A study found no link between long-term fluoridated water consumption and poorer cognition in older adults. The study used data from about 2,500 people around the age of 65. The study was in Ireland, and everyone in the study had been exposed to fluoridated water for at least 50 years. Ireland has had fluoridated water nationally since 1964.
Levels of fluoride concentration in water vary across Ireland. The study categorized people by high, medium or low levels of fluoride exposure, based on where they had lived throughout their lives. The participants took two cognitive assessments. The results were compared to the different exposure groups. No pattern was seen between fluoridated water and cognitive scores.
“Our findings provide reassurance that lifetime exposure to fluoridated drinking water at the levels used in Ireland is not associated with poorer cognitive function in older adults,” said Dr. Vinay Sharma, from Trinity’s School of Medicine, who is the lead author of the study, just published in the Journal of Dental Research. “This is an important public health question, and we hope these findings contribute to an evidence-based conversation about the safety of the community water fluoridation program in Ireland and internationally. Most previous studies have only looked at fluoride exposure over a short window, either in childhood or in adulthood, rather than tracking it continuously across a person’s life and then testing cognitive function later on. That’s what sets this study apart.”
There has been growing public debate about the safety and benefit of fluoride and whether it harms the brain. This study found no link between fluoride and cognitive problems in older people. But the researchers said that only five percent of participants in the study had fluoridated water as young children. Most people in the study were over the age of five in 1964. So, the study does not draw any conclusions about how fluoridated water may impact developing brains.
It’s also important to note that finding no link between fluoride and cognitive problems doesn’t prove that fluoride doesn’t harm the brain, just that evidence that it does wasn’t found. Several older studies found that excessive fluoride exposure may harm the brain. In this study, no one was drinking excessive amounts.
“Fluoridation has been one of the most effective tools we have for reducing tooth decay at a population level, so it matters that we now have long-term Irish evidence that it isn't costing anything in terms of cognitive health,” added Dr. Michael Crowe, co-principal investigator of the study.
