There are many clinical studies at the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH), supporting the contention coffee does have favorable effects against cognitive decline, dementia or Alzheimer's disease.

One of these online studies published in 2010 indicated three of the five studies it looked at agree coffee does have some positive effects on cognitive functioning. A 2016 published study noted that "in the future experts will recommend drinking coffee not only to satisfy individual taste preferences but also to decrease age-related mental deterioration." This study also stated it "seems safe to inform the general public that coffee drinkers need not fear for their health."

This seems to be good news for coffee drinkers worldwide that quaff two billion cups of coffee every day. It's also welcome news for those worried about contracting Alzheimer’s disease (AD), the most frequent cause of dementia in the world. It's estimated anywhere from 50 percent to 70 percent of people with dementia suffer from AD.

There are also many other studies dealing with the positive effects coffee has against cognitive decline. One source said many of these studies suggest regular coffee consumption over a lifetime reduces the risk of developing AD, especially in the elderly. On the other hand, some studies don't support this conclusion, while others show varying results.

What seems clear is coffee consumption might be especially beneficial before the occurrence of the AD, that is to say, during what's called the pre-morbid phase.

Some meta-analyses and reviews also support the view coffee consumption is associated with a reduced risk of AD. One of these, published in 2007, reviewed observational studies suggesting coffee consumption was associated with a reduced risk of AD by 30 percent, as compared to non-coffee drinkers.

Four studies conducted between 1990 and 2002 were included in this review. Overall, the results suggest coffee consumption does provide a protective effect.

A 2010 study found a daily intake of three to five cups of coffee in middle age might lower the risk of the dementia and AD by about 65 percent, compared to lower amounts of coffee. The study authors, however, also highlighted the fact some findings are inconsistent.

Woman drinking coffee
A smell test might be able to determine if a person has Alzheimer's. Photo courtesy of Pexels/Public Domain