Regional Cerebral Perfusion and Cerebrovascular Reactivity in Elderly Controls With Subtle Cognitive Deficits

Abstract

Background: Recent studies suggested that arterial spin labeling (ASL)-based measures of cerebral blood flow (CBF) as well as cerebral vasoreactivity to CO 2 (CVR CO 2 ) show significant alterations mainly in posterior neocortical areas both in mild cognitive impairment (MCI) and Alzheimer disease. It remains, however, unknown whether similar changes occur in at risk healthy elders without clinically overt symptoms. This longitudinal study investigated patterns of ASL perfusion and CVR CO 2 as a function of the cognitive trajectories in asymptomatic elderly individuals. Methods: Seventy-nine community-dwelling subjects (mean age: 78.7 years, 34 male) underwent three neuropsychological assessments during a subsequent 3-year period. Individuals were classified as stable-stable (SS), variable (V), or progressive-progressive (PP). Between-group comparisons were conducted for ASL CBF and transit-time delay maps and β-maps of CO 2 response. Spearman’s rho maps assessed the correlation between ASL (respectively, CVR CO 2 measures) and Shapes test for working memory, as well as Verbal fluency test for executive functions. Three group-with-continuous-covariate-interaction designs were implemented to investigate group-based differences on the association between neuropsychological scores and ASL or CO 2 measures. Results: Comparison of CBF maps demonstrates significantly lower perfusion in the V-group as to PP-cases predominantly in parietal regions, including the precuneus and, to a lesser degree, in temporal and frontal cortex. A stronger CVR CO 2 response was found in the PP-group in left parietal areas compared to the V-group. V-cases showed a stronger ASL-Shape value relationship than V-group in right temporoparietal junction and superior parietal lobule. CO 2 -Shape value correlation was significantly higher in both SS and PP-groups compared to the V-group in right insular and superior perisylvian regions. Conclusion: Our data indicate the presence of decreased ASL and CVR CO 2 values mainly in parietal and fronto-temporal areas in cases with the first signs of cognitive instability (V-group). Importantly, the PP-group, at high risk for MCI transition, displays an increase of both parameters in the same areas. Clinicoradiologic correlations also indicate a clear distinction between the V-group and both PP and SS-cases. These data imply the presence of an inverted U-shape pattern of regional blood flow and CVR in old age that might predict subsequent cognitive fate.

Brain hemodynamic changes in amnestic mild cognitive impairment measured by pulsed arterial spin labeling

“…Correlation is significant at the 0.05 level (two-tailed).CBF[38]. van der Thiel et al[39] and De Vis et al[40] demonstrated that local and global CBF were predictive of cognition among elderly patients during follow-up. Finally, Cecchetti et al found that brain hemodynamicFigure 1.…”

Contribution of Inflammation and Hypoperfusion to White Matter Hyperintensities-Related Cognitive Impairment

“…Moreover, previous studies confirmed a negative association between volume of WMHs and CBF values in the orbital frontal region ( 47 ). Of note, the results showed that both the hypoperfusion and hyperperfusion areas existed and we found that hyperperfusion in the IFG.L (triangular part) region was presented in WMHs, which was possibly attributable to neuronal adaptive responses and compensatory mechanisms in very early pathological processes to maintain cognitive function that actually reflect dysregulation of the neurovascular unit (NVU) ( 48 ). The hypoperfusion and hyperperfusion areas may simultaneously involve different brain regions and the asymmetrical results in this study may be due to the dominant left hemisphere being more often associated with various advanced cognitive functions ( 49 ).…”

Brain BOLD MRI O2and CO2stress testing: Implications for perioperative neurocognitive disorder following surgery

“…Other human studies have indicated that hyperoxia induces cerebral vasoconstriction as a consequence of altered regional nitric oxide potentially contributing to the stress diathesis under anaesthesia. 44 Also of note are findings of altered CVR with increasing age 45 and with signs of dementia in the elderly 46 or in patients with biomarkers such as APO4ε related to early onset Alzheimer's disease. 47 The identification of regional 'intracranial steal' or 'blue brain' on the BOLD images with a CO2 ramp protocol is increasingly being used to establish the need for and measure results from revascularization with superficial temporal artery to middle cerebral artery (STA-MCA) anastomoses in patients with severe intracranial vascular compromise.…”