Non-fasting High-Density Lipoprotein Is Associated With White Matter Microstructure in Healthy Older Adults

Association of Lp(a) With Stroke and Cerebral Injury on MRI: Insights From the HCHS/SOL (Hispanic Community Health Study/Study of Latinos) and Investigation of Neurocognitive Aging MRI (SOL-INCA MRI)

BACKGROUND

Lp(a) (lipoprotein[a]) is a risk factor for cardiovascular disease; however, its association with cerebrovascular disease is not as well established.

METHODS

Data from a population-based cohort of Hispanics/Latinos included 16 333 individuals with baseline Lp(a) levels (nmol/L) and self-reported prevalent stroke or transient ischemic attack (TIA). A subset of 2642 individuals with brain magnetic resonance imaging was also included. Linear and multivariate logistic regression assessed the association of Lp(a) with (1) self-reported stroke or TIA, (2) cerebral injury defined as self-reported stroke or TIA or evidence of a stroke on brain magnetic resonance imaging, (3) white matter hyperintensity volume, and (4) silent brain infarcts. Sampling weights were utilized given the HCHS/SOL (Hispanic Community Health Study/Study of Latinos) complex sample design.

RESULTS

Mean age±SE was 41.1±0.3 years, 52.0% female, and median interquartile range (Q1, Q3) Lp(a) level of 19.7 (7.3-60.6) nmol/L; brain magnetic resonance imaging subset mean age±SE was 49.9±0.4 years, 56.4% female, and median (interquartile range) Lp(a) level of 21.7 (8.1-62.9) nmol/L. Each unit increase in log-transformed Lp(a) was associated with higher odds of self-reported stroke or TIA (odds ratio, 1.13 [95% CI, 1.01-1.27]; P=0.03). Lp(a) levels in the highest quintile (>77 nmol/L) were significantly associated with higher odds of prevalent stroke or TIA compared with Lp(a) <6 nmol/L (first quintile: odds ratio, 1.74 [95% CI, 1.09-2.77]; P=0.02). The highest proportion of cerebral injury was noted in Q5, while the lowest proportion was noted in Q2. When comparing Lp(a) >77 nmol/L with Lp(a) of 6 to <13 nmol/L (second quintile), a significant association was found between Lp(a) and cerebral injury that persisted after fully adjusted models (odds ratio, 2.03 [95% CI, 1.05-3.93]; P=0.03). Each unit increase in log-Lp(a) was associated with a 0.10 increase in log-white matter hyperintensity (β, 0.10; P=0.005). No significant association was found between Lp(a) and silent brain infarcts.

CONCLUSIONS

Lp(a) is independently and significantly associated with prevalent stroke/TIA, and white matter hyperintensity, in a large diverse population of Hispanics/Latinos.

Physical activity may protect myelin via modulation of high-density lipoprotein

INTRODUCTION

Physical activity is associated with greater myelin content in older individuals with cerebral small vessel disease (CSVD), a condition marked by demyelination. However, potential mechanisms underlying this relationship remain understudied.

METHODS

We assessed cross-sectionally whether serum high-density lipoprotein (HDL), low-density lipoprotein, and triglycerides moderated the association between physical activity and in vivo myelin in older individuals with CSVD and mild cognitive impairment.

RESULTS

We included 81 highly educated, community-dwelling older individuals (mean age 74.57 years), 64% of whom were female. Regression models revealed that HDL levels significantly moderated the relationship between physical activity and myelin in the sagittal stratum, wherein higher physical activity levels were linked to greater myelin levels for those with average or high HDL (standardized B [95% CI] = 0.289 [0.087 to 0.491], p = 0.006).

DISCUSSION

Physical activity may promote myelin health partly through HDL. Data from longitudinal studies are needed to confirm our findings.

HIGHLIGHTS

Myelin loss is common in individuals with cerebral small vessel disease (CSVD). Physical activity was positively associated with myelin in older adults with CSVD. High-density lipoproteins (HDL) levels were also positively related to myelin. Physical activity effects on myelin were moderated by HDL levels.

SGLT1 and SGLT2 inhibition, circulating metabolites, and cerebral small vessel disease: a mediation Mendelian Randomization study

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) and SGLT1 inhibitors may have additional beneficial metabolic effects on circulating metabolites beyond glucose regulation, which could contribute to a reduction in the burden of cerebral small vessel disease (CSVD). Accordingly, we used Mendelian Randomization (MR) to examine the role of circulating metabolites in mediating SGLT2 and SGLT1 inhibition in CSVD.

METHODS

Genetic instruments for SGLT1/2 inhibition were identified as genetic variants, which were both associated with the expression of encoding genes of SGLT1/2 inhibitors and glycated hemoglobin A1c (HbA1c) level. A two-sample two-step MR was used to determine the causal effects of SGLT1/2 inhibition on CSVD manifestations and the mediating effects of 1400 circulating metabolites linking SGLT1/2 inhibition with CSVD manifestations.

RESULTS

A lower risk of deep cerebral microbleeds (CMBs) and small vessel stroke (SVS) was linked to genetically predicted SGLT2 inhibition. Better white matter structure integrity was also achieved, as evidenced by decreased mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), as well as lower deep (DWMH) and periventrivular white matter hyperintensity (PWMH) volume. Inhibiting SGLT2 could also lessen the incidence of severe enlarged perivascular spaces (EPVS) located at white matter, basal ganglia (BG) and hippocampus (HIP). SGLT1 inhibition could preserve white matter integrity, shown as decreased MD of white matter and DWMH volume. The effect of SGLT2 inhibition on SVS and MD of white matter through the concentration of 4-acetamidobutanoate and the cholesterol to oleoyl-linoleoyl-glycerol (18:1 to 18:2) ratio, with a mediated proportion of 30.3% and 35.5% of the total effect, respectively.

CONCLUSIONS

SGLT2 and SGLT1 inhibition play protective roles in CSVD development. The SGLT2 inhibition could lower the risk of SVS and improve the integrity of white matter microstructure via modulating the level of 4-acetamidobutanoate and cholesterol metabolism. Further mechanistic and clinical studies research are needed to validate our findings.

Relationship between physical activity and cerebral white matter hyperintensity volumes in older adults with depressive symptoms and mild memory impairment: a cross-sectional study

Introduction

Cerebral white matter hyperintensities (WMHs) are commonly found in the aging brain and have been implicated in the initiation and severity of many central nervous system diseases. Furthermore, an increased WMH volume indicates reduced brain health in older adults. This study investigated the association between WMH volume and physical activity in older adults with depressive symptoms (DS) and mild memory impairment (MMI). Factors associated with the WMH volume were also investigated.

Methods

A total of 57 individuals aged over 65 years with DS and MMI were included in this study. The participants underwent magnetic resonance imaging to quantify WMH volumes. After WMH volume was accumulated, normalized to the total intracranial volume (TIV), the percentage of WMH volume was calculated. In addition, all participants wore a triaxial accelerometer for 2 weeks, and the average daily physical activity and number of steps were measured. The levels of blood biomarkers including cortisol, interleukin-6 (IL-6), brain-derived insulin-like growth factor-1, and brain-derived neurotrophic factor were measured. Motor and cognitive functions were also assessed.

Results

Faster maximum walking speed and longer time spent engaged in moderate physical activity were associated with a smaller percent of WMH volume, whereas higher serum IL-6 levels were associated with a larger percent of WMH volume. The number of steps per day, time spent engaged in low levels of physical activity, cognitive function, and all other measured biomarkers were not significantly associated with percent of WMH volume.

Discussion

Higher blood inflammatory cytokine levels, shorter duration of moderate physical activity, and lower maximum walking speed were associated with a higher percent of WMH volume. Our results provide useful information for maintaining brain health in older adults at a high risk of developing dementia and may contribute to the development of preventive medicine for brain health.

Beyond BMI: cardiometabolic measures as predictors of impulsivity and white matter changes in adolescents

Obesity is characterized by cardiometabolic and neurocognitive changes. However, how these two factors relate to each other in this population is unknown. We tested the association that cardiometabolic measures may have with impulse behaviors and white matter microstructure in adolescents with and without an excess weight. One hundred and eight adolescents (43 normal-weight and 65 overweight/obesity; 11-19 years old) were medically and psychologically (Temperament Character Inventory Revised, Three-Factor Eating Questionnaire-R18, Conners' Continuous Performance Test-II, Stroop Color and Word Test, Wisconsin Card Sorting Test, Kirby Delay Discounting Task) evaluated. A subsample of participants (n = 56) underwent a brain magnetic resonance imaging acquisition. In adolescents, higher triglycerides and having a body mass index indicative of overweight/obesity predicted a more impulsive performance in Conners' Continuous Performance Test-II (higher commission errors). In addition, higher glucose and diastolic blood pressure values predicted increments in the Three-Factor Eating Questionnaire-R18 emotional eating scale. Neuroanatomically, cingulum fractional anisotropy showed a negative relationship with glycated hemoglobin. The evaluation of the neurocognitive differences associated with obesity, usually based on body mass index, should be complemented with cardiometabolic measures.

Effects of simvastatin on white matter integrity in healthy middle-aged adults

Background

The brain is the most cholesterol‐rich organ and myelin contains 70% of total brain cholesterol. Statins are potent cholesterol‐lowing medications used by millions of adults for prevention of vascular disease, yet the effect of statins on cholesterol‐rich brain white matter (WM) is largely unknown.

Methods

We used longitudinal neuroimaging data acquired from 73 healthy, cognitively unimpaired, statin‐naïve, middle‐aged adults during an 18‐month randomized controlled trial of simvastatin 40 mg daily (n = 35) or matching placebo (n = 38). ANCOVA models (covariates: age, sex, APOE‐ɛ4) tested the effect of treatment group on percent change in WM, gray matter (GM), and WM hyperintensity (WMH) neuroimaging measures at each study visit. Mediation analysis tested the indirect effects of simvastatin on WM microstructure through change in serum total cholesterol levels.

Results

At 18 months, the simvastatin group showed a significant preservation in global WM fractional anisotropy (β = 0.88%, 95% CI 0.27 to 1.50, P = 0.005), radial diffusivity (β = −1.10%, 95% CI −2.13 to −0.06, P = 0.039), and WM volume (β = 0.72%, 95% CI 0.13 to 1.32, P = 0.018) relative to the placebo group. There was no significant effect of simvastatin on GM or WMH volume. Change in serum total cholesterol mediated approximately 30% of the effect of simvastatin on WM microstructure.

Conclusions

Simvastatin treatment in healthy, middle‐aged adults resulted in preserved WM microstructure and volume at 18 months. The partial mediation by serum cholesterol reduction suggests both peripheral and central mechanisms. Future studies are needed to determine whether these effects persist and translate to cognitive outcomes.

Trial Registration

NCT00939822 (ClinicalTrials.gov).