medwireNews: Plasma levels of phosphorylated (p)-tau proteins could serve as a biomarker for cognitive decline in individuals with dementia with Lewy bodies (DLB), say researchers who found an association between increasing levels of the proteins and more rapid decline in Mini-Mental State Examination (MMSE) scores over time.
They caution, however, that “[t]he association with the decrease in MMSE score, although statistically significant, was small, and the clinical relevance may be questionable.”
Maria Gonzalez, from Stavanger University Hospital in Norway, and colleagues explain in JAMA Neurology that p-tau levels in blood have “proven to be an accurate biomarker for Alzheimer disease (AD) pathologic characteristics”.
Noting that AD “comorbid pathologic characteristics are common and are associated with more rapid cognitive decline” in people with DLB, they postulated that “plasma p-tau concentrations may have utility in assessing cognitive impairment in individuals with this disorder.”
In the study, which included 987 participants of the European-DLB Consortium, the mean baseline plasma levels of p-tau181 and p-tau231 were significantly higher among the 371 individuals with probable DLB than the 205 controls who were free from neurodegenerative disorders, with between-group differences of 2.58 and 1.96 pg/mL, respectively.
But DLB patients had significantly lower average concentrations of p-tau181 and p-tau231 than the 207 patients with AD; the corresponding differences between the groups were −3.53 and −3.30 pg/mL.
And there was no significant difference in the levels of either protein between the participants with DLB and the 204 with Parkinson’s disease.
Of note, in the DLB group, there was a significant association between higher plasma concentrations of p-tau181 and p-tau231 at baseline and lower MMSE scores after accounting for age and sex. The association remained statistically significant for p-tau231, but not p-tau181, after additional adjustment for years of education.
Moreover, annual longitudinal cognitive assessments up to 5.0 years (mean, 3.5 years) were available for 182 of the participants with DLB, and these showed that each unit (pg/mL) increase in plasma p-tau181 and p-tau231 levels was associated with a significant average annual decrease of 0.094 and 0.130 MMSE points, respectively, after adjusting for age and sex.
“This study suggests that plasma p-tau181 and p-tau231 levels may be used as cost-effective and accessible biomarkers to assess cognitive decline in individuals with DLB”, conclude the authors.
They continue: “Further studies are needed to assess whether plasma p-tau levels can be used to assess the response of patients with DLB to treatments targeting AD pathophysiology.”
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This independent news story was supported by an educational grant from L’Institut Servier, Suresnes, France.