Clare Dolman reports on research into the role of lithium in the prevention of dementia

If, like me, you take lithium, you may be glad to hear it has some unexpected benefits.  I’ve been taking the ‘little white pills’ for over 30 years now and I’m one of the lucky ones; not only is it very effective in controlling my mood swings but I also suffer virtually no side effects: no tremor, only slight weight gain which tennis helps with and the ‘mind dulling’ effect familiar to many has definitely lessened since I (very gradually) reduced my dose to put me at the very bottom of the therapeutic dose. 

Unfortunately many people who could definitely benefit from taking it (it’s the most effective treatment for bipolar disorder) are put off by its ‘scary’ associations. Take a look at the latest research to see that this stigma is misplaced and very damaging as lives could be saved if it’s definite benefits were recognised (see  the guardian: lithium should be more widely used for bipolar disorder).

Anyway, not only does it actually work for many of us – it might stop us from getting dementia too! For over a decade, researchers have been talking about the association between lithium as a possibly protective agent against dementia.  Results from the few studies conducted have been inconclusive, though experts in the field (including our own Bipolar UK Board member Professor Allan Young) think there is enough of an association to indicate it might play a role.  Certainly it’s been established that, though having bipolar slightly increases your chances of getting dementia, if you take lithium the odds return to at least the same as for the non-bipolar population.

But a fascinating population-wide study published in JAMA Psychiatry has now supported this theory by suggesting that lithium could be a potential candidate for dementia prevention.

Study co-author Dr. Lars Vedel Kessing, of the University of Copenhagen in Denmark, and his team set out to determine whether there might be a link between exposure to lithium in drinking water and the risk of dementia.

The team analysed data from a Danish population-based registry, including 73,731 adults who had been diagnosed with dementia between 1995 and 2013, alongside 733,653 adults who did not have dementia.

The researchers also analysed drinking water samples retrieved from 151 waterworks in Denmark, which supply water to around 42 percent of the country's population. By calculating the lithium content in each of the water samples and tracking the residential addresses of each participant, the researchers were able to estimate the subjects' mean lithium exposure since 1986.

Compared with adults who had not been diagnosed with dementia, adults who had received a dementia diagnosis were found to have been exposed to lower levels of lithium in drinking water.

In detail, the researchers found that the incidence of dementia was 17% lower for adults whose lithium exposure was 15 micrograms per litre or higher, compared with adults exposed to 2 to 5 micrograms per litre, though the association was non-linear.

Dr Kessing and colleagues acknowledged the study had limitations: for example, they did not account for participants' access to healthcare services, which could influence the likelihood of a dementia diagnosis.

Accordingly, the research community has greeted the study with a certain amount of caution.  But two experts in the field, Drs John McGrath and Michael Berk, are excited by the possibilities:

"[While acknowledging the study’s limitations], the prospect that a relatively safe, simple, and cheap intervention (i.e., optimizing lithium concentrations in the drinking water) could lead to the primary prevention of dementia is a tantalizing prospect," they write.

"If the findings of Kessing and colleagues are supported in future studies, even a marginal reduction in the incidence of dementia could result in major societal and economic gains."

And for those of us who are already taking lithium, it could add weight to the theory that by so doing we are also protecting ourselves from one of the most horrible diseases of old age.

Reference: Association of Lithium in drinking water with the incidence of Dementia. Lars Kessing et al. JAMA Psychiatry. 2017;74(10):1005-1010. doi:10.1001/jamapsychiatry.2017.2362