NINDS AIREN neuroimaging criteria do not distinguish stroke patients with and without dementia

Update on Vascular Dementia

Vascular dementia (VaD) is a major contributor to the dementia syndrome and is described as having problems with reasoning, planning, judgment, and memory caused by impaired blood flow to the brain and damage to the blood vessels resulting from events such as stroke. There are a variety of etiologies that contribute to the development of vascular cognitive impairment and VaD, and these are often associated with other dementia-related pathologies such as Alzheimer disease. The diagnosis of VaD is difficult due to the number and types of lesions and their locations in the brain. Factors that increase the risk of vascular diseases such as stroke, high blood pressure, high cholesterol, and smoking also raise the risk of VaD. Therefore, controlling these risk factors can help lower the chances of developing VaD. This update describes the subtypes of VaD, with details of their complex presentation, associated pathological lesions, and issues with diagnosis, prevention, and treatment.

Multimodality Imaging of Neurodegenerative Processes: Part 1, The Basics and Common Dementias

OBJECTIVE

Multimodality imaging plays an important role in the structural and functional characterization of neurodegenerative conditions. This article illustrates the basic concepts of anatomic, metabolic, and amyloid imaging and describes the application of a multimodality approach in the evaluation of patients with the more common neurodegenerative dementia processes. Proper utilization of clinically available imaging techniques allows greater insight into these common disease processes.

CONCLUSION

Recognizing the strength of combined anatomic, metabolic, and amyloid imaging can allow a more complete and confident assessment of patients with common degenerative dementias. This added knowledge can improve clinical care, allow initiation of appropriate therapies and counseling, and improve prognostication.

Neuropathological diagnosis of vascular cognitive impairment and vascular dementia with implications for Alzheimer's disease

Vascular dementia (VaD) is recognised as a neurocognitive disorder, which is explained by numerous vascular causes in the general absence of other pathologies. The heterogeneity of cerebrovascular disease makes it challenging to elucidate the neuropathological substrates and mechanisms of VaD as well as vascular cognitive impairment (VCI). Consensus and accurate diagnosis of VaD relies on wide-ranging clinical, neuropsychometric and neuroimaging measures with subsequent pathological confirmation. Pathological diagnosis of suspected clinical VaD requires adequate postmortem brain sampling and rigorous assessment methods to identify important substrates. Factors that define the subtypes of VaD include the nature and extent of vascular pathologies, degree of involvement of extra and intracranial vessels and the anatomical location of tissue changes. Atherosclerotic and cardioembolic diseases appear the most common substrates of vascular brain injury or infarction. Small vessel disease characterised by arteriolosclerosis and lacunar infarcts also causes cortical and subcortical microinfarcts, which appear to be the most robust substrates of cognitive impairment. Diffuse WM changes with loss of myelin and axonal abnormalities are common to almost all subtypes of VaD. Medial temporal lobe and hippocampal atrophy accompanied by variable hippocampal sclerosis are also features of VaD as they are of Alzheimer’s disease. Recent observations suggest that there is a vascular basis for neuronal atrophy in both the temporal and frontal lobes in VaD that is entirely independent of any Alzheimer pathology. Further knowledge on specific neuronal and dendro-synaptic changes in key regions resulting in executive dysfunction and other cognitive deficits, which define VCI and VaD, needs to be gathered. Hereditary arteriopathies such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy or CADASIL have provided insights into the mechanisms of dementia associated with cerebral small vessel disease. Greater understanding of the neurochemical and molecular investigations is needed to better define microvascular disease and vascular substrates of dementia. The investigation of relevant animal models would be valuable in exploring the pathogenesis as well as prevention of the vascular causes of cognitive impairment.

Genetic and degenerative disorders primarily causing dementia

Neuroimaging comprises a powerful set of instruments to diagnose the different causes of dementia, clarify their neurobiology, and monitor their treatment. Magnetic resonance imaging (MRI) depicts volume changes with neurodegeneration and inflammation, as well as abnormalities in functional and structural connectivity. MRI arterial spin labeling allows for the quantification of regional cerebral blood flow, characteristically altered in Alzheimer's disease, diffuse Lewy-body disease, and the frontotemporal dementias. Positron emission tomography allows for the determination of regional metabolism, with similar abnormalities as flow, and for the measurement of β-amyloid and abnormal tau deposition in the brain, as well as regional inflammation. These instruments allow for the quantification in vivo of most of the pathologic features observed in disorders causing dementia. Importantly, they allow for the longitudinal study of these abnormalities, having revealed, for instance, that the deposition of β-amyloid in the brain can antecede by decades the onset of dementia. Thus, a therapeutic window has been opened and the efficacy of immunotherapies directed at removing β-amyloid from the brain of asymptomatic individuals is currently being tested. Tau and inflammation imaging, still in their infancy, combined with genomics, should provide powerful insights into these disorders and facilitate their treatment.

Vascular dementia

Vascular dementia is one of the most common causes of dementia after Alzheimer's disease, causing around 15% of cases. However, unlike Alzheimer's disease, there are no licensed treatments for vascular dementia. Progress in the specialty has been difficult because of uncertainties over disease classification and diagnostic criteria, controversy over the exact nature of the relation between cerebrovascular pathology and cognitive impairment, and the paucity of identifiable tractable treatment targets. Although there is an established relation between vascular and degenerative Alzheimer's pathology, the mechanistic link between the two has not yet been identified. This Series paper critiques some of the key areas and controversies, summarises treatment trials so far, and makes suggestions for what progress is needed to advance our understanding of pathogenesis and thus maximise opportunities for the search for new and effective management approaches.

Role of neuroimaging in multidisciplinary approach towards Non-Alzheimer's dementia

Dementia is defined as chronic deterioration of intellectual function and cognitive skills significant enough to interfere with the ability to perform daily activities. Recent advances in the treatment of dementia have renewed interest in the use of various neuroimaging techniques that can assist in the diagnosis and differentiation of various subtypes. Neuroimaging and computational techniques have helped the radiological community to monitor disease progression of various neurodegenerative conditions presenting with dementia, such as Alzheimer disease, frontotemporal lobe dementia (FTLD), progressive supranuclear palsy (PSP) and multisystem atrophy-cerebellar variant (MSA-C), and their response to newer therapies. Prompt identification of treatable or reversible forms of dementia, such as tumours, subdural haemorrhage and intracranial dAVF, is crucial for the effective management of these conditions. It is also prudent to recognize the imaging spectrum of metabolic, infective and autoimmune diseases with rapidly progressing dementia, such as methanol toxicity, central pontine myelinolysis (CPM), delayed post hypoxic leukoencephalopathy (DPHL), HIV, Creutzfeldt-Jakob Disease (CJD), Sjogren's syndrome, multiple sclerosis (MS), radiation necrosis and Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS), which are difficult to treat and often require palliative care. This pictorial review emphasizes various non-Alzheimer’s dementia entities and discusses their imaging highlights.

Teaching Points

• Non Alzheimer’s dementia constitutes a broad spectrum of conditions.

• Neuroimaging plays an important role in differentiating treatable from irreversible dementia.

• Neuroimaging is often non-specific in early stages of neurodegenerative conditions with dementia.

• Neuroimaging plays an important role in the multimodal approach towards management of dementia.

Disproportionate subarachnoid space hydrocephalus-outcome and perivascular space

Objective

We sought to identify the prevalence of MRI features of disproportionately enlarged subarachnoid space hydrocephalus in possible idiopathic normal pressure hydrocephalus (DESH-iNPH) and to describe the clinico-radiological features and outcomes of a community-based investigation (The Vienna Trans-Danube Aging study).

Methods

Of the 697 inhabitants (all 75 years old), 503 completed extensive neurological examinations at baseline and were followed up every 30 months thereafter with MRIs, mini-mental state examination (MMSE), and the Unified Parkinson Disease Rating Scale-Motor Section (UPDRSM). The DESH-iNPH participant data were compared with the data from participants with Evans index ratios >0.3 (ex vacuo hydrocephalus), cerebral small-vessel diseases, and normal MRIs. The widening of perivascular space was also evaluated by MRI in these groups.

Results

Eight participants with DESH-iNPH (1.6%) and 76 with ex vacuo hydrocephalus (16.1%) at baseline were identified. The mean MMSE in DESH-iNPH, ex vacuo hydrocephalus, and normal MRIs was 26.4, 27.9, and 28.3, respectively, and the mean UPDRSM was 9.75, 2.96, and 1.87, respectively. After a 90-month follow-up, the mortality rates for DESH-iNPH, ex vacuo hydrocephalus, and normal MRIs were 25.0%, 21.3%, and 10.9%, respectively. The perivascular-space widening scores were significantly smaller in the DESH-iNPH cases, particularly at the centrum semiovale, compared to cerebral small-vessel disease and ex vacuo hydrocephalus cases.

Interpretation

The prevalence of DESH-iNPH was 1.6% for participants aged 75 years and revealed significantly lower MMSE and higher UPDRSM scores compared to the ex vacuo hydrocephalus and controls. Moreover, it is suggested that perivascular-space narrowing is a morphological and pathophysiological marker of DESH-iNPH.

Neuroimaging predictors of death and dementia in a cohort of older stroke survivors

BACKGROUND

Stroke is a risk factor for subsequent death and dementia. Being able to identify subjects at particular risk would be beneficial to inform treatment and patient management.

METHODS SUBJECTS

aged over 75 years with incident stroke were recruited. Subjects had a cognitive assessment at 3 months post stroke to exclude dementia, and had an MRI scan (n=106) at that time. Subjects were then followed longitudinally for incident dementia and/or death.

RESULTS

Independent neuroimaging predictors of survival to dementia were medial temporal atrophy (MTA; p=0.013) and the presence of thalamic infarcts (p=0.002). After inclusion of cognitive score in the model, the significance of MTA (p=0.049) and thalamic infarcts (p=0.04) was reduced, with survival being best predicted by baseline cognitive score (p=0.004). The only independent significant predictor of survival to death was MTA. Apart from thalamic infarcts, the NINDS/AIREN neuroimaging criteria did not independently predict survival to death or dementia.

CONCLUSIONS

MTA was associated with shorter time to dementia, suggesting a role for Alzheimer pathology in the development of post stroke dementia.

Vascular dementia: Diagnostic criteria and supplementary exams. Recommendations of the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology. Part I

Vascular dementia (VaD) is the most prevalent form of secondary dementia and the second most common of all dementias. The present paper aims to define guidelines on the basic principles for treating patients with suspected VaD (and vascular cognitive impairment - no dementia) using an evidence-based, systematized approach. The knowledge used to define these guidelines was retrieved from searches of several databases (Medline, Scielo, Lilacs) containing scientific articles, systematic reviews, meta-analyses, largely published within the last 15 years or earlier when pertinent. Information retrieved and selected for relevance was used to analyze diagnostic criteria and to propose a diagnostic system encompassing diagnostic criteria, anamnesis, as well as supplementary and clinical exams (neuroimaging and laboratory). Wherever possible, instruments were selected that had versions previously adapted and validated for use in Brazil that take into account both schooling and age. This task led to proposed protocols for supplementary exams based on degree of priority, for application in clinical practice and research settings.

Brain Glucose Metabolism in Vascular White Matter Disease With Dementia

Background and Purpose— The boundary between vascular dementia and Alzheimer disease (AD) continues to be unclear. Some posit that gradually progressive vascular dementia, as with small vessel disease, is simply vascular disease plus AD. Because AD presents a characteristic pattern on fluorodeoxyglucose positron emission tomography, we sought to determine whether the fluorodeoxyglucose pattern of vascular dementia resembled more AD or the pattern in nondemented patients with severe microvascular brain disease.

Methods— Vascular disease patients were selected on the basis of confluent white matter lesions on both hemispheres. Among them, with a similar degree of vascular disease on MRI, neuropsychological testing separated groups with dementia and without dementia. Patients with AD and healthy controls were also studied. The 4 groups, with 12 subjects each, were matched by age, gender, and educational level. Fluorodeoxyglucose distribution was analyzed using both voxel-based and volume of interest methods.

Results— The AD group had the characteristic pattern of bilaterally decreased metabolism in parieto-temporal association cortex and precuneus. By contrast, patients with vascular disease and dementia had a similar anatomic pattern to that of the vascular patients without dementia, but with greater metabolic abnormalities, particularly in the frontal lobes and deep nuclei.

Conclusions— The anatomy of metabolic abnormalities in vascular disease with dementia suggests that, at least in some cases, dementia with vascular disease may be independent of AD. The metabolic abnormality involves the thalamus, caudate, and frontal lobe, a pattern concordant with the neuropsychological findings of impaired executive function characteristic of vascular dementia.

Role of metabolic syndrome components in human immunodeficiency virus-associated stroke

Metabolic syndrome (MetS) is a cluster of risk factors, including elevated mean arterial pressure (MAP), atherogenic dyslipidemia (elevated triglycerides [TRG]), abdominal obesity (increased body mass index [BMI]), glucose intolerance (elevated glucose [GLU]), and prothrombotic/inflammatory state (increases in uric acid [UA]), that are associated with increased risk of cerebrovascular disease. We studied if an association existed between MetS components and human immunodeficiency virus (HIV)-associated cryptogenic strokes-those not caused by HIV complications, endocarditis, or stimulant abuse. We performed a retrospective case-control study. Eleven cryptogenic strokes were identified from 2346 HIV-infected (HIV+) participants. Each case was matched by age, sex, and date of stroke diagnosis to five HIV+ controls without stroke. Nonparametric stratified Wilcoxon ranked sum tests with subsequent mixed effect logistic regression determined the influence of each MetS component on HIV-associated cryptogenic stroke. Although each MetS component appeared higher for HIV+ cases with cryptogenic strokes than HIV+ controls, only MAP (odds ratio [OR] = 5.70, 95% confidence interval [CI] = 1.15-28.3) and UA (OR = 1.88, 95% CI = 1.06-3.32) were statistically different. A significantly higher percentage of HIV-associated cryptogenic stroke cases met criteria for MetS (4/11 = 36%) compared to HIV+ controls (6/55 = 11%). This observational study suggests a possible role for MetS components in HIV+ cryptogenic stroke cases. Although MetS is defined as a constellation of disorders, elevated hypertension and hyperuricemia may be involved in stroke pathogenesis. Reducing MetS component levels in HIV+ patients could therefore protect them from subsequent stroke.

Role of imaging techniques in the diagnosis of dementia

Dementia is a common and growing problem, affecting 5% of the over 65 s and 20% of the over 80s. The recent availability of new treatments for dementia, as well as the importance of subtype-specific management, has renewed interest in the use of brain imaging techniques that can assist in the accurate recognition of Alzheimer's disease (AD), dementia with Lewy bodies (DLB), vascular dementia (VaD) and frontotemporal dementia (FTD). Structural imaging, historically used to exclude an intracerebral lesion as a cause for dementia, is increasingly playing a role in "ruling in" diagnoses, with atrophy of the hippocampus and entorhinal cortex an early and sensitive marker for AD, and cortical and subcortical infarcts and white matter lesions characteristic of VaD. Regionally distinct patterns of hypoperfusion on single-photon emission computed tomography (SPECT) or hypometabolism on positron emission tomography (PET) can help differentiate FTD, AD and VaD, and dopaminergic loss in the basal ganglia can differentiate DLB from AD. Newer techniques show great promise to detect specific neuroreceptor changes as well as pathological underpinnings of dementia, such as amyloid and tau pathology.

Donepezil: an update

Donepezil hydrochloride is the most widely prescribed drug for Alzheimer's disease (AD). The main mechanism of action through which it influences cognition and function is presumed to be the inhibition of acetylcholinesterase enzyme in the brain; however, donepezil may also impact the pathophysiology of AD at several other points. Officially approved for mild-to-moderate and severe AD, donepezil has also been shown to be effective in early-stage AD, vascular dementia, Parkinson's disease dementia/Lewy body disease and cognitive symptoms associated with multiple sclerosis. In addition, one study suggested that donepezil may delay the onset of AD in subjects with mild cognitive impairment, a prodrome to AD. The pharmacokinetics, pharmacodynamics, safety/tolerability profile and drug interaction properties of donepezil make it an easy and safe agent to use. However, in general, the efficacy of donepezil is limited, and ongoing studies are investigating other agents that may ultimately overtake its present position as the mainstay of anti-AD therapy.

Cognitive dysfunction in 16 patients with carotid stenosis: detailed neuropsychological findings

Background

Impairment of cognitive function is often present in patients with carotid artery stenosis but the details of this dysfunction have rarely been reported. Our purpose was to elucidate the cognitive dysfunction in patients with unilateral severe carotid stenosis using comprehensive neuropsychological testing, and also to identify the specific underlying clinical and radiological factors.

Methods

We analyzed the results of neuropsychological testing, the clinical history, and MR findings in 16 consecutive patients with angiographically proven severe (70-99%) stenosis of the extra cranial internal carotid artery (ICA). Cognitive functions were examined using the Seoul Neuropsychological Screening Battery and the Neglect Battery. We excluded patients with cortical infarction and those with contra lateral ICA occlusion or severe stenosis.

Results

Our comprehensive neuropsychological testing revealed obvious cognitive deficits in all patients with unilateral severe ICA stenosis, the most common being frontal executive impairment. The mean cognitive score on the memory test was also significantly lower in patients with symptomatic ICA stenosis than in asymptomatic patients (29.33±10.98, mean±SD, p < 0.05). The total score on the global cognitive test was significantly lower in patients with an ischemic lesion on MRI than in no lesion patients (113.23±34.78, p < 0.05). The presence of symptoms related to the ICA stenosis was related to cognitive dysfunction even when there were no ischemic lesions on MRI. SPECT revealed ipsilateral cortical hypoperfusion in 9 of 12 patients (75%).

Conclusions

Cognitive deficits are common in patients with unilateral severe ICA stenosis. Our findings suggest that an additional mechanism beyond the structural lesion such as chronic hypoperfusion may affect cognitive function in patients with high-grade ICA stenosis.

Rethinking the dementia diagnoses in a population-based study: what is Alzheimer's disease and what is vascular dementia? A study from the kungsholmen project

OBJECTIVE

To explore the hypothesis that older adults often are affected by more than one disease, making the differential diagnosis between Alzheimer's disease (AD) and vascular dementia (VaD) difficult.

METHODS

Incident dementia cases (n = 308) from a population-based longitudinal study of people 75+ years were investigated. The DSM-III-R criteria were used for the clinical diagnosis of dementia. Data on vascular disorders (hypertension, cerebrovascular and ischemic heart diseases, heart failure, atrial fibrillation, diabetes) as well as type of onset/course of dementia were used retrospectively to reclassify dementias.

RESULTS

Only 47% of the AD cases were reclassified as pure AD without any vascular disorder. Among subjects with AD and with a vascular component, cerebrovascular disease was the most common (41%). Only 25% of VaD were reclassified as pure VaD. Further, 26% of the pure AD subjects developed a vascular disorder in the following 3 years.

CONCLUSIONS

Both vascular and degenerative mechanisms may often contribute to the expression of dementia among the elderly. Most of the AD cases have vascular involvements, and pure dementia types in very old subjects constitute only a minority of dementia cases.

Vascular cognitive impairment

Cerebrovascular disease is increasingly recognized as a common cause of cognitive impairment and dementia in later life either alone or in conjunction with other pathologies, most often Alzheimer disease (AD). Progress in the field has been limited by difficulties in terminology; for example, use of the term dementia necessitates the presence of memory impairment, which is the norm in AD, but not in cognitive disorders associated with cerebrovascular disease. The term vascular cognitive impairment (VCI) has been proposed as an umbrella term to recognize the broad spectrum of cognitive, and indeed behavioral, changes associated with vascular pathology. It is characterized by a specific cognitive profile with predominantly attentional and executive impairments together with particular noncognitive features (especially depression) and a relatively stable course, at least in clinical trial populations. Subtypes of VCI have been proposed based on clinical and pathologic differences, including cortical, subcortical, strategic infarct, hypoperfusion, hemorrhagic, and mixed (with AD) type. Diagnostic criteria are emerging but require refinement and validation, especially for mixed dementias. There remain fundamental gaps in our understanding of pathophysiology, predicting prognosis and outcome, and in therapeutics. Clinical trials to date, mainly in populations selected using currently accepted criteria for vascular dementia, have generally been disappointing. A relatively modest cognitive benefit of agents such as nimodipine, memantine, and cholinesterase inhibitors has been reported, although the clinical significance of these improvements remains to be established. Further studies, focusing on particular subtypes of VCI and involving subjects at earlier stages of the disease, are required. The aim of this article is to review the concept of VCI in terms of the evidence base surrounding diagnosis, clinical features, pathophysiology, and management and to make some recommendations regarding further research in the area. It begins with a discussion on the historical background, which is important to understand the different and somewhat confusing terminology that currently exists in the field.

The Role of Conventional MR and CT in the Work-Up of Dementia Patients

Dementia is a clinical syndrome with many causes. There often is overlap in the clinical manifestations of various forms of dementia, making them difficult to categorize. Neuroimaging can play an important role in distinguishing one form of dementia from another. Advanced imaging techniques continue to provide greater insight into the underlying pathologic processes in patients who have dementia. Conventional MRI and CT, however, still can contribute useful information when interpreting radiologists are familiar with the patterns of volume loss and signal or density changes that are characteristic of various forms of dementia.

Poststroke Dementia

The association between stroke and dementia is frequent. The prevalence of poststroke dementia (PSD) ranges from 6 to 32%, depending on the population studied, the criteria used for the diagnosis of dementia, and the time interval between the stroke and the neuropsychological assessment. The risk of PSD is high immediately after stroke and remains higher than in controls in stroke patients nondemented 3 months after stroke. Not all cases of PSD are vascular in origin, with about one third of demented patients diagnosed as having Alzheimer's disease plus stroke. The pathophysiology of PSD is probably multifactorial, with an influence of vascular lesions, associated Alzheimer's lesions and white matter changes. The risk of dementia is higher in older patients and in patients with preexisting cognitive decline - no dementia, severe stroke, a history of stroke, white matter changes and cerebral atrophy. The influence of stroke location, vascular risk factors and silent infarcts remains to be determined. PSD adversely influences the outcome in stroke patients.

Dementia and cerebrovascular disease

Cerebrovascular disease is an important cause of cognitive Impairment and dementia in elderly patients. This review highlights the challenges involved in examining the role of cerebrovascular disease In dementia, areas in which consensus is emerging, and an operational framework for clinicians. Two important challenges exist. First, there is no accepted neuropathologic scheme for quantitating cerebrovascular disease In cognitive disturbances. Second, agreement on clinical definitions of vascular dementia is incomplete. Despite the barriers posed by these 2 deficiencies, many consistencies in the clinical, imaging, epidemiological, and neuropathologic aspects of cerebrovascular disease and cognitive impairment have been Identified. Different levels of cerebrovascular disease related to cognitive impairment can be suggested on clinical and Imaging grounds. The overlap between cerebrovascular disease and Alzheimer disease produces a disorder that might be amenable to therapeutic approaches based on either mechanism.

The role of conventional MR and CT in the work-up of dementia patients

Neuroimaging can play an important role in distinguishing one form of dementia from another. Advanced imaging techniques continue to provide greater insight into the underlying pathologic processes in patients who have dementia. Conventional MRI and CT, however, can contribute useful information when interpreting radiologists are familiar with the patterns of volume loss and signal or density changes that are characteristic of various forms of dementia.

Clinical and radiographic subtypes of vascular cognitive impairment in a clinic-based cohort study

BACKGROUND AND PURPOSE

There is a need for empirical studies to define criteria for vascular cognitive impairment (VCI) subtypes. In this paper, we report the predictive validity of a subtype classification scheme based on clinical and radiographic features.

METHODS

Nine Canadian memory clinics participated in the Consortium to Investigate Vascular Impairment of Cognition. This cohort consisted of 1347 patients, of whom 324 had VCI, and was followed for up to 30 months.

RESULTS

Clinical and neuroimaging features defined three subtypes: vascular cognitive impairment, no dementia, (n=97), vascular dementia (n=101) and mixed neurodegenerative/vascular dementia (n=126). Any ischemic lesion on neuroimaging increased the odds (odds ratio=9.31; 95% confidence interval 6.46, 13.39) of a VCI diagnosis. No VCI subtype, however, was associated with a specific neuroimaging abnormality. Compared to those with no cognitive impairment, patients with each VCI subtype had higher rates of death and institutionalization (hazard ratio for combined adverse events=6.08, p<0.001).

CONCLUSIONS

Both clinical features and radiographic features help establish a diagnosis of VCI. The outcomes of VCI subtypes, however, are more strongly associated with clinical features than with radiographic ones.

Poststroke dementia

Dementia is one of the major causes of dependency after stroke. The prevalence of poststroke dementia (PSD)-defined as any dementia occurring after stroke-is likely to increase in the future. In community-based studies, the prevalence of PSD in stroke survivors is about 30% and the incidence of new onset dementia after stroke increases from 7% after 1 year 48% after 25 years. Having a stroke doubles the risk of dementia. Patient-related variables associated with an increased risk of PSD are increasing age, low education level, dependency before stroke, prestroke cognitive decline without dementia, diabetes mellitus, atrial fibrillation, myocardial infarction, epileptic seizures, sepsis, cardiac arrhythmias, congestive heart failure, silent cerebral infarcts, global and medial-temporal-lobe atrophy, and white-matter changes. Stroke-related variables associated with an increased risk of PSD are stroke severity, cause, location, and recurrence. PSD might be the result of vascular lesions, Alzheimer pathology, white-matter changes, or combinations of these. The cause of PSD differs among studies in relation to the mean age of patients, ethnicity, criteria used, and time after stroke. In developed countries, the proportion of patients with presumed Alzheimer's disease among those with PSD is between 19% and 61%. Patients with PSD have high mortality rates and are likely to be functionally impaired. These patients should be treated according to the current guidelines for stroke prevention.