A new drug has been hailed as a "turning point in the fight against Alzheimer's" after it was found to slow the progression of the disease.

Donanemab was found to slow "clinical decline" by up to 35%, meaning that people with disease could still go about performing day-to-day tasks including shopping, housekeeping, managing finances and taking medication.

Alzheimer's Research UK said that "we're entering a new era where Alzheimer's disease could become treatable".

And the Alzheimer's Society said that treatments like donanemab could one day mean that Alzheimer's could be likened to other long-term conditions such as asthma or diabetes.

READ MORE: Why we are at a 'historic moment' for Alzheimer's research 

The charity said that new treatments including donanemab heralds a "new era" for Alzheimer's disease.

It comes as scientists published the final results of the trial - known as TRAILBLAZER ALZ-2 - examining the safety and efficacy of the drug, manufactured by Eli Lilly and Company.

Donanemab is an antibody-based medication which works by teaching the immune cells to recognise and destroy clumps of a protein called amyloid, which build up in brains of people with Alzheimer's disease. 

It is thought that these amyloid clumps accumulate to a certain "tipping point" which then triggers the rapid spread of another protein, tau, which block neurons in the brain from working properly.

The Herald: Diagnosis of Alzheimer's at an early stage currently requires PET scanningDiagnosis of Alzheimer's at an early stage currently requires PET scanning (Image: Getty)

The double-blind, randomised control trial involved 1,736 participants aged 60 to 85 who had been diagnosed with early-stage Alzheimer's disease. 

Over 18 months, half received a monthly infusion of donanemab and the other half were given a placebo.

The study, published in the Journal of the American Medical Association (JAMA) and presented to the Alzheimer's Association International Conference in Amsterdam, concluded that after 76 weeks of treatment, donanemab "significantly slowed clinical progression" of the disease.

In participants whose PET brain scans showed low to medium levels of the tau protein, the drug was associated with a 35% slow-down in disease progression. 

Overall, for all participants combined, there was 22.3% slowdown effect.

In addition, 47% of people with early Alzheimer's and low to medium levels of tau who were taking donanemab experienced no progression in the disease at all for a year, compared to 29% in the placebo group. 

Eli Lilly and Company said that treatment with donanemab reduced amyloid plaques on average by 84% at 18 months, compared with a 1% decrease in the placebo group. 

READ MORE: TV presenter Fiona Phillips reveals Alzheimer's diagnosis

The pharmaceutical giant said some people taking the drug would be able to finish the course of treatment in six months once their amyloid proteins plaques had cleared.

However, rates of adverse events were higher among those taking donanemab.

A total of 112 patients had to discontinue the drug due to side effects such as brain swelling and micro-haemorrhages - tiny blood clots - compared to 38 receiving the placebo. 

Three deaths in the donanemab group were considered "treatment-related" compared to one in the placebo group.

Dr Mark Mintun, group vice president of neuroscience research and development at Lilly, said: "People living with early, symptomatic Alzheimer's disease are still working, enjoying trips, sharing quality time with family - they want to feel like themselves, for longer.

"The results of this study reinforce the importance of diagnosing and treating disease sooner than we do today."

The Herald:

The results exceed those of another similar drug - lecanemab - which was recently approved for use in the United States in Alzheimer's patients with mild cognitive impairment.

In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) is still considering an application from lecanemab manufacturer, Eisai. 

READ MORE: Number of people dying with dementia in Scotland up 50 per cent in 20 years 

However, campaigners have warned that access to these new drugs will require an "overhaul" of how Alzheimer's disease is diagnosed as the drugs are only effective at early stages, and not for other forms of dementia. 

This means patients would require a confirmed diagnosis of Alzheimer's, which is primarily achieved using a PET scan. 

However, the UK has one of the lowest numbers of PET scanners per capita in the developed world, and very few cases of Alzheimer's are detected early. 

Dr Richard Oakley, associate director of research and innovation at Alzheimer's Society, said: "We can't have a situation where treatments are approved for use in the UK but people aren't diagnosed early or accurately enough to be eligible."

He added: "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.

"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."

READ MORE: What's making you fat? - ultra-processed food, gut bacteria, or genes?

The Herald:

Dr Susan Kohlhaas, executive director of research and partnerships at Alzheimer's Research UK, said: "As a potential first-generation treatment, donanemab's effects are modest.

"But these results provide further confirmation that removing amyloid from the brain can change the course of Alzheimer's, and may help people affected by this devastating disease if they're treated at the right time.

"Set against this, it's clear that donanemab does come with side effects, which for some can be very serious.

"Regulators will need to balance these benefits and risks before it is given a license for use."

Sir John Hardy, professor of neuroscience and group leader at the UK Dementia Research Institute, UCL, added: "Scientists now need to work to understand what we need to do to stop the disease rather than just slow it, but the major immediate task will be to organise NHS Alzheimer provision to be able to use these therapies."