Resting-State Functional Connectivity Magnetic Resonance Imaging and Outcome After Acute Stroke.

Background and Purpose- Physiological effects of stroke are best assessed over entire brain networks rather than just focally at the site of structural damage. Resting-state functional magnetic resonance imaging can map functional-anatomic networks by analyzing spontaneously correlated low-frequency activity fluctuations across the brain, but its potential usefulness in predicting functional outcome after acute stroke remains unknown. We assessed the ability of resting-state functional magnetic resonance imaging to predict functional outcome after acute stroke. Methods- We scanned 37 consecutive reperfused stroke patients (age, 69±14 years; 14 females; 3-day National Institutes of Health Stroke Scale score, 6±5) on day 3 after symptom onset. After imaging preprocessing, we used a whole-brain mask to calculate the correlation coefficient matrices for every paired region using the Harvard-Oxford probabilistic atlas. To evaluate functional outcome, we applied the modified Rankin Scale at 90 days. We used region of interest analyses to explore the functional connectivity between regions and graph-computation analysis to detect differences in functional connectivity between patients with good functional outcome (modified Rankin Scale score ≤2) and those with poor outcome (modified Rankin Scale score >2). Results- Patients with good outcome had greater functional connectivity than patients with poor outcome. Although 3-day National Institutes of Health Stroke Scale score was the most accurate independent predictor of 90-day modified Rankin Scale (84.2%), adding functional connectivity increased accuracy to 94.7%. Preserved bilateral interhemispheric connectivity between the anterior inferior temporal gyrus and superior frontal gyrus and decreased connectivity between the caudate and anterior inferior temporal gyrus in the left hemisphere had the greatest impact in favoring good prognosis. Conclusions- These data suggest that information about functional connectivity from resting-state functional magnetic resonance imaging may help predict 90-day stroke outcome.

The Gut Metagenome Changes in Parallel to Waist Circumference, Brain Iron Deposition, and Cognitive Function.

Context: Microbiota perturbations seem to exert modulatory effects on emotional behavior, stress-, and pain-modulation systems in adult animals; however, limited information is available in humans. Objective: To study potential relationships among the gut metagenome, brain microstructure, and cognitive performance in middle-aged, apparently healthy, obese and nonobese subjects after weight changes. Design: This is a longitudinal study over a 2-year period. Setting: A tertiary public hospital. Patients or Other Participants: Thirty-five (18 obese) apparently healthy subjects. Intervention(s): Diet counseling was provided to all subjects. Obese subjects were followed every 6 months. Main Outcome Measure(s): Brain relaxometry (using magnetic resonance R2*), cognitive performance (by means of cognitive tests), and gut microbiome composition (shotgun). Results: R2* increased in both obese and nonobese subjects, independent of weight variations. Changes in waist circumference, but not in body mass index, were associated with brain iron deposition (R2*) in the striatum, amygdala, and hippocampus in parallel to visual-spatial constructional ability and circulating beta amyloid Aß42 levels. These changes were linked to shifts in gut microbiome in which the relative abundance of bacteria belonging to Caldiserica and Thermodesulfobacteria phyla were reciprocally associated with raised R2* in different brain nuclei. Of note, the increase in bacteria belonging to Tenericutes phylum was parallel to decreased R2* gain in the striatum, serum Aß42 levels, and spared visual-spatial constructional ability. Interestingly, metagenome functions associated with circulating and brain iron stores are involved in bacterial generation of siderophores. Conclusions: Changes in the gut metagenome are associated longitudinally with cognitive function and brain iron deposition.