Previous studies have suggested coffee consumption may lower the risk of mild cognitive impairment. But new research suggests this protective effect may depend on how coffee consumption habits change over time.
Published in the Journal of Alzheimer's Disease, the study involved 1,445 people aged 65-84 who were part of the Italian Longitudinal Study on Aging (ILSA).
Co-author Dr. Vincenzo Solfrizzi, of the University of Bari Aldo Moro in Italy, and colleagues followed the participants for an average of 3.5 years, monitoring their coffee consumption habits and the incidence of mild cognitive impairment (MCI).
MCI is the decline in cognitive abilities, such as memory and thinking skills. It is estimated that approximately 10-20% of individuals in the US aged 65 and older may have MCI, and the condition is considered a risk factor for Alzheimer's disease - the most common form of dementia.
The results of the study revealed that cognitively normal participants who increased their coffee consumption during the study period to more than one cup daily were twice as likely to develop MCI than those who reduced their coffee consumption to less than one cup a day.
Participants whose coffee consumption increased over time were also around 1.5 times more likely to develop MCI than those whose coffee consumption remained stable - no more or less than one cup of coffee each day.
However, participants who consistently drank a moderate amount of coffee - defined as one or two cups daily - were at lower risk of MCI compared with those who never or rarely consumed coffee.
No significant link was found between coffee consumption and MCI incidence among participants who consistently drank higher amounts of coffee - defined as more than two cups daily - compared with participants who never or rarely drank the beverage.
Commenting on their findings, the researchers say:
"These findings from the Italian Longitudinal Study on Aging suggested that cognitively normal older individuals who never or rarely consumed coffee and those who increased their coffee consumption habits had a higher risk of developing MCI.
Therefore, moderate and regular coffee consumption may have neuroprotective effects also against MCI, confirming previous studies on the long-term protective effects of coffee, tea, or caffeine consumption and plasma levels of caffeine against cognitive decline and dementia."
Moderate caffeine consumption may reduce damaging effects of beta-amyloid
While the exact mechanisms behind the neuroprotective effect of moderate coffee consumption identified in this study are unclear, Dr. Solfrizzi and colleagues have some theories.
- More than half of Americans aged 18 and older drink coffee every day
- On average, American adults drink around 3.1 cups of coffee daily
- The US spends around $40 billion on coffee each year.
For example, they hypothesize that the main compound in coffee, caffeine, may lower activation of adenosine A2A receptors (A2ARs), reducing damage caused by beta-amyloid - a protein fragment that builds up in the brains of people with Alzheimer's, impairing communication between nerve cells.
The team notes that animal studies have shown an optimal amount of caffeine is required to reduce activation of certain A2ARs, which may also explain why participants in this latest study who never or rarely consumed coffee or who consumed higher amounts had higher incidence of MCI.
The researchers say further studies are warranted to determine what drives coffee's protective effect against MCI.
"Larger studies with longer follow-up periods should be encouraged, addressing other potential bias and confounding sources, so hopefully opening new ways for diet-related prevention of dementia and Alzheimer's disease," they conclude.
In March, Medical News Today reported on a study that associated high coffee consumption with reduced liver cancer risk, while a study published in PLOS ONE in May found men who drink two to three cups of coffee daily may be at lower risk for erectile dysfunction.