age of 73 who did not have dementia. The participants drank two cups of hot cocoa per day for 30 days and did not consume any other chocolate during the study. They were given tests of memory and thinking skills. They also had ultrasounds tests to measure the amount of blood flow to the brain during the tests. \"We\'re learning more about blood flow in the brain and its effect on thinking skills,\" said study author Farzaneh A Sorond, of Harvard Medical School in Boston and a member of the American Academy of Neurology. \"As different areas of the brain need more energy to complete their tasks, they also need greater blood flow. This relationship, called neurovascular coupling, may play an important role in diseases such as Alzheimer\'s,\" Sorond said. Of the 60 participants, 18 had impaired blood flow at the start of the study. Those people had an 8.3 per cent improvement in the blood flow to the working areas of the brain by the end of the study, while there was no improvement for those who started out with regular blood flow. The people with impaired blood flow also improved their times on a test of working memory, with scores dropping from 167 seconds at the beginning of the study to 116 seconds at the end. There was no change in times for people with regular blood flow. A total of 24 of the participants also had MRI scans of the brain to look for tiny areas of brain damage. The scans found that people with impaired blood flow were also more likely to have these areas of brain damage. Half of the study participants received hot cocoa that was rich in the antioxidant flavanol, while the other half received flavanol-poor hot cocoa. There were no differences between the two groups in the results. \"More work is needed to prove a link between cocoa, blood flow problems and cognitive decline. But this is an important first step that could guide future studies,\" said Paul B Rosenberg, of Johns Hopkins School of Medicine in Baltimore, who wrote an editorial accompanying the study. The study was published in Neurology, the journal of the American Academy of Neurology.