Frontal systems impairment following multiple lacunar infarcts

Clinical correlates of white matter lesions in Parkinson's disease using automated multi-modal segmentation measures

BACKGROUND

Age-related white matter lesions (WML) are common, impact neuronal connectivity, and affect motor function and cognition. In addition to pathological nigrostriatal losses, WML are also common co-morbidities in Parkinson's disease (PD) that affect postural stability and gait. Automated brain volume measures are increasingly incorporated into the clinical reporting workflow to facilitate precision in medicine. Recently, multi-modal segmentation algorithms have been developed to overcome challenges with WML quantification based on single-modality input.

OBJECTIVE

We evaluated WML volumes and their distribution in a case-control cohort of PD patients to predict the domain-specific clinical severity using a fully automated multi-modal segmentation algorithm.

METHODS

Fifty-five subjects comprising of twenty PD patients and thirty-five age- and gender-matched control subjects underwent standardized motor/gait and cognitive assessments and brain MRI. Spatially differentiated WML obtained using automated segmentation algorithms on multi-modal MPRAGE and FLAIR images were used to predict domain-specific clinical severity. Preliminary statistical analysis focused on describing the relationship between WML and clinical scores, and the distribution of WML by brain regions. Subsequent stepwise regressions were performed to predict each clinical score using WML volumes in different brain regions, while controlling for age.

RESULTS

WML volume strongly correlates with both motor and cognitive dysfunctions in PD patients (p < 0.05), with differential impact in the frontal lobe and periventricular regions on cognitive domains (p < 0.01) and severity of motor deficits (p < 0.01), respectively.

CONCLUSION

Automated multi-modal segmentation algorithms may facilitate precision medicine through regional WML load quantification, which show potential as imaging biomarkers for predicting domain-specific disease severity in PD.

Cognitive impairment in sporadic cerebral small vessel disease: A systematic review and meta-analysis

This paper is a proposal for an update on the characterization of cognitive impairments associated with sporadic cerebral small vessel disease (SVD). We pose a series of questions about the nature of SVD-related cognitive impairments and provide answers based on a comprehensive review and meta-analysis of published data from 69 studies. Although SVD is thought primarily to affect executive function and processing speed, we hypothesize that SVD affects all major domains of cognitive ability. We also identify low levels of education as a potentially modifiable risk factor for SVD-related cognitive impairment. Therefore, we propose the use of comprehensive cognitive assessments and the measurement of educational level both in clinics and research settings, and suggest several recommendations for future research.

Behavioral Disturbances in Dementia and Beyond: Time for a New Conceptual Frame?

Alzheimer’s disease and vascular dementia are estimated to be the most common causes of dementia, although mixed dementia could represent the most prevalent form of dementia in older adults aged more than 80 years. Behavioral disturbances are common in the natural history of dementia. However, so far, there is a paucity of studies that investigated the causal association between behavioral psychological symptoms of dementia and dementia sub-types, due to the high heterogeneity of methodology, study design and type of clinical assessment. To understand the scant evidence on such a relevant clinical issue, it could be hypothesized that a new shifting paradigm could result in a better identification of the relationship between behavioral disturbances and dementia. This narrative review provides an update of evidence on the behavioral patterns associated with different dementia sub-types and offers a potential future perspective as common ground for the development of new translational studies in the field of behavioral disturbances in dementia and the appropriateness of psychoactive treatments.

Theoretical Modeling of Cognitive Dysfunction in Schizophrenia by Means of Errors and Corresponding Brain Networks

The current evidence of cognitive disturbances and brain alterations in schizophrenia does not provide the plausible explanation of the underlying mechanisms. Neuropsychological studies outlined the cognitive profile of patients with schizophrenia, that embodied the substantial disturbances in perceptual and motor processes, spatial functions, verbal and non-verbal memory, processing speed and executive functioning. Standardized scoring in the majority of the neurocognitive tests renders the index scores or the achievement indicating the severity of the cognitive impairment rather than the actual performance by means of errors. At the same time, the quantitative evaluation may lead to the situation when two patients with the same index score of the particular cognitive test, demonstrate qualitatively different performances. This may support the view why test paradigms that habitually incorporate different cognitive variables associate weakly, reflecting an ambiguity in the interpretation of noted cognitive constructs. With minor exceptions, cognitive functions are not attributed to the localized activity but eventuate from the coordinated activity in the generally dispersed brain networks. Functional neuroimaging has progressively explored the connectivity in the brain networks in the absence of the specific task and during the task processing. The spatio-temporal fluctuations of the activity of the brain areas detected in the resting state and being highly reproducible in numerous studies, resemble the activation and communication patterns during the task performance. Relatedly, the activation in the specific brain regions oftentimes is attributed to a number of cognitive processes. Given the complex organization of the cognitive functions, it becomes crucial to designate the roles of the brain networks in relation to the specific cognitive functions. One possible approach is to identify the commonalities of the deficits across the number of cognitive tests or, common errors in the various tests and identify their common "denominators" in the brain networks. The qualitative characterization of cognitive performance might be beneficial in addressing diffuse cognitive alterations presumably caused by the dysconnectivity of the distributed brain networks. Therefore, in the review, we use this approach in the description of standardized tests in the scope of potential errors in patients with schizophrenia with a subsequent reference to the brain networks.

Serum Brain-Derived Neurotrophic Factor Mediates the Relationship between Abdominal Adiposity and Executive Function in Middle Age

OBJECTIVES

Excessive adipose tissue, especially in the abdominal area, is associated with increased risk of dementia in older adults. However, the mechanisms underlying this relationship are poorly understood. As increased adiposity is also associated with lower circulating levels of brain-derived neurotrophic factor (BDNF), a key molecule modulating brain plasticity and neuronal regeneration, we hypothesized that the changes in cognition that occur as a result of excessive abdominal adiposity would be driven by lower levels of circulating BDNF.

METHODS

Fasting blood samples were obtained from 60 participants aged 40-60 years (mean±SD=52.3±5.6) and BDNF levels were assessed with an enzyme linked immunosorbent assay. Abdominal adiposity was measured using a ratio of waist circumference to hip circumference (WHR). Participants also completed a neuropsychological assessment battery to assess executive function. Statistical mediation was assessed using traditional causal steps and nonparametric bootstrapping.

RESULTS

Higher WHR was significantly associated with poorer performance on the Controlled Oral Word Association (COWA) letter fluency test (β=-0.489; p=.003) and lower levels of circulating BDNF (β=-0.345; p=.006). Linear regression and bootstrapping methods indicated that BDNF fully mediated the relationship between WHR and performance on the COWA (β=0.60; 95% confidence interval [-3.79, -0.26]).

CONCLUSIONS

The relationship between higher WHR and verbal fluency was fully statistically mediated by circulating BDNF levels. The BDNF pathway is thus a useful probable mechanism through which executive function decline occurs in individuals with high abdominal adiposity. BDNF enhancing interventions (physical exercise and dietary restriction) could thus be used to improve executive function in these individuals.

The contribution of white matter lesions to Parkinson's disease motor and gait symptoms: a critical review of the literature

White matter lesions (WML) associated with cerebrovascular disease (CVD) may be observed on magnetic resonance imaging in Parkinson's disease (PD) patients. WML are an important factor contributing to postural, gait, and cognitive impairment in the elderly without PD and worsening the course of Alzheimer's disease (AD). Numerous articles are available on this topic. Whether WML modify and negatively influence the clinical symptoms, and course of PD is a subject of debate. The aim of this review is to examine the available literature on the contribution of WML to PD motor symptoms in relation to clinical characteristics and methods of assessing WML on MRI. After reviewing the database, we identified 19 studies reporting the relationship between WML and PD; ten studies focusing on the impact of WML on the cognitive status in PD were excluded. We analysed altogether nine studies reporting the relationship between WML and motor signs of PD. The review found association between WML severity and freezing of gait, less significant to responsiveness to dopaminergic treatment and postural instability; no negative impact on tremor and falls was observed. The impact of WML on bradykinesia and rigidity was inconsistent. Comorbid WML is associated with worsening axial motor performance, probably independently from the degree of nigrostriatal dopaminergic denervation in PD. Reducing the vascular risk factors that cause WML may be helpful in preventing the development of axial symptoms and ultimately in improving the quality of life of patients with PD. Given the lack of systematic studies, additional research in this field is needed.

Silent New Brain Lesions: Innocent Bystander or Guilty Party?

With the advances in magnetic resonance imaging, previously unrecognized small brain lesions, which are mostly asymptomatic, have been increasingly detected. Diffusion-weighted imaging can identify small ischemic strokes, while gradient echo T2* imaging and susceptibility-weighted imaging can reveal tiny hemorrhagic strokes (microbleeds). In this article, we review silent brain lesions appearing soon after acute stroke events, including silent new ischemic lesions and microbleeds appearing 1) after acute ischemic stroke and 2) after acute intracerebral hemorrhage. Moreover, we briefly discuss the clinical implications of these silent new brain lesions.

Subclinical cerebrovascular disease inversely associates with learning ability: The NOMAS

OBJECTIVE

Memory has been examined in subjects with imaging markers of cerebrovascular disease, but learning has been less well studied. We examined the relationship among subclinical cerebrovascular disease, cerebral volumes, and verbal learning in an ethnically and racially diverse community sample.

METHODS

A clinically stroke-free subset of Northern Manhattan Study participants underwent cognitive testing and brain MRI with quantification of white matter hyperintensity volume (WMHV) and total cerebral volume (TCV) using semiautomated segmentation. We used generalized linear regression and mixed models to examine the association between imaging findings and verbal learning.

RESULTS

There were 1,272 participants (61% women, mean age 70 ± 9 years). Participants with greater WMHV and smaller TCV remembered fewer total words on a list-learning task (β = -0.83 per SD change in WMHV, 95% confidence interval [CI] = -1.22 to -0.45, p < 0.0001; and β = 0.48 per SD change in TCV, 95% CI = 0.05 to 0.90, p = 0.03, respectively). Subclinical brain infarction (SBI) was not associated with total words learned (β = -0.04, 95% CI = -1.08 to 1.00, p = 0.94). Those with greater WMHV had increased odds of a flatter learning slope. After excluding participants with SBI, the association between total words learned and WMHV remained significant. All measurements were adjusted for age, education, race/ethnicity, medical insurance status, and the presence of SBI.

CONCLUSIONS

White matter hyperintensities, a marker of cerebral small vessel disease, may have an impact on learning slope. This suggests that verbal learning performance can be incorporated into neuropsychological measures for vascular cognitive impairment and that cerebrovascular disease discovered on imaging affects the ability to learn new information.

A multidimensional risk factor model for suicide attempts in later life

BACKGROUND

Elderly suicide is a public health problem worldwide, and the risk factors are multidimensional. Chronic mental health problems, personality traits, stressful life events, comorbid medical conditions, social isolation, unemployment, and poverty are associated with higher risk for suicide in later life. There was a relative paucity of data on the neurobiological markers of elderly suicide.

OBJECTIVE

This study examines the conjoint roles of cerebrovascular risk factors (CVRFs) and other established biopsychosocial risk factors in older adults who had made a recent suicide attempt.

DESIGN

A cross-sectional, case-controlled study.

SETTING

A tertiary care setting in a public sector and a community setting.

SUBJECTS AND METHODS

Cases (N=77) were nondemented Chinese adults aged ≥65 years, enrolled in a regional psychogeriatric service following a suicide attempt; comparison subjects (N=99) were community-dwelling nondemented older adults with no lifetime history of suicide. Measures of sociodemographic profile, life events, suicidal behavior, Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) Axis I psychopathology, personality traits, functional status, physical health, CVRFs, and executive cognitive functions were administered.

RESULTS

WEIGHTED SUM OF CVRF SCORE WAS SIGNIFICANTLY HIGHER IN OLDER WOMEN WHO HAD MADE A RECENT SUICIDE ATTEMPT (MEAN: 10.56; standard deviation [SD]: 5.46) than comparison subjects (mean: 7.24; SD: 4.04) (t=3.52, P=0.001; df=99). Logistic regression showed that CVRF score (Exp[B]: 1.289, P=0.033), DSM-IV depressive disorders (current) (Exp[B]: 348, P<0.001), number of life events in the past 12 weeks (Exp[B]: 10.4; P<0.001), and being married (Exp[B]: 12.2, P<0.048) significantly increased odds for suicide attempt status in older women (Nagelkerke R (2): 0.844). Association of CVRF score and suicide attempt status was not observed in older men for whom number of life events in the past 12 weeks (Exp[B]: 9.164; P<0.001), higher neuroticism (Exp[B]: 1.028; P=0.048), and impaired performance on a Modified Card Sorting Test (Exp[B]: 0.646; P=0.032) significantly increased odds for suicide attempt status in a logistic regression model (Nagelkerke R (2): 0.611).

CONCLUSION

Risk factors for cerebrovascular diseases may be associated with higher risk for attempted suicide in older women, but not in older men. Older men and women have distinct risk factor profiles that may inform targeted intervention and prevention strategies.

White matter hyperintensities, exercise, and improvement in gait speed: does type of gait rehabilitation matter?

OBJECTIVES

To examine whether white matter hyperintensities (WMHs) on brain magnetic resonance imaging (MRI) in tracts in older adults with mobility impairment are linked to outcomes of gait rehabilitation interventions.

DESIGN

Twelve-week randomized controlled single-blind trial.

SETTING

University-based mobility research laboratory.

PARTICIPANTS

Ambulatory adults aged 65 and older with mobility impairment.

INTERVENTION

A conventional gait intervention focusing on walking, endurance, balance, and strength (WEBS, n = 21) and a task-oriented intervention focused on timing and coordination of gait (TC, n = 23).

MEASUREMENTS

Self-paced gait speed was measured over an instrumented walkway before and after the intervention, and WMH and brain volumes were quantified on preintervention brain MRI using an automated segmentation process. A white matter tract atlas was overlaid on the segmented images to measure tract WMH volumes, and WMH volumes were normalized to total brain volume. Aggregate WMH volumes in all white matter tracts and individual WMH volumes in specific longitudinal tracts (superior longitudinal fasciculus, inferior longitudinal fasciculus, and fronto-occipital fasciculus) and the cingulum were measured.

RESULTS

Gait speed gains in the TC group were of the same magnitude, independent of WMH volume measures in all except the cingulum, but in the WEBS group, gain in gait speed was smaller with greater overall tract WMH volumes (P < .001) and with greater WMH volume in the three longitudinal tracts (P < .001 to .02).

CONCLUSION

Gains in gait speed with two types of gait rehabilitation are associated with individual differences in WMHs. Task-oriented therapy that targets timing and coordination of gait may particularly benefit older adults with WMHs in brain tracts that influence gait and cognition.

Effects of hypertension and diabetes on sentence comprehension in aging

OBJECTIVES

To assess the impact of hypertension and diabetes mellitus on sentence comprehension in older adults.

METHOD

Two hundred and ninety-five adults aged 55 to 84 (52% men) participated in this study. Self-report mail survey combined with medical evaluations were used to determine eligibility. Multiple sources were used to determine whether hypertension and diabetes were present or absent and controlled or uncontrolled. Sentence comprehension was evaluated with two tasks: embedded sentences (ES) and sentences with multiple negatives (MN). Outcome measures were percent accuracy and mean reaction time of correct responses on each task.

RESULTS

Regression models adjusted for age, gender, and education showed that the presence of hypertension impaired comprehension on the multiple negatives task (p < .01), whereas the presence of diabetes impaired the comprehension of embedded sentences (p < .05). Uncontrolled diabetes significantly impaired accurate comprehension of sentences with multiple negatives (p < .05). No significant patterns were found for reaction time.

DISCUSSION

The presence of hypertension and diabetes adversely affected sentence comprehension, but the relative contribution of each was different. These findings support the researchers' earlier speculations on the neurobiological mechanisms underlying the effects of hypertension and diabetes on language and cognition in aging. Uncontrolled disease status demonstrated more complicated age-related effects on sentence processing, highlighting the clinical importance for cognitive aging of identifying and managing vascular risk factors.

Frequency and predictors of proxy-confirmed post-stroke cognitive complaints in lacunar stroke patients without major depression

OBJECTIVE

Many lacunar stroke patients complained of cognitive decline after stroke. This study aims to investigate the factors underlying post-stroke cognitive complaints in these patients.

METHODS

Seventy-five consecutive lacunar stroke patients without major depression were recruited for the study. Stroke severity was measured using NIHSS score and MRI was performed during the acute admission period. At 3 months, objective psychometric performance and depressive symptoms were assessed. Post-stroke cognitive complaints were corroborated by a proxy. Using logistic regression we examined the contribution of demographic features, stroke severity, objective psychometric scores, depressive symptoms, and imaging features (white matter lesion volume and infarct measures) to post-stroke cognitive complaints.

RESULTS

Thirty-two (42.7%) patients had post-stroke cognitive complaints. Patients with post-stroke cognitive complaints had more depressive symptoms and worse psychometric performance than those without. In the multivariate logistic regression model, only the severity of depressive symptoms was independently associated with post-stroke cognitive complaints.

CONCLUSIONS

This study suggests that post-stroke cognitive complaints are frequent among lacunar stroke patients without major depression and are prominently determined by the subclinical depressive symptomatology.

Inflammatory markers and neuropsychological functioning: the Framingham Heart Study

BACKGROUND/AIMS

We hypothesized that inflammatory markers are cross-sectionally and longitudinally associated with neuropsychological indicators of early ischemia and Alzheimer's disease.

METHODS

Framingham Offspring Study participants, free of clinical stroke or dementia (n = 1,878; 60 ± 9 years; 54% women), underwent neuropsychological assessment and ascertainment of 11 inflammatory markers. Follow-up neuropsychological assessments (6.3 ± 1.0 years) were conducted on 1,352 of the original 1,878 participants.

RESULTS

Multivariable linear regression related the inflammatory markers to cross-sectional performance and longitudinal change in neuropsychological performances. Secondary models included a twelfth factor, tumor necrosis factor-α (TNF-α), available on a subset of the sample (n = 1,393 cross-sectional; n = 1,213 longitudinal). Results suggest a few modest cross-sectional inflammatory and neuropsychological associations, particularly for tests assessing visual organization (C-reactive protein, p = 0.007), and a few modest relations between inflammatory markers and neuropsychological change, particularly for executive functioning (TNF-α, p = 0.004). Secondary analyses suggested that inflammatory markers were cross-sectionally (TNF-α, p = 0.004) related to reading performance.

CONCLUSIONS

Our findings are largely negative, but suggest that specific inflammatory markers may have limited associations with poorer cognition and reading performance among community-dwelling adults. Because of multiple testing concerns, our limited positive findings are offered as hypothesis generating and require replication in other studies.

Training of goal-directed attention regulation enhances control over neural processing for individuals with brain injury

Deficits in attention and executive control are some of the most common, debilitating and persistent consequences of brain injuries. Understanding neural mechanisms that support clinically significant improvements, when they do occur, may help advance treatment development. Intervening via rehabilitation provides an opportunity to probe such mechanisms. Our objective was to identify neural mechanisms that underlie improvements in attention and executive control with rehabilitation training. We tested the hypothesis that intensive training enhances modulatory control of neural processing of perceptual information in patients with acquired brain injuries. Patients (n=12) participated either in standardized training designed to target goal-directed attention regulation, or a comparison condition (brief education). Training resulted in significant improvements on behavioural measures of attention and executive control. Functional magnetic resonance imaging methods adapted for testing the effects of intervention for patients with varied injury pathology were used to index modulatory control of neural processing. Pattern classification was utilized to decode individual functional magnetic resonance imaging data acquired during a visual selective attention task. Results showed that modulation of neural processing in extrastriate cortex was significantly enhanced by attention regulation training. Neural changes in prefrontal cortex, a candidate mediator for attention regulation, appeared to depend on individual baseline state. These behavioural and neural effects did not occur with the comparison condition. These results suggest that enhanced modulatory control over visual processing and a rebalancing of prefrontal functioning may underlie improvements in attention and executive control.

Voxel-based analysis of diffusion tensor imaging in patients with subcortical vascular cognitive impairment: correlates with cognitive and motor deficits

BACKGROUND AND PURPOSE

Patients with small vessel disease show high-signal intensity on T2-weighted magnetic resonance (MR) images that represent ischemic cell damage. However, despite a similar degree of ischemic change, the amount and the severity of clinical presentations may vary. We investigated the clinical correlations of ischemic changes using voxel-based morphometric analyses of diffusion tensor imaging (DTI).

METHODS

Twenty-seven MCI and 34 dementia patients were included who all had significant small vessel disease on magnetic resonance imaging (MRI). In all patients, neuropsychological tests, a rating on the Pyramidal and Extrapyramidal scale (PEPS) for motor deficits, and 3-Tesla MRI including DTI scans were performed. Voxel-based analysis of the fractional anisotropy and mean diffusivity maps were computed.

RESULTS

Cognitive scores correlated with the DTI abnormalities in supratentorial areas with regional specificity according to each cognitive test. Unexpectedly, cognitive deficits in most neuropsychological tests, even in some frontal tasks, were associated with disruption of posterior white matter integrities. Motor deficits correlated with both supra- and infratentorial lesions.

CONCLUSION

Our findings suggest that in patients with small vessel disease who show cognitive and motor impairments, a specific distribution of fiber tract damage is more related with clinical deficits than is the severity of the total ischemia.

Lacune-associated cerebral hypoperfusion correlates with cognitive testing

The hypothesis was tested among 83 patients with multiple lacunar infarctions that cerebral hypoperfusion will correlate with cognitive impairments. Patients were subdivided according to Cognitive Capacity Screening Examination (CCSE) scores into a cognitively impaired group (Group D, n = 40; mean age, 68.2 years) with CCSE scores between 6 and 25 (mean, 19.9) and a cognitively intact group (Group I, n = 43; mean age, 66.0) with normal scores (mean, 29.4). Gray and white matter tissue densities were measured by plain computed tomography (CT), and their compartmental perfusions were estimated during stable xenon inhalation. Eighty infarcts in basal ganglia and white matter were detected in Group D and 62 in Group I. Cognitive impairments correlated with (a) multiplicity and bilaterality of lacunes; (b) hypertension, diabetes mellitus, and multiplicity of risk factors for stroke; (c) hypoperfusion of white and gray matter, but particularly of frontal white matter; (d) leuko-araiosis; (e) aging; and (f) lower education. The conclusion was that hypertension and diabetes mellitus are potent risk factors for cerebral small vessel disease or arteriolosclerosis ultimately resulting in lacunar infarcts, leuko-araiosis, white matter hypoperfusion, and impaired cognitive test performance.

Mild cognitive impairment in stroke patients with ischemic cerebral small-vessel disease: a forerunner of vascular dementia?

Ischemic cerebral small-vessel disease accounts for a third of acute cerebral ischemic events and contributes to the development of cognitive decline and dementia. Cerebral small-vessel disease can be visualized on MRI studies as lacunar infarcts, white matter lesions and cerebral microbleeds. In general, the short-term prognosis of ischemic cerebral small-vessel disease compared with other stroke subtypes is more favorable, with almost negligible early mortality, absence of neuropsychological impairment and excellent neurological recovery. However, it has been shown recently that the proportion of dementia caused by small-vessel disease ranges from 36 to 67%. On the other hand, patients with a first-ever lacunar infarction present with cognitive impairment (mainly executive dysfunction) in more than half of cases and more than 55% of patients fulfil the criteria of mild cognitive impairment of the vascular type. Moreover, patients with small-vessel disease have an increase in the mid- and long-term risk of death, stroke recurrence and dementia. Neuropsychological abnormalities in small-vessel disease occurred more frequently than previously recognized. Ischemic cerebral small-vessel disease should be regarded as a potentially severe condition prodrome of subcortical vascular dementia rather than a relatively benign disorder.

Cognitive consequences of multiple lacunes and leukoaraiosis as vascular cognitive impairment in community-dwelling elderly individuals

The aim of our study was to investigate the effects of silent brain lesions on cognitive function of community-dwelling elderly individuals. Brain magnetic resonance imaging and other medical examinations were performed on 350 nondemented elderly individuals (121 male and 229 female, average age 72.4 years) who resided in the rural community of Sefuri Village, Saga, Japan. The mini mental state examination and modified Stroop test (MST) were used to identify cognitive impairment. White matter lesions (WMLs) and cerebral atrophy on magnetic resonance imaging were measured quantitatively. Multivariate analyses were done using a logistic regression model with a software package. Cognitive impairment defined by mini mental state examination score less than 24 was present in 55 individuals (15.7%). They had a lower educational level, significantly larger quantity of WMLs, and more remarkable cerebral atrophy. Frontal lobe dysfunction was detected in 52 individuals (14.9%) through prolonged MST score (>36 seconds). Impaired frontal lobe function was related to number of silent lacunar infarcts, larger WMLs, and more prominent cerebral atrophy. MST score in individuals with two or more infarcts was significantly more prolonged compared with MST score in those without infarction. These results suggest that WMLs may cause rather diffuse cognitive decline, whereas multiple lacunar infarcts are specifically involved in frontal lobe dysfunction. Silent ischemic lesions in apparently healthy elderly individuals seem to form a distinctive group of people with vascular cognitive impairment without dementia. This group should be the primary target of prevention of vascular dementia.

Subcortical ischemic vascular disease and cognition: A systematic review

Subcortical Ischemic Vascular Disease (SIVD) is underdiagnosed. This review investigates the relationship among SIVD severity, cognitive status and neuroimaging markers.

Cognitive function after carotid endarterectomy: greater risk of decline in symptomatic patients with left internal carotid artery disease

BACKGROUND

The risk of cognitive decline in patients undergoing carotid endarterectomy (CE) for left internal carotid artery (ICA) (LICA) disease before or after the occurrence of ischemic symptoms has not been fully elucidated. We evaluated whether patients undergoing CE for symptomatic LICA stenosis have greater risk of cognitive decline than patients with asymptomatic LICA disease or right ICA disease.

METHODS

In a series of patients aged 65 years and older, consecutively undergoing CE and free from cognitive impairment, cognitive function was evaluated through the age- and education-adjusted Mini Mental State Examination and the Clock Drawing Task at baseline and at the end of the study period (average follow-up: 44.4 +/- 14.3 months).

RESULTS

The analysis included 103 patients (mean age 72.6 +/- 7.0 years; 73 men), of whom 50 had LICA disease (29 symptomatic). At the end of the study period, Mini Mental State Examination score was reduced in patients with symptomatic LICA disease (P < .001) but not in other patients, whereas the Clock Drawing Task score was reduced in both patients with LICA and right ICA. Patients with symptomatic LICA disease had greater risk of cognitive decline than other individuals, either measured by the Mini Mental State Examination score (F = 5.18, P = .002) or by the Clock Drawing Task score (F = 9.42, P = .001).

CONCLUSIONS

Patients undergoing CE for symptomatic LICA disease appear to be at increased risk of cognitive decline than other individuals. Further studies are needed to confirm these findings and to evaluate whether LICA endarterectomy before occurrence of cerebrovascular ischemic symptoms may provide additive benefit in the prevention of cognitive decline.

Japanese version of the Frontal Assessment Battery for dementia

The Frontal Assessment Battery (FAB) was developed as a short bedside cognitive and behavioral battery to assess frontal lobe functions. The purpose of this study was to evaluate the validity and reliability of a Japanese version of the FAB to measure cognitive dysfunction in patients with dementia. We studied 25 normal subjects and 105 patients with Alzheimer's disease, n=58, vascular dementia, n=24, and frontotemporal dementia, n=23. The neuropsychological test battery included the FAB, the Mini Mental State Examination (MMSE), a memory test, and the Wisconsin Card Sorting Test (Keio version: KWCST). Patients with dementia performed significantly more poorly than controls on all tests. The FAB showed a good correlation with other cognitive measures: MMSE (r=0.725), KWCST number of categories completed (r=0.654), KWCST number of perseveration errors (r=-0.484), and memory test (r=0.643). Patients with more severe Clinical Dementia Rating scores showed lower scores on the FAB. There was good inter-rater reliability (r=0.972), test-retest reliability (r=0.769), and internal consistency (Cronbach's coefficient alpha=0.715). The FAB is a valid and reliable screening test to evaluate cognitive dysfunction among patients with dementia.

The enigma of vascular cognitive disorder and vascular dementia

The prevalence, morphology and pathogenesis of vascular dementia (VaD), recently termed vascular cognitive impairment, are a matter of discussion, and currently used clinical diagnostic criteria show moderate sensitivity (average 50%) and variable specificity (range 64-98%). In Western clinic-based series, VaD is suggested in 8-10% of cognitively impaired aged subjects. Its prevalence in autopsy series varies from 0.03 to 58%, with reasonable values of 8-15%, while in Japan it is seen in 22-35%. Neuropathologic changes associated with cognitive impairment include multifocal and/or diffuse disease and focal lesions: multi-infarct encephalopathy, white matter lesions or arteriosclerotic subcortical (leuko)encephalopathy, multilacunar state, mixed cortico-subcortical type, borderline/watershed lesions, rare granular cortical atrophy, post-ischemic encephalopathy and hippocampal sclerosis. They result from systemic, cardiac and local large or small vessel disease. Recent data indicate that cognitive decline is commonly associated with widespread small ischemic/vascular lesions (microinfarcts, lacunes) throughout the brain with predominant involvement of subcortical and functionally important brain areas. Their pathogenesis is multifactorial, and their pathophysiology affects neuronal networks involved in cognition, memory, behavior and executive functioning. Vascular lesions often coexist with Alzheimer disease (AD) and other pathologies. Minor cerebrovascular lesions, except for severe amyloid angiopathy, appear not essential for cognitive decline in full-blown AD, while both mild Alzheimer pathology and small vessel disease may interact synergistically. The lesion pattern of "pure" VaD, related to arteriosclerosis and microangiopathies, differs from that in mixed-type dementia (AD with vascular encephalopathy), more often showing large infarcts, which suggests different pathogenesis of both types of lesions. Due to the high variability of cerebrovascular pathology and its causative factors, no validated neuropathologic criteria for VaD are available, and a large variability across laboratories still exists in the procedures for morphologic examination and histology techniques.

White matter hyperintensities and cortical acetylcholinesterase activity in parkinsonian dementia

OBJECTIVE

To investigate the relationship between the severity of white matter hyperintensities (WMH) and cortical acetylcholinesterase (AChE) activity in parkinsonian dementia (PDem).

METHODS

PDem (n = 11) and control subjects (n = 14) underwent [11C]methyl-4-piperidinyl propionate (11C-PMP) AChE brain positron emission tomography and magnetic resonance (MR) imaging. Presence of WMH on proton density and T2 MR images was scored using a modified version of the semi-quantitative rating scale by Scheltens et al. [J Neurol Sci114 (1993)].

RESULTS

Analysis demonstrated significantly lower mean cortical (11)C-PMP k3 hydrolysis rates in PDem (-19.9%) when compared with control subjects (P < 0.0001). PDem subjects had higher mean severity of WMH (+20.1%) when compared with control subjects (P < 0.05). When WMH severity was entered into the analysis of variance model, there was no significant co-variate effect on cortical AChE activity (F = 0.24, ns).

CONCLUSIONS

The concomitant presence of mild to moderate WMH in patients with PDem does not have a significant effect on cortical AChE activity.

Determinants of prestroke cognitive impairment in stroke associated with small vessel disease

Understanding the determinants of prestroke cognitive impairment (PCI) in stroke associated with small vessel disease (SVD) may shed light on how to prevent further cognitive deterioration after stroke. We administered the Informant Questionnaire on Cognitive Decline (IQCODE) to close informants of 78 consecutive stroke patients who had SVD. PCI, as defined by an average score of IQCODE > or =3.4 was found in 19 (24%) patients. Regression analyses were performed on the following risk factors for PCI: age, years of education, gender, previous stroke, volume of white matter changes, measures of silent lacunes, cerebral atrophy index, medial temporal lobe atrophy and frontal lobe atrophy. Multivariate regression analyses revealed that only cerebral atrophy index (OR 1.5, CI 1.2-1.9, p < 0.001) predicted PCI among patients with SVD.

Cerebral small-vessel disease and decline in information processing speed, executive function and memory

Cerebral small-vessel disease is common in older people and may contribute to the development of dementia. The objective of the present study was to evaluate the relationship between measures of cerebral small-vessel disease on MRI and the rate of decline in specific cognitive domains in participants from the prospective, population-based Rotterdam Scan Study. Participants were 60-90 years of age and free from dementia at baseline in 1995-1996. White matter lesions (WML), cerebral infarcts and generalized brain atrophy were assessed on the baseline MRI. We performed neuropsychological testing at baseline and repeatedly in 1999-2000 and in 2001-2003. We used random-effects models for repeated measures to examine the association between quantitative MRI measures and rate of decline in measures of global cognitive function, information processing speed, executive function and memory. There were a total of 2266 assessments for the 832 participants in the study, with an average time from the initial to last assessment of 5.2 years. Increasing severity of periventricular WML and generalized brain atrophy and the presence of brain infarcts on MRI were associated with a steeper decline in cognitive function. These structural brain changes were specifically associated with decline in information processing speed and executive function. The associations between MRI measures of cerebral small-vessel disease and cognitive decline did not change after additional adjustment for vascular risk factors or depressed mood. After exclusion of participants with an incident stroke, some of the associations of periventricular WML, brain infarcts and generalized brain atrophy with measures of information processing speed and executive function were no longer significant. This may indicate that stroke plays an intermediate role in the relationship between cerebral small-vessel disease and cognitive decline. Our results suggest that in older people cerebral small-vessel disease may contribute to cognitive decline by affecting information processing speed and executive function.

Hypertension and dementia: does blood pressure control favorably affect cognition?

Dementia and aging are not synonymous. Dementia is a progressive deterioration in cognitive and social and/or occupational functions that can eventually impair a patient's ability to live independently. Alzheimer's disease is the most common form of dementia. It accounts for 50% to 70% of all patients with dementia. Vascular dementia, responsible for up to 15% of all diagnosed cases, is the second most common form of dementia. Hypertension remains a significant risk factor for vascular dementia. The optimal level of blood pressure control for the prevention of dementia and whether one particular class of antihypertensive drug is more beneficial than another remains uncertain.

White matter lesions impair frontal lobe function regardless of their location

OBJECTIVE

To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function.

METHODS

Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high-resolution three-dimensional T1-weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function.

RESULTS

WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlated with WMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects.

CONCLUSIONS

The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and executive dysfunction.

Vascular factors in dementia: an overview

Alzheimer's disease and cerebrovascular disease are two illnesses common to the elderly. Conventional wisdom has sought to separately describe and treat these two diseases. Accumulating evidence, however, shows that cerebrovascular risk factors may cause asymptomatic brain injury, share genetic risk with Alzheimer's disease and possibly accelerate the Alzheimer's process. Such evidence suggests that these two diseases may act additively or synergistically to cause clinical dementia. This review focuses on evolving data that support this hypothesis.

Cognitive impairment and functional outcome after stroke associated with small vessel disease

OBJECTIVES

Although stroke associated with small vessel disease (SSVD) can induce both motor and cognitive impairment, the latter has received less attention. We aimed to evaluate the frequency of the varying severity levels of cognitive impairment, the determinants of severe cognitive impairment, and the association of cognitive impairment with functional outcome after SSVD.

METHODS

Consecutive patients admitted to hospital because of SSVD were assessed at 3 months after stroke. We performed a semi-structured clinical interview to screen for cognitive symptoms. Severity of cognitive symptoms was graded according to the Clinical Dementia Rating Scale (CDR). Performance on psychometric tests (Mini-Mental State Examination, Alzheimer's Disease Assessment Scale (cognition subscale), Mattis Dementia Rating Scale (initiation/perseverence subscale; MDRS I/P)) of patients of different CDR gradings was compared with that of 42 healthy controls. Basic demographic data, vascular risk factors, stroke severity (National Institute of Health Stroke Scale; NIHSS), pre-stroke cognitive decline (Informant Questionnaire on Cognitive Decline in the Elderly; IQCODE), functional outcome (Barthel index; BI), Instrumental Activities Of Daily Living; IADL), and neuroimaging features (site of recent small infarcts, number of silent small infarcts, white matter changes) were also compared among the groups. Regression analyses were performed to find predictors of severe cognitive impairment and poor functional outcome.

RESULTS

Among the 75 included patients, 39 (52%) complained of cognitive symptoms. The number of patients in each CDR grading was as follows: 39 (52%) had a CDR of 0, 26 (34.7%) had a CDR of 0.5, 10 (13.3%) had a CDR of > or =1. Pre-stroke IQCODE and previous stroke predicted CDR> or =1. The NIHSS was associated with more impaired BI. The NIHSS and MDRS I/P contributed most to impaired IADL.

CONCLUSIONS

Half of the patients with SSVD complained of varying severity of cognitive problems 3 months after stroke. Pre-stroke cognitive decline and previous stroke predict severe cognitive impairment post stroke. Stroke severity and executive dysfunction contribute most to a poor functional outcome.

Clinical features of MRI-defined subcortical vascular disease

BACKGROUND AND PURPOSE

Vascular cognitive impairment and vascular dementia are now seen to extend much beyond the traditional multi-infarct dementia.A more homogeneous subtype is the subcortical ischemic vascular disease (SIVD). We applied magnetic resonance imaging (MRI) criteria based on research criteria for SIVD in a large cohort of patients with ischemic stroke. We compared clinical features of patients with SIVD and patients with other stroke type.

SUBJECT AND METHODS

The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischemic stroke completed a comprehensive neuropsychological test battery and MRI, including structured medical, neurologic, and laboratory evaluations; clinical mental status examination; interview of a knowledgeable informant; detailed history of risk factors; and evaluation of stroke type, localization, and syndrome.

RESULTS

Patients with SIVD (n = 86) more often had a history of progressive cognitive decline (22.8% vs. 6.9%, P = 0.0002), walking disorder before stroke (27.9% vs. 2.0%, P = 0.02), and urinary difficulties (12.8% vs. 5.6%, P = 0.028) in comparison with patients with other stroke type (n = 251). Of the study population, 107 (31.8%) had DSM-III dementia. The patients with SIVD more often had DSM-III dementia (40.7% vs. 28.7%, P = 0.04), had less severe stroke as measured by Scandinavian Stroke Scale (56.6 vs. 55.1, P = 0.03), were more dependent in activities of daily living (ADL) functions as measured by FAQ scale (8.9 vs. 5.4, P = 0.001), were more dependent in instrumental activities of daily living (IADL) functions as measured by the Lawton scale (5.5 vs. 6.3, P = 0.01), and were more depressed as measured by the Beck Depression Inventory (11.8 vs. 8.4, P = 0.0003) poststroke than the patients without SIVD. The main cognitive domain that differentiated the patients with SIVD from those without was executive dysfunction (51.2% vs. 38.7%, P = 0.04). According to multiple regression model, apractic-atactic gait disorder (odds ratio 2.82, 95% confidence interval 1.21-6.53), ADL functions (odds ratio 1.04, 95% confidence interval 1.01-1.08), and the Beck Depression Inventory (odds ratio 1.05, 95% confidence interval 1.02-1.09) related to SIVD.

CONCLUSIONS

The most significant clinical features of MRI-defined SIVD were found to be apractic-atactic gait, impaired ADL functions, and depression.

MRI correlates of executive dysfunction in patients with ischaemic stroke

Executive dysfunction (ED) may lead to problem behaviour and impaired activities of daily living in many neuropsychiatric disorders, but the neuroanatomical correlates of ED are still not well known. Different aspects of executive functions were studied by widely used neuropsychological tests in 214 elderly patients 3 months after ischaemic stroke, and a sum score of eight different measures was counted in each patient. The number and site of brain infarcts as well as severity and location of white matter lesions (WMLs) and brain atrophy on magnetic resonance imaging were recorded and compared between patients with and without ED. ED was present in 73 (34.1%) of the 214 patients. The mean frequency of brain infarcts in the brain and in the left hemisphere was higher in the patients with ED. Lesions affecting the frontal-subcortical circuits (e.g. pallidum, corona radiata or centrum semiovale) were more frequent in patients with ED than in those without. Also, patients with pontine brain infarcts frequently had ED, but this may have been due to more extensive ischaemic changes in these patients in general. Mean number of brain infarcts affecting the pons and posterior centrum semiovale on the left side, moderate to severe medial temporal atrophy, the Fazekas white matter score, the Mini-Mental State Examination score and low education were independent correlates of ED. Brain infarcts and WML affecting the frontal-subcortical circuits or the pons may increase risk for ED in stroke patients.

The Validity and Reliability of Chinese Frontal Assessment Battery in Evaluating Executive Dysfunction Among Chinese Patients With Small Subcortical Infarct

OBJECTIVES

Frontal Assessment Battery (FAB) is a valid and reliable screening test for evaluating executive dysfunction among whites with frontal and subcortical degenerative lesions. We studied the properties of a Chinese version of FAB (CFAB) in evaluating executive dysfunction among Chinese stroke patients with small subcortical infarct.

METHODS

Concurrent validity was evaluated using Wisconsin Card Sorting Tst (WCST) and Mattis Dementia Rating Scale-Initiation/Perseveration Subset (MDRS I/P) among 41 controls and 30 stroke patients with small subcortical infarct. Discriminant validities of CFAB and its subitems were compared with those of Mini-Mental State Examination (MMSE). Internal consistency, test-retest, and interrater reliability of CFAB were evaluated.

RESULTS

The CFAB had low to good correlation with various executive measures: MDRS I/P (r = 0.63, p < 0.001), number of category completed (r = 0.45, p < 0.001), and number of perseverative errors (r = -0.37, p < 0.01) of WCST. Among the executive measures, only number of category completed had significant but small contribution (6.5%, p = 0.001) to the variance of CFAB. A short version of CFAB using three items yielded higher overall classification accuracy (86.6%) than that of CFAB full version (80.6%) and MMSE (77.6%). Internal consistency (alpha = 0.77), test-retest reliability (rho = 0.89, p < 0.001), and interrater reliability (rho = 0.85, p < 0.001) of CFAB were good.

CONCLUSION

Although CFAB is reliable, it is only moderately valid in evaluating executive dysfunction among Chinese stroke patients with small subcortical infarct. The clinical use of CFAB in the evaluation of executive dysfunction among this group of patients cannot be recommended at this stage.