Effect of worry, depressed affect, and sensitivity to environmental stress owing to neurotic personality on MRI markers of cerebral small vessel disease: A univariable and multivariable Mendelian randomization study.

OBJECTIVE: Neuroticism was found to be associated with cerebral small vessel disease (CSVD) in observational studies. We aimed to explore the causal relationship between distinct components of neuroticism and CSVD. METHODS: Two-sample mendelian randomization (MR) study was conducted to explore the bidirectional causal relationships between three genetically distinct subclusters of neuroticism (depressed affect, worry, and sensitivity to environmental stress and adversity [SESA]) and MRI markers of CSVD using publicly available genome-wide association studies (GWAS) data. Inverse variance weighted (IVW) method was used for the primary causal estimates. Alternative MR approaches and extensive sensitivity analyses were conducted to ensure the robustness of the findings. Multivariable MR (MVMR) analysis was used to estimate the direct causal effects with adjustment of other known risk factors for CSVD. RESULTS: Genetically determined SESA was significantly associated with reduced fractional anisotropy (FA) (beta: -1.94, 95%CI: -3.04 to -0.84, p=5.29e-4), and associated with increased mean diffusivity (MD) (beta=1.55, 95%CI: 0.29 to 2.81, p=0.016) and white matter hyperintensities (WMH) (beta=0.25, 95% CI: 0.03 to 0.47, p=0.029) at the nominally significant level. MVMR analysis suggested the significant associations remained significant after accounting for body mass index (BMI), smoking, alcohol drinking, type 2 diabetes (T2D), hypertension, and depression. The other two neuroticism subclusters (depressed affect and worry) didn't have significant causal effects on the MRI markers. In the reverse MR analysis with the MRI markers as exposures, no significant associations were found. CONCLUSION: This study supported the casual role of SESA in the development of CSVD. Further research to explore the underlying mechanism are warranted.

Regional cortical thinning, demyelination and iron loss in cerebral small vessel disease.

The link between white matter hyperintensities (WMH) and cortical thinning is thought to be an important pathway by which WMH contributes to cognitive deficits in cerebral small vessel disease (SVD). However, the mechanism behind this association and the underlying tissue composition abnormalities are unclear. The objective of this study is to determine the association between WMH and cortical thickness, and the in vivo tissue composition abnormalities in the WMH-connected cortical regions. In this cross-sectional study, we included 213 participants with SVD who underwent standardized protocol including multimodal neuroimaging scans and cognitive assessment (i.e. processing speed, executive function and memory). We identified the cortex connected to WMH using probabilistic tractography starting from the WMH and defined the WMH-connected regions at three connectivity levels (low, medium and high connectivity level). We calculated the cortical thickness, myelin and iron of the cortex based on T1-weighted, quantitative R1, R2* and susceptibility maps. We used diffusion-weighted imaging to estimate the mean diffusivity of the connecting white matter tracts. We found that cortical thickness, R1, R2* and susceptibility values in the WMH-connected regions were significantly lower than in the WMH-unconnected regions (all Pcorrected < 0.001). Linear regression analyses showed that higher mean diffusivity of the connecting white matter tracts were related to lower thickness (ß = -0.30, Pcorrected < 0.001), lower R1 (ß = -0.26, Pcorrected = 0.001), lower R2* (ß = -0.32, Pcorrected < 0.001) and lower susceptibility values (ß = -0.39, Pcorrected < 0.001) of WMH-connected cortical regions at high connectivity level. In addition, lower scores on processing speed were significantly related to lower cortical thickness (ß = 0.20, Pcorrected = 0.030), lower R1 values (ß = 0.20, Pcorrected = 0.006), lower R2* values (ß = 0.29, Pcorrected = 0.006) and lower susceptibility values (ß = 0.19, Pcorrected = 0.024) of the WMH-connected regions at high connectivity level, independent of WMH volumes and the cortical measures of WMH-unconnected regions. Together, our study demonstrated that the microstructural integrity of white matter tracts passing through WMH is related to the regional cortical abnormalities as measured by thickness, R1, R2* and susceptibility values in the connected cortical regions. These findings are indicative of cortical thinning, demyelination and iron loss in the cortex, which is most likely through the disruption of the connecting white matter tracts and may contribute to processing speed impairment in SVD, a key clinical feature of SVD. These findings may have implications for finding intervention targets for the treatment of cognitive impairment in SVD by preventing secondary degeneration.

Comparative Study of Risk Factors and Cognitive Profile of Small- and Large-Vessel Vascular Dementia - A Clinic Based Study.

Background: Vascular dementia (VaD) is a clinically heterogeneous entity. There is a dearth of studies for comparison of the cognitive profile of cerebral small-vessel disease (SVD) with large-vessel disease. Objective: We planned to evaluate and compare the cognitive profile of SVD and large-vessel VaD and evaluate various risk factors associated with them. Materials and Methods: Patients of VaD were recruited after excluding mixed and ambiguous cases. Patients were classified into SVD and large-vessel VaD and analyzed for their clinic-epidemiological and cognitive profiles. Results: Among 76 patients, 48 (62.5%) have SVD and 28 (37.5%) have large-vessel disease. Hypertension (93.4%) was the commonest risk factor, followed by smoking (34.21%), hyperlipidemia (26.31%), and diabetes mellitus (DM, 22.36%). Hypertension (P < 0.05) and DM were common in SVD, whereas smoking, hyperlipidaemia, and cardiac diseases were common in large-vessel disease. Attention (77.1% vs 25%), executive function (68.8% vs 28.6%), and calculation (58.3% vs 32.1%) were significantly more impaired in SVD compared to large-vessel disease, whereas visuoperceptual (21.4% vs 6.3%), praxis (28.6% vs 4.2%), and gnosis (14.3% vs 2.1%) were significantly more impaired in large-vessel disease than in SVD. Disruption of frontal-subcortical connection was responsible for the cognitive profile in SVD, but in large-vessel disease, it resulted from the cumulative loss of function from different lesions. Conclusions: Despite having common vascular risk factors, few are more common in SVD than in large-vessel disease. The different clinical and cognitive profile is due to the diverse anatomical lesions in these two subclasses of VaD.

An Assessment of the Relationship between Structural and Functional Imaging of Cerebrovascular Disease and Cognition-Related Fibers.

In order to assess the relationship between structural and functional imaging of cerebrovascular disease and cognition-related fibers, this paper chooses a total of 120 patients who underwent cerebral small vessel disease (CSVD) treatment at a designated hospital by this study from June 2013 to June 2018 and divides them into 3 groups according to the random number table method: vascular dementia (VaD) group, vascular cognitive impairment no dementia (VCIND) group, and noncognition impairment (NCI) group with 40 cases of patients in each group. Cognitive function measurement and imaging examination were performed for these 3 groups of patients, and the observation indicators of cognitive state examination (CSE), mental assessment scale (MAS), clock drawing test (CDT), adult intelligence scale (AIS), frontal assessment battery (FAB), verbal fluency test (VFT), trail making test (TMT), cognitive index (CI), white matter lesions (WML), third ventricle width (TVW), and frontal horn index (FHI) were tested, respectively. The results shows that the average scores of CSE, MAS, AIS, and VFT in the VaD and VCIND group are lower than those of the NCI group and the differences are statistically significant (P < 0.05); the average scores of FAB, TMT, and CI in the VaD group are higher than those of the VCIND group and the differences are also statistically significant (P < 0.05); the average scores of FHI and TVW in the VaD group are lower than those of the VCIND and NCI group with statistically significant differences (P < 0.05); the average scores of WML, CDT, and AIS in the VaD group are higher than those of the VCIND and NCI group with statistically significant differences (P < 0.05). Therefore, it is believed that the structural and functional imaging features of cerebrovascular disease are closely related to cognition-related fibers, and the incidence of white matter lesions is closely related to the degree of lesions and cognitive dysfunction of cerebral small vessel disease, in which a major risk factor for cognitive dysfunction in patients with small blood vessels is the severity of white matter lesions; brain imaging and neuropsychiatric function assessment can better understand the relationship between cerebrovascular disease and cognitive impairment. The results of this study provide a reference for the further research studies on the relationship between structural and functional imaging of cerebrovascular disease and cognition-related fibers.

Influences of the TLR4/NF-κB pathway on memory function and inflammatory factors in rats with cerebral small vessel disease.

OBJECTIVE: To explore the influences of toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway on the memory function and inflammatory factors in rats with cerebral small vessel disease (CSVD). MATERIALS AND METHODS: CSVD model in rats was established. Expressions of TLR4/NF-κB-related proteins and inflammatory factors were detected. CSVD rats were treated with the TLR4/NF-κB pathway agonist and inhibitor to evaluate the regulatory effect of TLR4/NF-κB pathway on the expressions of TLR4, NF-κB p50 and NF-κB p65. Moreover, their influences on the cerebral edema, memory function and expressions of inflammatory factors [interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α)] in CSVD rats were also analyzed. RESULTS: In model group, the mRNA and protein expressions of TLR4 and NF-κB-related proteins in rat hippocampus were significantly higher than those in sham group (p<0.01), and the expressions of IL-1ß and TNF-αsignificantly increased (p<0.05). The agonist lipopolysaccharide (LPS) significantly increased the proportion of TLR4-positive cells (p<0.01) and protein expression of TLR4 (p<0.01). The inhibitor CLI-095 obviously reduced the proportion of TLR4-positive cells and TLR4 expression (p<0.05). Pyrrolidine dithiocarbamate (PDTC) remarkably reduced the expressions of NF-κB p50 and NF-κB p65 in model group (p<0.05). LPS promoted cerebral edema, leading to memory dysfunction and enhanced inflammatory response in rats of model group. The inhibitor CLI-095+PDTC significantly reduced cerebral edema, lowered memory impairment and relieved inflammatory response in CSVD rats (p<0.05). CONCLUSIONS: The inhibitor of the TLR4/NF-κB signaling pathway can restore memory function and reduce inflammatory response in CSVD rats.

3-n-butylphthalide inhibits the apoptosis of nerve cells in rats with cerebral small vessel disease via the PI3K/Akt pathway.

OBJECTIVE: The aim of this study was to investigate the effect of 3-n-butylphthalide (NBP) on the apoptosis of nerve cells in vascular dementia (VaD) model rats caused by cerebral small vessel disease (CSVD), and to explore its regulatory mechanism. MATERIALS AND METHODS: The model of VaD was successfully established in rats by carotid artery ligation. All rats were randomly divided into three groups, including the sham operation group, model group and NBP group. The neurobehavioral score was used to verify whether the model was successfully established. The changes in learning and memory abilities of rats were detected via water maze experiment. The levels of Bcl-2-associated X protein (Bax) and cysteinyl aspartate specific proteinase-3 (Caspase-3) in the serum of rats was detected by enzyme-linked immunosorbent assay (ELISA). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was adopted to detect the apoptosis of nerve cells in brain tissues of rats. Moreover, the protein levels of phosphorylated phosphatidylinositol-3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in brain tissues of rats were measured using Western blotting. RESULTS: Compared with the sham operation group, the neurobehavioral score of rats increased significantly, whereas learning and memory abilities decreased markedly in the model group. The levels of Bax and Caspase-3 in rat serum were remarkably up-regulated, and the apoptosis rate of nerve cells in brain tissues of rats increased significantly in the model group as well. Meanwhile, the levels of phosphorylated PI3K and phosphorylated Akt were notably declined. Compared with the model group, the neurobehavioral score decreased markedly, while learning and memory abilities were remarkably improved in the NBP group. The levels of Bax and Caspase-3 in rat serum were significantly down-regulated, and the apoptosis rate of nerve cells in brain tissues of rats were reduced in the NBP group. Furthermore, the protein levels of phosphorylated PI3K and phosphorylated Akt were remarkably elevated in the NBP group. CONCLUSIONS: NBP can improve the morphology of brain tissue cells and the learning and memory abilities, and inhibit the apoptosis of nerve cells in VaD model rats with CSVD. The possible underlying mechanism may be related to the activation of the PI3K/Akt signaling pathway.

Deep microbleeds and periventricular white matter disintegrity are independent predictors of attention/executive dysfunction in non-dementia patients with small vessel disease.

BACKGROUND: Cerebral small vessel disease (SVD) is the common cause of cognitive decline in the old population. MRI can be used to clarify its mechanisms. However, the surrogate markers of MRI for early cognitive impairment in SVD remain uncertain to date. We investigated the cognitive impacts of cerebral microbleeds (CMBs), diffusion tensor imaging (DTI), and brain volumetric measurements in a cohort of post-stroke non-dementia SVD patients. METHODS: Fifty five non-dementia SVD patients were consecutively recruited and categorized into two groups as no cognitive impairment (NCI) (n = 23) or vascular mild cognitive impairment (VaMCI) (n = 32). Detailed neuropsychological assessment and multimodal MRI were completed. RESULTS: The two groups differed significantly on Z scores of all cognitive domains (all p < 0.01) except for the language. There were more patients with hypertension (p = 0.038) or depression (p = 0.019) in the VaMCI than those in the NCI group. Multiple regression analysis of cognition showed periventricular mean diffusivity (MD) (ß = -0.457, p < 0.01) and deep CMBs numbers (ß = -0.352, p < 0.01) as the predictors of attention/executive function, which explained 45.2% of the total variance. Periventricular MD was the independent predictor for either memory (ß = -0.314, p < 0.05) or visuo-spatial function (ß = -0.375, p < 0.01); however, only small proportion of variance could be accounted for (9.8% and 12.4%, respectively). Language was not found to be correlated with any of the MRI parameters. No correlation was found between brain atrophic indices and any of the cognitive measures. CONCLUSION: Arteriosclerotic CMBs and periventricular white matter disintegrity seem to be independent MRI surrogated markers in the early stage of cognitive impairment in SVD.

Cerebral small vessel disease: Capillary pathways to stroke and cognitive decline.

Cerebral small vessel disease (SVD) gives rise to one in five strokes worldwide and constitutes a major source of cognitive decline in the elderly. SVD is known to occur in relation to hypertension, diabetes, smoking, radiation therapy and in a range of inherited and genetic disorders, autoimmune disorders, connective tissue disorders, and infections. Until recently, changes in capillary patency and blood viscosity have received little attention in the aetiopathogenesis of SVD and the high risk of subsequent stroke and cognitive decline. Capillary flow patterns were, however, recently shown to limit the extraction efficacy of oxygen in tissue and capillary dysfunction therefore proposed as a source of stroke-like symptoms and neurodegeneration, even in the absence of physical flow-limiting vascular pathology. In this review, we examine whether capillary flow disturbances may be a shared feature of conditions that represent risk factors for SVD. We then discuss aspects of capillary dysfunction that could be prevented or alleviated and therefore might be of general benefit to patients at risk of SVD, stroke or cognitive decline.