Caffeine's effect on the brain's adenosine receptors visualized for the first time

November 1, 2012

Molecular imaging with positron emission tomography (PET) has enabled scientists for the first time to visualize binding sites of caffeine in the living human brain to explore possible positive and negative effects of caffeine consumption. According to research published in the November issue of The Journal of Nuclear Medicine, PET imaging with F-18-8-cyclopentyl-3-(3-fluoropropyl)-1-propylxanthine (F-18-CPFPX) shows that repeated intake of caffeinated beverages throughout a day results in up to 50 percent occupancy of the brain's A1 adenosine receptors.

"The effects of caffeine to the human body are generally attributed to the cerebral . In the the A1 adenosine receptor is the most abundant," said David Elmenhorst, MD, lead author of "Caffeine Occupancy of Human Cerebral A1 Adenosine Receptors: In Vivo Quantification with F-18-CPFPX and PET." "In vitro studies have shown that commonly consumed quantities of caffeine have led to a high A1 adenosine occupancy. Our study aimed to measure the A1 adenosine receptor occupancy with in vivo imaging."

Fifteen male volunteers participated in the study. They abstained from caffeine intake for 36 hours and then underwent a PET scan with F-18-CPFPX. Caffeine was then introduced in short , increasing in amount. To estimate the occupancy of A1 adenosine receptors by caffeine, the distribution volume at the baseline period of the PET scan was compared with the distribution volume after caffeine administration. Researchers determined that the concentration of the caffeine that displaces 50 percent of the binding of F-18-CPFPX to the A1 adenosine receptor was 13 mg/L, or approximately four to five cups of coffee.

An important finding of the study is that in most regular about half of the A1 adenosine receptors may be occupied by caffeine. 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.

"There is substantial evidence that caffeine is protective against neurodegenerative diseases like Parkinson's or Alzheimer's disease," noted Elmenhorst. "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. 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."

Caffeine is the most commonly consumed psychoactive substance worldwide and an active ingredient in innumerable food and beverages. Eighty percent of U.S. adults consume caffeine every day; the average for adults is 200 mg of caffeine per day (two 5-ounce cups of coffee or four sodas). It affects an individual's alertness, attention, cognitive performance, as well as reduces sleepiness.

Explore further: Probing Question: Is caffeine harmful to your health?

More information: "Caffeine Occupancy of Human Cerebral A1 Adenosine Receptors: In Vivo Quantification with 18F-CPFPX and PET", The Journal of Nuclear Medicine, 2012.

Related Stories

Probing Question: Is caffeine harmful to your health?

October 5, 2006

A steaming cup of black coffee in the morning is to many people what gasoline is to their cars: essential fuel. The active ingredient in that fuel? Caffeine, a central-nervous-system stimulant found in the leaves and beans ...

Caffeine prevents multiple sclerosis-like disease in mice

April 7, 2008

Mice given caffeine equivalent to a human drinking six to eight cups of coffee a day were protected from developing experimental autoimmune encephalomyelitis (EAE), the animal model for the human disease Multiple Sclerosis ...

Recommended for you

Basic research fuels advanced discovery

August 26, 2016

Clinical trials and translational medicine have certainly given people hope and rapid pathways to cures for some of mankind's most troublesome diseases, but now is not the time to overlook the power of basic research, says ...

New method creates endless supply of kidney precursor cells

August 25, 2016

Salk Institute scientists have discovered the holy grail of endless youthfulness—at least when it comes to one type of human kidney precursor cell. Previous attempts to maintain cultures of the so-called nephron progenitor ...

New avenue for understanding cause of common diseases

August 25, 2016

A ground-breaking Auckland study could lead to discoveries about many common diseases such as diabetes, cancer and dementia. The new finding could also illuminate the broader role of the enigmatic mitochondria in human development.

Strict diet combats rare progeria aging disorders

August 25, 2016

Mice with a severe aging disease live three times longer if they eat thirty percent less. Moreover, they age much healthier than mice that eat as much as they want. These are findings of a joint study being published today ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

MikeBudd
not rated yet Nov 25, 2012
Very interesting! With friends doctors we just finished a global review of the health risks and benefits of coffee and our conclusion is that coffee is great in moderation only, mainly due to antioxidant and antimutagenic properties: ephedrinewheretobuy.com/ephedrine-where-to-buy-eca-stacks/coffee-a-true-wonder-drug
We will read this study with great interest and add it to our references.
Many thanks, Mike

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.