Lay summary by Natalie Pye, reviewed by Dr Ryan West and a Dementia Lay Panel
Background
Biological markers or biomarkers are traits that doctors can measure from blood, skin or other body fluids that indicate whether a bodily function is working normally or if something is wrong, such as measuring blood pressure to see if a heart is working properly. Doctors can use specific biomarkers to determine if a person has Alzheimer’s and monitor the progression of the disease, by tracking disease-associated changes in the brain.
Currently these biomarkers can be measured from fresh blood samples. These fresh samples must be stored at specific temperatures, processed using expensive equipment and measured soon after collection. This can make it difficult for some people to get these tests, such as those living in remote areas or whose local medical centre does not have the equipment needed.
Why is the study important?
Using dried blood samples to test for biomarkers could make these tests more available to people in remote areas or living in nursing homes, who cannot easily access hospitals or medical centres. Also, by making these biomarker tests more available it could reduce the number of people waiting for more complicated diagnostic tests such as brain scans, and so allow earlier diagnosis and treatment.
What did the authors do and how did they do it?
The researchers recruited 2 groups of people either diagnosed with or suspected to have Alzheimer’s. The first group had 154 people and the second group 115 people. The second group took a questionnaire used to check for cognitive impairment (problems with thinking, communication, understanding and memory) known as a Mini-Mental State Examination (MMSE).
The researchers collected fresh blood from each participant and stored the blood using normal procedures. They then took a small portion of this fresh blood to spot onto special paper discs, which were then stored at room temperature as dried blood spots. After 48 hours they rehydrated the discs to release the blood from the paper and tested both fresh and rehydrated blood samples for 6 widely used biomarkers for Alzheimer’s.
What are the results?
The researchers first compared the amount of each biomarker in the fresh blood versus the dried blood spots for each participant. In first group they found a positive correlation in all 6 biomarkers tested, meaning if there was a high level of biomarker in the fresh blood, they also saw a high level in the dried blood. In the second group they only found a positive correlation in 5 out of 6 biomarkers.
Lastly, they compared the level of each biomarker from dried blood in participants with or without cognitive impairment (problems with thinking, communication, understanding and memory) as scored by the questionnaire, to see if the level of biomarker changed with progression of Alzheimer’s. They found that 3 out of 6 biomarkers changed between people with and without cognitive impairment.
What do the findings mean going forward for people with the disease?
This study shows that it may be possible to use dried blood spots to measure for at least 5 out of 6 commonly used biomarkers of Alzheimer’s disease. The level of 3 out of 6 biomarkers were similar in the fresh and dried blood samples and were changed in samples from people with and without cognitive impairment, suggesting these may be used to track progression of the disease.
Going forward the researchers should focus on developing better tests for these biomarkers using dried blood to allow easier diagnosis and monitoring of people with Alzheimer’s living in remote areas.
This study can be found at
https://doi.org/10.1002/alz.13697
Paper title
Biomarkers of Alzheimer’s disease and neurodegeneration in dried blood spots—A new collection method for remote settings
Lead Authors
Hanna Huber & Laia Montoliu-Gaya
Publication details including date of publication
This research article was published on the 29th of January 2024 in Alzheimer’s & Dementia – The Journal of the Alzheimer’s Association.