Genetics of Vascular Cognitive Impairment

Chronic cerebral hypoperfusion: a critical feature in unravelling the etiology of vascular cognitive impairment

Vascular cognitive impairment (VCI) describes a wide spectrum of cognitive deficits related to cerebrovascular diseases. Although the loss of blood flow to cortical regions critically involved in cognitive processes must feature as the main driver of VCI, the underlying mechanisms and interactions with related disease processes remain to be fully elucidated. Recent clinical studies of cerebral blood flow measurements have supported the role of chronic cerebral hypoperfusion (CCH) as a major driver of the vascular pathology and clinical manifestations of VCI. Here we review the pathophysiological mechanisms as well as neuropathological changes of CCH. Potential interventional strategies for VCI are also reviewed. A deeper understanding of how CCH can lead to accumulation of VCI-associated pathology could potentially pave the way for early detection and development of disease-modifying therapies, thus allowing preventive interventions instead of symptomatic treatments.

Cross-sectional and prospective inter-relationships between depressive symptoms, vascular disease and cognition in older adults

BACKGROUND

It has been proposed that vascular disease is the mechanism linking depression and cognition, but prospective studies have not supported this hypothesis. This study aims to investigate the inter-relationships between depressive symptoms, cognition and cerebrovascular disease using a well-characterised prospective cohort.

METHOD

Data came from waves 1 (2005-2007) and 2 (2007-2009) of the Sydney Memory and Ageing Study (n = 462; mean age = 78.3 years).

RESULTS

At wave 1, there was an association between depressive symptoms and white matter hyperintensity (WMH) volume [b = 0.016, t(414) = 2.34, p = 0.020]. Both depressive symptoms [b = -0.058, t(413) = -2.64, p = 0.009] and WMH volume [b = -0.011, t(413) = -3.77, p < 0.001], but not stroke/transient ischaemic attack (TIA) [b = -0.328, t(413) = -1.90, p = 0.058], were independently associated with lower cognition. Prospectively, cerebrovascular disease was not found to predict increasing depressive symptoms [stroke/TIA: b = -0.349, t(374.7) = -0.76, p = 0.448; WMH volume: b = 0.007, t(376.3) = 0.875, p = 0.382]. Depressive symptoms predicted increasing WMH severity [b = 0.012, t(265.9) = -3.291, p = 0.001], but not incident stroke/TIA (odds ratio = 0.995; CI 0.949-1.043; p = 0.820). When examined in separate models, depressive symptoms [b = -0.027, t(373.5) = -2.16, p = 0.032] and a history of stroke/TIA [b = -0.460, t(361.2) = -4.45, p < 0.001], but not WMH volume [b = 0.001, t(362.3) = -0.520, p = 0.603], predicted declines in cognition. When investigated in a combined model, a history of stroke/TIA remained a predictor of cognitive decline [b = -0.443, t(360.6) = -4.28, p < 0.001], whilst depressive symptoms did not [b = -0.012, t(359.7) = -0.96, p = 0.336].

CONCLUSIONS

This study is contrasted with previous prospective studies which indicate that depressive symptoms predict cognitive decline independently of vascular disease. Future research should focus on further exploring the vascular mechanisms underpinning the relationship between depressive symptoms and cognition.

Adrenomedullin, a Novel Target for Neurodegenerative Diseases

Neurodegenerative diseases represent a heterogeneous group of disorders whose common characteristic is the progressive degeneration of neuronal structure and function. Although much knowledge has been accumulated on the pathophysiology of neurodegenerative diseases over the years, more efforts are needed to understand the processes that underlie these diseases and hence to propose new treatments. Adrenomedullin (AM) is a multifunctional peptide involved in vasodilation, hormone secretion, antimicrobial defense, cellular growth, and angiogenesis. In neurons, AM and related peptides are associated with some structural and functional cytoskeletal proteins that interfere with microtubule dynamics. Furthermore, AM may intervene in neuronal dysfunction through other mechanisms such as immune and inflammatory response, apoptosis, or calcium dyshomeostasis. Alterations in AM expression have been described in neurodegenerative processes such as Alzheimer's disease or vascular dementia. This review addresses the current state of knowledge on AM and its possible implication in neurodegenerative diseases.

Effect of mesenchymal stem cells and galantamine nanoparticles in rat model of Alzheimer's disease

AIM

The present study investigated the efficacy of bone marrow-derived mesenchymal stem cells (BM-MSCs) in combination with galantamine hydrobromide-loaded solid lipid nanoparticles (GH-SLNs) in intracerebroventricular (ICV)-isoproterenol-induced rat model of Alzheimer's disease.

MATERIALS & METHODS

BM-MSCs were harvested by dissecting femur and tibia of 8-10-week-old Wistar rats. 1 × 10(6) cells were administered intravenously once in ICV-isoproterenol-induced rats followed by GH-SLNs (5 mg/kg) for 3 weeks.

RESULTS & CONCLUSION

ICV-isoproterenol resulted in significant memory deficit. The results demonstrated rapid regain of memory in isoproterenol-induced amnesic rats, following single intravenous administration of BM-MSCs and oral administration of GH-SLNs for 21 days. The combination of BM-MSCs and GH-SLNs produced a more pronounced protective effect, therefore, could be explored for the management of Alzheimer's disease.

Genetic susceptibility to vascular cognitive impairment: a pathophysiological view

The heterogeneity of the vascular cognitive impairment (VCI) creates challenges for research on its genetic basis and pathophysiology. Despite well-known monogenic forms may be useful to understand some pathogenic mechanisms leading to VCI, most of VCIs are sporadic disorders resulting from the interaction between environmental, vascular and genetic factors. Genetic investigation for VCI may encompass both candidate genes that affect critical biological processes to VCI and common and rare genetic variants identified across the entire genome study technology, thereby enabling us to confirm or expose new biological mechanisms in VCI and develop new therapeutic and preventive approaches. Notwithstanding genetic susceptibility to VCI remains largely unknown owing to methodological issues. Collaborative efforts emerge as an interesting strategy to overcome these problems.

Brain health and shared risk factors for dementia and stroke

Impaired brain health encompasses a range of clinical outcomes, including stroke, dementia, vascular cognitive impairment, cognitive ageing, and vascular functional impairment. Conditions associated with poor brain health represent leading causes of global morbidity and mortality, with projected increases in public health burden as the population ages. Many vascular risk factors are shared predictors for poor brain health. Moreover, subclinical brain MRI markers of vascular damage are risk factors shared between stroke and dementia, and can be used for risk stratification and early intervention. The broad concept of brain health has resulted in a conceptual shift from vascular risk factors to determinants of brain health. Global campaigns to reduce cardiovascular diseases by targeting modifiable risk factors are necessary and will have a broad impact on brain health. Research is needed on the distinct and overlapping aetiologies of brain health conditions, and to define MRI markers to help clinicians identify patients who will benefit from aggressive prevention measures.

Age-Related Cognitive Impairment as a Sign of Geriatric Neurocardiovascular Interactions: May Polyphenols Play a Protective Role?

It is known that endothelial dysfunction plays an important role in the development and progression of cardiovascular diseases implicated also in cognitive decline. Experimental studies pointed to the fact that the modification of NO levels via NOS activity may affect the blood pressure level as well as several higher nervous functions—for example, learning and memory. There are emerging evidences from in vitro and animal studies suggesting that polyphenols may potentially have a protective effect on the development of neurodegenerative diseases and may improve cognitive function as well as positively affecting the blood pressure regulatory mechanisms. This review accentuates the need for precisely defined clinically controlled studies as well as for use of adequate experimental procedures discriminating between the human higher brain functions and the only overall activation of the brain cortex. The physiological neurocardiovascular interactions are implicated in the increased healthy life span as well.

Genetic markers in biological fluids for aging-related major neurocognitive disorder

Aging-related major neurocognitive disorder (NCD), formerly named dementia, comprises of the different acquired diseases whose primary deficit is impairment in cognitive functions such as complex attention, executive function, learning and memory, language, perceptual/motor skills, and social cognition, and that are related to specific brain regions and/or networks. According to its etiology, the most common subtypes of major NCDs are due to Alzheimer' s disease (AD), vascular disease (VaD), Lewy body disease (LBD), and frontotemporal lobar degeneration (FTLD). These pathologies are frequently present in mixed forms, i.e., AD plus VaD or AD plus LBD, thus diagnosed as due to multiple etiologies. In this paper, the definitions, criteria, pathologies, subtypes and genetic markers for the most common age-related major NCD subtypes are summarized. The current diagnostic criteria consider cognitive decline leading to major NCD or dementia as a progressive degenerative process with an underlying neuropathology that begins before the manifestation of symptoms. Biomarkers associated with this asymptomatic phase are being developed as accurate risk factor and biomarker assessments are fundamental to provide timely treatment since no treatments to prevent or cure NCD yet exist. Biological fluid assessment represents a safer, cheaper and less invasive method compared to contrast imaging studies to predict NCD appearance. Genetic factors particularly have a key role not only in predicting development of the disease but also the age of onset as well as the presentation of comorbidities that may contribute to the disease pathology and trigger synergistic mechanisms which may, in turn, accelerate the neurodegenerative process and its resultant behavioral and functional disorders.

Vascular cognitive impairment

PURPOSE OF REVIEW

Clinically apparent and subclinical forms of vascular disease including stroke are important causes of cognitive dysfunction. In this review, we will describe the current nomenclature for vascular cognitive impairment (VCI) from the histopathological and clinical perspectives to raise awareness among practitioners about the interaction between conventional and novel vascular risk factors and VCI, with an emphasis on the prevention and risk factor modification.

RECENT FINDINGS

There is substantial evidence from observational studies and clinical trials that conventional risk factors such as hypertension, diabetes, dyslipidemia, smoking, and atrial fibrillation play a role in the development of VCI. Additional novel risk factors such as the metabolic syndrome have been associated with cognitive dysfunction as well. Targeting these risk factors will minimize the burden of VCI in our aging population.

SUMMARY

The concept of VCI has evolved to describe a continuum of cognitive disorders in which vascular brain injury plays a role, ranging from mild cognitive impairment to dementia. Future research is needed to clarify the role of risk factor modification in limiting vascular brain injury to prevent VCI and progression to dementia.

Pathology and pathogenesis of vascular cognitive impairment-a critical update

Vascular cognitive impairment (VCI) [vascular cognitive disorder (VCD), vascular dementia] describes a continuum of cognitive disorders ranging from mild cognitive impairment (MCI) to dementia, in which vascular brain injury involving regions important for memory, cognition and behavior plays an important role. Clinical diagnostic criteria show moderate sensitivity (ca 50%) and variable specificity (range 64-98%). In Western clinical series, VaD is suggested in 8-10% of cognitively impaired elderly subjects. Its prevalence in autopsy series varies from 0.03 to 58%, with means of 8 to 15% (in Japan 22-35%). Major types of sporadic VaD are multi-infarct encephalopathy, small vessel and strategic infarct type dementias, subcortical arteriosclerotic leukoencephalopathy (SAE) (Binswanger), multilacunar state, mixed cortico-subcortical type, granular cortical atrophy (rare), postischemic encephalopathy, and a mixture of cerebrovascular lesions (CVLs). They result from systemic, cardiac and local large or small vessel disease (SVD); their pathogenesis is multifactorial. Hereditary forms of VaD caused by gene mutations are rare. Cognitive decline is commonly associated with widespread small ischemic vascular lesions involving subcortical brain areas (basal ganglia and hemispheral white matter). The lesions affect neuronal networks involved in cognition, memory, and behavior (thalamo-cortical, striato-subfrontal, cortico-subcortical, limbic systems). CVLs often coexist with Alzheimer-type lesions and other pathologies; 25-80% of elderly demented show mixed pathologies. The lesion pattern of "pure" VaD differs from that in mixed dementia (AD + CVLs) suggesting different pathogenesis of both phenotypes. Minor CVLs, except for severe amyloid angiopathy, appear not essential for cognitive impairment in full-blown AD, while both mild AD-type pathology and SVD may interact synergistically in promoting dementia. However, in a large percentage of non-demented elderly individuals, both AD-related and vascular brain pathologies have been reported. Despite recent suggestions for staging and grading CVLs in specific brain areas, due to the high variability of CVLs associated with cognitive impairment, no validated neuropathological criteria are currently available for VaD and mixed dementia. Further clinico-pathological studies and harmonization of neuropathological procedures are needed to validate the diagnostic criteria for VaD and mixed dementia in order to clarify the impact of CVLs and other coexistent pathologies on cognitive impairment as a basis for further successful therapeutic options.

Intelligence Impairment, Personality Features and Psychopathology Disturbances in a Family Affected with CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a small-vessel disease of the brain that is characterized by headache, recurring lacunar strokes, mood changes and progressive cognitive deterioration. The disease is transmitted with an autosomal dominant pattern and usually starts during midadulthood (at 30–50 years of age). Cognitive deficits in patients with CADASIL develop slowly. The dementia causes frontal-like symptoms and it typically develops after a history of recurrent stroke. We describe three patients from one Spanish family affected by this disease. All three cases underwent comprehensive clinical and neuropsychological examination, and were monitored for seven years. The results obtained in this study describe a) a significant loss of the intelligence quotient (IQ) and noticeable damage to abstract ability (g factor), b) mood and psychopathological disturbances (major depression and dysthymia), and c) a personality with neurotic features.

Vascular dementia

The epidemic growth of dementia causes great concern for the society. It is customary to consider Alzheimer's disease (AD) as the most common cause of dementia, followed by vascular dementia (VaD). This dichotomous view of a neurodegenerative disease as opposed to brain damage caused by extrinsic factors led to separate lines of research in these two entities. Indeed, accumulated data suggest that the two disorders have additive effects and probably interact; however it is still unknown to what degree. Furthermore, epidemiological studies have shown "vascular" risk factors to be associated with AD. Therefore, a clear distinction between AD and VaD cannot be made in most cases, and is furthermore unhelpful. In the absence of efficacious treatment for the neurodegenerative process, special attention must be given to the vascular component, even in patients with presumed mixed pathology. Symptomatic treatment of VaD and AD is similar, although the former is less effective. For prevention of dementia it is important to treat all factors aggressively, even in stroke survivors who do not show evidence of cognitive decline. In this review, we will give a clinical and pathological picture of the processes leading to VaD and discuss its interaction with AD.

Cardiac output, blood pressure variability, and cognitive decline in geriatric cardiac patients

OBJECTIVE

To prospectively investigate whether baseline findings on specific cardiovascular indices are predictive of subsequent rate of decline in Attention-Executive-Psychomotor function in a cohort of ambulatory older adults with cardiovascular diseases (CVDs).

METHODS

One hundred seventy-two older adults with CVD were administered a neuropsychological battery of executive functions tests at study entry, and at 12 and 36 months thereafter. At study entry, they also underwent vascular assessments including cardiac output, ejection fraction, blood pressure (BP), brachial artery reactivity, and carotid intima media thickness. Random coefficient regressions were used to investigate the effect of these cardiac indices on rate of decline in Attention-Executive-Psychomotor function.

RESULTS

Cardiac output, systolic BP variability, and diastolic BP variability predicted decline in Attention-Executive-Psychomotor function. Specifically, lower cardiac output, reduced variability in systolic BP, and increased variability in diastolic BP were associated with a faster rate of decline in Attention-Executive-Psychomotor function. Mean resting systolic and diastolic blood pressure did not predict decline in Attention-Executive-Psychomotor function.

CONCLUSIONS

Decline in frontal-subcortical cognitive functions among patients with CVDs appears to be mediated by systemic hypoperfusion and variability in blood pressure. The precise nature of these relationships, especially with regard to blood pressure variability, is complex and demands continued investigation.

Cognitive reserve moderates the association between heart failure and cognitive impairment

BACKGROUND

Cognitive impairment in persons with heart failure is common. Theories of cognitive reserve suggest that premorbid factors, such as intellectual ability, may provide a buffer against cognitive impairment due to neuropathological insult. No study has examined the influence of cognitive reserve on cognitive functioning in older adults with heart failure.

AIM

This study examined whether cognitive reserve moderates the relationship between heart failure severity and cognitive function.

METHODS

A total of 157 persons with heart failure (69.26 ± 9.26 years; 39% female) completed neuropsychological testing and a brief fitness assessment. Cognitive reserve was operationalized using estimated premorbid intellect on the American National Adult Reading Test (AMNART).

RESULTS

A moderation analysis was performed using hierarchical regression models for each cognitive domain. An interaction term between the AMNART and 2-Minute Step Test was created and entered into the final block of the model, with demographic, psychosocial, and heart failure severity entered in the previous blocks. The interaction term was significant for attention, t(155) = -2.54, p = .012, executive function, t(155) = -3.30, p = .001, and language, t(155) = -2.83, p = .005, domains.

CONCLUSION

The current findings suggest that cognitive reserve moderates the association between heart failure severity and cognitive function in multiple cognitive domains. Further work is needed to clarify the mechanisms by which cognitive reserve attenuates cognitive impairment in this population.

Frontal subcortical ischemia is crucial for post stroke cognitive impairment

BACKGROUND

The incidence of post stroke cognitive impairment (PSCI) and predictive factors for PSCI among patients with acute lacunar infarcts is unclear.

OBJECTIVE

To study the impact of acute lacunar infarcts and chronic white matter disease in the development of PSCI.

METHODS

Prospective cohort study of stroke patients attending a tertiary neurology center. Patients with MRI confirmed acute lacunar infarcts without pre-existing dementia were recruited. Logistic regression was used to determine risk factors for developing PSCI.

RESULTS

145 patients with a mean age of 55.8 years were studied of which 48 patients (33.1%) were identified to have PSCI. Patients with PSCI performed worse on the MMSE, MOCA and FAB and had significantly greater white matter hyperintensity (WMH) in the frontal subcortical (FSC) region (p = 0.006) and higher frontal subcortical acute infarct load (p = 0.002). Logistic regression demonstrated that deep subcortical WMH (odds ratio, OR = 1.45) and acute FSC infarcts (OR = 1.51) were associated with PSCI. High WMH load without acute FSC infarcts was associated with increased risk of PSCI (OR = 4.1). When patients developed acute FSC infarcts on pre-existing severe WMH, the risk of PSCI increased substantially (OR = 11.0).

CONCLUSIONS

Patients with acute lacunar infarcts in the FSC region have 1.5 times risk of PSCI. This risk increases substantially to 11 times when there is pre-existing severe white matter disease.

Vascular cognitive impairment: disease mechanisms and therapeutic implications

The prevalence of vascular cognitive impairment (VCI) is likely to increase as the population ages and cardiovascular disease survival improves. We provide an overview of the definition and disease mechanisms of VCI and present a systematic literature review of the current evidence for the pharmacologic and nonpharmacologic therapies used to treat the VCI symptoms of cognitive dysfunction or to modify VCI through primary and secondary prevention. The Cochrane Database of Systematic Reviews was searched from 2005 to October 2010 using the keywords "vascular dementia" or "vascular cognitive impairment and therapy." MEDLINE was searched for English-language articles published within the last 10 years using the combined Medical Subject Headings (MeSH) "therapeutics and dementia," "vascular" or "vascular cognitive impairment." Although cholinesterase inhibitors and memantine produce small cognitive improvements in patients with VCI, these drugs do not improve global clinical outcomes and have adverse effects and costs. Selective serotonin reuptake inhibitors and dihydropyridine calcium channel blockers may improve short-term cognitive function in patients with VCI. Anti-hypertensive therapy with an ACE inhibitor-based regimen and statins may prevent the major subtype of VCI known as poststroke cognitive decline. Clinical and effectiveness studies with long-term follow-up are needed to determine the benefits and risks of pharmacologic and nonpharmacologic therapies to prevent and treat VCI. Given its growing health, social, and economic burden, the prevention and treatment of VCI are critical priorities for clinical care and research.

Longitudinal trajectories of cognitive decline among older adults with cardiovascular disease

BACKGROUND

The long-term course of cognitive impairments secondary to cardiovascular disease (CVD) is unclear. In this study, we prospectively investigated the temporal pattern, rate and hierarchy of cognitive decline attributable to CVD--a risk factor for the development of vascular cognitive impairment (VCI)--and examined the influence of cardiac surgery and heart failure on cognitive decline.

METHODS

A total of 172 older adults with CVD were administered a comprehensive battery of neuropsychological tests at study entry, and at 12 and 36 months thereafter. Random coefficient regressions were used to investigate the temporal course, rate and hierarchy of cognitive decline, as well as to examine the effect of heart failure (reported by 21% of the sample) and cardiac surgery (reported by 44% of the sample) on trajectories of cognitive change.

RESULTS

The course of decline in cognition was linear for language and attention-executive function-psychomotor speed, and curvilinear for visuospatial abilities, memory and overall cognition. The decline in attention-executive function-psychomotor speed was smaller than the decline in other domains. The greatest decline occurred in visuospatial abilities. The rate of decline in cognition was not altered by a history of heart failure. Patients who had undergone cardiac surgery exhibited slower deceleration in their rates of decline in overall cognition. At baseline, patients with a history of heart failure had comparatively poorer attention-executive function-psychomotor speed, overall cognition and, to a lesser extent, visuospatial scores.

CONCLUSION

There is measurable decline in neurocognitive function among patients with CVD. This decline is linear in some cognitive domains and curvilinear in others and is not attributable to the normal aging process. Cardiac surgery, but not heart failure, significantly affects the trajectory of cognitive decline. Because most vascular risk factors are modifiable, preventive measures such as lifestyle changes may be useful in retarding cognitive decline among patients with CVD, thus preventing the onset of VCI.

Pathophysiology of vascular dementia

The concept of Vascular Dementia (VaD) has been recognized for over a century, but its definition and diagnostic criteria remain unclear. Conventional definitions identify the patients too late, miss subjects with cognitive impairment short of dementia, and emphasize consequences rather than causes, the true bases for treatment and prevention. We should throw out current diagnostic categories and describe cognitive impairment clinically and according to commonly agreed instruments that document the demographic data in a standardized manner and undertake a systematic effort to identify the underlying aetiology in each case. Increased effort should be targeted towards the concept of and criteria for Vascular Cognitive Impairment and Post-Stroke Dementia as well as for genetic factors involved, especially as these categories hold promise for early prevention and treatment.

Diagnosis and management of vascular cognitive impairment

Accurate diagnosis of vascular cognitive impairment (VCI) is important but may be difficult. VCI diagnoses depend on determinations of the presence of both cognitive impairment and cerebrovascular disease (CVD), temporal causal links between cognitive impairment and CVD, and the presence or absence of other potential contributors to cognitive impairment, such as Alzheimer's disease (AD). Diagnostic criteria differ across currently utilized systems, resulting in widely differing VCI prevalence rates. Also, current systems may not be able to differentiate "pure" VCI from "mixed" AD and CVD. National Institute of Neurological Disorders and Stroke harmonization criteria for VCI have been developed for study and validation to help bridge gaps in our understanding of VCI diagnosis. VCI management begins with atherogenic risk factor control. Current VCI treatment options demonstrate statistical improvement but not consistent global clinical efficacy. Future clinical trials should concentrate on both primary risk factor control and development of new therapeutic agents to treat patients already diagnosed with VCI.

Genetic correlates of brain aging on MRI and cognitive test measures: a genome-wide association and linkage analysis in the Framingham Study

BACKGROUND

Brain magnetic resonance imaging (MRI) and cognitive tests can identify heritable endophenotypes associated with an increased risk of developing stroke, dementia and Alzheimer's disease (AD). We conducted a genome-wide association (GWA) and linkage analysis exploring the genetic basis of these endophenotypes in a community-based sample.

METHODS

A total of 705 stroke- and dementia-free Framingham participants (age 62 +9 yrs, 50% male) who underwent volumetric brain MRI and cognitive testing (1999-2002) were genotyped. We used linear models adjusting for first degree relationships via generalized estimating equations (GEE) and family based association tests (FBAT) in additive models to relate qualifying single nucleotide polymorphisms (SNPs, 70,987 autosomal on Affymetrix 100K Human Gene Chip with minor allele frequency > or = 0.10, genotypic call rate > or = 0.80, and Hardy-Weinberg equilibrium p-value > or = 0.001) to multivariable-adjusted residuals of 9 MRI measures including total cerebral brain (TCBV), lobar, ventricular and white matter hyperintensity (WMH) volumes, and 6 cognitive factors/tests assessing verbal and visuospatial memory, visual scanning and motor speed, reading, abstract reasoning and naming. We determined multipoint identity-by-descent utilizing 10,592 informative SNPs and 613 short tandem repeats and used variance component analyses to compute LOD scores.

RESULTS

The strongest gene-phenotype association in FBAT analyses was between SORL1 (rs1131497; p = 3.2 x 10(-6)) and abstract reasoning, and in GEE analyses between CDH4 (rs1970546; p = 3.7 x 10(-8)) and TCBV. SORL1 plays a role in amyloid precursor protein processing and has been associated with the risk of AD. Among the 50 strongest associations (25 each by GEE and FBAT) were other biologically interesting genes. Polymorphisms within 28 of 163 candidate genes for stroke, AD and memory impairment were associated with the endophenotypes studied at p < 0.001. We confirmed our previously reported linkage of WMH on chromosome 4 and describe linkage of reading performance to a marker on chromosome 18 (GATA11A06), previously linked to dyslexia (LOD scores = 2.2 and 5.1).

CONCLUSION

Our results suggest that genes associated with clinical neurological disease also have detectable effects on subclinical phenotypes. These hypothesis generating data illustrate the use of an unbiased approach to discover novel pathways that may be involved in brain aging, and could be used to replicate observations made in other studies.

Dementia epidemiology research: it is time to modify the focus of research

The incidence and prevalence of dementia are increasing. There is an urgent need to develop a preventive strategy. The identification of modifiable risk factors must therefore be a high priority. Newer imaging techniques provide an opportunity to identify subclinical manifestations of "dementias" that can be limited to the risk factors and subsequent clinical disease. The contribution of vascular disease to dementia and Alzheimer's disease (AD) should be a high priority as it offers a potential preventive strategy. Study designs need to be modified, including a greater emphasis on geographic variations in AD and dementia based on imaging studies, longitudinal studies of successful aging without cardiovascular disease (CVD) or AD, gene-environment interactions, and studies of unique populations that may be at lower risk because of specific lifestyles. Primary prevention trials for vascular disease should include a dementia component. Most, if not all, studies should include newer imaging studies.

Disease progression in vascular cognitive impairment: Cognitive, functional and behavioural outcomes in the Consortium to Investigate Vascular Impairment of Cognition (CIVIC) cohort study

BACKGROUND AND PURPOSE

Empirical studies to clarify the outcomes in Vascular Cognitive Impairment (VCI) are needed. We compared cognitive, functional, and behavioural outcomes in patients with VCI to patients with no cognitive impairment (NCI), and Alzheimer's disease (AD).

METHODS

Secondary analysis of the Consortium to Investigate Vascular Impairment of Cognition (CIVIC), a multi-centre Canadian memory clinic 30-month cohort study.

RESULTS

Of 1347 patients, 938 were eligible for follow-up, of whom 239 (24.5%) were lost and 29 (3%) had died. Of the remaining 697 patients, 125 had NCI, 229 had VCI, and 343 had AD at baseline. Compared to people with NCI, of whom 20-40% showed progression based on cognitive and functional measures, those with VCI were more likely to progress (50-65%), as were people with AD (50-80%) (p<0.01). More people with VCI showed progression of affective symptoms (30%) than those with NCI (12%) or AD (15% p<0.01). Progression of impaired judgment (rated clinically) in VCI (15%) was similar to AD (11%) but more common than in NCI (4%, p<0.01).

CONCLUSIONS

Most people with VCI show readily detectable progression by 30 months. Depressive symptoms were more common and more progressive in VCI than in Alzheimer's disease, whereas clinical evidence of progressive executive dysfunction was common in both AD and VCI.

National Institute of Neurological Disorders and Stroke-Canadian Stroke Network vascular cognitive impairment harmonization standards

BACKGROUND AND PURPOSE

One in 3 individuals will experience a stroke, dementia or both. Moreover, twice as many individuals will have cognitive impairment short of dementia as either stroke or dementia. The commonly used stroke scales do not measure cognition, while dementia criteria focus on the late stages of cognitive impairment, and are heavily biased toward the diagnosis of Alzheimer disease. No commonly agreed standards exist for identifying and describing individuals with cognitive impairment, particularly in the early stages, and especially with cognitive impairment related to vascular factors, or vascular cognitive impairment.

METHODS

The National Institute for Neurological Disorders and Stroke (NINDS) and the Canadian Stroke Network (CSN) convened researchers in clinical diagnosis, epidemiology, neuropsychology, brain imaging, neuropathology, experimental models, biomarkers, genetics, and clinical trials to recommend minimum, common, clinical and research standards for the description and study of vascular cognitive impairment.

RESULTS

The results of these discussions are reported herein.

CONCLUSIONS

The development of common standards represents a first step in a process of use, validation and refinement. Using the same standards will help identify individuals in the early stages of cognitive impairment, will make studies comparable, and by integrating knowledge, will accelerate the pace of progress.

White matter grade and ventricular volume on brain MRI as markers of longevity in the cardiovascular health study

High white matter grade (WMG) on magnetic resonance imaging (MRI) is a risk factor for dementia, stroke and disability. Higher ventricular size is a marker of brain "atrophy." In the Cardiovascular Health Study (CHS) (n=3245) mean age 75 years, 50% black and 40% men, we evaluated WM and ventricular grade (VG), total, cardiovascular and noncardiovascular mortality and longevity before and after adjusting for numerous determinants of longevity over an approximate 10-12 years of follow-up. A low WMG and VG was a marker for low total, cardiovascular and noncardiovascular mortality and for increased longevity over 10+ years of follow-up. We estimated that a 75-year-old with WMG below median would have about a 5-6 years greater longevity and for VG about 3 years, than above the median even after adjustment for numerous risk factors. Low WMG and VG on MRI is a powerful determinant of long-term survival among older individuals.