Lithium in tap water might protect brain from dementia, suggests new research

Drinking water with higher levels of lithium may reduce the risk of developing dementia, according to scientists in Denmark.

Lithium is a substance naturally found in tap water, although the amount varies from area to area. It is known to affect the brain and is used for treating bipolar disorder. But lithium in tap water is present at much lower levels than those used in medication.

The study

The researchers, from the University of Copenhagen, studied 800,000 people. Tap water was tested in 151 areas of the country.

But the results are a little confusing. Moderate levels of lithium appeared to increase the risk of developing the brain disorder more than low levels. But higher levels were associated with the biggest reduction in the risk of getting dementia.

The findings show moderate lithium levels (between 5.1 and 10 micograms per litre) increased the risk of dementia by 22% compared with low levels (below five micrograms per litre).

But – and it’s a big but – those drinking water with the highest lithium levels (above 15 micograms per litre) had a 17% reduction in risk for developing the brain disease.

What do experts think?

David Smith, professor emeritus of pharmacology at University of Oxford said the study was high-quality research, but doesn’t think it will lead us to add more lithium to our water supply.

“The association between the levels of lithium in drinking water and a diagnosis of dementia was significant, however, it was not a linear relationship: the relative risk of dementia increased by 22% when the lithium level increased slightly and then decreased by 17% when the level became much higher. Thus, the study does not have any public health implications: we should not be adding lithium salts to our tap water because we would not know what amount to use.”

While Dr James Pickett, head of research at Alzheimer’s Society explained that lithium can trigger a number of useful responses in brain cells. So, in theory, it might work as a treatment for Alzheimer’s disease. But at the moment, there’s not enough evidence for us to be sure it would be useful in preventing dementia.

“It’s almost too good to be true that something as cheap and plentiful as Lithium might have a role in future prevention of Alzheimer’s disease. However, more research including clinical trials are needed, and until then we should not consider increasing lithium in drinking water. In high doses, or even at low doses in some people, lithium can be toxic so it is important that people consult with their doctor before they consider taking it as a supplement,” he concluded.