The effect of white matter hyperintensities on verbal memory

Abstract

Across dementia syndromes, WMH contribute indirectly to verbal memory deficits considered pathognomonic of Alzheimer disease, specifically by contributing to temporal lobe atrophy.

White matter hyperintensities mediate gray matter volume and processing speed relationship in cognitively unimpaired participants

“…On the other hand, the previous results in older and/or cognitively impaired individuals indicate that in these individuals with a higher WMH burden, GMv exerts an additional effect of cognitive function that is independent of WMH burden. This may also explain why, in contrast to previous findings (Rizvi et al, ; Swardfager et al, ), we did not find a significant mediation effect with EM performance in our main model. An additional factor that could explain such a discrepancy might be the test that we used to measure EM (MBT), whose characteristics may differ from those of the other memory tests used in similar reports.…”

“…In this work, we have studied whether WMH volume mediates the relationship between GMv and cognition in cognitively unimpaired middle‐aged participants to extend previous findings in older populations with additional comorbidities (Knopman et al, ; Rizvi et al, ; Swardfager et al, ; Tuladhar et al, ), to a younger and healthier cohort both from the cognitive and cerebrovascular standpoint. Our results show that, even in such a low‐risk population, higher WMH lesion volume is significantly associated with a widespread pattern of lower GMv in frontal, occipital, and temporal regions, including the hippocampus, as well as in the thalamus and cerebellum.…”

“…Previous cross‐sectional studies in older nondemented samples (Knopman et al, ) or including MCI and AD patients (Rizvi et al, ; Swardfager et al, ) that used mediation pathway analysis selected WMH as predictor, whose association with cognition was mediated by GMv. For comparability with these previous reposts, we built an alternative mediation model with GMv as the mediator of the association between WMH load and cognitive performance (Figure ).…”

“…Authors also looked for the effect in ADrelated regions, such as the entorhinal cortex and the hippocampus and showed an indirect effect in the association of frontal, parietal and occipital WMH with memory performance. Previous studies showed that GMv mediated the association between WMH burden with EF and EM, again in nondemented individuals , and in mixed populations of individuals with cardiovascular risk factors and AD patients (Swardfager et al, 2018) (details of these previous studies are shown in Table 1). However, the extent to which these associations are present in cognitively unimpaired individuals has not yet been fully assessed.…”

“…Prior studies have shown that high WMH burden is associated with GM atrophy (Wen, Sachdev, Chen, & Anstey, 2006) in the temporal lobe (Habes et al, 2016;Rizvi et al, 2018;Swardfager et al, 2018) and the frontal cortex (Raji et al, 2012;Rizvi et al, 2018). However, the regional patterns of brain atrophy associated with higher WMH burden are still not widely understood in cognitively unimpaired young individuals.…”