In a study involving 29,618 patients, prescription lithium use was associated with a lower risk of receiving a diagnosis of dementia and its subtypes, including Alzheimer’s disease and vascular dementia.
Dementia is the leading cause of death and disability in elderly Western populations: approximately 47 million people had dementia worldwide in 2015, and this number is projected to triple by 2050.
Preventative interventions that could delay dementia onset even modestly would provide a major public health impact.
It has been estimated that delaying onset by 5 years would reduce the prevalence and economic impact of dementia by 40%.
Lithium, a mood stabilizer usually prescribed for conditions such as bipolar affective disorder and depression, has been proposed as a potential therapy.
It has positive effects in cell and animal models of dementia, and there is evidence for its neuroprotective effects from experimental research and clinical studies using brain imaging.
“The number of people with dementia continues to grow, which puts huge pressure on healthcare systems,” said lead authors Dr. Shanquan Chen, a researcher in the Department of Psychiatry at the University of Cambridge.
In their study, Dr. Chen and his colleagues analyzed data from patients who accessed mental health services from Cambridgeshire and Peterborough NHS Foundation Trust between 2005 and 2019.
Patients were all over 50 years of age, received at least a one-year follow-up appointment, and had not been previously diagnosed with either mild cognitive impairment or dementia.
Of the 29,618 patients in the study cohort, 548 patients had been treated with lithium.
Their mean age was 73.9 years; a total of 40.2% were male, 33.3% were married or in a civil partnership, and 71% were of white ethnicity.
Lithium-exposed patients were more likely to be married, cohabiting or in a civil partnership, to be a current/former smoker, to have used antipsychotics, and to have comorbid depression, mania/bipolar affective disorder, hypertension, central vascular disease, diabetes mellitus, or hyperlipidemias.
For the group that had received lithium, 53 patients (9.7%) were diagnosed with dementia. For the group that had not received lithium, 3,244 patients (11.2%) were diagnosed with dementia.
After controlling for factors such as smoking, other medications, and other physical and mental illnesses, lithium use was associated with a lower risk of dementia, both for short and long-term users.
However, since the overall number of patients receiving lithium was small and this was an observational study, larger clinical trials would be needed to establish lithium as a potential treatment for dementia.
Another limitation of the study was the number of patients who had been diagnosed with bipolar disorder, which is normally associated with an increased risk of dementia.
“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,” Dr. Chen said.
“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.”
The study was published online in the journal PLoS Medicine.
S. Chen et al. 2022. Association between lithium use and the incidence of dementia and its subtypes: A retrospective cohort study. PLoS Med 19 (3): e1003941; doi: 10.1371/journal.pmed.1003941
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