New marker for Alzheimer's discovered

The substance is a beta-amyloid protein called Abeta16. The thesis shows in two independent studies that Alzheimer's patients have higher levels of the protein in their spinal fluid than do healthy individuals.

'The discovery of the new protein could be used to diagnose patients with Alzheimer's and also help determine which medications are most effective for the disease', says biochemist Erik Portelius, the author of the thesis.

Alzheimer's disease includes the formation of plaque on the brain. Neurons and other cell types form around 20 different beta-amyloid proteins, and these are excreted into the spinal fluid around the brain.

'These types of beta-amyloid proteins can be analysed with great precision, and our research team has also shown that the analyses can be used to distinguish between Alzheimer's patients and healthy individuals with a high degree of accuracy', says Portelius.

The beta-amyloid protein Abeta42 is particularly prevalent in the plaque. Abeta42 is created when a larger protein is cut into pieces by certain enzymes. The new Alzheimer's drugs that are currently being tested aim to reduce the production of Abeta42 by blocking these enzymes. Portelius found that these drugs increase the level of the newly discovered Abeta16.

'Abeta42 and Abeta16 are formed from the same precursor molecule, but the enzymatic process is different and Abeta16 is not harmful. The finding that Abeta16 is a very sensitive biomarker for the effect of these drugs may become very useful in future treatment studies', says Portelius.

The research was conducted in the proteomics lab at the neurochemistry unit in Mölndal, Sweden.

ABOUT ALZHEIMER'S DISEASE
Alzheimer's disease is one of our most common diseases, affecting more than 100 000 Swedes. The disease is caused by harmful changes in the nerve cells of the brain. Memory loss is very common, and so is premature death. Alzheimer's not only causes severe suffering among patients and their families, it also leads to enormous costs for society.
For more information, please contact:
Erik Portelius, biochemist, telephone +46 (0)31 343 23 90, +46 (0)70 480 00 59, erik.portelius@neuro.gu.se
Supervisor:
Professor Kaj Blennow, telephone +46 (0)31 343 17 91, kaj.blennow@neuro.gu.se
Thesis for the degree of Doctor of Medical Science at the Sahlgrenska Academy, Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry.
Title of the thesis: Targeted ABeta proteomics – a tool to study the pathogenesis of Alzheimer's disease
Link to thesis
http://hdl.handle.net/2077/20444