Alzheimer's disease is the most common form of dementia, affecting over 35 million people worldwide. It is generally assumed that the clumping of beta-amyloid (Aβ) protein causes neuronal loss in patients. Medication focuses on reducing Aβ42, one of the most common proteins and the most harmful. University of Twente PhD student Annelies Vandersteen is refining the current approach. She explains: "The results of my research provide a broader understanding of the processes that lead to Alzheimer's disease and in this way may help to bring about new medication".
The Aβ protein occurs in the body in various lengths, ranging from 33 to 49 amino acids. The shorter varieties are regarded as 'safe', unlike the longer ones - Aβ42 and longer - which are highly aggregating. Current therapeutic strategy tries to reduce the clumping of Aβ42, and its harmful effects, by limiting the release of Aβ42. Reducing Aβ42 production at the same time results in a rise in Aβ38 levels. Vandersteen comments: "One of the findings of my research is that small amounts of Aβ38 can in fact increase or temper the clumping and toxic effects of longer Aβ proteins. The processes that result in Alzheimer's disease are determined by the whole spectrum of Aβ proteins. So the picture is far less black and white than has been assumed so far, and less common forms of Aβ are far less harmless than we thought."
The study
Vandersteen examined the protein mixtures in a laboratory situation. She devised a series of experiments based on a computer-calculated hypothesis. The behaviour of the various Aβ proteins and mixtures was studied in detail and described using various biophysical techniques. The influence of the various Aβ proteins and mixtures on neurons was then studied in a cell culture.
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