The Impact of Magnetic Resonance Imaging-Detected White Matter Hyperintensities on Longitudinal Changes in Regional Cerebral Blood Flow

Abstract

White matter hyperintensities are frequently detected on cranial magnetic resonance imaging (MRI) scans of older adults. Given the presumed ischemic contribution to the etiology of these lesions and the posited import of resting brain activity on cognitive function, we hypothesized that longitudinal changes in MRI-detected white matter disease, and its severity at a given time point, would be associated with changes in regional cerebral blood flow (rCBF) over time. We evaluated MRI scans and resting H(2)(15)O positron emission tomographic rCBF at baseline and after an average of 7.7-year follow-up in Baltimore Longitudinal Study of Aging participants without dementia. Differences in patterns of rCBF were evident at baseline and at follow-up between the group of subjects showing increased white matter disease over the 8-year interval compared with the group with stable white matter ratings. Furthermore, longitudinal changes over time in rCBF also differed between the two groups. Specifically, the group with progressive white matter abnormalities showed greater increase in the right inferior temporal gyrus/fusiform gyrus, right anterior cingulate, and the rostral aspect of the left superior temporal gyrus. Regions of greater longitudinal decrease in this group were evident in the right inferior parietal lobule and at the right occipital pole. Changes in white matter disease over time and its severity at any given time are associated significantly with both cross-sectional and longitudinal patterns of rCBF. The longitudinal increases may reflect cortical compensation mechanisms for reduced efficacy of interregional neural communications that result from white matter deterioration.

Cortical Surface Thickness in the Middle-Aged Brain with White Matter Hyperintense Lesions

“…The fusiform gyrus has been linked with various neural pathways related to recognition, including synesthesia, dyslexia and prosopagnosia (Weiner and Zilles, 2016). Reduced cortical volume and an increase in subcortical WMH lesions in the fusiform gyrus have been reported to be associated with age-related augmentation in tissue-preserving functions (Gunning-Dixon and Raz, 2003) and compensated regional cerebral blood flow (rCBF), leading to reduced efficacy of interregional neural communications as a result of WM deterioration (Kraut et al, 2008). The fusiform gyrus should therefore be investigated in future studies of middle-aged WMH subjects.…”

Volume of white matter hyperintensities in healthy adults: Contribution of age, vascular risk factors, and inflammation-related genetic variants

“…Indeed, regional CBF [92, 93] is reduced within WMH borders, and persons with significant expansion of WMH evidence greater decline in CBF than those whose WMH burden evidenced lesser increases [94]. It is worth noting that in the frontal and parietal regions, anti-hypertensive therapy was the least influential in reducing age-related declines in rCBF [89].…”

“…In the occipital lobe, middle-aged individuals with high tHcy levels have the largest WMH. Elevated tHcy is a risk factor for vascular disease [37,38], longitudinal expansion of occipital WMH may be associated with elevated vascular risk [94] and accumulation of WMH in the occipital lobe is linked to poor vascular and psychiatric outcomes [96]. Thus, it is possible that the participants who exhibited large WMH volume in the occipital lobes represent a subgroup that is at risk for cerebral and cognitive declines, a hypothesis that only a longitudinal study can test.…”

Multimodal white matter imaging to investigate reduced fractional anisotropy and its age-related decline in schizophrenia

“…Hypertension and other cerebrovascular disorders have been determined to be the risk factors for both the accelerated rise in HWM and decline in FA (Kochunov et al, 2009a; Kochunov et al, 2010; Kochunov et al, 2011c; Kochunov et al, 2012a). This aging-related change in white matter integrity occurs concurrently with decline in the overall cerebral integrity (Kochunov et al, 2008), cerebral blood flow (Kraut et al, 2008) and glucose metabolism (Kochunov et al, 2009b). Patients with schizophrenia have twice the rate of hypertension, cardiovascular, and metabolic illnesses compared with normal aging ( Tsuang and Woolson, 1978; Brown, 1997; Hennekens et al, 2005; Saha et al, 2007; Kirkpatrick et al, 2008; Ito and Barnes, 2009; Jeste et al, 2011).…”