More hope in dementia: a new modifiable risk and numbers continue to fall

‘Does Vitamin D help prevent against dementia?’ asked Dave Piper in a TWR UK interview. He was responding to a news release from the University of Exeter about a joint 10-year study with the University of Calgary’s Hotchkiss Brain Institute in Canada on vitamin D supplementation and dementia. In a group of 12, 388 participants they found 40% fewer dementia diagnoses in those taking Vitamin D supplements. Conversely, in a larger study of 427,000 participants, Harvard University found a 54% higher risk of dementia among participants with low vitamin D blood levels. Older people do not absorb vitamins as efficiently from their normal diet, but it’s still wise to consult their GPs before taking supplements. And be careful not to overdose: the Harvard website says that the maximum daily intake for vitamin D for adults and children ages 9+ is 4,000 IU (100 mcg). These studies add hope by identifying another ‘modifiable risk’ that can be mitigated, helping to prevent dementia.

The Harvard study information can be read here. - Scroll down and click on ‘Cognitive Decline'

Professor Zahinoor Ismail, who lead the research in Exeter said, ‘overall, we found evidence to suggest that earlier supplementation might be particularly beneficial, before the onset of cognitive decline. All 12,388 participants, with a mean age of 71, were dementia free at the outset. Vitamin D supplements were taken by 37%, that is 4,637. There were 40% fewer dementia diagnoses in the group that took supplements, and taking vitamin D was also associated with living dementia-free for longer. Read the study here

Slowly but surely reducing incidence

Clicking a link to a specific page on the Alzheimer’s Society website used to bring up the number of people diagnosed with dementia in the UK, as well as the Society’s speculative figures. But the website has been revised and only states that ‘There are currently 944,000 people with dementia in the UK, more than ever before, and this number is projected to increase.‘

However, the figures are available on the NHS Digital website. The information is gathered from GP practices and updated each month. The NHS website gives the number of recorded diagnoses of dementia at 31^st January 2023 as 431,845, a decrease of 2,566 patients since 31 December 2022. It says that 61.8% of patients aged 65 or over who are estimated to have dementia had a recorded diagnosis of dementia on 31 January 2023, a decrease from 62.5% on 31 December 2022.

Other studies have shown a continuing decline in incidence. From Harvard Research and the Journal of the American Medical Association

“The steady decline in incidence over three decades suggests that preventive efforts involving lifestyle education and health interventions such as blood pressure control and antithrombotic medication can offset at least part of the growing burden of dementia from global gains in life expectancy,” said Lori Chibnik, assistant professor in the Department of Epidemiology at Harvard Chan School. “Providing this evidence of a decline is the first step toward elucidating the factors at play behind that decline and eventually effective interventions to promote brain health.”

In the meantime Japanese company Eisai has engaged a lobbyist firm to put pressure on Medicare (the programme in America that provides free treatment for the over 65s) to remove the restriction on its drug Leqembi that limits it to people enrolled in clinical trials, as it did with the controversial drug Aduhelm, produced by Biogen, its partner in marketing Leqembi. While some commentators have said Leqembi is a ‘game-changer,’ others have stated that it is not. See here.

Dr Adriane Fugh-Berman, is a professor who teaches graduate and medical students about evidence-based medicine and critical assessment of drugs and other therapeutics in the Department of Pharmacology and Physiology at Georgetown University Medical Centre. Writing an op-ed in the Miami Herald she said, ‘A treatment that improves Alzheimer’s disease would be a great advance, but Leqembi (lecanemab), which recently received accelerated approval from the FDA, is not that drug. Yes, lecanemab slows decline to an extent detectable on a test, but not to an extent that a relative or caretaker would notice. This drug doesn’t actually make anything better. It just slows the rate that someone goes downhill over 18 months — by less than half a point on an 18-point scale.’ Also Leqembi can produce severe side effects, such as brain swelling and bleeds, and three deaths have been attributed to the drug.