New research from the University of Surrey has revealed that the time of day when blood is taken can significantly impact test results used to diagnose dementia.
The study, published in Translational Psychiatry, shows that key biomarkers for diagnosing Alzheimer’s disease, including a promising early diagnostic marker, vary depending on the time of day the blood sample is collected.
The researchers found that biomarker levels were at their lowest in the morning, right after participants woke up, and peaked in the evening.
One of the most important biomarkers, p-tau217, which could help with early dementia diagnosis, showed substantial differences between morning and evening levels.
The changes observed were similar to the variations seen in people whose mild memory issues worsen over time.
Dr. Ciro della Monica, a research fellow at the Surrey Sleep Research Centre and lead author of the study, emphasized the importance of considering the time of day when taking diagnostic blood samples.
“This work highlights how the timing of sample collection can impact the clinical picture for diagnosing dementia,” said Dr. della Monica.
“By standardizing the time of day that samples are taken, we can improve the accuracy of diagnosing dementia and tracking its progression.”
The study involved 38 participants with mild Alzheimer’s disease, as well as their caregivers and healthy individuals, who were all residents at the Surrey Sleep Research Centre.
Unlike standard clinical practices, where only one blood sample is typically taken, these participants had blood drawn every three hours over a 24-hour period.
The researchers found that four out of five key biomarkers—p-tau217, Aβ40, Aβ42, and NfL—fluctuated throughout the day. Only GFAP did not show significant variation.
It is still unclear why these biomarkers change with the time of day, but researchers believe it could be related to sleep, posture, activity, meals, or circadian rhythms, which regulate many body functions.
Regardless of the cause, the study suggests that the timing of blood sample collection is crucial in the diagnosis and monitoring of dementia. Standardizing the time of sampling or at least recording it could help improve the accuracy of dementia tests in both research and clinical care.
Professor Derk-Jan Dijk, Director of the Surrey Sleep Research Centre and senior author of the study, added, “Circadian rhythms affect nearly all aspects of brain and body function.
This study shows how understanding these rhythms can lead to better diagnosis and treatment of Alzheimer’s disease.”
If you care about brain health ,please read studies about Vitamin B9 deficiency linked to higher dementia risk, and cranberries could help boost memory.
For more information about brain health, please see recent studies about heartburn drugs that could increase risk of dementia, and results showing this MIND diet may protect your cognitive function, prevent dementia.
