Brain Microbleeds and Cognitive Function

Correlation between insulin resistance and cerebral microbleeds among Chinese patients with cerebral small vessel disease

BACKGROUND AND OBJECTIVES

Insulin resistance (IR) plays an important role in the pathogenesis of cerebral small vessel disease (CSVD); however, little is known about the relationship between IR and the incidence of cerebral microbleeds (CMBs) in Asian populations. The aim of this study is to investigate the relationship between CMBs and IR in Chinese patients with CSVD.

METHODS

This retrospective study included 240 patients with CSVD. Patients were categorized by the homeostatic model assessment of insulin resistance (HOMA-IR): Quartile 1 (≤1.26), Quartile 2 (1.27-1.92), Quartile 3 (1.93-2.89), and Quartile 4 (>2.89). The medical record of each patient was reviewed, and demographic, clinical and laboratory information was abstracted. All patients completed an MRI scan, and CMBs were defined as round or ovoid hypointense lesions on SWI sequence.

RESULTS

CMBs were present in 82 (34.17%) of the 240 patients that were included in the study (mean age, 71 years; male, 54.89%). After adjustment for potential confounding variables, insulin resistance was associated with the presence of CMBs (adjusted odds ratio 2.298, 95% confidence interval 1.017-5.194 for Q4:Q1; P = 0.046). According to receiver operating characteristic analysis, the best discriminating factor for CMBs was a HOMA-IR level ≥2.215 (area under the curve 0.595; sensitivity 51.2%; specificity 65.2%).

CONCLUSIONS

IR is significantly associated with the presence of CMBs, suggesting the potential role of IR as a predictive marker for CMBs in patients with CSVD.

Characterization of white matter microstructural abnormalities associated with cognitive dysfunction in cerebral small vessel disease with cerebral microbleeds

BACKGROUND

Diffusion tensor imaging (DTI) is recommended as a sensitive method to explore white matter (WM) microstructural alterations. Cerebral small vessel disease (CSVD) may be accompanied by extensive WM microstructural deterioration, while cerebral microbleeds (CMBs) are an important factor affecting CSVD.

METHODS

Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) images from 49 CSVD patients with CMBs (CSVD-c), 114 CSVD patients without CMBs (CSVD-n), and 83 controls were analyzed using DTI-derived tract-based spatial statistics to detect WM diffusion changes among groups.

RESULTS

Compared with the CSVD-n and control groups, the CSVD-c group showed a significant FA decrease and AD, RD and MD increases mainly in the cognitive and sensorimotor-related WM tracts. There was no significant difference in any diffusion metric between the CSVD-n and control groups. Furthermore, the widespread regional diffusion alterations among groups were significantly correlated with cognitive parameters in both the CSVD-c and CSVD-n groups. Notably, we applied the multiple kernel learning technique in multivariate pattern analysis to combine multiregion and multiparameter diffusion features, yielding an average accuracy >77 % for three binary classifications, which showed a considerable improvement over the single modality approach.

LIMITATIONS

We only grouped the study according to the presence or absence of CMBs.

CONCLUSIONS

CSVD patients with CMBs have extensive WM microstructural deterioration. Combining DTI-derived diffusivity and anisotropy metrics can provide complementary information for assessing WM alterations associated with cognitive dysfunction and serve as a potential discriminative pattern to detect CSVD at the individual level.

Altered Brain Morphometry in Cerebral Small Vessel Disease With Cerebral Microbleeds: An Investigation Combining Univariate and Multivariate Pattern Analyses

Purpose

The objective of this study was to evaluate whether altered gray matter volume (GMV) and white matter volume (WMV) are associated with the presence of cerebral microbleeds (CMBs) in cerebral small vessel disease (CSVD).

Materials and Methods

In this study, we included 26 CSVD patients with CMBs (CSVD-c), 43 CSVD patients without CMBs (CSVD-n) and 39 healthy controls. All participants underwent cognitive assessment testing. Both univariate analysis and multivariate pattern analysis (MVPA) approaches were applied to investigate differences in brain morphometry among groups.

Results

In univariate analysis, GMV and WMV differences were compared among groups using voxel-based morphometry (VBM) with diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL). Compared to healthy controls, the CSVD-c group and CSVD-n group showed significantly lower GMV than the control group in similar brain clusters, mainly including the right superior frontal gyrus (medial orbital), left anterior cingulate gyrus, right inferior frontal gyrus (triangular part) and left superior frontal gyrus (medial), while the CSVD-n group also showed significantly lower WMV in the cluster of the left superior frontal gyrus (medial). No significant GMV or WMV differences were found between the CSVD-c group and the CSVD-n group. Specifically, we applied the multiple kernel learning (MKL) technique in MVPA to combine GMV and WMV features, yielding an average of >80% accuracy for three binary classification problems, which was a considerable improvement over the individual modality approach. Consistent with the univariate analysis, the MKL weight maps revealed default mode network and subcortical region damage associated with CSVD compared to controls. On the other hand, when classifying the CSVD-c group and CSVD-n group in the MVPA analysis, we found that some WMVs were highly weighted regions (left olfactory cortex and right middle frontal gyrus), which hinted at the presence of different white matter alterations in the CSVD-c group.

Conclusion

Our findings not only suggested that the localized alterations in GMV and WMV appeared to be associated with the pathophysiology of CSVD but also indicated that altered brain morphometry could be a potential discriminative pattern to detect CSVD at the individual level.

Cerebral Microbleeds Are Associated With Increased Brain Iron and Cognitive Impairment in Patients With Cerebral Small Vessel Disease: A Quantitative Susceptibility Mapping Study

BACKGROUND

Cerebral microbleeds (CMBs) have been recognized to play an important role in cognitive impairment of cerebral small vessel disease (CSVD) patients. However, the mechanism of this effect is still unclear.

PURPOSE

Comparing the susceptibility values in the selected subcortical gray matter structures of CSVD patients without CMBs (CSVD-N) and with CMBs (CSVD-C) as well as healthy controls (HCs).

STUDY TYPE

Prospective.

SUBJECTS

Sixty-nine CSVD patients and 28 HCs were included; 24 CSVD patients (34.78%) had CMBs and 45 CSVD patients (65.22%) had no CMBs.

FIELD STRENGTH/SEQUENCE

All subjects were imaged on a 3.0 T MR scanner. The protocol consisted of a three-dimensional (3D) T1-weighted sequence and a 3D multi-echo gradient echo (mGRE) sequence. Brain QSM maps were computed from mGRE data using the morphology-enabled dipole inversion with automatic uniform cerebrospinal fluid zero reference algorithm (MEDI+0).

ASSESSMENT

The mean susceptibility value within each region of interest was recorded. All participants underwent the cognitive assessment. Brain iron deposition burden of CMB lesions of every CSVD-C patient was computed.

STATISTICAL TESTS

One-way analysis of variance test followed by Tukey's honest significance test and Kruskal-Wallis test were used with significance level of 0.05. Stepwise multivariate linear analysis was used to explore the factors influencing cognitive scores.

RESULTS

Montreal cognitive assessment (MoCA), trail-making test (TMT)-A and TMT-B scores in the three groups were significantly different (all P < 0.05). Stepwise multivariate linear regression analysis revealed that the factors influenced MoCA scores were having CMBs (P < 0.05), white matter hyperintensities (P < 0.05), lacunes (P < 0.05) in brain, and the brain iron deposition burden of CMB lesions (P < 0.05) and for TMT scores (TMT-A + TMT-B), the influencing factors were age (P < 0.05), education years (P < 0.05), and the brain iron deposition burden of CMB lesions (P < 0.05).

DATA CONCLUSION

The higher iron deposition burden of CMB lesions in brain may be an imaging quantitative marker of cognitive decline in patients with CSVD-C.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.

Lobar microbleeds are associated with cognitive impairment in patients with lacunar infarction

Associations between cognitive decline and cerebral microbleeds (CMBs) have received increasing attention. An association between CMB distribution (deep or lobar) and cognitive decline has been reported, but these findings are controversial. We investigated the association between magnetic resonance imaging (MRI) findings, including CMBs, and cognitive function in patients with first-ever lacunar infarction. We retrospectively included consecutive patients admitted with first-ever lacunar infarction identified by MRI from July 1, 2011, to December 31, 2018. We excluded patients diagnosed with dementia, including strategic single-infarct dementia, before or after the onset of stroke. The Mini-Mental State Examination (MMSE) was performed within 3 days of admission. We searched the records of 273 patients (age 72.0 ± 11.2 years, 95 females). The median MMSE score was 27 (interquartile range 25.5–29). In a univariate analysis, the MMSE score was associated with age, body mass index (BMI), education, dyslipidemia, chronic kidney disease (CKD), periventricular hyperintensity, medial temporal atrophy, lobar CMBs, and mixed CMBs (p < 0.20). The lacunar infarction location was not associated with the MMSE score. In a multivariate analysis of these factors, lobar CMBs (p < 0.001) and mixed CMBs (p = 0.008) were independently associated with the MMSE score. Lobar CMBs were associated with cognitive impairment.

Gut Microbiota Disorder, Gut Epithelial and Blood-Brain Barrier Dysfunctions in Etiopathogenesis of Dementia: Molecular Mechanisms and Signaling Pathways

Emerging evidences indicate a critical role of the gut microbiota in etiopathogenesis of dementia, a debilitating multifactorial disorder characterized by progressive deterioration of cognition and behavior that interferes with the social and professional functions of the sufferer. Available data suggest that gut microbiota disorder that triggers development of dementia is characterized by substantial reduction in specific species belonging to the Firmicutes and Bacteroidetes phyla and presence of pathogenic species, predominantly, pro-inflammatory bacteria of the Proteobacteria phylum. These changes in gut microbiota microecology promote the production of toxic metabolites and pro-inflammatory cytokines, and reduction in beneficial substances such as short chain fatty acids and other anti-inflammatory factors, thereby, enhancing destruction of the gut epithelial barrier with concomitant activation of local and distant immune cells as well as dysregulation of enteric neurons and glia. This subsequently leads to blood-brain barrier dysfunctions that trigger neuroinflammatory reactions and predisposes to apoptotic neuronal and glial cell death, particularly in the hippocampus and cerebral cortex, which underlie the development of dementia. However, the molecular switches that control these processes in the histo-hematic barriers of the gut and brain are not exactly known. This review integrates very recent data on the molecular mechanisms that link gut microbiota disorder to gut epithelial and blood-brain barrier dysfunctions, underlying the development of dementia. The signaling pathways that link gut microbiota disorder with impairment in cognition and behavior are also discussed. The review also highlights potential therapeutic options for dementia.

Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping

The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

Are transversal MR images sufficient to distinguish persons with mild cognitive impairment from healthy controls?

RATIONALE AND OBJECTIVES

Mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. This study aims to determine whether current standard magnetic resonance imaging (MRI) is providing markers that can distinguish between subjects with amnestic MCI (aMCI), nonamnestic MCI (naMCI), and healthy controls (HCs).

MATERIALS AND METHODS

A subset of 126 MCI subjects and 126 age-, gender-, and education-appropriate HCs (mean age, 70.9 years) were recruited from 4157 participants in the longitudinal community-based Heinz Nixdorf Recall Study. The burden of white matter hyperintensities (WMHs), cerebral microbleeds, and brain atrophy was evaluated on transversal MR images from a single 1.5-T MR scanner by two blinded neuroradiologists. Logistic regression and receiver-operating characteristic analysis were used for statistical analysis.

RESULTS

Occipital WMH burden was significantly increased in aMCI, but not in naMCI relative to HCs (P = .01). The combined MCI group showed brain atrophy relative to HCs (P = .01) pronounced at caudate nuclei (P = .01) and temporal horn level (P = .004) of aMCI patients and increased at the frontal and occipital horns of naMCI patients compared to either aMCI or HCs. Microbleeds were equally distributed in the MCI and control group, but more frequent in aMCI (22 of 84) compared to naMCI subjects (3 of 23).

CONCLUSIONS

In his cohort, increased occipital WMHs and cortical and subcortical brain atrophies at temporal horn and caudate nuclei level distinguished aMCI from naMCI subjects and controls. Volumetric indices appear of interest and should be assessed under reproducible conditions to gain diagnostic accuracy.

Susceptibility Weighted Imaging and Mapping of Micro-Hemorrhages and Major Deep Veins after Traumatic Brain Injury

Micro-hemorrhages are a common result of traumatic brain injury (TBI), which can be quantified with susceptibility weighted imaging and mapping (SWIM), a quantitative susceptibility mapping approach. A total of 23 TBI patients (five women, 18 men; median age, 41.25 years old; range, 21.69-67.75 years) with an average Glasgow Coma Scale score of 7 (range, 3-15) at admission were recruited at mean 149 d (range, 57-366) after injury. Susceptibility-weighted imaging data were collected and post-processed to create SWIM images. The susceptibility value of small hemorrhages (diameter ≤10 mm) and major deep veins (right septal, left septal, central septal, right thalamostriate, left thalamostriate, internal cerebral, right basal vein of Rosenthal, left basal vein of Rosenthal, and pial veins) were evaluated. Different susceptibility thresholds were tested to determine SWIM's sensitivity and specificity for differentiating hemorrhages from the veins. A total of 253 deep veins and 173 small hemorrhages were identified and evaluated. The mean susceptibility of hemorrhages was 435±206 parts per billion (ppb) and the mean susceptibility of deep veins was 108±56 ppb. Hemorrhages showed a significantly higher susceptibility than all deep veins (p<0.001). With different thresholds (250, 227 and 200 ppb), the specificity was 97%, 95%, and 92%, and the sensitivity was 84%, 90%, and 92%, respectively. These results show that SWIM could be used to differentiate hemorrhages from veins in TBI patients in a semi-automated manner with reasonable sensitivity and specificity. A larger cohort will be needed to validate these findings.

Cerebral microbleeds and cognition: the epidemiology of dementia in Singapore study

Cerebral microbleeds (CMBs) are considered to be a novel marker of cerebral small vessel disease. However, the link with cognitive impairment remains unclear. We investigated whether CMBs-independent of other traditional markers of cerebral small vessel disease-are related to cognition. Chinese subjects from the population-based Singapore Chinese Eye Study, who failed an initial cognitive screening and were recruited into the ongoing Epidemiology of Dementia in Singapore Study, underwent neuropsychological testing and 3 T brain magnetic resonance imaging. The presence and number of CMBs were graded using Brain Observer Microbleed Scale on susceptibility-weighted images. Other magnetic resonance imaging lesions that were graded included presence of lacunes, white matter lesion, and total brain volumes. A comprehensive neuropsychological battery was administered and cognitive function was summarized as composite and domain-specific Z-scores. Among 282 subjects, 91 had any CMBs (32.3%), of whom 36 (12.8%) had multiple CMBs. CMBs were-independent of cardiovascular risk factors and other markers of cerebral small vessel disease-significantly associated with poorer cognitive function as reflected by composite Z-score (mean difference per CMB increase: -0.06; 95% confidence interval: -0.11, -0.01] and with domain-specific Z-scores including executive function, attention, and visuoconstruction. Among Chinese subjects CMBs were, independent of other concomitant markers of cerebral small vessel disease, associated with poorer cognitive function.

A meta-analysis of association between cerebral microbleeds and cognitive impairment

Background

The clinical effect of cerebral microbleeds (CMBs) on cognition has been receiving much research attention, but results are often inconsistent.

Material/Methods

We searched PubMed, Embase, Web of Science, and some Chinese electronic databases. A total of 15 studies were included.

Results

Patients with CMBs had higher incidence of cognitive dysfunction (OR 3.14; 95% CI 1.66–5.92) and lower scores of cognitive function (SMD was −0.36 [−0.55, −0.18] in the MMSE group and −0.65 [−0.99, −0.32] in the MoCA [Montreal Cognitive Assessment] group). The results also indicated that a higher number of CMB lesions led to more severe cognitive dysfunction (SMD was −2.41 [−5.04, −0.21] in the mild group and −2.75 [−3.50, −2.01] in the severe group). We also found that cognitive performance was significantly impaired when CMBs were located in deep (−0.4 [−0.69, −0.11]), lobar regions (−0.50 [−0.92, −0.09]), basal ganglia (−0.72 [−1.03, −0.41]), and thalamus brain regions (−0.65 [−0.98, −0.32]).

Conclusions

This meta-analysis showed that CMBs were associated with cognitive dysfunction according to higher number and different locations of CMBs. Future work should focus on long-term prognosis of continuing cognitive decline and specific treatments to reduce the formation of CMBs.

Prestroke statins, progression of white matter hyperintensities, and cognitive decline in stroke patients with confluent white matter hyperintensities

Cerebral white matter hyperintensities (WMH) are a consequence of cerebral small vessel disease. Statins have been shown to reduce recurrent stroke among patients with various stroke subtypes, including lacunar stroke, which also arises from small vessel disease. In this study, we investigated the hypothesis that prestroke statin use would reduce the progression of WMH and/or cognitive decline among stroke patients with confluent WMH. Patients (n = 100) were participants of the VITAmins To Prevent Stroke magnetic resonance imaging substudy. All patients had confluent WMH on magnetic resonance imaging at baseline. Eighty-one patients completed the 2-year follow-up. We assessed general cognition and executive function using the mini-mental state examination and Mattis dementia rating scale-initiation/perseveration subscale, respectively. We compared the change in volume of WMH and cognition between prestroke statin use and prestroke nonstatin use groups. We also evaluated the effects of prestroke statin use on incident lacunes and microbleeds. The prestroke statin use group (n = 51) had less WMH volume progression (1.54 ± 4.52 cm(3) vs 5.01 ± 6.00 cm(3), p = 0.02) compared with the prestroke nonstatin use group (n = 30). Multivariate linear regression modeling identified prestroke statin use as an independent predictor of WMH progression (β = -0.31, p = 0.008). Prestroke statin use was also associated with less decline (Mattis dementia rating scale-initiation/perseveration subscale; β = 0.47, p = 0.001). No association was observed with changes in mini-mental state examination scores. There were no between group differences on incident lacunes or incident microbleeds. Prestroke statin use may reduce WMH progression and decline in executive function in stroke patients with confluent WMH.

Study protocol: The Whitehall II imaging sub-study

BACKGROUND

The Whitehall II (WHII) study of British civil servants provides a unique source of longitudinal data to investigate key factors hypothesized to affect brain health and cognitive ageing. This paper introduces the multi-modal magnetic resonance imaging (MRI) protocol and cognitive assessment designed to investigate brain health in a random sample of 800 members of the WHII study.

METHODS/DESIGN

A total of 6035 civil servants participated in the WHII Phase 11 clinical examination in 2012-2013. A random sample of these participants was included in a sub-study comprising an MRI brain scan, a detailed clinical and cognitive assessment, and collection of blood and buccal mucosal samples for the characterisation of immune function and associated measures. Data collection for this sub-study started in 2012 and will be completed by 2016. The participants, for whom social and health records have been collected since 1985, were between 60-85 years of age at the time the MRI study started. Here, we describe the pre-specified clinical and cognitive assessment protocols, the state-of-the-art MRI sequences and latest pipelines for analyses of this sub-study.

DISCUSSION

The integration of cutting-edge MRI techniques, clinical and cognitive tests in combination with retrospective data on social, behavioural and biological variables during the preceding 25 years from a well-established longitudinal epidemiological study (WHII cohort) will provide a unique opportunity to examine brain structure and function in relation to age-related diseases and the modifiable and non-modifiable factors affecting resilience against and vulnerability to adverse brain changes.

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.

Serial susceptibility weighted MRI measures brain iron and microbleeds in dementia

A new iron sensitive MR sequence (susceptibility weighted imaging - SWI) enabling the simultaneous quantitation of regional brain iron levels and brain microbleeds (BMB) has been acquired serially to study dementia. Cohorts of mildly cognitively impaired (MCI) elderly (n = 73) and cognitively normal participants (n = 33) have been serially evaluated for up to 50 months. SWI phase values (putative iron levels) in 14 brain regions were measured and the number of BMB were counted for each SWI study. SWI phase values showed a left putaminal mean increase of iron (decrease of phase values) over the study duration in 27 participants who progressed to dementia compared to Normals (p = 0.035) and stable MCI (p = 0.01). BMB were detected in 9 out of 26 (38%) MCI participants who progressed to dementia and are a significant risk factor for cognitive failure in MCI participants [risk ratio = 2.06 (95% confidence interval 1.37-3.12)]. SWI is useful to measure regional iron changes and presence of BMB, both of which may be important MR-based biomarkers for neurodegenerative diseases.

MRI correlates of cognitive decline in CADASIL

Background: Cognitive decline is one of the clinical hallmarks of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a cerebrovascular disease caused by NOTCH3 mutations. In this 7-year follow-up study, we aimed to determine whether there are associations between the different radiologic hallmarks in CADASIL and decline in specific cognitive domains.

Methods: Twenty-five NOTCH3 mutation carriers and 13 controls had standardized neuropsychological testing and MRI examinations at baseline and after a follow-up of 7 years. To identify longitudinal associations between MRI abnormalities and cognitive decline, correlation analysis was used.

Results: At follow-up, mutation carriers showed a decline in global cognitive function (CAMCOG, p < 0.01) and in the cognitive domains language, memory, and executive function, compared to controls. Cognitive decline, especially executive dysfunction, was associated with increase in lacunar infarcts, microbleeds, and ventricular volume. In contrast, WMHs and brain atrophy were not associated with cognitive decline.

Conclusion: Increase in lacunar infarcts, microbleeds, and ventricular volume, but not white matter lesions or atrophy, are associated with cognitive decline in the process of CADASIL in younger-aged, mildly affected patients with CADASIL.

Brain Microbleeds and Global Cognitive Function in Adults Without Neurological Disorder

Background and Purpose— Increasing attention has been paid to associations between cognitive dysfunction and brain microbleeds (MBs). Because all previous studies have investigated patients with neurological disorders, we examined subjects without neurological disorder in order to clarify pathogenic relationships.

Methods— A total of 518 consecutive adults without neurological disorder who had undergone health-screening tests of the brain were studied prospectively. Gradient-echo T2*-weighted MRI using a 1.5-T system was used to detect MBs. The Mini-Mental State Examination (MMSE) was administered to determine cognitive functions. MMSE scores <27 or >1.5 SDs below the age-related mean were regarded as subnormal.

Results— MBs were found in 35 subjects (6.8%). MMSE score <27 was found in 25 subjects (4.8%), with MMSE score >1.5 SDs below the age-related mean in 34 subjects (6.6%). Univariate analysis showed presence and number of MBs, short duration of education, and severe white matter hyperintensities as significantly associated with subnormal scores. In logistic regression analysis, presence of MBs (odds ratio [OR], 5.44; 95% CI, 1.83 to 16.19) and number of MBs (OR, 1.32; 95% CI, 1.04 to 1.68) still displayed significant associations with MMSE score <27. Logistic regression analysis revealed a significant relationship between presence (OR, 3.93; 95% CI, 1.44 to 10.74) and number (OR, 1.26; 95% CI, 1.01 to 1.59) of MBs and MMSE score >1.5 SDs below the age-related mean. Among MMSE subscores, “attention and calculation” was significantly lower in MB-positive subjects ( P =0.017).

Conclusions— MBs appear to be primarily associated with global cognitive dysfunction.