The study published in The Journals of Gerontology found there was a lower chance of dementia or cognitive impairment in older women whose caffeine consumption was above average.
The findings support other research showing that in older adults, caffeine can improve memory, which tends to peak in the morning and decline during the late afternoon,
The results go some way in supporting claims that caffeinated drinks such as coffee, tea and cola beverages have a role in halting cognitive decline.
Of these drinks, it is coffee that is the main contributing source of caffeine in the diet. The EFSA Comprehensive European Food Consumption Database shows coffee consumption is at its highest in adults at 36.5-319.4 mg per day.
When you drink coffee-or anything else that has caffeine as an ingredient-your central nervous system gets a mild jolt. The presence of caffeine in your system does a number of things. It 'wakes up' your brain, gets your digestive tract going, speeds up your metabolism and raises the brain levels of serotonin, a neurotransmitter that affects mood. Because caffeine is known to help release additional free fatty acids for energy, some people will drink a cup of coffee or take caffeine pills before they workout.
A typical cup of black coffee contains around 85 mg of caffeine. The exact amount depends on brewing approach, brew strength and specific coffee bean.
The study looked at the recorded caffeine consumption of a total of 6,467 women.
Differences in when dementia or cognitive impairment were diagnosed among women and their caffeine intake were assessed.
In yearly cognitive assessments that lasted up to 10 years, 388 women were diagnosed with probable dementia.
Risk factors such as age, race, education, body mass index (BMI), prior cardiovascular disease, diabetes, smoking and alcohol consumption were also taken into account.
Future prevalence of neurodegenerative conditions such as Alzheimer's Disease is expected to quadruple by 2050,
The team, from the University of Wisconsin-Milwaukee, found women consuming above median levels of caffeine intake (mean intake - 261mg/day) for this group were less likely to develop incident dementia or any cognitive impairment compared to those consuming below median amounts (mean intake - 64mg/day) of caffeine for this group.
"The literature suggests several possible mechanisms that may provide clues to the causal pathways. At normal daily consumption range per person, which is 2-4 cups of coffee, the primary action of caffeine is that of a nonselective adenosine receptor antagonist."
Compounds such as caffeine and theophylline act as non-selective antagonists receptors in both the heart and brain and have a stimulatory effect and increase heart rate.
These findings are generally consistent with available literature. A study looking into similar observations in European men found those who consumed three cups of coffee per day had the lowest cognitive decline over a 10-year period.
Likewise, a recent literature review reported a modest reduction in rates of cognitive decline across six studies.
While the evidence appears compelling study lead Ira Driscoll, a professor of psychiatry at the University of Wisconsin-Milwaukee expressed caution at her study's findings until further research could be carried out.
"We are certainly not suggesting that caffeine cures or prevents neurodegenerative conditions such as Alzheimer's disease (AD)." she said. "I would suggest that it certainly isn't harmful and may in fact be protective."
"We know that AD is a multifactorial disease, and it is unlikely that altering this one component of one's diet will cure us of AD. But when it comes to AD, I think we can all agree that this is a pretty innocuous way of potentially lowering one's odds of developing AD."
An Adjustable Dietary Factor
The European Union has the highest per capita coffee consumption in the world.
Accumulating evidence of caffeine intake as a possible protective factor against neurodegeneration is exciting as caffeine is an easily adjustable dietary factor with very few side effects.
The study concluded by recommending research that further quantified its relationship with cognitive health outcomes to better understand underlying mechanisms and their role in dementia and cognitive impairment.
Commenting on future AD prevalence, which is expected to quadruple by 2050 , Driscoll said: "Anything that potentially lowers the odds of AD could have an enormous impact on what is rapidly becoming a global healthcare and economic crisis."
According to the European Coffee Federation, the EU has the highest per capita coffee consumption in the world.
The EU consumes 2.5 million tonnes coffee per year, which equates to four kilos of roasted coffee per EU inhabitant per year. Every day some 725 million cups of coffee are drunk in the EU.