GROUNDBREAKING research has revealed that biomarker levels, particularly p-tau217, vary depending on the time of day, which could impact their clinical applicability.
Recent advancements in neurology have highlighted the promising use of plasma biomarkers for diagnosing Alzheimer’s disease and other neurological conditions. Additionally, these biomarkers hold significant potential for clinical trial stratification, disease monitoring, and evaluating treatment outcomes for Alzheimer’s disease. Researchers sought to explore the topic further, by investigating the diurnal variation of dementia biomarkers in 38 participants with an average age of 70.8 years. The cohort included people with mild Alzheimer’s disease (n = 8), their partners or caregivers (n = 6), and cognitively healthy older adults (n = 24).
The participants were studied under two protocols: one with two blood samples taken 12 hours apart, and another with 3-hourly blood samples collected over 24 hours while participants maintained a normal sleep-wake cycle. Using single-molecule array technology, the levels of phosphorylated tau (p-tau217), amyloid-beta 40 (Aβ40), amyloid-beta 42 (Aβ42), glial fibrillary acidic protein, and neurofilament light (NfL) were measured. Linear mixed model analysis revealed that p-tau217, Aβ40, Aβ42, and NfL varied significantly during the day, and p-tau217 levels were significantly influenced by participant group. In particular, p-tau217 levels were lowest in the morning and highest in the afternoon.
These findings suggest that the time of day when plasma samples are collected should be considered when implementing the use of biomarkers in clinical practice, as the results suggest that biomarker levels may differ between morning and afternoon clinics. For now, the researchers recommended that reference limits for dementia biomarkers be established using samples collected in the morning, after fasting. Furthermore, clinicians should standardise or document the timing of sample collection to ensure consistency when diagnosing dementia and monitoring disease progression.
Katrina Thornber, EMJ
Reference
Della Monica C et al. P-tau217 and other blood biomarkers of dementia: variation with time of day. Transl Psychiatry. 2024;14(1):373.
