Brain atrophy and cognition: Interaction with cerebrovascular pathology?

Cerebral white matter burden is linked to cognitive function in patients undergoing hemodialysis

INTRODUCTION

Chronic kidney disease is related to neurodegeneration and structural changes in the brain which might lead to cognitive decline. The Fazekas scale used for assessing white matter hyperintensities (WMHs) was associated with poor cognitive performance. Therefore, this study investigated the associations between the mini-mental status examination (MMSE), Montreal cognitive assessment (MoCA), cognitive abilities screening instrument (CASI), and Fazekas scale in patients under hemodialysis (HD).

METHODS

The periventricular (PV) WMHs and deep WMHs (DWMHs) in brain magnetic resonance images of 59 patients under dialysis were graded using the Fazekas scale. Three cognition function tests were also performed, then multivariable ordinal regression and logistic regression were used to identify the associations between cognitive performance and the Fazekas scale.

RESULTS

There were inverse associations between the three cognitive function tests across the Fazekas scale of PVWMHs (p = .037, .006, and .008 for MMSE, MoCA, and CASI, respectively), but the associations were attenuated in the DWMHs group. In CASI, significant differences were identified in short-term memory, mental manipulation, abstract thinking, language, spatial construction, and name fluency in the PVWMHs group. However, DWMHs were only significantly correlated with abstract thinking and short-term memory.

CONCLUSION

An inverse correlation existed between the Fazekas scale, predominantly in PVWMHs, and cognition in patients undergoing HD. The PVWMHs were associated with cognitive performance assessed by MMSE, MoCA, and CASI, as well as with subdomains of CASI such as memory, language and name fluency in patients undergoing HD.

Arterial Aging and Cerebrovascular Function: Impact of Aerobic Exercise Training in Older Adults

Advanced age is the major risk factor for dementia including Alzheimer's disease. The clinical effects of recently developed anti-amyloid therapy for Alzheimer's disease were modest and the long-term outcome is unknown. Thus, an in-depth understanding of the mechanisms of brain aging is essential to develop preventive interventions to maintain cognitive health in late life. Mounting evidence suggests that arterial aging manifested as increases in central arterial stiffness is associated closely with cerebrovascular dysfunction and brain aging while improvement of cerebrovascular function with aerobic exercise training contributes to brain health in older adults. We summarized evidence in this brief review that 1) increases in central arterial stiffness and arterial pulsation with age are associated with increases in cerebrovascular resistance, reduction in cerebral blood flow, and cerebrovascular dysfunction, 2) aerobic exercise training improves cerebral blood flow by modifying arterial aging as indicated by reductions in cerebrovascular resistance, central arterial stiffness, arterial pulsation, and improvement in cerebrovascular function, and 3) improvement in cerebral blood flow and cerebrovascular function with aerobic exercise training may lead to improvement in cognitive function. These findings highlight the associations between arterial aging and cerebrovascular function and the importance of aerobic exercise in maintaining brain health in older adults.

Genetic and Clinical Correlates of AI-Based Brain Aging Patterns in Cognitively Unimpaired Individuals

Importance

Brain aging elicits complex neuroanatomical changes influenced by multiple age-related pathologies. Understanding the heterogeneity of structural brain changes in aging may provide insights into preclinical stages of neurodegenerative diseases.

Objective

To derive subgroups with common patterns of variation in participants without diagnosed cognitive impairment (WODCI) in a data-driven manner and relate them to genetics, biomedical measures, and cognitive decline trajectories.

Design, Setting, and Participants

Data acquisition for this cohort study was performed from 1999 to 2020. Data consolidation and harmonization were conducted from July 2017 to July 2021. Age-specific subgroups of structural brain measures were modeled in 4 decade-long intervals spanning ages 45 to 85 years using a deep learning, semisupervised clustering method leveraging generative adversarial networks. Data were analyzed from July 2021 to February 2023 and were drawn from the Imaging-Based Coordinate System for Aging and Neurodegenerative Diseases (iSTAGING) international consortium. Individuals WODCI at baseline spanning ages 45 to 85 years were included, with greater than 50 000 data time points.

Exposures

Individuals WODCI at baseline scan.

Main Outcomes and Measures

Three subgroups, consistent across decades, were identified within the WODCI population. Associations with genetics, cardiovascular risk factors (CVRFs), amyloid β (Aβ), and future cognitive decline were assessed.

Results

In a sample of 27 402 individuals (mean [SD] age, 63.0 [8.3] years; 15 146 female [55%]) WODCI, 3 subgroups were identified in contrast with the reference group: a typical aging subgroup, A1, with a specific pattern of modest atrophy and white matter hyperintensity (WMH) load, and 2 accelerated aging subgroups, A2 and A3, with characteristics that were more distinct at age 65 years and older. A2 was associated with hypertension, WMH, and vascular disease-related genetic variants and was enriched for Aβ positivity (ages ≥65 years) and apolipoprotein E (APOE) ε4 carriers. A3 showed severe, widespread atrophy, moderate presence of CVRFs, and greater cognitive decline. Genetic variants associated with A1 were protective for WMH (rs7209235: mean [SD] B = -0.07 [0.01]; P value = 2.31 × 10-9) and Alzheimer disease (rs72932727: mean [SD] B = 0.1 [0.02]; P value = 6.49 × 10-9), whereas the converse was observed for A2 (rs7209235: mean [SD] B = 0.1 [0.01]; P value = 1.73 × 10-15 and rs72932727: mean [SD] B = -0.09 [0.02]; P value = 4.05 × 10-7, respectively); variants in A3 were associated with regional atrophy (rs167684: mean [SD] B = 0.08 [0.01]; P value = 7.22 × 10-12) and white matter integrity measures (rs1636250: mean [SD] B = 0.06 [0.01]; P value = 4.90 × 10-7).

Conclusions and Relevance

The 3 subgroups showed distinct associations with CVRFs, genetics, and subsequent cognitive decline. These subgroups likely reflect multiple underlying neuropathologic processes and affect susceptibility to Alzheimer disease, paving pathways toward patient stratification at early asymptomatic stages and promoting precision medicine in clinical trials and health care.

Transitions of dialysis status and outcomes after the unplanned first dialysis: a nationwide population-based cohort study

In Taiwan, most first-time dialysis was started without the creation of an arteriovenous shunt. Here, we aimed to elucidate the transitions of dialysis status in the unplanned first dialysis patients and determine factors associated with their outcomes. A total of 50,315 unplanned first dialysis patients aged more than 18 years were identified from the National Health Insurance Dataset in Taiwan between 2001 and 2012. All patients were followed for 5 years for the transitions in dialysis status, including robust (dialysis-free), sporadic dialysis, continued dialysis, and death. Furthermore, factors associated with the development of continued dialysis and death were examined by the Cox proportional hazard models. After 5 years after the first dialysis occurrence, there were 5.39% with robust status, 1.67% with sporadic dialysis, 8.45% with continued dialysis, and 84.48% with death. Notably, we have identified common risk factors for developing maintenance dialysis and deaths, including male gender, older age, diabetes, coronary heart disease, stroke, heart failure, sepsis, and surgery. There was an extremely high mortality rate among the first unplanned dialysis patients in Taiwan. Less than 10% of these patients underwent continued dialysis during the 5-year follow-up period. This study highlighted the urgent need for interventions to improve patient outcomes.

Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.

Central arterial stiffness, brain white matter hyperintensity and total brain volume across the adult lifespan

OBJECTIVES

Mounting evidence suggests that central arterial stiffening is associated with brain ageing in older adults. The purpose of this study was to determine the associations of age with carotid arterial stiffness and carotid-femoral pulse wave velocity (cfPWV), both measurements of central arterial stiffness, the relationship between age-related arterial stiffness, brain white matter hyperintensity (WMH) and total brain volume (TBV), and whether effects of central arterial stiffness on WMH volume and TBV are mediated by pulsatile cerebral blood flow (CBF).

METHODS

One hundred and seventy-eight healthy adults (21-80 years) underwent measurements of central arterial stiffness using tonometry and ultrasonography, WMH and TBV via MRI, and pulsatile CBF at the middle cerebral artery via transcranial Doppler.

RESULTS

Advanced age was associated with increases in both carotid arterial stiffness and cfPWV, increases in WMH volume and decreases in TBV (all P  < 0.01). Multiple linear regression analysis showed that carotid β-stiffness was positively associated with WMH volume (B = 0.015, P  = 0.017) and cfPWV negatively with TBV (B = -0.558, P  < 0.001) after adjustment for age, sex and arterial pressure. Pulsatile CBF mediates the associations between carotid β-stiffness and WMH (95% confidence interval: 0.0001-0.0079).

CONCLUSION

These findings suggest that age-related central arterial stiffness is associated with increased WMH volume and decreased TBV, which is likely mediated by increased arterial pulsation.

Multivariable Analysis of Pre-operative Brain Atrophy as a Predictor of Long Term Mortality After Carotid Endarterectomy

OBJECTIVE

Brain atrophy is associated with an increased mortality rate in elderly trauma patients and in patients treated with mechanical thrombectomy for acute ischaemic stroke. In the setting of ischaemic stroke, the association between brain atrophy and death is stronger than that of sarcopenia. It has previously been shown that lower masseter area, as a marker of sarcopenia, is linked to lower survival after carotid endarterectomy (CEA). The aim of this study was to investigate whether brain atrophy is also associated with long term mortality in patients undergoing CEA.

METHODS

A cohort of patients treated with CEA between 2004 and 2010 was retrieved from the Tampere University Hospital vascular registry and those with available pre-operative computed tomography (CT) imaging were analysed retrospectively. CT images were evaluated for brain atrophy index (BAI) and masseter muscle surface area and density. The association between BAI and mortality was investigated with Cox regression.

RESULTS

Two hundred and thirty-three patients with a median (interquartile range [IQR]) age of 71 years (64.0, 77.0) were included. Most patients were operated on for symptomatic stenosis (n = 203; 87.1%). The median (IQR) duration of follow up was 115.0 months (66.0, 153.0), and 155 patients (66.5%) died during follow up. BAI was statistically significantly correlated with age (r = .489), average masseter density (r = -.202), and smoking (r = -.186; all p <.005). Increased BAI was statistically significantly associated with overall mortality (hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.25 - 1.68, per one standard deviation [SD] increase) in the univariable analysis, and the association remained (HR 1.23, 95% CI 1.04 - 1.46, per one SD increase) in the multivariable models. Age, peripheral artery disease, and chronic obstructive pulmonary disease were also independently associated with mortality. The optimal cutoff value for BAI was 0.133.

CONCLUSION

Brain atrophy independently predicts the long term post-operative mortality rate after CEA in a cohort containing mainly symptomatic patients. Future studies are needed to validate the results in prospective settings and in asymptomatic patients.

Association of Income with Post-Stroke Cognition and the Underlying Neuroanatomical Mechanism

OBJECTIVE

To investigate the association between income and post-stroke cognition at 3 months, and the underlying neuroanatomical mechanism.

METHODS

Patients with first-ever ischemic stroke were enrolled and analyzed. Baseline information on income and neuroimaging measurements with predictive values for post-stroke cognitive impairment (PSCI) were collected within 7 days of the admission. Three months after the index stroke, all participants underwent a detailed neuropsychological test battery. The associations between income and PSCI and between income and brain structural measurements were investigated.

RESULTS

A total of 294 patients were recruited for this study. Lower income was independently associated with poor cognitive performance on Stroop tests, Clinical Dementia Rating, Boston Naming Test, and Verbal Fluency Test. Regarding neuroimaging parameters, lower income was associated with a lower total brain volume (TBV)/total intracranial volume (TICV) ratio (p = 0.004).

CONCLUSIONS

Lower income is associated with an increased chance of post-stroke cognitive decline, particularly in executive function and language domains. Since global brain atrophy (measured by TBV/TICV ratio) is a strong predictor for PSCI, its correlation with income may help explain the neuroanatomical mechanism between income and post-stroke cognition.

Association of Cerebral Small Vessel Disease With Gait and Balance Disorders

Cerebral small vessel disease (CSVD) is a common cerebrovascular disease and an important cause of gait and balance disorders. Gait and balance disorders can further lead to an increased risk of falls and a decreased quality of life. CSVD can damage gait and balance function by affecting cognitive function or directly disrupting motor pathways, and different CSVD imaging features have different characteristics of gait and balance impairment. In this article, the correlation between different imaging features of sporadic CSVD and gait and balance disorders has been reviewed as follows, which can provide beneficial help for standardized management of CSVD.

Prevalence and Consequences of Cerebral Small Vessel Diseases: A Cross-Sectional Study Based on Community People Plotted Against 5-Year Age Strata

PURPOSE

To study the variation tendency of cerebral small vessel disease (CSVD) imaging markers and total burden with aging and to research the relationship between aging, CSVD markers and cognitive function.

METHODS

Participants in local urban communities were recruited for neuropsychological and magnetic resonance imaging assessments. Montreal Cognitive Assessment (MoCA), Mini-mental State Examination (MMSE), Number Connection Test A (NCT-A) and Digital Symbol Test (DST) were adopted as neuropsychological scale. Age was stratified at 5-year intervals, and the variation tendency of imaging markers and variables of neuropsychological scales in different age groups was studied. We further studied the relationship between aging, image markers and neuropsychological scales by multi-linear regression.

RESULTS

Finally, a total of 401 stroke-free participants (age, 54.83±7.74y; 45.9% were male) were included in the present analysis. With the increase of age, the incidence of imaging markers of CSVD were increased with aging except cerebral microbleeds. The performance results of NCT-A and DST were significant difference in 6 age groups (P < 0.001). In addition, linear decline of the neuropsychological function reflected by NCT-A and DST variables was observed. Linear regression found that age was an independent factor affecting the neuropsychological function reflected by NCT-A and DST variables, and the standard correction coefficients among different age groups increased gradually with age. In addition, brain atrophy is an independent factor affecting neuropsychological variables (odds ratio: -2.929, 95% CI: [-5.094 to -0.765]). There was no correlation between the number of neuroimaging markers and neuropsychological variables after full adjustment.

CONCLUSION

There are many CVSD markers even in younger people, the incidence rate and CVSD marker numbers increase with age. Aging and CSVD may eventually affect cognitive function through brain atrophy.

Neurovascular Alterations in Vascular Dementia: Emphasis on Risk Factors

Vascular dementia (VaD) constitutes the second most prevalent cause of dementia in the world after Alzheimer’s disease (AD). VaD regroups heterogeneous neurological conditions in which the decline of cognitive functions, including executive functions, is associated with structural and functional alterations in the cerebral vasculature. Among these cerebrovascular disorders, major stroke, and cerebral small vessel disease (cSVD) constitute the major risk factors for VaD. These conditions alter neurovascular functions leading to blood-brain barrier (BBB) deregulation, neurovascular coupling dysfunction, and inflammation. Accumulation of neurovascular impairments over time underlies the cognitive function decline associated with VaD. Furthermore, several vascular risk factors, such as hypertension, obesity, and diabetes have been shown to exacerbate neurovascular impairments and thus increase VaD prevalence. Importantly, air pollution constitutes an underestimated risk factor that triggers vascular dysfunction via inflammation and oxidative stress. The review summarizes the current knowledge related to the pathological mechanisms linking neurovascular impairments associated with stroke, cSVD, and vascular risk factors with a particular emphasis on air pollution, to VaD etiology and progression. Furthermore, the review discusses the major challenges to fully elucidate the pathobiology of VaD, as well as research directions to outline new therapeutic interventions.

Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a cluster of various vascular disorders with different pathological backgrounds. The advanced vasculature net of cerebral vessels, including small arteries, capillaries, arterioles and venules, is usually affected. Processes of oxidation underlie the pathology of CSVD, promoting the degenerative status of the epithelial layer. There are several classifications of cerebral small vessel diseases; some of them include diseases such as Binswanger’s disease, leukoaraiosis, cerebral microbleeds (CMBs) and lacunar strokes. This paper presents the characteristics of CSVD and the impact of the current knowledge of this topic on the diagnosis and treatment of patients.

Moderate aerobic training modulates cytokines and cortisol profiles in older adults with cognitive abilities

Excessive expression of cortisol and pro-inflammatory cytokines exerts a negative affect on cognitive functioning and hippocampal structure in older adults. Although the interrelation between cortisol and cytokines was fully elucidated previously, few studies considered how their association with exercise can affect brain structures or play an anti-inflammatory role in preserving cognitive function among older adults. To evaluate both the neuro-protective and anti-inflammatory activities of moderate aerobic exercise in improving cognitive performance among healthy older adults, the serum levels of CRP, TNF-α, IL-6, and cortisol and their correlation with cognitive performance were estimated in all participants. A total of 60 healthy older adults aged 50-85 years were included in this study. The Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) test, colorimetric testing, and ELISA immunoassays were used to measure cognitive abilities; blood sugar; and glycated hemoglobin (HbA1c), cortisol, IL-6, TNF-α, and CRP, respectively, in older adults before and after 12-week exercise interventions. Exactly 50% of the participants showed moderate cognitive impairment (MCI) (LOTCA scores: 84.8 ± 8.2), and the remaining 50% of the participants (n = 30) were diagnosed as normal healthy subjects (LOTCA scores: 98.7 ± 8.1). There was a significant association between cognitive decline in LOTCA scores of motor praxis, vasomotor organization, thinking operations, and attention and concentration and higher levels of cortisol, CRP, TNF-α, and IL-6, as well as adiposity markers BMI and WHR, in the MCI group compared to control subjects. However, significant improvements in the same LOTCA score domains in MCI subjects were recorded along with decrements in the levels of cortisol and cytokine CRP, TNF-α, and IL-6, as well as improved adiposity markers, following a 12-week moderate exercise program. Cognitive performance correlated positively with cortisol levels and negatively with physical activity, adiposity markers, and cytokine levels. Also, in participants with normal and abnormal cortisol profiles, there was a positive interrelation between cytokine levels and cortisol. Moderate aerobic exercise for 12 weeks showed beneficial effects on cognitive performance in older adults. Our results suggest that 12 weeks of aerobic exercise improves cognitive disorders in older adults via modulating stress and pro-inflammatory cytokines. This may have been due to significant changes in the levels of cortisol, IL-6, TNF-α, and CRP, and physical activity may thus be used as non-drug strategy for treating cognitive disorders.

Heavy Metal-Induced Cerebral Small Vessel Disease: Insights into Molecular Mechanisms and Possible Reversal Strategies

Heavy metals are considered a continuous threat to humanity, as they cannot be eradicated. Prolonged exposure to heavy metals/metalloids in humans has been associated with several health risks, including neurodegeneration, vascular dysfunction, metabolic disorders, cancer, etc. Small blood vessels are highly vulnerable to heavy metals as they are directly exposed to the blood circulatory system, which has comparatively higher concentration of heavy metals than other organs. Cerebral small vessel disease (CSVD) is an umbrella term used to describe various pathological processes that affect the cerebral small blood vessels and is accepted as a primary contributor in associated disorders, such as dementia, cognitive disabilities, mood disorder, and ischemic, as well as a hemorrhagic stroke. In this review, we discuss the possible implication of heavy metals/metalloid exposure in CSVD and its associated disorders based on in-vitro, preclinical, and clinical evidences. We briefly discuss the CSVD, prevalence, epidemiology, and risk factors for development such as genetic, traditional, and environmental factors. Toxic effects of specific heavy metal/metalloid intoxication (As, Cd, Pb, Hg, and Cu) in the small vessel associated endothelium and vascular dysfunction too have been reviewed. An attempt has been made to highlight the possible molecular mechanism involved in the pathophysiology, such as oxidative stress, inflammatory pathway, matrix metalloproteinases (MMPs) expression, and amyloid angiopathy in the CSVD and related disorders. Finally, we discussed the role of cellular antioxidant defense enzymes to neutralize the toxic effect, and also highlighted the potential reversal strategies to combat heavy metal-induced vascular changes. In conclusion, heavy metals in small vessels are strongly associated with the development as well as the progression of CSVD. Chelation therapy may be an effective strategy to reduce the toxic metal load and the associated complications.

Association of Apolipoprotein E Polymorphisms with White Matter Lesions and Brain Atrophy

OBJECTIVE

Apolipoprotein E (ApoE) is mainly synthesized in the liver. So far, it is unknown the relationship among APOE gene polymorphisms and WML, brain atrophy. Therefore, the aim of the study was to assess the associations of APOE gene polymorphisms in patients with WML and brain atrophy.

METHODS

A total of 58 patients with WML, 128 patients with brain atrophy, 112 patients with co-occurrence of WML and brain atrophy and 95 healthy elderly volunteers were recruited from Renmin Hospital of WuHan University.

RESULTS

Allele E3 was the most common allele. The alleles E2 had significantly higher levels of ApoB and lower age in WML group. The alleles E2 was associated with the lower level of ApoB, LDL-Ch, TCh, and sdLDL in co-occurrence group. The E3/E3 genotype has higher level of sdLDL, but lower age and female frequency in WML. The E3/E4 genotype had higher level of TG, but lower age in WML. Gender, Age, E2, Hyperhomocysteinemia and UA were also significantly associated with disease progression.

CONCLUSION

This study found that clinical data, lipids and metabolic complications were closely related to ApoE genotypes and alleles, and also disease progression and type.

The new insights into human brain imaging after stroke

Over the last two decades, developments of human brain stroke imaging have raised several questions about the place of new MRI biomarkers in the acute management of stroke and the prediction of poststroke outcome. Recent studies have demonstrated the main role of perfusion-weighted imaging in the identification of the best cerebral perfusion profile for a better response after reperfusion therapies in acute ischemic stroke. A major issue remains the early prediction of stroke outcome. While voxel-based lesion-symptom mapping emphasized the influence of stroke location, the analysis of the brain parenchyma underpinning the stroke lesion showed the relevance of prestroke cerebral status, including cortical atrophy, white matter integrity, or presence of chronic cortical cerebral microinfarcts. Moreover, besides the evaluation of the visually abnormal brain tissue, the analysis of normal-appearing brain parenchyma using diffusion tensor imaging and magnetization transfer imaging or spectroscopy offered new biomarkers to improve the prediction of the prognosis and new targets to follow in therapeutic trials. The aim of this review was to depict the main new radiological biomarkers reported in the last two decades that will provide a more thorough prediction of functional, motor, and neuropsychological outcome following the stroke. These new developments in neuroimaging might be a cornerstone in the emerging personalized medicine for stroke patients.

White Matter Hyperintensities and Hippocampal Atrophy in Relation to Cognition: The 90+ Study

OBJECTIVES

To study the interactive effect of white matter hyperintensities (WMH) and hippocampal atrophy on cognition in the oldest old.

DESIGN

Ongoing longitudinal study.

SETTING

In Southern California, brain magnetic resonance imaging (MRI) scans were conducted between May 2014 and December 2017.

PARTICIPANTS

Individuals from The 90+ Study with a valid brain MRI scan (N = 141; 94 cognitively normal and 47 with cognitive impairment).

MEASUREMENTS

Cognitive testing was performed every 6 months with a mean follow-up of 2 years and included these tests: Mini-Mental State Examination (MMSE), modified MMSE (3MS), California Verbal Learning Test (CVLT) immediate recall over four trials and delayed recall, Digit Span Backward, Animal Fluency, and Trail Making Test (TMT) A, B, and C. We used one linear mixed model for each cognitive test to study the baseline and longitudinal association of WMH and hippocampal volume (HV) with cognition. Models were adjusted for age, sex, and education.

RESULTS

Mean age was 94.3 years (standard deviation [SD] = 3.2 y). At baseline, higher WMH volumes were associated with worse scores on the 3MS, CVLT immediate and delayed recall, and TMT B. Lower HVs were associated with worse baseline scores on all cognitive tests, except for the Digit Span Backward. Longitudinally, higher WMH and lower HVs were associated with faster decline in the 3MS and MMSE, and lower HV was also associated with faster decline in the CVLT immediate recall. No association was observed between WMH and HV and no interaction between WMH and HV in their association with baseline cognition or cognitive decline.

CONCLUSION

We show that WMH and hippocampal atrophy have an independent, negative effect on cognition that make these biomarkers relevant to evaluate in the diagnostic work-up of the oldest-old individuals with cognitive complaints. However, the predictive value of WMH for cognitive decline seems to be less evident in the oldest-old compared with a younger group of older adults. J Am Geriatr Soc 67:1827-1834, 2019.

Small Vessel Cerebrovascular Pathology Identified by Magnetic Resonance Imaging Is Prevalent in Alzheimer's Disease and Mild Cognitive Impairment: A Potential Target for Intervention

BACKGROUND

There is evidence that Alzheimer's disease (AD) has significant cerebrovascular etiopathogenesis. Understanding potentially modifiable risk factors for vascular disease can help design long-term intervention strategies for controlling or preventing cognitive dysfunction attributable to cerebrovascular disease.

OBJECTIVE

To evaluate the presence and severity of markers of cerebrovascular pathology, its relationship to diagnostic categories of dementia, including AD, and association with the metabolic biomarker homocysteine.

METHODS

In a cross-sectional observational study, 340 community-dwelling elders received a clinical evaluation including brain MRI and neuropsychological tests. Dementia and mild cognitive impairment (MCI) were diagnosed by consensus committee. Fasting total plasma homocysteine was measured. Statistical analyses were adjusted for demographics and cerebrovascular risk factors.

RESULTS

Nearly 25% of those diagnosed with AD had small vessel infarcts (SVI). Periventricular white matter hyperintensity (pvWMHI) was prevalent in participants with AD (61%) or MCI (amnesic 61% and non-amnesic 54%, respectively). Participants with SVI and/or pvWMHI also had greater brain atrophy. Homocysteine concentrations were higher in individuals with cerebrovascular findings than in those without. In individuals with cerebrovascular disease, homocysteine was inversely related to executive function (p = 0.022) and directly related to degree of brain atrophy (p = 0.009).

CONCLUSIONS

We demonstrated a significant prevalence of small vessel markers of cerebrovascular pathology in individuals diagnosed with AD, with a significant concurrence between cerebrovascular disease and brain and ventricular atrophy. While current research on AD has focused on amyloid-βpeptide deposition, tau-pathology, and microglial activation and inflammation, greater attention to the cerebrovascular contribution to this neurodegenerative disease presents an additional target for therapeutic prevention and intervention.

Impact of cerebral large-artery disease and blood flow in the posterior cerebral artery territory on cognitive function

OBJECTIVES

The purpose of this study was to elucidate the association of cerebral large artery disease (CLAD) with cerebral blood flow (CBF) in the posterior cerebral artery (PCA) territory and cognitive performance.

METHOD

We prospectively registered patients with CLAD who had internal carotid or middle cerebral artery (MCA) with the degree of stenosis ≥50%. Automated brain segmentation was used to quantify CBF in the thalamus, hippocampus, and PCA and MCA territories. We measured cognitive function of patients using the Wechsler Memory Scale Revised (WMS-R), the Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment. Patients were divided into 3 groups according to CBF of the cortical and subcortical PCA territory.

RESULTS

There were 60 patients included in this study. The degree of stenosis was significantly correlated with CBF in the PCA territory (Γ = 0.35, P = .006) and hippocampus (Γ = 0.34, P = .008). Verbal memory, general memory, and reproduction on WMS-R and MMSE were significantly reduced areas with low CBF in the PCA territory compared with areas with middle and high CBF.

CONCLUSIONS

CBF of the PCA territory was significantly inversely correlated with the degree of stenosis in CLAD patients. Low CBF of the PCA territory was significantly associated with reduced cognitive and memory functions.

Acquired Hemicerebral Atrophy Secondary to Chronic Internal Carotid Steno-Occlusive Disease: A Case Series

Cerebral atrophy is a common finding in elderly patients; however, cerebrovascular disease causing progressive focal cerebral atrophy and dysfunction is unusual. In this report, we present 3 cases of hemicerebral atrophy due to ipsilateral internal carotid artery (ICA) stenosis or occlusion mimicking neurodegenerative conditions. Patient 1 had a frontal dysexecutive syndrome potentially consistent with a diagnosis of behavioral variant frontotemporal dementia; however, neuroimaging revealed a chronically occluded left ICA and a pattern of atrophy restricted to the left middle cerebral artery territory, suggestive of a vascular etiology. Patient 2 presented with progressively worsening seizures and right-sided weakness consistent with left hemispheric dysfunction, with radiographic evidence of left hemicerebral atrophy. Angiography revealed a chronic dissection of the left ICA leading to left cerebral hypoperfusion. Patient 3 had asymmetric parkinsonism, alien limb, and cognitive impairment consistent with a diagnosis of corticobasal syndrome. His imaging, however, revealed atrophy and encephalomalacia within the anterior circulation watershed territories with chronic, severe stenosis of the left ICA suggestive of a chronic hypoperfused state. In this case series, we report 3 examples of hemicerebral atrophy secondary to chronic ipsilateral ICA vascular disease with diverse progressive clinical symptoms mimicking primary neurodegenerative conditions. This case series highlights the importance of considering chronic hypoperfusion and large-vessel severe stenosis or occlusion in patients with cognitive impairment and evidence of asymmetric brain atrophy. In addition to symptomatic treatment, the management of vascular risk factors including treatment with antiplatelet agents, statins, and revascularization procedures can be considered.

Cortical thickness and cognitive performance in asymptomatic unilateral carotid artery stenosis

Background

We investigated changes of cortical thickness and its association with cognitive performance in patients with high-grade carotid artery stenosis without ischemic brain lesions.

Methods

We studied 25 patients with unilateral carotid artery stenosis ≥50% and 25 age-matched controls. All subjects underwent T1-weighted MRI, and cortical thickness was measured in 33 regions of interest in each hemisphere, as well as in brain regions belonging to the vascular territory of the middle cerebral artery (MCA). General linear mixed models were fitted to the dependent variable cortical thickness. Cognitive assessment comprised the Stroop Test and Trail Making Test B.

Results

In the linear mixed model, presence of carotid stenosis had no effect on cortical thickness. There was a significant interaction of stenosis and region with a trend towards lower cortical thickness in the MCA region on the side of carotid stenosis. Patients with carotid stenosis performed significantly worse on the Stroop test than controls, but there was no correlation with cortical thickness.

Conclusion

In patients with carotid stenosis without ischemic brain lesions, neither a clear pattern of reduced cortical thickness nor an association of cortical thickness with cognitive function was observed. Our data do not support the hypothesized association of cortical thinning and cognitive impairment in carotid stenosis.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1127-y) contains supplementary material, which is available to authorized users.

Additive effect of cerebral atrophy on cognition in dementia-free elderly with cerebrovascular disease

Objective

To explore the additive effect of neurodegenerative diseases, measured by atrophy, on neurocognitive function in Asian dementia-free elderly with cerebrovascular disease (CeVD).

Methods

The present study employed a cross-sectional design and was conducted between 2010 and 2015 among community-dwelling elderly participants recruited into the study. Eligible participants were evaluated with an extensive neuropsychological battery and neuroimaging. The weighted CeVD burden scale comprising markers of both small- and large-vessel diseases was applied, with a score of ≥2, indicating significant CeVD burden. Cortical atrophy (CA) and medial temporal atrophy (MTA) were graded using the global cortical atrophy scale and Schelten’s scale, respectively. Global and domain-specific (attention, executive function, language, visuomotor speed, visuoconstruction, visual memory, and verbal memory) neurocognitive performance was measured using a locally validated neuropsychological battery (Vascular Dementia Battery, VDB).

Results

A total of 819 dementia-free participants were included in the analysis. Among none-mild CeVD subjects, there was no significant difference in the global cognitive performance across atrophy groups (no atrophy, CA, and CA+MTA). However, in moderate-severe CeVD subjects, CA+MTA showed significantly worse global cognitive performance compared with those with CA alone (mean difference=−0.35, 95% CI −0.60 to −0.11, p=0.002) and those without atrophy (mean difference=−0.46, 95% CI −0.74 to −0.19, p<0.001, p<0.001). In domain-specific cognitive performance, subjects with CA+MTA performed worse than other groups in visual memory (p=0.005), executive function (p=0.001) and visuomotor speed (p<0.001) in moderate-severe CeVD but not in none-mild CeVD.

Conclusions and relevance

Atrophy and moderate-severe CeVD burden showed an additive effect on global and domain-specific cognitive performance. This study highlights the importance of investigating the mechanisms of clinico-pathological interactions between neurodegenerative processes and vascular damage, particularly in the pre-dementia stage.

Characterization of White Matter Hyperintensities in Large-Scale MRI-Studies

Background: White matter hyperintensities of presumed vascular origin (WMH) are a common finding in elderly people and a growing social malady in the aging western societies. As a manifestation of cerebral small vessel disease, WMH are considered to be a vascular contributor to various sequelae such as cognitive decline, dementia, depression, stroke as well as gait and balance problems. While pathophysiology and therapeutical options remain unclear, large-scale studies have improved the understanding of WMH, particularly by quantitative assessment of WMH. In this review, we aimed to provide an overview of the characteristics, research subjects and segmentation techniques of these studies.

Methods: We performed a systematic review according to the PRISMA statement. One thousand one hundred and ninety-six potentially relevant articles were identified via PubMed search. Six further articles classified as relevant were added manually. After applying a catalog of exclusion criteria, remaining articles were read full-text and the following information was extracted into a standardized form: year of publication, sample size, mean age of subjects in the study, the cohort included, and segmentation details like the definition of WMH, the segmentation method, reference to methods papers as well as validation measurements.

Results: Our search resulted in the inclusion and full-text review of 137 articles. One hundred and thirty-four of them belonged to 37 prospective cohort studies. Median sample size was 1,030 with no increase over the covered years. Eighty studies investigated in the association of WMH and risk factors. Most of them focussed on arterial hypertension, diabetes mellitus type II and Apo E genotype and inflammatory markers. Sixty-three studies analyzed the association of WMH and secondary conditions like cognitive decline, mood disorder and brain atrophy. Studies applied various methods based on manual (3), semi-automated (57), and automated segmentation techniques (75). Only 18% of the articles referred to an explicit definition of WMH.

Discussion: The review yielded a large number of studies engaged in WMH research. A remarkable variety of segmentation techniques was applied, and only a minority referred to a clear definition of WMH. Most addressed topics were risk factors and secondary clinical conditions. In conclusion, WMH research is a vivid field with a need for further standardization regarding definitions and used methods.

Structural changes in white matter lesion patients and their correlation with cognitive impairment

BACKGROUND

White matter lesions (WMLs) play a role in cognitive decline and dementia. Little is known about gray matter (GM) changes in WMLs. This study aimed to investigate GM changes in WML patients.

MATERIALS AND METHODS

Correlations between altered structural volume and cognitive assessment scores were investigated. GM and white matter (WM) changes in 23 WML-vascular dementia (VaD) patients, 22 WML-non-dementia vascular cognitive impairment (VCIND) patients, and 23 healthy control (HC) subjects were examined. Gray matter density (GMD) was calculated by measuring local proportions of GM at thousands of homologous cortical locations. WM volume was obtained by fully automated software using voxel-based morphometry (VBM).

RESULTS

Widespread GMD was significantly lower in WML patients compared to control subjects in cortical and subcortical regions (p<0.05). Greatest differences were found in the bilateral anterior cingulate cortex, inferior frontal gyrus, insula, angular gyrus, caudate, precentral gyrus, and right middle temporal gyrus, right thalamus. Secondary region of interest (ROI) analysis indicated significantly greater GMD in the bilateral caudate among WML-VCIND patients (n=22) compared to HCs (p<0.05). There was a significant difference in WM volume between WML patients and control subjects (p<0.05). Greatest differences were located in the genu/body/splenium of the corpus callosum and superior corona radiata L, and posterior corona radiata L. There was a significant association between structural changes and cognitive scores (Montreal Cognitive Assessment [MoCA] score) (p<0.05). There was no significant correlation between structural changes and Mini Mental State Examination (MMSE) scores (p>0.05).

CONCLUSION

GMD and WM volume were changed in WMLs, and the changes were detectable. Correlation between structural changes and cognitive function was promising in understanding the pathological and physiological mechanisms of WMLs.

Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) is composed of several diseases affecting the small arteries, arterioles, venules, and capillaries of the brain, and refers to several pathological processes and etiologies. Neuroimaging features of CSVD include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. The main clinical manifestations of CSVD include stroke, cognitive decline, dementia, psychiatric disorders, abnormal gait, and urinary incontinence. Currently, there are no specific preventive or therapeutic measures to improve this condition. In this review, we will discuss the pathophysiology, clinical aspects, neuroimaging, progress of research to treat and prevent CSVD and current treatment of this disease.

Brain-predicted age in Down syndrome is associated with beta amyloid deposition and cognitive decline

Individuals with Down syndrome (DS) are more likely to experience earlier onset of multiple facets of physiological aging. This includes brain atrophy, beta amyloid deposition, cognitive decline, and Alzheimer's disease—factors indicative of brain aging. Here, we employed a machine learning approach, using structural neuroimaging data to predict age (i.e., brain-predicted age) in people with DS (N = 46) and typically developing controls (N = 30). Chronological age was then subtracted from brain-predicted age to generate a brain-predicted age difference (brain-PAD) score. DS participants also underwent [¹¹C]-PiB positron emission tomography (PET) scans to index the levels of cerebral beta amyloid deposition, and cognitive assessment. Mean brain-PAD in DS participants' was +2.49 years, significantly greater than controls (p < 0.001). The variability in brain-PAD was associated with the presence and the magnitude of PiB-binding and levels of cognitive performance. Our study indicates that DS is associated with premature structural brain aging, and that age-related alterations in brain structure are associated with individual differences in the rate of beta amyloid deposition and cognitive impairment.

The concept of sporadic cerebral small vessel disease: A road map on key definitions and current concepts

Sporadic cerebral small vessel disease is considered to be among the most common known neuropathological processes and has an important role in stroke, cognitive impairment, and functional loss in elderly persons. The term is now commonly used to describe a range of neuroimaging, neuropathological, and associated clinical features, the pathogenesis of which is largely unclear but that are thought to arise from disease affecting the perforating cerebral arterioles, capillaries, and venules. Modern neuroimaging has revolutionized our understanding of the consequences of small vessels disease on the brain parenchyma, even though small arteries, arterioles, capillaries, and venules are difficult to be directly visualized with current techniques used in clinical practice. In this short review, we focus on histopathological and neuroimaging perspectives, basic definitions, and recent advances in the field.

Early-Stage White Matter Lesions Detected by Multispectral MRI Segmentation Predict Progressive Cognitive Decline

White matter lesions (WML) are the main brain imaging surrogate of cerebral small-vessel disease. A new MRI tissue segmentation method, based on a discriminative clustering approach without explicit model-based added prior, detects partial WML volumes, likely representing very early-stage changes in normal-appearing brain tissue. This study investigated how the different stages of WML, from a “pre-visible” stage to fully developed lesions, predict future cognitive decline. MRI scans of 78 subjects, aged 65–84 years, from the Leukoaraiosis and Disability (LADIS) study were analyzed using a self-supervised multispectral segmentation algorithm to identify tissue types and partial WML volumes. Each lesion voxel was classified as having a small (33%), intermediate (66%), or high (100%) proportion of lesion tissue. The subjects were evaluated with detailed clinical and neuropsychological assessments at baseline and at three annual follow-up visits. We found that voxels with small partial WML predicted lower executive function compound scores at baseline, and steeper decline of executive scores in follow-up, independently of the demographics and the conventionally estimated hyperintensity volume on fluid-attenuated inversion recovery images. The intermediate and fully developed lesions were related to impairments in multiple cognitive domains including executive functions, processing speed, memory, and global cognitive function. In conclusion, early-stage partial WML, still too faint to be clearly detectable on conventional MRI, already predict executive dysfunction and progressive cognitive decline regardless of the conventionally evaluated WML load. These findings advance early recognition of small vessel disease and incipient vascular cognitive impairment.

Intracranial Arterial 4D-Flow is Associated with Metrics of Brain Health and Alzheimer's Disease

Introduction

Although cerebrovascular disease has long been known to co-occur with Alzheimer's disease (AD), recent studies suggest an etiologic contribution to AD pathogenesis. We used four dimensional (4D)-flow magnetic resonance imaging (MRI) to evaluate blood flow and pulsatility indices in the circle of Willis. We hypothesized decreased mean blood flow and increased pulsatility, metrics indicative of poor vascular health, would be associated with cerebral atrophy and an AD cerebrospinal fluid (CSF) profile.

Methods

A total of 312 patients along the AD continuum (172 middle aged, 60 cognitively healthy older, 44 mild cognitive impairment, and 36 AD) underwent MRI, CSF, and medical examinations. Regression was used to predict CSF biomarkers and atrophy from 4D-flow and analysis of covariance to compare vascular health between groups.

Results

Decreased mean flow in the middle cerebral artery (MCA) and superior portion of the internal carotid artery (sICA) and increased pulsatility in the MCA were associated with greater brain atrophy. Decreased mean flow in the sICA was associated with lower amyloid beta 1–42 (Aβ₄₂) in the CSF, a pathologic biomarker profile associated with AD. Interestingly, although metrics of flow and pulsatility differed markedly across the AD spectrum, there were no significant differences in cardiovascular risk score, mean arterial pressure, and pulse pressure across the three age-matched older cohorts.

Discussion

By measuring intracranial arterial health directly with 4D-flow MRI, these data suggest that intracranial arterial health is compromised in symptomatic AD. Even after accounting for disease stage, cerebral artery health is associated with atrophy and an AD Aβ₄₂ profile, suggesting neurovascular health may contribute to the etiopathogenesis of AD.

Relationships between Cognitive Performance, Neuroimaging and Vascular Disease: The DHS-MIND Study

BACKGROUND

Type 2 diabetes mellitus increases the risk of cognitive decline and dementia, and elevated burdens of vascular disease are hypothesized to contribute to this risk. These relationships were examined in the Diabetes Heart Study-MIND using a battery of cognitive tests, neuroimaging measures and subclinical cardiovascular disease (CVD) burden assessed by coronary artery calcified (CAC) plaque. We hypothesized that CAC would attenuate the association between neuroimaging measures and cognition performance.

METHODS

Associations were examined using marginal models in this family-based cohort of 572 European Americans from 263 families. All models were adjusted for age, gender, education, type 2 diabetes and hypertension, with some neuroimaging measures additionally adjusted for intracranial volume.

RESULTS

Higher total brain volume was associated with better performance on the Digit Symbol Substitution Task and Semantic Fluency (both p ≤ 7.0 × 10(-4)). Higher gray matter volume was associated with better performance on the Modified Mini-Mental State Examination and Semantic Fluency (both p ≤ 9.0 × 10(-4)). Adjusting for CAC caused minimal changes to the results.

CONCLUSIONS

Relationships exist between neuroimaging measures and cognitive performance in a type 2 diabetes-enriched European American cohort. Associations were minimally attenuated after adjusting for subclinical CVD. Additional work is needed to understand how subclinical CVD burden interacts with other factors and impacts relationships between neuroimaging and cognitive testing measures.

Carotid Arterial Hemodynamic in Ischemic Levkoaraiosis Suggests Hypoperfusion Mechanism

BACKGROUND

Leukoaraiosis (ILA) is believed to be ischaemic in origin due to its similar location as that of lacunar infarctions and its association with cerebrovascular risk factors. However, its pathophysiology is not well understood. The ischaemic injuries may be a result of increased pulsatility or cerebral hypo-perfusion. We used carotid duplex ultrasound to prove that the underlying mechanism is hypo-perfusion.

METHODS

We compared 55 ILA patients to 44 risk factor-matched controls with normal magnetic resonance imaging (MRI) of the head. ILA diagnosis was based on MRI and was further categorised according to the Fazekas scale. We measured carotid artery blood flow velocity and diameter and calculated carotid blood flow and resistance indexes.

RESULTS

Blood flow velocities and blood flows were significantly lower in the ILA group, including diastolic, systolic and mean pressures (p ≤ 0.05). The resistance indices were higher in the ILA group, but the differences were not statistically significant. All the velocities and blood flows showed a decreasing trend with higher Fazekas score, whereas resistance indexes showed an increasing trend.

CONCLUSIONS

Lower blood flow and higher resistance of carotid arteries are consistent with the hypo-perfusion theory of ILA. Carotid ultrasound could have a diagnostic and prognostic role in ILA patients.

Vascular imaging abnormalities and cognition: mediation by cortical volume in nondemented individuals: atherosclerosis risk in communities-neurocognitive study

BACKGROUND AND PURPOSE

The relationships between cerebrovascular lesions visible on imaging and cognition are complex. We explored the possibility that the cerebral cortical volume mediated these relationships.

METHODS

Total of 1906 nondemented participants (59% women; 25% African-American; mean age, 76.6 years) in the Atherosclerosis Risk in Communities (ARIC) study underwent cognitive assessments, risk factor assessments, and quantitative MRI for white matter hyperintensities (WMH) and infarcts. The Freesurfer imaging analysis pipeline was used to determine regional cerebral volumes. We examined the associations of cognitive domain outcomes with cerebral volumes (hippocampus and separate groups of posterior and frontal cortical regions of interest) and cerebrovascular imaging features (presence of large or small cortical/subcortical infarcts and WMH volume). We performed mediation pathway analyses to assess the hypothesis that hippocampal and cortical volumes mediated the associations between cerebrovascular imaging features and cognition.

RESULTS

In unmediated analyses, WMH and infarcts were both associated with worse psychomotor speed/executive function. In mediation analyses, WMH and infarct associations on psychomotor speed/executive function were significantly attenuated, but not abolished, by the inclusion of the posterior cortical regions of interest volume in the models, and the infarcts on psychomotor speed/executive function association were attenuated, but not abolished, by inclusion of the frontal cortical regions of interest volume.

CONCLUSIONS

Both WMH and infarcts were associated with cortical volume, and both lesions were also associated with cognitive performance, implying shared pathophysiological mechanisms. Although cross-sectional, our findings suggest that WMH and infarcts could be proxies for clinically covert processes that directly damage cortical regions. Microinfarcts are 1 candidate for such a clinically covert process.

Physical activity, structural brain changes and cognitive decline. The SMART-MR study

OBJECTIVE

We aimed to examine the cross-sectional and prospective relationship between leisure time physical activity, brain MRI abnormalities and cognitive performance in patients with vascular disease.

METHODS

Within the SMART-MR study, 1.5 T MRI of the brain and neuropsychological examinations were performed at baseline (n = 1232) and after 3.9 ± 0.4 years follow-up (n = 663). Automatic brain segmentation was used to quantify intracranial (ICV), total brain, ventricular, and white matter lesion (WML) volumes. Brain infarcts were rated visually. Level of physical activity was expressed in metabolic equivalents (MET) hours p/week. With linear regression analysis we examined associations of level of physical activity with brain MRI measures and with cognitive performance, adjusted for potential confounders. For the association with brain infarcts relative risks (RR) were calculated with Poisson regression.

RESULTS

At baseline, an increase in physical activity of one SD (39.7 METh/w) was significantly associated with larger total brain volume (B = 0.20% of ICV; 95% CI 0.06; 0.33%). A trend was found for the association of physical activity with smaller ventricular volume (B = -0.04% of ICV; 95% CI -0.09; 0.02%) and with a decreased risk for brain infarcts (RR = 0.91, 95% CI: 0.82-1.02). No association was found with smaller WML volume (B = -0.02% of ICV; 95% CI -0.07; 0.04%). No associations with change in brain structures over time were observed. Also, no associations between physical activity and cognitive performance or cognitive decline were found.

CONCLUSION

These data suggest that leisure time physical activity does not have a significant contribution in preventing or slowing down brain abnormalities and cognitive decline in this cohort of middle-aged individuals already burdened with vascular disease.

Regional white matter hyperintensities: aging, Alzheimer's disease risk, and cognitive function

White matter hyperintensities (WMH) of presumed vascular origin, as seen on T2-weighted fluid attenuated inversion recovery magnetic resonance imaging, are known to increase with age and are elevated in Alzheimer's disease (AD). The cognitive implications of these common markers are not well understood. Previous research has primarily focused on global measures of WMH burden and broad localizations that contain multiple white matter tracts. The aims of this study were to determine the pattern of WMH accumulation with age, risk for AD, and the relationship with cognitive function utilizing a voxel-wise analysis capable of identifying specific white matter regions. A total of 349 participants underwent T1-weighted and high-resolution T2-weighted fluid attenuated inversion recovery magnetic resonance imaging and neuropsychological testing. Increasing age and lower cognitive speed and flexibility (a component of executive function), were both significantly associated with regional WMH throughout the brain. When age was controlled, lower cognitive speed and flexibility was independently associated with WMH in the superior corona radiata. Apolipoprotein E ε4 and parental family history of AD were not associated with higher burden of WMH. The results contribute to a larger body of literature suggesting that white matter measures are linked with processing speed, and illustrate the utility of voxel-wise analysis in understanding the effect of lesion location on cognitive function.

Vascular brain lesions, brain atrophy, and cognitive decline. The Second Manifestations of ARTerial disease--Magnetic Resonance (SMART-MR) study

We examined the association between brain atrophy and vascular brain lesions (i.e., white matter lesions [WMLs] or brain infarcts), alone or in combination, with decline in memory and executive functioning over 4 years of follow-up in 448 patients (57 ± 9.5 years) with symptomatic atherosclerotic disease from the Second Manifestations of ARTerial disease--Magnetic Resonance SMART-MR study. Automated brain segmentation was used to quantify volumes of total brain, ventricles, cortical gray matter, and WMLs on 1.5-T magnetic resonance imaging (MRI). Brain infarcts were rated visually. WML volume was associated with significant decline in z score of executive functioning. No independent associations between MRI measures and memory decline were found. Significant declines in z scores of memory performance and of executive functioning were observed in patients with a combination of severe atrophy (upper quartile) and most vascular brain lesions (upper quartile) compared with those with minimal atrophy (lowest quartile) and fewest vascular brain lesions (lowest quartile). Our findings suggest that in patients with symptomatic atherosclerotic disease, the combination of brain atrophy and WMLs or brain infarcts accelerates cognitive decline over 4 years.

Diabetes mellitus and progression of vascular brain lesions and brain atrophy in patients with symptomatic atherosclerotic disease. The SMART-MR study

AIM

Diabetes mellitus (DM) is associated with brain atrophy and vascular brain lesions. Cardiovascular disease is a key determinant in this association. We assessed whether DM increased the rate of progression of brain atrophy, vascular brain lesions, and cognitive decline in patients with symptomatic atherosclerotic disease.

METHODS

In 663 patients (58±10years) from the SMART-MR study (n=89 with DM), 1.5T MRI and neuropsychological examination were performed at baseline and after 3.9±0.4years follow-up.

RESULTS

Repeated measures ANCOVA (adjusted for age, sex, and vascular risk factors) showed that patients with DM had smaller total brain volume (mean differences as percentage of intracranial volume (ICV) [95% CI]: -1.36% [-1.81; -0.91]), smaller gray matter volume (-1.23% [-1.85; -0.61]), larger ventricular volume (0.32% [0.14; 0.49]), and larger white matter lesion volume (0.31% [0.09; 0.53]) than patients without DM. Patients with DM had accelerated increase in ventricular volume over time compared with patients without DM (mean differences ventricular volume as percentage of ICV: 0.32% [0.25; 0.39] vs. 0.17% [0.15; 0.19]; p-interaction DM×time<0.01). Poisson regression showed that patients with DM had an increased risk for incident brain infarcts (relative risk [95% CI]: 1.62 [1.04; 2.53]). Patients with and without DM had similar performance on cognition.

CONCLUSIONS

DM on top of existing symptomatic atherosclerotic disease is associated with increased brain atrophy and vascular brain lesion load that proceed at a slightly higher rate than in patients without DM.

Association between subcortical vascular lesion location and cognition: a voxel-based and tract-based lesion-symptom mapping study. The SMART-MR study

Introduction

Lacunar lesions (LLs) and white matter lesions (WMLs) affect cognition. We assessed whether lesions located in specific white matter tracts were associated with cognitive performance taking into account total lesion burden.

Methods

Within the Second Manifestations of ARTerial disease Magnetic Resonance (SMART-MR) study, cross-sectional analyses were performed on 516 patients with manifest arterial disease. We applied an assumption-free voxel-based lesion-symptom mapping approach to investigate the relation between LL and WML locations on 1.5 Tesla brain MRI and compound scores of executive functioning, memory and processing speed. Secondly, a multivariable linear regression model was used to relate the regional volume of LLs and WMLs within specific white matter tracts to cognitive functioning.

Results

Voxel-based lesion-symptom mapping identified several clusters of voxels with a significant correlation between WMLs and executive functioning, mostly located within the superior longitudinal fasciculus and anterior thalamic radiation. In the multivariable linear regression model, a statistically significant association was found between regional LL volume within the superior longitudinal fasciculus and anterior thalamic radiation and executive functioning after adjustment for total LL and WML burden.

Conclusion

These findings identify the superior longitudinal fasciculus and anterior thalamic radiation as key anatomical structures in executive functioning and emphasize the role of strategically located vascular lesions in vascular cognitive impairment.

Brain atrophy associations with white matter lesions in the ageing brain: the Lothian Birth Cohort 1936

OBJECTIVE

Cerebral atrophy and white matter lesions (WMLs) are common in older people with common risk factors, but it is unclear if they are related. We investigated whether and to what degree they are related in deep and superficial structures using both volumetric and visual ratings.

METHODS

The intracranial, total brain tissue (TBV), cerebrospinal fluid (CSF), ventricular superficial subarachnoid space (SSS), grey matter, normal-appearing white matter, WMLs, and combined CSF, venous sinuses and dural volumes were measured. WMLs were also rated using the Fazekas scale.

RESULTS

Amongst 672 adults (mean age 73 ± 1 years), WMLs were associated with global brain atrophy (TBV, β = -0.43 mm(3), P < 0.01) and specifically with deep (ventricular enlargement, β = 0.10 mm(3), P = 0.03) rather than superficial (SSS, β = 0.09 mm(3), P = 0.55) atrophy. A 1 mm(3) increase in WML volume was associated with a 0.43 mm(3) decrease in TBV and 0.10 mm(3) increase in ventricular volume. WMLs were associated with combined CSF + Venous Sinuses + Meninges volumes, but not CSF volume alone. Some of the associations were attenuated after correcting for vascular risk factors. The associations were similar for visually scored WMLs.

CONCLUSION

WMLs are associated with brain atrophy, primarily with deep brain structures. Measures of brain atrophy should include all intracranial structures when assessing brain shrinkage.

Antidepressant use is related to larger white matter lesion volume in patients with symptomatic atherosclerotic disease: the SMART-MR study

Although a relation between depression and white matter lesions (WML) is frequently observed, the direction of causation remains unknown. We investigated whether depressed mood was associated with baseline severity and change in WML volume during 4 years of follow-up, and the relative contribution of mood symptoms and antidepressant use to this relation. Within the SMART-MR study 594 patients (58 ± 10 years) with symptomatic atherosclerotic disease had assessments of mood symptoms and antidepressant use and 1.5 T MRI at baseline and after 3.9 ± 0.4 years of follow-up. Mood symptoms were assessed using the Mental Health Index (MHI-5). Depressed mood was defined as antidepressant use and/or MHI-5 score ≤ 52. Volumetric WML measures (deep and periventricular) were obtained with automated segmentation. Linear regression analyses were adjusted for age, sex, baseline WML volume, follow-up time, vascular risk factors and infarcts. Depressed mood was not associated with larger WML volume at baseline. However, when separate contributions were distinguished, antidepressant use was associated with greater deep (B = 0.50 mL, 95 % CI 0.04-0.96) and periventricular WML volume (B = 0.47 mL, 95 % CI 0.05-0.89) at baseline, while mood symptoms were not. Antidepressants were associated with a modest but non-significant increase in progression of periventricular WML volume over 4 years of follow-up (B = 0.21 mL, 95 % CI -0.05 to 0.47). WML at baseline were not associated with new-onset depressed mood at follow-up. Antidepressants, but not mood symptoms, were associated with greater WML volume and a modest, although non-significant increase in periventricular WML volume in patients with symptomatic atherosclerotic disease. Future studies are needed to determine whether this may be a direct effect, or whether other underlying diseases for which antidepressants are prescribed influence this relation.

White matter lesions and brain gray matter volume in cognitively normal elders

Cerebral white matter lesions (WMLs) reflect small vessel disease, are common in elderly individuals, and are associated with cognitive impairment. We sought to determine the relationships between WMLs, age, gray matter (GM) volume, and cognition in the Cardiovascular Health Study (CHS). From the Cardiovascular Health Study we selected 740 cognitively normal controls with a 1.5 T magnetic resonance imaging (MRI) scan of the brain and a detailed diagnostic evaluation. WML severity was determined using a standardized visual rating system. GM volumes were analyzed using voxel-based morphometry implemented in the Statistical Parametric Mapping software. WMLs were inversely correlated with GM volume, with the greatest volume loss in the frontal cortex. Age-related atrophy was observed in the hippocampus and posterior cingulate cortex. Regression analyses revealed links among age, APOE*4 allele, hypertension, WMLs, GM volume, and digit symbol substitution test scores. Both advancing age and hypertension predict higher WML load, which is itself associated with GM atrophy. Longitudinal data are needed to confirm the temporal sequence of events leading to a decline in cognitive function.

Location and progression of cerebral small-vessel disease and atrophy, and depressive symptom profiles: the Second Manifestations of ARTerial disease (SMART)-Medea study

BACKGROUND

The 'vascular depression' hypothesis states that brain changes located in frontal-subcortical pathways increase vulnerability for specific depressive symptom profiles, but studies examining locations of small-vessel and degenerative changes with individual symptoms are scarce. We examined whether location and progression of white-matter lesions (WMLs), lacunar infarcts and atrophy were associated with motivational and mood symptoms in patients with symptomatic atherosclerotic disease.

METHOD

In 578 patients [63 (s.d.=8) years] of the Second Manifestations of ARTerial disease (SMART)-Medea study, volumes of WMLs and atrophy and visually rated infarcts were obtained with 1.5 T magnetic resonance imaging at baseline and after 3.9 (s.d.=0.4) years' follow-up. Depressive symptoms were assessed with Patient Health Questionnaire-9 at follow-up and categorized into motivational and mood symptoms.

RESULTS

Regression analyses adjusted for age, gender, education, Mini-Mental State Examination, physical functioning, antidepressant use and vascular risk factors showed that location in mainly deep white-matter tracts and progression of WMLs were associated with symptoms of anhedonia, concentration problems, psychomotor retardation and appetite disturbance. Lacunar infarcts in deep white matter were associated with greater motivational [Incidence rate ratio (IRR) 1.7, 95% confidence interval (CI) 1.2-2.4] and mood (IRR 1.7, 95% CI 1.1-2.6) sumscores, and with symptoms of psychomotor retardation, energy loss and depressed mood; lacunar infarcts in the thalamus were associated with psychomotor retardation only. Cortical atrophy was associated with symptoms of anhedonia and appetite disturbance. Excluding patients with major depression did not materially change the results.

CONCLUSIONS

Our findings suggest that disruption of frontal-subcortical pathways by small-vessel lesions leads to a symptom profile that is mainly characteristic of motivational problems, also in the absence of major depression.

Neuroanatomical substrates of age-related cognitive decline

There are many reports of relations between age and cognitive variables and of relations between age and variables representing different aspects of brain structure and a few reports of relations between brain structure variables and cognitive variables. These findings have sometimes led to inferences that the age-related brain changes cause the age-related cognitive changes. Although this conclusion may well be true, it is widely recognized that simple correlations are not sufficient to warrant causal conclusions, and other types of correlational information, such as mediation and correlations between longitudinal brain changes and longitudinal cognitive changes, also have limitations with respect to causal inferences. These issues are discussed, and the existing results on relations of regional volume, white matter hyperintensities, and diffusion tensor imaging measures of white matter integrity to age and to measures of cognitive functioning are reviewed. It is concluded that at the current time the evidence that these aspects of brain structure are neuroanatomical substrates of age-related cognitive decline is weak. The final section contains several suggestions concerning measurement and methodology that may lead to stronger conclusions in the future.