Thostenson, Kaely

Abstract Background White matter (WM) abnormalities have been implicated in clinically relevant functional decline in multiple system atrophy (MSA). Objective To identify the WM and gray matter (GM) abnormalities in MSA and assess the utility of longitudinal structural and diffusion changes as surrogate markers for tracking disease progression in MSA. Methods Twenty‐seven participants with early MSA [15 with clinically predominant cerebellar (MSA‐C) and 12 with clinically predominant parkinsonian features (MSA‐P)] and 14 controls were enrolled as a part of our prospective, longitudinal study of synucleinopathies. Using structural magnetic resonance imaging (MRI) and diffusion MRI (diffusion tensor and neurite orientation and dispersion density imaging), we analyzed whole and regional brain changes in these participants. We also evaluated temporal imaging trajectories based on up to three annual follow‐up scans and assessed the impact of baseline diagnosis on these imaging biomarkers using mixed‐effect models. Results MSA patients exhibited more widespread WM changes than GM, particularly in the cerebellum and brainstem, with greater severity in MSA‐C. Structural and diffusion measures in the cerebellum WM and brainstem deteriorated with disease progression. Rates of progression of these abnormalities were similar in both MSA subtypes, reflecting increasing overlap of clinical features over time. Conclusion WM abnormalities are core features of MSA disease progression and advance at similar rates in clinical MSA subtypes. Multimodal MRI imaging reveals novel insights into the distribution and pattern of brain abnormalities and their progression in MSA. Selected structural and diffusion measures may be useful for tracking disease progression in MSA clinical trials.

AbstractBackgroundElevated systolic blood pressure (SBP) and diastolic blood pressure (DBP) are risk factors for white matter (WM) injury associated with cognitive decline and dementia. White matter hyperintensities (WMH) on MRI, markers of WM injury, increase with aging and are more common in women than in men after the age of 60. We examined SBP and DBP in relation to WMH volume and diffusion MRI measures of WM integrity in postmenopausal women.MethodWomen (n=144) with median age of 67 (range 58‐72) and of good cardiovascular health who were previously enrolled in the multi‐site randomized clinical trial, Kronos Early Estrogen Prevention Study (KEEPS), participated in the present observational KEEPS Continuation Study. SBP, DBP, and MRI data were collected approximately 9 years after the end of KEEPS menopausal hormones versus placebo 4‐year interventions. WM integrity was assessed with WMH volume measurements (log transformed) on structural MRI and with measures of WM microstructure on diffusion MRI. Multiple linear regression analyses, adjusted for age, were used to test for associations of SBP and DBP with MRI measures.ResultThe median SBP was 128 (range 86‐180) and DBP was 77 (range 47‐106). Higher SBP (r=0.332;p=0.015) and DBP (r=0.346;p=0.007) were associated with higher WMH volumes. Among the WM tracts, higher SBP was associated with lower fractional anisotropy (FA) in lateral orbitofrontal gyrus WM (r=0.198;p=0.039) and sagittal stratum (r=0.226;p=0.043), and higher DBP was associated with lower FA in the superior occipital gyrus WM (r=0.370;p=0.045). Higher SBP and DBP were associated with higher mean diffusivity (MD) in the external capsule [(r=0.311;p=0.007);(r=375;p<0.001)] and the fronto‐occipital fasciculus [(r=0.286;p=0.016); (r=0.303;p=0.008)]. Furthermore, higher DBP was associated with higher MD in the anterior corona radiata (r=0.233;p=0.039), internal capsule (r=0.303;p=0.042), and the middle (r=0.275; p=0.03) and superior frontal gyrus (r=0.269;p=0.03) WM.ConclusionElevated SBP and DBP measurements are associated with greater WM injury in postmenopausal women. In particular, the frontal lobe WM and its connecting tracts may be more vulnerable to elevation in SBP and DBP. Whether BP control reduces the risk for WM injury, a risk factor for dementia, in post‐menopausal women warrants study.

Background: Chronic kidney disease (CKD), a growing public health issue in the elderly, is associated with increased risk of cognitive impairment. Objective: To investigate the mechanisms through which CKD impacts brain health using longitudinal imaging. Methods: We identified 97 participants (74 CKD and 23 non-CKD) from the BRINK (BRain IN Kidney Disease), a longitudinal study of CKD with two MRI scans (baseline and 3-year follow-up). We measured the associations between baseline and change in kidney disease biomarkers of estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (UACR), considered a measure of microvascular inflammation, and imaging outcomes of cortical thickness and ventricular volume from structural MRI, white matter hyperintensities (WMH) volume from FLAIR images, and fractional anisotropy of the corpus callosum (FACC). Results: There were white matter-specific changes as observed by increased WMH volume and decreased FACC in CKD participants, as well as ventricular volume increase in both CKD and non-CKD groups reflective of aging-related changes. Decline in eGFR was associated with decrease in the FACC, suggesting that subtle early white matter changes due to kidney disease can be captured using DTI. An increase in UACR was associated with increase in ventricular volume. Conclusion: Our results support the role of eGFR as a measure of kidney microvascular disease which is associated with concurrent white matter damage in CKD. Future work is needed to investigate the possible link between endothelial microvascular inflammation (as measured by an increased UACR) and ventricular volume increase.

AbstractBackgroundWe report the associations between change in renal biomarkers in CKD and non‐ CKD participants and change in structural MRI outcomes over 3 years in the BRain IN Kidney disease (BRINK) study MRI cohort. The imaging outcomes were cortical thickness in Alzheimer’s disease signature regions, white matter hyperintensities (WMH), and fractional anisotropy in the corpus callosum (FA CC), an early marker of cerebrovascular disease.MethodsParticipants were ≥ 45 years with CKD (estimated glomerular filtration rate (eGFR) in mL/min/1.73 m2< 60; non‐ dialysis) or non – CKD (eGFR ≥ 60) in Minneapolis/St. Paul. CKD severity was measured by the eGFR and urine albumin creatinine ratio (UACR‐albuminuria, a measure of microvascular disease). Brain images were obtained on a 1.5 T Phillips Ingenia machine at baseline and 3 years. Linear regression models measured the associations between 3 year change in eGFR and UACR, as predictors of change in MRI measures: AD cortical thickness, WMH, and FA CC over 3 years. Adjusted models included age, gender, AA race, education years, cerebrovascular disease risk factor score (CVD RF), smoker/alcohol use, and pulse pressure as covariates, and TIV for change in WMH models.ResultsAt baseline, mean age of the 97 participants was 67 years, and mean eGFR was 37 for the CKD group vs. 83.2 for non‐ CKD (Table 1). Mean change in eGFR and UACR in the CKD group were ‐3.6 and +212, respectively compared with ‐ 8.5 and +1.7 in the non‐ CKD group. Mean WMH volume increase (+5.8 cc) and mean FA CC decrease (‐0.012) were significant in CKD (p < 0.001) for both (Table 2). In adjusted models both a 1% decrease and a ≥ 3 unit/year decline in eGFR were associated with a decline in FA CC over 3 years in the CKD group (β (SE) =‐0.020 (0.007); p = 0.004) and ‐0.0097 (0.0042); p = 0.025, respectively). Cortical thickness models were not significant. Unexpectedly, change in UACR was not associated with change in any MRI outcomes.ConclusionsDecreased eGFR was associated with decreased FA CC in CKD, suggesting that CKD progression exerts its influence largely through cerebrovascular mechanisms.