Alzheimer’s is one of those horrible diseases that, unfortunately, most people will come into contact with at some point in their lives.
With humans living longer and longer lives, the disease is becoming more prevalent, and treatments are virtually non-existent. In fact, there have been no new Alzheimer’s medications in 20 years, and the drugs that do exist only manage symptoms.
After decades of research, scientists are cautiously optimistic about an upcoming first generation of Alzheimer’s treatments that can slow the progress of the disease.
“I would regard this as the end of the beginning in Alzheimer’s therapies,” Associate Professor Michael Woodward told the ABC.
“The word breakthrough is used perhaps a little too often, but this is a major breakthrough.
“We now have three drugs that have been shown that can critically slow down the decline.”
The results of a new global trial of a drug called donanemab have shown a 35% slowdown in the progression of Alzheimer’s in those with early stages of the disease. Over 18 months, 1,700 patients were trialled on donanemab, with an overall average slowdown of 22%.
Donanemab joins a similar drug, lecanemab, which works in a similar way to ‘clean’ the brain of plaque scientists believe is the cause of the disease. Lecanemab, created by Japanese pharmaceutical company Eisai and Biogen, has been shown to reduce the progression of Alzheimer’s by 27%.
Already, health regulators are being urged to rapidly approve the drugs for use in the general population. In the US, the Food and Drug Administration approved the use of lecanemab in January in the American market, with full approval pending.
Dementia is the second leading cause of death in Australia, with data suggesting that it will soon become the leading cause. Thankfully, it looks as though we may be entering a new era of treatment.
What is Alzheimer’s?
Dementia and Alzheimer’s are two separate things. There are many different kinds of dementia. They all cause a progressive decline in cognitive function. Meanwhile, Alzheimer’s is a form of dementia.
Alzheimer’s, named after the German physician, Alois Alzheimer, who first described the illness in 1901, is a particularly aggressive form of dementia. It’s associated with the slow destruction of memory, thinking, and, eventually, the ability to carry out basic tasks or understand the world around. It’s also the most common.
The causes of Alzheimer’s have long eluded science. In fact, we’re still not really sure how the disease works, although we have some good ideas.
Lifestyle and genetic factors are thought to play a strong role in the development of the disease. Smoking, depression, stress, and having relatives with the disease are all strongly correlated with Alzheimer’s.
It’s believed to occur when levels of an amino acid called amyloid beta build up in the brain, collecting as amyloid plaque and tau proteins. The ability of our brains to clear these proteins becomes more limited over time, but people with Alzheimer’s see a greater-than-normal buildup. The amyloid beta build-up effectively kills brain cells and limits the connections between them, shrinking the brain and resulting in cognitive decline.
Donanemab and Lecanemab
Both donanemab and lecanemab work on the assumption that it is the buildup of these plaques and proteins causing the disease. They bind to the amyloid, removing it from the brain and helping to slow the progress of the disease.
In one clinical trial released on Monday, donanemab was shown to be able to clear nearly 90% of amyloid plaque from the brain.
Notably, they’re not cures. While the drugs can slow the progress of the disease, they can’t reverse it. Patients taking the drug in clinical trials still got worse over time, but the rate of cognitive decline was much slower than if they hadn’t been taking it.
For the past few decades, scientists have been targeting amyloid beta removal as a potential treatment for the disease. Previous trials of similar drugs have not shown promising results, yet, and there is still some debate as to far much of a role amyloid beta plays in Alzheimer’s.
However, these latest drugs appear to have proven that the amyloid beta hypothesis is at least partially correct. On Assistant Professor at Harvard Medical School has said that the natural next step in Alzheimer’s treatment would be multi-drug approaches that go after other aspects of the disease, like tau proteins. In that way, we may end up treating Alzheimer’s as we currently do cancer.
While this the case, cost for the treatments is expected to be a big factor. Lecanemab is priced in the US at US$26,500 for a year’s worth of fortnightly infusions. Donanemab has no pricing yet but involves weekly injections. That said, Alzheimer’s care in Australia costs roughly $6 to $7 billion each year, and savings could be made by treating the disease early.
There are also risks. Both drugs have been shown to cause swelling and even bleeding in the brain in a small percentage of people treated in clinical trials. However, these side effects are thought to be mild and not of major concern in a terminal illness. Patients on blood thinning medications are thought to be at greater risk of stroke and larger brain bleeds, and doctors will likely be reluctant to prescribe these medications to them.
Those who are treated with these drugs in the early stages of the disease stand the most to gain. If these clinical results can be replicated in the real world, we could be looking at shifting Alzheimer’s away from a critical condition to a chronic but not life-threatening one.
“This is truly a turning point in the fight against Alzheimer’s, and science is proving that it is possible to slow down the disease,” Dr Richard Oakley, an Associate Director of Research and Innovation at the UK’s Alzheimer’s Society, has said.
“Treatments like donanemab are the first steps towards a future where Alzheimer’s disease could be considered a long-term condition alongside diabetes or asthma – people may have to live with it, but they could have treatments that allow them to effectively manage their symptoms and continue to live fulfilled lives”.
One patient, Mike Colley, has been on donanemab for the past two years as part of the clinical trial. He told BBC News that he feels more and more confident every day that this drug will be a success.
“I am one of the luckiest people you will ever meet, just for this,” he said.