They found variations in the make-up of the brain and spinal fluid of 419 people with the most common form of dementia.
The discovery led them to believe medication could only work on some.
The landmark study suggests that what was once thought to be a single condition in fact has five sub-types, each with distinct clinical progression and life expectancy.
One caused an unusually high level of brain cell growth, driving production of abnormal proteins that fuelled the grip of the disease.
A second was spurred by issues within the brain’s internal immune system and a third related to problems with protein production. Problems with blood supply to the brain was linked to a fourth, and a fifth triggered issues with the blood-brain barrier – a border of cells preventing larger substances from reaching delicate tissue.
MRI scans showed those with the second and fourth variations had the greatest thinking and memory problems. Patients with the third type had the worst progression of the disease. They lived on average five and a half years after being diagnosed.
Some proteins identified in each sub-type were linked to specific genes – meaning certain ones were naturally more predisposed to one type of Alzheimer’s, claimed the Netherlands study by the Alzheimer Centre Amsterdam and Amsterdam and Maastricht universities.
Around one million people are living with dementia in the UK, 600,000 of them with Alzheimer’s.
One in three born today will go on to develop dementia, which remains incurable. By 2050, estimates suggest two million will be struck down.
Historically, drugs have been able to help patients only manage symptoms, rather than treat the causes of dementia. But there is now renewed optimism in the fight against the disease.
Donanemab, the latest generation of immunotherapy drugs, is already used widely to treat diseases like cancer.
It works by teaching immune cells to recognise and remove a toxic
protein called amyloid – a hallmark
of dementia.
The new drug follows breakthrough trials of lecanemab, found to reduce memory decline among those with early-stage dementia and licensed in the US and Japan.
In May, its Japanese manufacturer, Eisai, applied to the Medicines and Healthcare Products Regulatory Agency for approval in the UK. A decision is expected this year.
