In more good news for coffee lovers, a new study suggests that middle-aged adults who regularly drink a cup of java may have a lower risk of developing dementia later in life.

Whether coffee itself deserves the credit is not yet clear, but researchers say the findings at least suggest that coffee drinkers can enjoy that morning cup "in good conscience."

The study found that among 1,400 Finnish adults followed for 20 years, those who drank three to five cups of coffee per day in middle-age were two-thirds less likely than non-drinkers to develop dementia, including Alzheimer's disease.

The findings, reported in the Journal of Alzheimer's Disease, add to a string of studies finding that coffee drinkers have lower risks of several diseases, including Parkinson's disease, certain cancers and diabetes.

No one is recommending that people start drinking coffee to ward off any disease, however. Researchers do not know if it's components of coffee itself — like caffeine or certain antioxidants — or something else about coffee drinkers that explains the recent study observations.

The current study was an epidemiological one, explained lead researcher Marjo H. Eskelinen, which means it can point to an association between coffee and dementia risk, but does not prove cause-and-effect.

Still, "the results open a possibility that dietary interventions could modify the risk of dementia," Eskelinen, a doctoral candidate at the University of Kuopio in Finland, told Reuters Health.

There are a few potential reasons why coffee could help stave off dementia, researchers point out. One reason is related to the fact that coffee drinkers may have a lower risk of type 2 diabetes, and diabetes, in turn, is linked to a higher risk of dementia.

Coffee also contains plant chemicals, such as chlorogenic acid, that act as antioxidants and may help protect body cells from damage over time. For its part, caffeine may have a protective effect on brain cells because it blocks receptors for a chemical called adenosine, which has depressant effects in the central nervous system.

More research is needed to determine whether coffee is truly protective, but for now, Eskelinen said, "those people who have been drinking coffee can still do so in good conscience."