Plasma tau not elevated in subjective cognitive decline
Concentrations of the tau proteins in the plasma are not elevated in patients in the premild cognitive impairment (MCI) stage of subjective cognitive decline (SCD), a new study from Germany shows.
Single-molecular array showed that there was no significant difference in the plasma concentrations of the tau protein between SCD patients (3.4 pg/mL) and healthy controls (3.6 pg/mL; p=0.627).
Similarly, cerebrospinal fluid (CSF) concentrations of p-tau181 (p=0.573), tau (p=0.456), Aβ42 (p=0.072), and ratios of Aβ42/40 (p=0.785) and tau/Aβ42 (p=0.335) were comparable between healthy controls and SCD patients.
Additionally, tau plasma concentrations in SCD patients showed no significant correlation with CSF concentrations of p-tau181 (p=0.171), tau (p=0.298) and Aβ42 (p=0.663) after controlling for confounders like educational level, gender and age.
Even between healthy controls with normal Aβ42 levels (≥600 pg/mL) and SCD patients with abnormal Aβ42 levels (<600 pg/mL), tau plasma levels were not significantly different (3.45 vs 3.29 pg/mL; p=0.654).
Tau plasma levels were also not significantly associated with CSF concentrations of Aβ42 (p=0.782), tau (p=0.142) and p-tau181 (p=0.436) in SCD patients with abnormal Aβ42 levels.
The study included 111 SCD patients and 134 cognitively healthy controls who were matched by age and gender. Participants were recruited from the DZNE longitudinal study on cognition and dementia, and were administered the Mini-Mental State Examination and Clinical Dementia Rating tests to assess cognitive status.
One-way analyses of covariance were used to determine the differences in cognitive status, and plasma and CSF biomarkers between healthy controls and SCD patients. Linear regression was used to determine relationships between biomarkers.