Lithium is naturally found in vegetables, grains and, at very low concentrations, in the water supply. These trace levels of lithium in water vary depending on the geology of a particular area. At much higher levels, lithium is sometimes prescribed as a treatment for bipolar disorder.
This Danish study involved 73,731 people with dementia and 733,635 unaffected control participants. The researchers looked at address records to calculate how much lithium each participant had been exposed to through the water supply. Their analysis indicated that people who had been exposed to the highest levels of lithium had the lowest rates of dementia. But this relationship was not straight forward and people exposed to the lowest levels of lithium were not found to have the highest rates of dementia.
Dr David Reynolds, Chief Scientific Officer of Alzheimer’s Research UK, said:
“While, overall, this research pointed to lower rates of dementia in areas with higher levels of lithium in the water supply, this relationship was not straight forward and the study does not suggest that regular doses of lithium that may be prescribed for conditions like bipolar disorder could reduce the risk of dementia. Previous studies investigating whether lithium could treat or affect the risk of dementia have been mixed and we need to see much more research before we can tell if lithium could benefit people’s lives in this way.
“This well-conducted study was able to take advantage of comprehensive health and address records for hundreds of thousands of people in Denmark to determine how much lithium each participant was exposed to through the water supply. Large population-based studies like this are extremely useful for identifying factors linked with dementia risk, but they can’t tell us what the root cause of an association might be. A number of factors relating to where someone lives could play a role in how many people go on to develop dementia and this study did not take differences in access to healthcare across the country into account, nor does it look at how financially well-off people are in these different areas– a factor that is closely interwoven with many aspects of our health.
“It is potentially exciting that low doses of a drug already available in the clinic could help limit the number of people who develop dementia but these findings need to be followed up in future studies. Analysis carried out by Alzheimer’s Research UK suggests that a treatment that could delay dementia by just five years would mean that 666,000 fewer people develop dementia by 2050 and save the economy billions every year. It is crucial that we see continued investment in dementia research so that scientists are able to evaluate and realise the clinical potential of interesting findings like this.”