Drinking cocoa may benefit the brain in old age, a study suggests.

The research, funded by the Mars confectionery company, tested the effects of daily cocoa intake on 90 elderly volunteers.

Participants were given milk-based cocoa drinks containing high, intermediate or low levels of plant compounds called flavanols, which are said to reduce the risk of dementia.

After eight weeks, mental performance increased significantly for those given the "high" and "intermediate" drinks.

Consuming the flavanol-rich drinks led to better scores in tests of working memory, verbal memory and task-switching.

Blood pressure and insulin resistance - a pre-diabetic condition - decreased in volunteers drinking high and intermediate levels of flavanols.

Lead researcher Dr Giovambattista Desideri, from the University of L'Aquila in Italy, said: "This study provides encouraging evidence that consuming cocoa flavanols, as part of a calorie-controlled and nutritionally balanced diet, could improve cognitive function.

"The positive effect on cognitive function may be mainly mediated by an improvement in insulin sensitivity. It is yet unclear whether these benefits in cognition are a direct consequence of cocoa flavanols or a secondary effect of general improvements in cardiovascular function."