Long-Term Study Finds No Link Between Fluoridated Water and Cognitive Decline

Fluoride has been added to drinking water for decades worldwide to reduce tooth decay, a practice considered a major public health success. However, recent debates have questioned whether fluoride exposure might also affect brain development and cognitive function. A new long-term study based on data from over 10,000 individuals in Wisconsin, USA, found no evidence that fluoride levels typical of water fluoridation in the United States are associated with lower cognitive abilities.

The study tracked participants who graduated high school in 1957, comparing those from areas with fluoridated water to those without. Researchers assessed IQ scores in adolescence and conducted repeated memory and cognitive function tests up to age 80. The results showed no correlation between fluoridated water exposure and reduced IQ, memory impairment, or other cognitive declines over the lifespan.

Fluoride naturally occurs in rocks and water sources and strengthens tooth enamel, helping prevent cavities. Excessive fluoride can cause dental fluorosis, leading to tooth discoloration, which led to controlled fluoridation policies starting in the 1940s in the US, Canada, and other countries. The World Health Organization recommends fluoride concentrations in drinking water not exceed 1.5 mg per liter to avoid health risks, with US guidelines suggesting 0.7 mg per liter for optimal dental benefits.

The study's limitations include indirect fluoride exposure estimates based on residence and water fluoridation history, without measuring individual fluoride intake from other sources like toothpaste or diet. Nonetheless, the research focused on fluoride levels typical of controlled water fluoridation, not the higher natural concentrations examined in some previous studies raising concerns.

In Israel, fluoride discussions have gained urgency due to widespread use of desalinated water, which removes natural fluoride, and the 2014 cancellation of mandatory water fluoridation. Although health authorities support reinstating fluoridation, it has not yet resumed. This new research contributes important evidence suggesting that fluoridated water at recommended levels does not impair cognitive development, though the debate continues globally.