Lithium Linked to Small Reduction in Dementia Onset

Peter Russell

March 17, 2022

Lithium could be linked to a decrease in the risk of developing dementia for some people, according to a small study.

Researchers at the University of Cambridge described their preliminary findings as "promising" and said that they justified conducting larger, randomised trials to test the results.

Lithium has been proposed as a possible preventative treatment for dementia, but little population-level research has been conducted to support the idea that its use might delay onset.

Observational Investigation Using Medical Records

To try to fill the evidence base, the researchers carried out a retrospective analysis of health records for people over the age of 50 who had accessed NHS mental health services, from Cambridgeshire and Peterborough NHS Foundation Trust, between 2005 and 2019 with a follow-up of at least 12 months. Patients were excluded from the analysis if they had been diagnosed previously with dementia or mild cognitive impairment.

Of the 29,618 patients in the study cohort, mean age of 73.9, 548 had been treated with lithium and 29,070 had not.

The study, published in the journal PLoS Medicine, found that among those who had received lithium, 9.7% were diagnosed with dementia, including Alzheimer's and vascular dementia, compared with 11.2% of those who had not been treated with lithium.

After taking sociodemographic factors, smoking status, other medications, other mental comorbidities, and physical comorbidities into account, lithium use was associated with a lower risk of dementia (hazard ratio 0.56, 95% CI 0.40 to 0.78) both for short- and long-term use. A lack of data meant the researchers were unable to judge possible effectiveness in the medium-term.

Study Limitations

The authors stressed that they could not prove any link between lithium and a decreased risk of dementia because of the observational nature of their investigation and the small number of patients (53) who had been treated with the drug. Crucially, the main limitation was that 73% of the patients in the lithium cohort had mania/bipolar affective disorder with the accompanying, significant risk for dementia.

However, Dr Shanquan Chen PhD, from the university's Department of Psychiatry, and study first author, said: "We expected to find that patients with bipolar disorder were more likely to develop dementia, since that is the most common reason to be prescribed lithium, but our analysis suggested the opposite."

He added: "It's far too early to say for sure, but it's possible that lithium might reduce the risk of dementia in people with bipolar disorder."

Larger scale observational studies should be carried out into the possible association between lithium and dementia, as well as randomised trials to establish whether lithium could delay the onset of dementia in people with mild cognitive impairment, the researchers concluded.

The study was partly funded by the UK Medical Research Council and the National Institute for Health Research Cambridge Biomedical Research Centre.

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