Drug prescribed for depression could lower the risk of dementia

Lithium – a drug usually prescribed for conditions such as bipolar disorder and depression – may lower the risk of developing dementia, a new study suggests.

Researchers say the findings support the possibility that lithium could be a preventative treatment for dementia, and could be tested in clinical trials.

While previous studies have proposed lithium as a potential treatment for those diagnosed with dementia or early cognitive impairment, it is unclear whether it can delay or prevent the development of the condition as these studies have been limited in size.

Dementia is one of the leading causes of death in elderly people across western populations, and there is currently no preventative treatment available.

It is thought more than 55 million people worldwide have dementia, with Alzheimer’s disease being the most common form.

‘The number of people with dementia continues to grow, which puts huge pressure on healthcare systems,’ said Shanquan Chen from the University of Cambridge’s department of psychiatry, who is the study’s author.

‘It’s been estimated that delaying the onset of dementia by just five years could reduce its prevalence and economic impact by as much as 40%,’ said Chen.

The researchers, from the University of Cambridge, conducted an analysis of the health records of nearly 30,000 patients over the age of 50 from the Cambridgeshire and Peterborough NHS Foundation Trust.

According to the study, the patients who received lithium were less likely to develop dementia than those who did not, although the overall number of patients who received lithium was small.

Lithium is a mood stabiliser usually prescribed for conditions such as bipolar affective disorder and depression.

‘Bipolar disorder and depression are considered to put people at increased risk of dementia, so we had to make sure to account for this in our analysis,’ said Chen.

Researchers analysed data from patients who accessed mental health services from Cambridgeshire and Peterborough NHS Foundation Trust between 2005 and 2019.

The patients 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, 548 patients had been treated with lithium. Their average age was just under 74 years with around 40% of patients being male.

For the group that had received lithium, 53 or 9.7% were diagnosed with dementia. In the group that had not received lithium, 3,244 or 11.2%, were diagnosed with dementia, researchers found.

But since the overall number of patients receiving lithium was small and this was an observational study, researchers feel the need for larger clinical trials 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. The findings were published in the PLoS Medicine journal.

‘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,’ said Chen.

‘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,’ he said.

Dr Sara Imarisio, head of research at Alzheimer’s Research UK, said: ‘Alzheimer’s Research UK are now funding science at the University of Newcastle to see whether lithium could be a future treatment for Alzheimer’s disease using a new brain imaging technique.

‘This project will help lay the groundwork for careful clinical trials, which are ultimately the only way to know if lithium could be an effective treatment for people with Alzheimer’s.’

There is a desperate need for new dementia treatments and where there is evidence that an existing, widely used, relatively safe and inexpensive drug could help, it is vital that researchers follow up on this as quickly as possible,’ she added.

In separate research, published in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association, researchers found extended napping in elderly people may signal dementia.

Researchers from UC San Francisco (UCSF) and Harvard Medical School together with Brigham and Women’s Hospital, also found that once dementia or mild cognitive impairment was diagnosed, they also started napping more, and for longer.

They suggest their findings depart from the theory that daytime napping in older people only compensates for poor night-time sleep. Instead, it points to work by other UCSF researchers suggesting dementia may affect the key areas of the brain related to sleep.

‘I don’t think we have enough evidence to draw conclusions about a causal relationship, that it’s the napping itself that caused cognitive ageing, but excessive daytime napping might be a signal of accelerated ageing or cognitive ageing process,’ said the study’s co-senior author Yue Leng.

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