Cerebral white matter lesions and hypertension status in the elderly Korean: the Ansan Study

Age and Diastolic Blood Pressure Play an Important Role in the Progression of White Matter Lesions: A Meta-Analysis

INTRODUCTION

White matter lesions (WMLs) are currently considered as a cerebral microvascular disease, and hypertension is considered as its most important risk factor. This study analysis systematically evaluated the effects of systolic blood pressure (SBP) and diastolic blood pressure (DBP) on the progression of WMLs.

METHODS

We searched the MeSH terms: "white matter," "blood pressure," "hypertension," "Leukoencephalopathy," and "leukoaraiosis" on PubMed and Cochrane from January 2000 to August 2019. A total of 12 closely related literature were included for research.

RESULTS

The results of the meta-analysis showed that the increase of both SBP and DBP can promote the progression of WMLs (respectively, odds ratio [OR] = 2.90, 95% confidence interval [CI] 2.86-2.94; OR = 3.13, 95% CI 3.03-3.23). Subgroup analysis found that patients with hypertension aged younger than 70 years are at a greater risk of WML progression when their DBP increased (OR = 4.69, 95% CI 3.31-6.65).

CONCLUSION

The relationship between DBP and WMLs is closer than that of SBP. Also, the risk of WML progression in patients aged under 70 years was higher than that in patients aged over 70 years. Furthermore, when DBP is elevated in patients younger than 70 years of age, the risk of WML progression may be higher. Therefore, it is expected that more researchers will attach importance to the change in DBP and identify the range of blood pressure and strategies that control DBP, thus contributing to delay the progression of WMLs.

Age-related white matter changes

Age-related white matter changes (WMC) are considered manifestation of arteriolosclerotic small vessel disease and are related to age and vascular risk factors. Most recent studies have shown that WMC are associated with a host of poor outcomes, including cognitive impairment, dementia, urinary incontinence, gait disturbances, depression, and increased risk of stroke and death. Although the clinical relevance of WMC has been extensively studied, to date, only very few clinical trials have evaluated potential symptomatic or preventive treatments for WMC. In this paper, we reviewed the current understanding in the pathophysiology, epidemiology, clinical importance, chemical biomarkers, and treatments of age-related WMC.

Correlation between degree of white matter hyperintensities and global gray matter volume decline rate

INTRODUCTION

Whether the degree of white matter hyperintensities (WMHs) shows a significant correlation with the rate of global gray matter volume decline over a period following initial baseline measurement remains unclear. The purpose of the present study was to reveal the relationship between the degree of WMHs at baseline and the rate of global gray matter volume decline by applying a longitudinal design.

METHODS

Using a 6-year longitudinal design and magnetic resonance images of the brains of 160 healthy individuals aged over 50 years and living in the community, we analyzed the correlation between degree of WMHs using Fazekas scaling at baseline and rate of global gray matter volume decline 6 years later. To obtain the rate of global gray matter volume decline, we calculated global gray matter volume and intracranial volume at baseline and at follow-up using a fully automated method.

RESULTS

The annual percentage change in the gray matter ratio (GMR, APC(GMR)), in which GMR represents the percentage of gray matter volume in the intracranial volume, showed a significant positive correlation with the degree of deep WMHs and periventricular WMHs at baseline, after adjusting for age, gender, present history of hypertension, and diabetes mellitus.

CONCLUSION

Our results suggest that degree of WMHs at baseline predicts the rate of gray matter volume decline 6 years later and that simple visual scaling of WMHs could contribute to predicting the rate of global gray matter volume decline.

Longitudinal follow-up of individual white matter hyperintensities in a large cohort of elderly

INTRODUCTION

We report on a method for the longitudinal follow-up of individual white matter hypersignals (WMH) and on its application to the study of WMH natural evolution in a cohort of 1,118 elderly over a 4-year period.

MATERIALS AND METHODS

For each subject, automated WMH detection was performed on T2-weighted MR images acquired both at baseline and at follow-up after registration in a common space. The detection algorithm was designed both to track WMH previously existing at baseline and to identify newly formed WMH.

RESULTS

The average annual change in WMH load was found to be 0.25 cm(3)/year, 36% of this change being attributable to newly formed WMH. Quantitative analyses showed that change in WMH was mainly explained by progression of juxtaventricular and periventricular WMH while the load of WMH in the deep white matter zones was found stable over 4 years of the study. Statistical parametric mapping confirmed these spatial WMH change distributions in the juxta- and periventricular zones. High blood pressure was not a significant predictor of the annual change in WMH.

CONCLUSION

This study proposes a new scheme for the longitudinal study of WMH change by dissociating worsening of existent WMH from surfacing of new WMH and may thus contribute to help understanding and characterizing the neurological and etiological bases of these two processes and their potential differences.

An automated procedure for the assessment of white matter hyperintensities by multispectral (T1, T2, PD) MRI and an evaluation of its between-centre reproducibility based on two large community databases

INTRODUCTION

An automated procedure for the detection, quantification, localization and statistical mapping of white matter hyperintensities (WMH) on T2-weighted magnetic resonance (MR) images is presented and validated based on the results of a between-centre reproducibility study.

METHODS

The first step is the identification of white matter (WM) tissue using a multispectral (T1, T2, PD) segmentation. In a second step, WMH are identified within the WM tissue by segmenting T2 images, isolating two different classes of WMH voxels - low- and high-contrast WMH voxels, respectively. The reliability of the whole procedure was assessed by applying it to the analysis of two large MR imaging databases (n = 650 and n= 710, respectively) of healthy elderly subjects matched for demographic characteristics.

RESULTS

Average overall WMH load and spatial distribution were found to be similar in the two samples, (1.81 and 1.79% of the WM volume, respectively). White matter hyperintensity load was found to be significantly associated with both age and high blood pressure, with similar effects in both samples. With specific reference to the 650 subject cohort, we also found that WMH load provided by this automated procedure was significantly associated with visual grading of the severity of WMH, as assessed by a trained neurologist.

CONCLUSION

The results show that this method is sensitive, well correlated with semi-quantitative visual rating and highly reproducible.

High Prevalence of Leukoaraiosis in Cerebral Magnetic Resonance Images of Patients on Peritoneal Dialysis

BACKGROUND

Leukoaraiosis is a term used to define the abnormal appearance of subcortical white matter of the brain by means of neuroimaging and is regarded as an intermediate surrogate of stroke. The goal of this study is to identify the prevalence of leukoaraiosis and analyze predictors of risk of leukoaraiosis.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

57 peritoneal dialysis (PD) patients without diabetes treated in 3 academic medical-associated dialysis units who did not have a history of cerebrovascular disease or neurological symptoms compared with a convenience sample of 57 age- and sex-matched hypertensive control subjects with normal renal function.

PREDICTOR

End-stage renal disease treated by PD compared with hypertension, adjusted for clinical and laboratory characteristics.

OUTCOME & MEASUREMENT

Hyperintense areas on magnetic resonance imaging T2 high-signal intensity scoring system.

RESULTS

The prevalence of leukoaraiosis was significantly greater in patients on PD therapy than controls (68.4% versus 17.5%; P < 0.001). High T2 signal intensity score in patients on PD therapy compared with controls was significantly higher in the anterior circulation of the brain, relatively sparing the posterior fossa. End-stage renal disease, age, and poor control of blood pressure were significant independent predictors of leukoaraiosis.

LIMITATIONS

There is the possibility that biases regarding the selection of enrolled patients had an influence on a study result.

CONCLUSIONS

Cerebral magnetic resonance imaging of PD patients without evidence of cerebrovascular disease showed a high prevalence of leukoaraiosis in the anterior circulation of the brain. Old age, poorly controlled hypertension, and the PD procedure itself and/or end-stage renal disease seem to be associated with the presence of leukoaraiosis.

A Glu487Lys polymorphism in the gene for mitochondrial aldehyde dehydrogenase 2 is associated with myocardial infarction in elderly Korean men

BACKGROUND

A homozygous mutant (ALDH2*2/*2) of the gene for mitochondrial aldehyde dehydrogenase 2 (ALDH2) at codon 487 was reported to be associated with myocardial infarction (MI) among Japanese men. However, such an association has never been studied in a Korean population.

METHOD

The subjects consisted of 122 men (60-81 y) with MI recruited randomly from Yonsei University Medical Center, Korea. A total of 439 men (60-84 y) without MI were selected as controls from the Ansan Geriatric Study. ALDH2 genotypes were determined using the TaqMan fluorogenic 5' nuclease polymerase chain reaction assay.

RESULTS

Genotypes carrying the mutant ALDH2 allele (ALDH2*1/*2 plus ALDH2*2/*2) were significantly more frequent in patients with MI than in the controls (42.6% vs. 30.5%, P=0.0163). Multiple logistic regression analysis revealed that ALDH2*1/*2 plus ALDH2*2/*2, together with abnormal high density lipoprotein cholesterol and elevated body mass index, was an independent risk factor for MI in elderly Korean men (odds ratio=1.976, 95% CI: 1.202-3.248).

CONCLUSIONS

ALDH2 polymorphisms may play an important role in the pathogenesis of MI in elderly Korean men.

Critical factors in gene expression in postmortem human brain: Focus on studies in schizophrenia

BACKGROUND

Studies of postmortem human brain are important for investigating underlying pathogenic molecular mechanisms of neuropsychiatric disorders. They are, however, confounded by pre- and postmortem factors. The purpose of this study was to identify sources of variation that will enable a better design of gene expression studies and higher reliability of gene expression data.

METHODS

We assessed the contribution of multiple variables to messenger RNA (mRNA) expression of reference (housekeeping) genes measured by reverse transcriptase-polymerase chain reaction (RT-PCR) by multiple regression analysis in a large number (N = 143) of autopsy samples from the hippocampus and white and grey matter of the dorsolateral prefrontal cortex (DLPFC) of patients with schizophrenia and normal control subjects.

RESULTS

The strongest predictor of gene expression was total RNA quality. Other significant factors included pH, postmortem interval, age and the duration of the agonal state, but the importance of these factors depended on transcript measured, brain region analyzed, and diagnosis. The quality of RNA obtained from the DLPFC white matter was also adversely affected by smoking.

CONCLUSIONS

Our results show that normalization of expression data of target genes with a geometric mean of multiple housekeeping genes should be used to control for differences in RNA quality between samples. The results also suggest that accurate assessment of other confounding factors and their inclusion as regressors in the analysis is critical for obtaining reliable and accurate quantification of mRNA expression.