Differences in functional connectivity in mild cognitive impairment for amyloid‐positive versus SNAP

• Published in: Alzheimer's & dementia Vol. 16
• Main Authors: Magalhaes, Thamires Naela Cardoso, Casseb, Raphael Fernandes, de Campos, Brunno, Teixeira, Camila Vieira de Ligo, Forlenza, Orestes Vicente, Talib, Leda Leme, Cendes, Fernando, Balthazar, Marcio Luiz Figueredo
• Format: Journal Article
• Language: English
• Published: 01-12-2020
• ISSN: 1552-5260; 1552-5279
• DOI: 10.1002/alz.042600

Background
The default mode network (DMN) is a neurofunctional network particularly relevant to Alzheimer's disease (AD) since its structures are vulnerable to the deposition of amyloid (Aβ) and neurofibrillary tangles [1]. Observing the more up‐to‐date classifications, we classified our patients according to AT(N) (alterations in amyloid (A), tau (T) and neurodegeneration (N)) classification: normal AD biomarkers (AD‐) (A‐T‐N‐); suspected non‐Alzheimer pathophysiology (SNAP) (A‐T+N‐, A‐T‐N+, or A‐T+N+) and AD pathophysiologic continuum (AD+) (any A+ combination) [2]. We investigated whether the activity and functional connectivity (FC) can differentiate MCI subgroups according to AD biomarkers classification.
Method
We recruited 58 mild cognitive impairment (MCI) patients who underwent: lumbar puncture to analyze Aβ1‐42, p‐Tau and t‐Tau levels; Magnetic Resonance Imaging in a 3T Philips Achieva scanner; and a broad neuropsychological evaluation. Was considered pathophysiological evidence of AD (AD continuum) low Aβ1‐42 concentrations < 416 pg/m and was considered Tau alteration: p‐Tau > 36.7 pg/mL and t‐Tau > 76.7 pg/mL [3]. To identify the DMN we used the UF2C software and seed‐based analysis using a mask of the posterior cingulate cortex to extract the reference time‐series. We obtained FC values for 8 DMN regions for each patient. We performed a general linear model to compare the groups with FC values of DMN regions.
Result
There was a statistically significant difference between groups SNAP and AD continuum and FC of left hippocampus (p = .017). AD continuum group shows more connectivity than SNAP group.
Conclusion
CSF protein profiles seem to be related to alterations in resting state activity. In this study we were able to differentiate clinically similar patients through neuroimaging biomarkers. With further refinement, resting‐state connectivity hold promise as non‐invasive neuroimaging markers. References: [1] Matura S, et al., doi: 10.1017/neu.2019.49; [2] Jack CR, et al., doi: 10.1016/j.jalz.2018.02.018; [3] Forlenza OV, et al., doi: 10.1016/j.dadm.2015.09.003.