A new drug for Alzheimer's is being hailed as the biggest treatment breakthrough since the disease was discovered in 1906.

Early results show Aducanumab slowed cognitive decline in patients given it at an early stage by 22% after 18 months.

Clinical trial data is being analysed and if found to work by US regulators it could be available on the NHS by next year.

A landmark approval decision by the Food and Drug Administration would indicate UK regulators could also give the drug the green light by Autumn and be offered on the NHS as soon as 2022.

Despite billions of pounds of investment over decades, until now no disease-altering drug has been shown to stop or reverse its progression.

The only drugs available can temporarily alleviate symptoms in some patients and the last one of these was developed 17 years ago.

Aducanumab, developed by US firm Biogen, uses an artificially created antibody, which is designed to latch on to amyloid plaques and destroy them.

Trials were initially stopped last year when statistical analyses suggested that it was having no effect.

But in October last year Biogen reversed that position, claiming that a larger dataset showed that in patients with the first symptoms who received a very high dose, it slowed their mental decline.

US regulators have been analysing its extended datasets ever since and their much anticipated conclusion will come within days.

Dr Kohlaas has called on the UK regulator to fast track it review of Aducanumab like it did with Covid-19 vaccines.

Dr Susan Kohlaas, director of research at Alzheimer’s Research UK, said: “There is huge hope in dementia research now.

“It’s really important that we start to see the first disease modifying therapies for dementia come through.

“This could be a really important step in changing the whole research field.”

More than 50 million people worldwide are living with dementia and this is expected to almost double every 20 years. Around 90,000 are affected in Scotland.

Alzheimer’s disease is the most common cause of dementia and may contribute to 60 to 70% of cases.

If granted Medicines and Healthcare products Regulatory Agency approval, then NICE could take around a year before deciding whether to provide the drug for free on the NHS.

Existing drugs such as Aricept increase the communication between remaining healthy nerve cells in the brain. Other existing drugs include Reminyl, Exelon and Memantine.