How many cups of coffee can you drink per day and what does it do to the brain?
Many of us enjoy a cup or two of coffee throughout the day, but a new study suggests what more coffee can do to the brain.
The study found that those who drink a lot more may cause their brains to shrink and increase their risk of dementia over time.
A new study published in Nutritional Neuroscience found that people who drank six or more cups a day were 53% more likely to develop dementia than those who drank one or two cups or less.
The study included 17,702 participants aged 37 to 73, whose data was taken from Britain's Biobank project, a long-term project that collected information on a range of health and lifestyle metrics including coffee consumption, brain size and disease, as well as additional data such as socioeconomic status.
"Coffee is one of the most popular drinks in the world," says epidemiologist Kitty Pam from the University of South Australia.
"However, with global consumption rising to more than £9 billion a year, it is critical to understand that this is likely to have potential health consequences," she adds.
She explains that this is the most comprehensive research on the relationship between coffee and measurements of brain volume, dementia risk and stroke risk.
And while we know that coffee affects the brain in many ways — including maintaining alertness — previous studies have been unclear, and in some cases contradictory, when it comes to the relationship between brain size and dementia.
After including variables such as gender, age, body mass index and long-term disease, the researchers found an association between drinking more coffee and smaller brain volume among participants, as well as an increased risk of dementia.
"Given all the potential changes, we have consistently found that higher coffee consumption is significantly associated with lower brain volume - in fact, drinking more than six cups of coffee per day may increase the risk of brain diseases such as dementia and stroke," says Pam.
The study did not provide a clear reason why this occurs and it remains to be known how caffeine and coffee interact with brain cells and whether these interactions are positive or ultimately negative.
One way these changes occur may be the way caffeine binds to adenosine receptors in the brain, although it may be less direct due to coffee's effect on other parts of the body (such as the cardiovascular system).
What we can say from this study is that multiple coffee consumption appears to be associated with a higher risk of dementia.
