- A new study concludes that lithium exposure could reduce the risk of dementia in people over the age of 50.
- Previous studies have shown that lithium disrupts the production of proteins in the brain that are associated with Alzheimer’s disease.
- The retrospective cohort study also demonstrated that people with mental health conditions who were prescribed lithium had a lower risk of developing dementia.
According to the World Health Organization (WHO), cases of dementia have been increasing by 10 million each year, globally. This is due in part to an aging population because the risk of developing dementia increases with age.
With this increase comes a high health and social care cost. In fact, scientists believe that delaying dementia onset by just 5 years could reduce its prevalence and economic impact by as much as 40%.
The causes of dementia are both environmental and genetic and there are a number of factors that can increase the risk of developing dementia.
While some research has shown that people with bipolar affective disorder have a higher risk of developing dementia, a recent study provides an interesting new perspective.
The retrospective cohort study found that people who had been exposed to lithium — a drug that is sometimes prescribed to people with bipolar affective disorder and major depressive disorder — were less likely to develop dementia.
The results of the research appear in the journal PLOS Medicine.
Dr. Christopher Weber director of global science initiatives at the Alzheimer’s Association, who was not involved in the study, told Medical News Today:
“[O]verall, when I looked at the paper, I was very interested and excited about it because we’re looking at new ways to understand and potentially treat, slow, and prevent dementia. And this is just another avenue that scientists are looking at […] to reduce your risk for dementia.”
A 15-year follow-up
To investigate, researchers from the University of Cambridge in the United Kingdom accessed electronic clinical records. They obtained these from secondary mental health services in Cambridge and Peterborough National Health Service (NHS) Foundation Trust.
They compared the records of 548 people who had been prescribed lithium with 29,070 people who had not taken the medication.
None of the participants had dementia at baseline and all were aged 50 years or older. Their mean age was 73.9 years.
The clinical records provided information about participants’ weight, BMI, ethnicity, diabetes, cardiovascular disease, smoking, marital status, and other factors that could influence the analysis.
Nearly three-quarters of people prescribed lithium had bipolar affective disorder.
The participants who had taken lithium were followed for a mean of 4.8 years (1–14.9 years) and 9.7% of the participants were diagnosed with dementia during this time. This included 6.8% with Alzheimer’s disease and 2.6% with vascular dementia.
Those who had not taken lithium were followed for an average of 4.3 years (1–14.9 years). In this group, 11.2% developed dementia, including 8.1% with Alzheimer’s disease and 2.6% with vascular dementia.
Although the study was small, even after accounting for other factors, the protective effect of lithium remained statistically significant.
The effect was most pronounced in people who had taken lithium for less than 1 year or more than 5 years.
MNT spoke with Prof. Rob Howard, a professor of old age psychiatry at University College London who was not involved in the research. He said:
“There’s an enzyme called glycogen synthase kinase, or GSK3, which is involved in the abnormal phosphorylation of tau protein, which makes tangles in Alzheimer’s disease. And lithium is a potent inhibitor of that enzyme. [..] This isn’t the first study to have shown the link between lithium use and reduced potential risk.”
Limiting factors
The authors warn that, while the results were surprising, they are not necessarily generalizable to the wider population. The primary reason for this is the relatively small number of people who were taking lithium.
They call for scientists to conduct similar studies in larger more diverse populations.
New diagnostic techniques could help identify people in the very early stages of dementia said Prof. Howard. This could be used to identify people for future trials investigating whether lithium could delay the onset of dementia.
He believes that the next steps should include “a trial in very early, very mild Alzheimer’s disease, just to see if you can show some effect of slowing the progression of the disease over a couple of years.”
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