Effects of white matter lesions on brain perfusion in patients with mild cognitive impairment

Impact of cannabis use on brain metabolism using 31P and 1H magnetic resonance spectroscopy

PURPOSE

This prospective cross-sectional study investigated the influence of regular cannabis use on brain metabolism in young cannabis users by using combined proton and phosphorus magnetic resonance spectroscopy.

METHODS

The study was performed in 45 young cannabis users aged 18-30, who had been using cannabis on a regular basis over a period of at least 2 years and in 47 age-matched controls. We acquired 31P MRS data in different brain regions at 3T with a double-resonant 1H/31P head coil, anatomic images, and 1H MRS data with a standard 20-channel 1H head coil. Absolute concentration values of proton metabolites were obtained via calibration from tissue water as an internal reference, whereas a standard solution of 75 mmol/l KH2PO4 was used as an external reference for the calibration of phosphorus signals.

RESULTS

We found an overall but not statistically significant lower concentration level of several proton and phosphorus metabolites in cannabis users compared to non-users. In particular, energy-related phosphates such as adenosine triphosphate (ATP) and inorganic phosphate (Pi) were reduced in all regions under investigation. Phosphocreatine (PCr) showed lowered values mainly in the left basal ganglia and the left frontal white matter.

CONCLUSION

The results suggest that the increased risk of functional brain disorders observed in long-term cannabis users could be caused by an impairment of the energy metabolism of the brain, but this needs to be verified in future studies.

Whether jugular venous reflux relates to more serious ischemic white matter lesions?

OBJECTIVE

To evaluate whether jugular venous reflux (JVR) relates to more serious ischemic white matter lesions (WMLs).

PATIENTS AND METHODS

Fifty cases were enrolled and divided into absent to mild ischemic WMLs group and moderate to severe ischemic WMLs group. Then the univariate and multivariate analyses were conducted to evaluate the relationship between JVR and moderate to severe ischemic WMLs, and a receiver operating characteristic (ROC) curve was used to evaluate the predictive value of JVR for moderate to severe ischemic WMLs.

RESULTS

There were 28 patients in the absent to mild ischemic WMLs group and 22 patients in the moderate to severe ischemic WMLs group. There was no significant difference between the two groups in gender, blood lipid indexes, proportions of diabetes, and abnormal deep cerebral veins (all p > 0.05). However, compared with the absent to mild ischemic WMLs group, the moderate to severe ischemic WMLs group was older and had a higher proportion of hypertension and JVR (p = 0.005; p < 0.001; p < 0.001, respectively). Multivariate logistic regression analysis showed that JVR was an independent risk factor for moderate to severe ischemic WMLs (OR = 17.679, 95 % CI: 3.056-102.286, p = 0.001). Furthermore, the area under curve of JVR combined with hypertension was 0.912 (p < 0.001), and the specificity of predicting moderate to severe ischemic WMLs was 92.9 %.

CONCLUSION

Our study suggested that JVR might relate to more severe ischemic WMLs.

Cerebral white matter lesions and regional blood flow are associated with reduced cognitive function in early-stage cognitive impairment

Background

Differences in the extent of cerebral white matter lesions (WML) and regional cerebral blood flow (rCBF) in early-stage cognitive impairment (ESCI) contribute to the prognosis of cognitive decline; however, it is unclear precisely how WML and rCBF affect cognitive decline in ESCI.

Objective

We examined the association between WML, rCBF, and cognitive impairment in the ESCI, using path analysis to clarify how these variables affect each other.

Methods

Eighty-three patients who consulted our memory clinic regarding memory loss were included in this study based on the Clinical Dementia Rating. Participants underwent the Mini-Mental State Examination (MMSE), brain magnetic resonance imaging (MRI) for voxel-based morphometry analysis, and brain perfusion single-photon emission computed tomography (SPECT) for rCBF evaluation in cortical regions, using 3D stereotactic surface projection (3D-SSP) analysis.

Results

Path analysis was performed on the MRI voxel-based morphometry and SPECT 3D-SSP data, showing a significant correlation between both and MMSE scores. In the most suitable model (GFI = 0.957), correlations were observed between lateral ventricular (LV-V) and periventricular WML (PvWML-V) volumes [standardized coefficient (SC) = 0.326, p = 0.005], LV-V and rCBF of the anterior cingulate gyrus (ACG-rCBF; SC = 0.395, p < 0.0001), and ACG-rCBF and PvWML-V (SC = 0.231, p = 0.041). Furthermore, a direct relationship between PvWML-V and MMSE scores was identified (SC = -0.238, p = 0.026).

Conclusion

Significant interrelationships were observed among the LV-V, PvWML-V, and ACG-rCBF that directly affected the MMSE score in the ESCI. The mechanisms behind these interactions and the impact of PvWML-V on cognitive function require further investigation.

Research Progress on MRI for White Matter Hyperintensity of Presumed Vascular Origin and Cognitive Impairment

White matter hyperintensity of presumed vascular origin (WMH) is a common medical imaging manifestation in the brains of middle-aged and elderly individuals. WMH can lead to cognitive decline and an increased risk of cognitive impairment and dementia. However, the pathogenesis of cognitive impairment in patients with WMH remains unclear. WMH increases the risk of cognitive impairment, the nature and severity of which depend on lesion volume and location and the patient's cognitive reserve. Abnormal changes in microstructure, cerebral blood flow, metabolites, and resting brain function are observed in patients with WMH with cognitive impairment. Magnetic resonance imaging (MRI) is an indispensable tool for detecting WMH, and novel MRI techniques have emerged as the key approaches for exploring WMH and cognitive impairment. This article provides an overview of the association between WMH and cognitive impairment and the application of dynamic contrast-enhanced MRI, structural MRI, diffusion tensor imaging, 3D-arterial spin labeling, intravoxel incoherent motion, magnetic resonance spectroscopy, and resting-state functional MRI for examining WMH and cognitive impairment.

Plasma osteoprotegerin levels are associated with the presence and burden of cerebral small vessel disease in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Osteoprotegerin (OPG) is a component of the tumor necrosis factor receptor superfamily. Several studies have shown a relationship between OPG and cardiovascular diseases. We hypothesized that there is a relationship between plasma OPG levels and cerebral small vessel disease (SVD).

METHODS

Patients diagnosed with their first cerebral ischemic infarction between April 2014 and March 2017 were enrolled. All the enrolled patients were evaluated through the hospital stroke protocol, including routine blood tests, brain imaging, and measuring the plasma OPG levels. The presence and burden of cerebral SVD [cerebral microbleeds (CMBs), asymptomatic lacunar infarction (ALI), high-grade perivascular space (HPVS), high-grade white matter hyperintensity (HWMH)], and total SVD score were assessed through brain magnetic resonance imaging.

RESULTS

Of the 270 patients included in our study, 158 (58.5%) were men. The mean age of the patients was 63.8 ± 11.6 years. In multivariable analysis, plasma OPG levels were positively associated with the presence and burden of each cerebral SVD. The odds ratios (OR) of CMBs, ALI, HPVS, and HWMH for the association of OPG per standard deviation (SD) increase were 1.58 [95% confidence interval (CI), 1.09-2.27], 1.40 (95% CI, 1.04-1.88), 1.88 (95% CI, 1.27-2.78), and 1.47 (95% CI, 1.04-2.08), respectively. Plasma OPG levels were positively correlated with total SVD score (beta = 0.211, standard error = 0.061, p-value = 0.009, R² = 0.275).

CONCLUSIONS

Plasma OPG levels correlate with the presence and burden of cerebral SVD in patients with acute ischemic stroke.

Abnormal Cerebral Blood Flow and Functional Connectivity Strength in Subjects With White Matter Hyperintensities

White matter hyperintensities (WMHs) are common neuroimaging findings in the aging population and are associated with various clinical symptoms, especially cognitive impairment. Abnormal global cerebral blood flow (CBF) and specific functional connections have been reported in subjects with higher WMH loads. Nevertheless, the comprehensive functional mechanisms underlying WMH are yet to be established. In this study, by combining resting-state functional magnetic resonance imaging and arterial spin labeling, we investigated the neurovascular dysfunction in subjects with WMH in CBF, functional connectivity strength (FCS), and CBF–FCS coupling. The whole-brain alterations of all these measures were explored among non-dementia subjects with different WMH loads using a fine-grained Human Brainnetome Atlas. In addition, exploratory mediation analyses were conducted to further determine the relationships between these neuroimaging indicators, WMH load, and cognition. The results showed that subjects with higher WMH loads displayed decreased CBF and FCS mainly in regions involving the cognitive- and emotional-related brain networks, including the default mode network, salience network, and central executive network. Notably, subjects with higher WMH loads also showed an abnormal regional CBF–FCS coupling in several regions of the thalamus, posterior cingulate cortex, and parahippocampal gyrus involving the default mode network. Furthermore, regional CBF in the right inferior temporal gyrus and right dorsal caudate may mediate the relationship between WMH load and cognition in WMH subjects. These findings indicated characteristic changes in cerebral blood supply, brain activity, and neurovascular coupling in regions involving specific brain networks with the development of WMH, providing further information on pathophysiology underpinnings of the WMH and related cognitive impairment.

Sex Differences in Cerebral Small Vessel Disease: A Systematic Review and Meta-Analysis

Background: Cerebral small vessel disease (SVD) is a common cause of stroke, mild cognitive impairment, dementia and physical impairments. Differences in SVD incidence or severity between males and females are unknown. We assessed sex differences in SVD by assessing the male-to-female ratio (M:F) of recruited participants and incidence of SVD, risk factor presence, distribution, and severity of SVD features. Methods: We assessed four recent systematic reviews on SVD and performed a supplementary search of MEDLINE to identify studies reporting M:F ratio in covert, stroke, or cognitive SVD presentations (registered protocol: CRD42020193995). We meta-analyzed differences in sex ratios across time, countries, SVD severity and presentations, age and risk factors for SVD. Results: Amongst 123 relevant studies (n = 36,910 participants) including 53 community-based, 67 hospital-based and three mixed studies published between 1989 and 2020, more males were recruited in hospital-based than in community-based studies [M:F = 1.16 (0.70) vs. M:F = 0.79 (0.35), respectively; p < 0.001]. More males had moderate to severe SVD [M:F = 1.08 (0.81) vs. M:F = 0.82 (0.47) in healthy to mild SVD; p < 0.001], and stroke presentations where M:F was 1.67 (0.53). M:F did not differ for recent (2015-2020) vs. pre-2015 publications, by geographical region, or age. There were insufficient sex-stratified data to explore M:F and risk factors for SVD. Conclusions: Our results highlight differences in male-to-female ratios in SVD severity and amongst those presenting with stroke that have important clinical and translational implications. Future SVD research should report participant demographics, risk factors and outcomes separately for males and females. Systematic Review Registration: [PROSPERO], identifier [CRD42020193995].

Value of Magnetic Resonance Diffusion Tensor Imaging Combined with Quantitative Electroencephalogram in Diagnosis of Neurocognitive Impairment in Patients with White Matter Demyelination

This paper aimed to explore the clinical value of combined adoption of magnetic resonance diffusion tensor imaging (DTI) and quantitative electroencephalogram (QEEG) in assessing microstructure changes and mild neurocognitive dysfunction in patients with white matter demyelination. 128 cases of white matter demyelination admitted to the hospital from October 2018 to October 2019 were rolled into the research group, and 100 healthy patients physically examined during the same period were rolled into the control (ctrl) group. QEEG and magnetic resonance DTI examinations were performed for all patients. The wave power of δ, θ, α, and β and the ratio of α/θ and (δ + θ)/(α + β) were recorded. The FA values of white matter fibers in different brain areas were measured, and the Montreal Cognitive Assessment (MoCA) and Addenbrooke Cognitive Evaluation rating (ACE-R) were adopted to assess the neurocognitive function of patients. It was found that the dominant frequency of each brain area in the research group was 8-9 Hz slow α wave. In contrast with the ctrl, the α wave and α/θ values in the research group were lower, while θ wave and δ + θ/α + β values were higher (P < 0.05); the scores of ACE-R and MoCA were lower (P < 0.01); the fractional anisotropy (FA) values of the right frontal lobe white matter (0.335 ± 0.068), the left temporal lobe white matter (0.391 ± 0.032), and the corpus callosum knee white matter (0.658 ± 0.053) were lower (P < 0.05). The FA values of these three areas were positively correlated with attention and calculation, memory, and memory of MoCA scale, respectively (P < 0.05). The FA value of the right frontal white matter was positively correlated with the attention and calculation score of the ACE-R scale (P < 0.05). In conclusion, magnetic resonance DTI combined with QEEG could reflect the microstructural changes of white matter, which may be associated with mild neurocognitive impairment. The primary objective of the study was to explore the clinical value of combined adoption of magnetic resonance DTI and QEEG in assessing microstructure changes and mild neurocognitive dysfunction in patients with white matter demyelination, expected to provide a theoretical basis for the treatment of white matter demyelination.

Association of Blood Pressure, White Matter Lesions, and Regional Cerebral Blood Flow

Background

At present, the association between blood pressure, regional cerebral blood flow, and white matter lesions is not well understood.

Material/Methods

A total of 147 subjects aged from 40 to 80 years were assessed by the Fazekas score for white matter lesions, CT perfusion imaging for regional cerebral blood flow, and 24-h ambulatory blood pressure monitoring for blood pressure level and rhythm. Logistic regression analysis was used to obtain the odds ratio and 95% confidence interval between Fazekas scores and relevant factors. The relationship between blood pressure index and regional cerebral blood flow was analyzed through cubic curve estimation.

Results

Fazekas score was negatively correlated with regional cerebral blood flow (r=−0.801; r=−0.831, P<0.001). For subcortical lesion, the regional cerebral blood flow of Fazekas grade 0 was 1.976 times that of Fazekas grade 3 (OR=1.976, 95% CI=1.576–2.477), and for periventricular lesion, the regional cerebral blood flow of Fazekas grade 0 was 2.034 times that of Fazekas grade 3 (OR=2.034, 95% CI=1.602–2.583). Increased nighttime systolic blood pressure may be more dangerous (OR=1.112, 95% CI=1.059–1.169). The day-night systolic blood pressure ratio (OR=0.801, 95% CI 0.711–0.902) and the day-night diastolic blood pressure ratio (OR=0.876, 95% CI 0.807–0.950) were significantly correlated with Fazekas score.

Conclusions

The decrease of white matter regional cerebral blood flow caused by hypertension is probably one of the important causes of white matter lesions. Patients with white matter lesions should also pay attention to the rhythm of blood pressure when controlling hypertension, especially if their blood pressure is too high or too low at night.

Associations Between White Matter Hyperintensity Burden, Cerebral Blood Flow and Transit Time in Small Vessel Disease: An Updated Meta-Analysis

Cerebral small vessel disease (SVD) is a major contributor to stroke and dementia, characterized by white matter hyperintensities (WMH) on neuroimaging. WMH are associated with reduced cerebral blood flow (CBF) cross-sectionally, though longitudinal associations remain unclear. We updated a 2016 systematic review, identifying 30 new studies, 27 cross-sectional (n = 2,956) and 3 longitudinal (n = 440). Cross-sectionally, 10/27 new studies (n = 1,019) included sufficient data for meta-analysis, which we meta-analyzed with 24 previously reported studies (n = 1,161), total 34 (n = 2,180). Our meta-analysis showed that patients with lower CBF had worse WMH burden (mean global CBF: standardized mean difference (SMD): −0.45, 95% confidence interval (CI): −0.64, −0.27). Longitudinally, associations between baseline CBF and WMH progression varied: the largest study (5 years, n = 252) found no associations, while another small study (4.5 years, n = 52) found that low CBF in the periventricular WMH penumbra predicted WMH progression. We could not meta-analyse longitudinal studies due to different statistical and methodological approaches. We found that CBF was lower in WMH than in normal-appearing white matter in an additional meta-analysis (5 cross-sectional studies; n = 295; SMD: −1.51, 95% CI: −1.94, −1.07). These findings highlight that relationships between resting CBF and WMH are complex. Further longitudinal studies analyzing regional CBF and subsequent WMH change are required to determine the role of CBF in SVD progression.

Cognition in Vascular Aging and Mild Cognitive Impairment

Cardiovascular health declines with age, due to vascular risk factors, and this leads to an increasing risk of cognitive decline. Mild cognitive impairment (MCI) is defined as the negative cognitive changes beyond what is expected in normal aging. The purpose of the study was to compare older adults with vascular risk factors (VRF), MCI patients, and healthy controls (HC) in main dimensions of cognitive control. The sample comprised a total of 109 adults, aged 50 to 85 (M = 66.09, S.D. = 9.02). They were divided into three groups: 1) older adults with VRF, 2) MCI patients, and 3) healthy controls (HC). VRF and MCI did not differ significantly in age, educational level, or gender as was the case with HC. The tests used mainly examine inhibition, cognitive flexibility, and working memory processing. Results showed that the VRF group had more Set Loss Errors in drawing designs indicating deficits in establishing cognitive set and in cognitive shifting. MCI patients displayed lower performance in processing. Hence, different types of specific impairments emerge in vascular aging and MCI, and this may imply that discrete underlying pathologies may play a role in the development of somewhat different profiles of cognitive decline.

Association between Matrix Metalloproteinases, Their Tissue Inhibitor and White Matter Lesions in Mild Cognitive Impairment

BACKGROUND

White matter lesions are frequently found in mild cognitive impairments and Alzheimer's disease. Matrix metalloproteinases and the tissue inhibitor of metalloproteinases are implicated in amyloid-β catabolism and blood brain barrier permeability. However, it remains unclear whether they are associated with white matter lesions in Alzheimer's disease.

OBJECTIVE

The aim of this study was to examine the association of matrix metalloproteinases and tissue inhibitor of metalloproteinases with white matter degeneration in subjects with amyloid-positive mild cognitive impairment.

METHODS

Thirty subjects with amnestic mild cognitive impairment (14 men and 16 women; mean age, 75.6 ± 5.8 years) underwent magnetic resonance imaging, ¹¹C-Pittsburgh Compound B positron emission tomography, and ¹⁸F-fluorodeoxyglucose positron emission tomography. Levels of plasma matrix metalloproteinases and tissue inhibitor of metalloproteinases were measured using multiplex assays. All subjects had an abnormal brain amyloid burden. Subjects were divided into two groups according to the presence of white matter lesions using the Fazekas scale. Cognitive function testing results i.e., mean ¹¹C-Pittsburgh Compound B and ¹⁸F-fluorodeoxyglucose uptake, concentrations of matrix metalloproteinases and tissue inhibitor of metalloproteinases, and matrix metalloproteinases/tissue inhibitor of metalloproteinases ratios were compared between the groups. Correlation analysis was conducted to investigate the association between Fazekas scale score and clinical and neuroimaging variables as well as concentrations of matrix metalloproteinases and tissue inhibitor of metalloproteinases.

RESULTS

Matrix metalloproteinases-2, -8, and -9 levels, matrix metalloproteinases-2/ tissue inhibitor of metalloproteinases-2, matrix metalloproteinases-8/ tissue inhibitor of metalloproteinases-1, and matrix metalloproteinases-9/tissue inhibitor of metalloproteinases-1 significantly increased and tissue inhibitor of metalloproteinases-1 and-2 levels significantly decreased in the group with white matter lesions compared with the group without white matter lesions. Matrix metalloproteinases-2, -8, and -9 levels correlated positively and tissue inhibitor of metalloproteinases-1 and -2 levels correlated negatively with Fazekas scale score.

CONCLUSION

Plasma matrix metalloproteinases-2, -8, -9 and tissue inhibitor of metalloproteinases-1 and -2 levels are associated with white matter lesions in the mild cognitive impairment stage of Alzheimer's disease.