Clues why coffee drinkers are at a lower risk of developing dementia

by Damien Gayle for The Daily Mail:Brain scans have for the first time revealed the effects of caffeine on the living human brain and have offered clues as to why coffee drinks are at a lower risk of developing of dementia.Caffeine is the world's most commonly consumed psychoactive drug and an active ingredient in a range of different foods and drinks. In the U.S., 80 per cent of adults taking caffeine everyday - each consuming an average of 200mg, equivalent to two 5oz cups or four cans of Coca-Cola.

'There is substantial evidence that caffeine is protective against neurodegenerative diseases like Parkinson's or Alzheimer's disease,' said Dr David Elmenhorst, of the the Institute of Neuroscience and Medicine. 'Several investigations show that moderate coffee consumption of 3 to 5 cups per day at mid-life is linked to a reduced risk of dementia in late life.'

To investigate why, Dr Elmenhorst and his team used molecular imaging with positron emission tomography to investigate the effects of caffeine on the brains of 15 male volunteers aged between 24 and 66.The volunteers were asked to abstain from any caffeine intake for 36 hours, before an initial PET scan to determine their brains' baseline state. Researchers then injected caffeine directly into the subjects in increasing amounts, scanning their brains as they went along.

The team found that the repeated intake of caffeine can occupy up to 50 per cent of the brain's A1 adenosine receptors, stopping these from receiving the sleep-promoting neurotransmitter they were intended to absorb.It is likely that this blockage of a substantial amount of cerebral A1 adenosine receptors will result in adaptive changes and lead to chronic alterations of receptor express and availability, they said.They determined that it was this structure that may offer some insight as to why coffee drinkers were at lesser risk of dementia.'The present study provides evidence that typical caffeine doses result in a high A1 adenosine receptor occupancy and supports the view that the A1 adenosine receptor deserves broader attention in the context of neurodegenerative disorders,' said Dr Elmenhorst, lead author of the study published in The Journal of Nuclear Medicine.Source: http://bit.ly/Sz7ncNPicture: Alamy