Alzheimer is one of the most common diseases in old age. However, the causes are not clear. The chances of successful therapy are slim. Although there are medications (Lecanemab and Donanemab)which can slow down the progression, but stopping the disease is not yet possible.
Researchers led by Betty Tijms from the Alzheimer Center in Amsterdam now report in the “Nature Aging” specialist magazine that they have discovered a fifth subtype of Alzheimer’s. Four different subtypes were known so far. All subtypes are associated with specific symptoms, such as dementia and survival time of those affected.
The researchers examined which proteins were found in increased quantities in the spinal cords of Alzheimer’s patients. For this purpose, spinal fluid was taken from 419 Alzheimer’s patients and 197 healthy people and analyzed. In total, the researchers found 3,800 different proteins. It turned out that 1,058 proteins were significantly changed in Alzheimer’s patients. The altered proteins can be used to identify which subtype the sick person belongs to.
The five subtypes
The fifth subtype now discovered, like subtype 2, has the highest risk of progressing from mild cognitive impairment to dementia. The difference between subtypes 2 and 5 lies in the cause of the disease.
In subtype 2, the cause is suspected to be an overactive innate immune system. In subtype 5, the cause is a permeable blood-brain barrier that can no longer fulfill its protective function.
Subtype 1 leads to severe memory problems. With an average of 8.9 years, patients have the highest life expectancy.
In subtype 3, those affected have difficulty orienting themselves and have difficulty distinguishing between shapes.
In subtype 4, mental decline is severe and language problems occur.
The differences between the five subtypes explain why certain therapies only work in some patients. The team from the Alzheimer Center in Amsterdam assumes that the Alzheimer subtypes require specific treatments.