Scientists at the University of Leeds (UniLe) have developed a new technology that could form the basis of a simple blood test for Alzheimer’s disease (lat. morbus Alzheimerianus). The new biosensor measures harmful clusters of the protein amyloid-beta, an early indicator of Alzheimer’s disease. Alzheimer’s disease is the most common form of dementia, with more than 37 million sufferers worldwide, but currently cannot be conclusively diagnosed until after death. According to Dr. Jo Rushworth, who led the study by a team in the University of Leeds’ Faculty of Biological Sciences, at present, if a person goes to a doctor, they will do a memory test and they may say a person has dementia. They may also say that Alzheimer’s is the probable cause, but the only way to definitely find out whether someone had the disease is to examine the brain after death. Because scientists are relying on symptoms, drugs are given to the patient late. What they need is a reliable early test so they can intervene when it is actually going to be of some use.
If scientists were able to diagnose Alzheimer’s disease earlier, the symptoms could be better managed and future treatments could be given at a time when they would have the most effect. The team at the University of Leeds devised a biosensor that can detect very small quantities of amyloid-beta clusters, an early indicator of Alzheimer’s disease. The biosensor, which is contained on a small gold chip, generates an electrical signal in the presence of amyloid clusters, the strength of which indicates the number of clusters in the sample. Previous research had shown that the level of amyloid clusters in a patient’s bloodstream correlates with the level of amyloid clusters in the brain, which is linked to Alzheimer’s disease onset and severity.
Dr. Rushworth thinks that amyloid-beta is a bit like chewing gum; it is very sticky and clumps together in balls. In Alzheimer’s disease, a human gets lots of big sticky balls of amyloid-beta, made up of many individual amyloids, which latch on to brain neurons. This key event triggers disruption of neuronal communication and leads to the eventual death of the neurons. Until now, it has been very difficult to pick out these amyloid clusters from the individual amyloid proteins which are present in healthy people. Their biosensor test uses a new molecular recognition tool that works like a lock that only fits one key; it picks out the ball-shaped amyloid clusters without detecting the individual amyloids.
The team at Leeds tested their biosensor on amyloid clusters generated by cells grown in a test tube. The biosensor was able to pick out amyloid clusters similar to those found in human Alzheimer’s disease patients. Scientists are still at the laboratory stage but, eventually, if they are able to develop this technology, they would be looking to have a mobile phone-sized device where could do a finger-prick blood test and get an immediate readout telling the doctor the level of these markers in your system. Biosensors, such as the finger-prick blood sugar monitor used by diabetics, have the advantage of being rapid, easy to handle and can be used in a doctor’s surgery or by a patient at home. As well as speeding up diagnosis, an Alzheimer’s biosensor would also allow doctors to distinguish Alzheimer’s from other types of dementia and avoid prescribing drugs that are not relevant to a patient’s condition.