Alzheimer's-like disease in patients with Parkinson's

David Bäckström, neurologist and researcher at Department of Clinical Sciences, Umeå University.ImageSamuel Petterson

"This is an important result that can change our understanding of the course of the disease and, in the long run, affect the treatment of some patients diagnosed with Parkinson's," says David Bäckström, neurologist, senior lecturer at Umeå University and one of the study's lead authors.

can change our understanding

The researchers have performed a so-called α-synuclein seed amplification assay (αSyn-SAA) of cerebrospinal fluid in 140 patients at Norrland University Hospital who had been diagnosed with Parkinson's disease and similar diseases, as well as in 30 healthy people in a control group.

The protein α-synuclein is usually linked to Parkinson's disease. Surprisingly, the sampling showed that about ten percent of the Parkinson's patients examined lacked aggregation of this protein, which is otherwise considered a marker for Parkinson's.

When the researchers examined these α-synuclein-negative patients more closely, they found that they often had typical markers in the cerebrospinal fluid of Alzheimer's disease, such as amyloid and tau proteins. These patients also showed slightly poorer cognitive ability and balance than normal for Parkinson's patients.

It seems to be something of an intermediate form of Parkinson's and Alzheimer's that the researchers have now found. It has previously been clinically observed that some patients with Alzheimer's have also shown symptoms similar to Parkinson's. What is new that the researchers can now show is that the similarity is so great that many of these patients have instead been diagnosed with Parkinson's, and that these patients have a specific profile of biomarkers. This may affect how diagnosis and treatment are made in the future.

"One possible development is that these patients can be treated with drugs used for Alzheimer's. It is at least a track to research further and something that could be tested in drug studies," says David Bäckström.

The research has been carried out in collaboration between researchers in Umeå, Gothenburg, Sweden, and San Diego in the United States. The study is published in the scientific journal Alzheimer's & Dementia.