Saliva sample enables very early detection of Alzheimer's and Parkinson's disease

With the help of molecules from the brain that can be measured in saliva, it is possible to detect early changes that can lead to Alzheimer's or Parkinson's disease – long before symptoms appear. In a new scientific article, researchers at Luleå University of Technology propose a strategy for early diagnosis of neurological diseases.

Alzheimer's and Parkinson's disease are two of the most common neurological diseases that lead to degradation of the brain's nerve cells. They affect thousands of people annually, and by the time someone gets a diagnosis, there is already extensive damage to the brain. Researchers at Luleå University of Technology are now proposing a new screening method for early detection of the diseases. Through a simple saliva sample, molecules from the brain can be analyzed. The method has the potential to diagnose the diseases up to 10 years before the first symptoms appear.

“These diseases severely affect the lives of many people. A saliva sample is a simple method that could lead to early diagnosis. It provides the opportunity to introduce early interventions for the individual that could make a big difference in their life. It also provides an opportunity to understand the disease better which can lead to new treatments,” says Vaibhav Sharma, postdoctoral researcher in Biomedical Engineering at Luleå University of Technology, and main author of the scientific article.

Messages from the brain

The method uses exosomes – nano-sized bubbles that are excreted from the cells in the body. When first discovered in the 1980s, the content of the bubbles was regarded as garbage that the cells got rid of. More recent research has shown that the main task of exosomes is to carry information between cells – like a nanoscale message in a bottle. The message reaches the right recipient through proteins on the outside of the bubble which other cells recognize, similar to an address label.

Between the brain and the rest of the body is the blood-brain barrier, a protective layer for the brain cells preventing large molecules to get in or out. However, exosomes are so small that they can cross the blood-brain barrier to tell the tale of what is happening in the brain cells. Vaibhav Sharma and his research colleagues have been able to show that Parkinson's and Alzheimer's disease can be diagnosed by analyzing exosomes in saliva. By using the exosome's address tag – the protein on the outside – they can distinguish which exosomes come from brain cells.

Measuring with laser

By measuring the bubbles' movements with a laser, the quantity and size can be analyzed by the method nanoparticle tracking analysis. The exosomes can tell if there are signs of disease and indicate how far the disease has progressed. The technology used by the researchers is already available, but the application is new. The researchers have focused on Parkinson's and Alzheimer's disease, but there is potential to develop the method for other neurological diseases, for example ALS.

“Our motivation is the possibility of detecting the diseases as early as possible. We already know that the molecular degradation processes begin long before the symptoms appear. This is a method that can potentially detect the changes before the brain is so damaged that medication is less likely to help. There is a possibility that it could also be used as a screening tool,” says Fredrik Nikolajeff, professor of Biomedical Engineering.

The article “Employing nanoparticle tracking analysis of salivary neuronal exosomes for early detection of neurodegenerative diseases” External link, opens in new window.is published in the scientific journal Translational Neurodegeneration.