Cynthia Picard’s research while affiliated with Douglas Mental Health University Institute and other places

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Publications (1)

Fig. 5 Baseline cognition as a function of the polygenic risk scores of CSF ADAM22. Polygenic risk scores (PRS) of ADAM22 (n = 83) were calculated using genotyping data, which were measured by Omni2.5 M-8 array and filtered using PLINK toolset, contrasted with cognitive performance assessed over a period of 7 years using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), adjusted for age, sex and years of education. A illustrated the immediate memory index score, B the delayed memory index score, C visuospatial-constructional memory index score, D language index score, E attention index score, and F the total scale index score. Significant linear regressions are represented with a gray confidence region of the fitted line. Individual R squares and P values are shown in the top left corners of each figure. R squares are adjusted for the number of independent variables in the model.
Novel synaptic markers predict early tau pathology and cognitive deficit in an asymptomatic population at risk of Alzheimer’s disease
  • Conference Paper
  • Full-text available

January 2025

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108 Reads

Molecular Psychiatry

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Cynthia Picard

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Cognitive dysfunction in Alzheimer’s disease (AD) correlates closely with pathology in the neuronal microtubule-associated protein tau. Tau pathology may spread via neural synapses. In a population of cognitively unimpaired elderly at elevated risk of AD, we investigated four cerebrospinal (CSF) markers of synaptic dysfunction and degeneration. Three of these (SYT1, SNAP25, and ADAM23) are derived from pre-synaptic structures, while ADAM22 reflects post-synaptic changes. All four markers correlated strongly with tau protein measures. In statistical models, SYT1 accounted for more than half the total variance in both total- and P(181)-tau levels. Observed correlations with CSF levels of Alzheimer amyloid-β (Aβ42) were somewhat weaker. In longitudinal data, baseline levels of ADAM22 and ADAM23 robustly predicted increase over time in both total- and P-tau. CSF SYT1 levels also correlated with PET image uptake of tau and (at a trend level) Aβ in areas of interest for early AD pathology. CSF SYT1 and SNAP25 levels correlated inversely with a global psychometric score and several of its domain subscales. In quantitative trait loci analyses, all four synaptic markers were associated with at least one AD genetic risk locus. Upon “staging” participants by their evidence of amyloid and tau pathology (A/T/N framework), the CSF synaptic markers were unexpectedly reduced in participants with CSF evidence of amyloid but not tau pathology. They were clearly elevated, however, in the CSF of persons with indications of both tau and amyloid pathology. These observations provide evidence for clear pre-synaptic degeneration in cognitively unimpaired persons with biomarker evidence of early AD pathology.

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