Hippocampal size and dementia in stroke patients: the Sydney stroke study

MRI factors associated with cognitive functioning after acute onset brain injury: Systematic review and meta-analysis

Impairments of memory, attention, and executive functioning are frequently reported after acute onset brain injury. MRI markers hold potential to contribute to identification of patients at risk for cognitive impairments and clarification of mechanisms. The aim of this systematic review was to summarize and value the evidence on MRI markers of memory, attention, and executive functioning after acute onset brain injury. We included ninety-eight studies, on six classes of MRI factors (location and severity of damage (n = 15), volume/atrophy (n = 36), signs of small vessel disease (n = 15), diffusion-weighted imaging measures (n = 36), resting-state functional MRI measures (n = 13), and arterial spin labeling measures (n = 1)). Three measures showed consistent results regarding their association with cognition. Smaller hippocampal volume was associated with worse memory in fourteen studies (pooled correlation 0.58 [95% CI: 0.46-0.68] for whole, 0.11 [95% CI: 0.04-0.19] for left, and 0.34 [95% CI: 0.17-0.49] for right hippocampus). Lower fractional anisotropy in cingulum and fornix was associated with worse memory in six and five studies (pooled correlation 0.20 [95% CI: 0.08-0.32] and 0.29 [95% CI: 0.20-0.37], respectively). Lower functional connectivity within the default-mode network was associated with worse cognition in four studies. In conclusion, hippocampal volume, fractional anisotropy in cingulum and fornix, and functional connectivity within the default-mode network showed consistent associations with cognitive performance in all types of acute onset brain injury. External validation and cut off values for predicting cognitive impairments are needed for clinical implementation.

Correlations between cognitive function and gray matter alterations in patients with acute lacunar stroke

Researchers emphasized acute lacunar stroke (ALS) patients suffer from poor social/physical outcomes, cognitive decline, and decreased quality of life. We hypothesized brain abnormalities may occur in ALS during this particular stage and may be associated with cognitive deficits upon evaluation. We investigated structural abnormalities in ALS using magnetic resonance imaging and voxel-based morphometry conducted on 28 healthy controls (HC) and 29 patients with ALS and proximal anterior circulation occlusion within 12 hours of symptom onset. Mini-Mental State Examination (MMSE) scores were used to evaluate cognitive dysfunction. Decreased gray matter (GM) in ALS vs. HC was predominantly in the superior frontal gyrus, inferior frontal gyrus, insula, superior temporal gyrus (STG), heschl gyrus, middle temporal gyrus (MTG), posterior cingulate cortex (PCC), hippocampus (HIP), and others. Positive correlation was found between GM density and MMSE scores in STG ( r = 0.59, p = 0.0007), MTG ( r = 0.46, p = 0.01), PCC ( r = 0.42, p = 0.02), HIP ( r = 0.4, p = 0.03), and medial prefrontal cortex ( r = 0.5, p = 0.005). This study provided further information on pathophysiological/morphological mechanisms related to cognitive impairment in ALS and is the basis for further studies in aging-related diseases.

Dynamic Regional Brain Atrophy Rates in the First Year After Ischemic Stroke

BACKGROUND AND PURPOSE

Brain atrophy can be regarded as an end-organ effect of cumulative cardiovascular risk factors. Accelerated brain atrophy is described following ischemic stroke, but it is not known whether atrophy rates vary over the poststroke period. Examining rates of brain atrophy allows the identification of potential therapeutic windows for interventions to prevent poststroke brain atrophy.

METHODS

We charted total and regional brain volume and cortical thickness trajectories, comparing atrophy rates over 2 time periods in the first year after ischemic stroke: within 3 months (early period) and between 3 and 12 months (later period). Patients with first-ever or recurrent ischemic stroke were recruited from 3 Melbourne hospitals at 1 of 2 poststroke time points: within 6 weeks (baseline) or 3 months. Whole-brain 3T magnetic resonance imaging was performed at 3 time points: baseline, 3 months, and 12 months. Eighty-six stroke participants completed testing at baseline; 125 at 3 months (76 baseline follow-up plus 49 delayed recruitment); and 113 participants at 12 months. Their data were compared with 40 healthy control participants with identical testing. We examined 5 brain measures: hippocampal volume, thalamic volume, total brain and hemispheric brain volume, and cortical thickness. We tested whether brain atrophy rates differed between time points and groups. A linear mixed-effect model was used to compare brain structural changes, including age, sex, years of education, a composite cerebrovascular risk factor score, and total intracranial volume as covariates.

RESULTS

Atrophy rates were greater in stroke than control participants. Ipsilesional hemispheric, hippocampal, and thalamic atrophy rates were 2 to 4 times greater in the early versus later period.

CONCLUSIONS

Regional atrophy rates vary over the first year after stroke. Rapid brain volume loss in the first 3 months after stroke may represent a potential window for intervention. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02205424.

A Role for New Brain Magnetic Resonance Imaging Modalities in Daily Clinical Practice: Protocol of the Prediction of Cognitive Recovery After Stroke (PROCRAS) Study

Background

Cognitive impairment is common after acute ischemic stroke, affecting up to 75% of the patients. About half of the patients will show recovery, whereas the others will remain cognitively impaired or deteriorate. It is difficult to predict these different cognitive outcomes.

Objective

The objective of this study is to investigate whether diffusion tensor imaging–based measures of brain connectivity predict cognitive recovery after 1 year, in addition to patient characteristics and stroke severity. A specific premise of the Prediction of Cognitive Recovery After Stroke (PROCRAS) study is that it is conducted in a daily practice setting.

Methods

The PROCRAS study is a prospective, mono-center cohort study conducted in a large teaching hospital in the Netherlands. A total of 350 patients suffering from an ischemic stroke who screen positive for cognitive impairment on the Montreal Cognitive Assessment (MoCA<26) in the acute stage will undergo a 3Tesla-Magnetic Resonance Imaging (3T-MRI) with a diffusion-weighted sequence and a neuropsychological assessment. Patients will be classified as being unimpaired, as having a mild vascular cognitive disorder, or as having a major vascular cognitive disorder. One year after stroke, patients will undergo follow-up neuropsychological assessment. The primary endpoint is recovery of cognitive function 1 year after stroke in patients with a confirmed poststroke cognitive disorder. The secondary endpoint is deterioration of cognitive function in the first year after stroke.

Results

The study is already ongoing for 1.5 years, and thus far, 252 patients have provided written informed consent. Final results are expected in June 2019.

Conclusions

The PROCRAS study will show the additional predictive value of diffusion tensor imaging-based measures of brain connectivity for cognitive outcome at 1 year in patients with a poststroke cognitive disorder in a daily clinical practice setting.

Registered Report Identifier

RR1-10.2196/9431

Consensus Approaches to Identify Incident Dementia in Cohort Studies: Systematic Review and Approach in the Successful Aging after Elective Surgery Study

OBJECTIVES

To survey the current methods used to ascertain dementia and mild cognitive impairment (MCI) in longitudinal cohort studies, to categorize differences in approaches and to identify key components of expert panel methodology in current use.

METHODS

We searched PubMed for the past 10 years, from March 6, 2007 to March 6, 2017 using a combination of controlled vocabulary and keyword terms to identify expert panel consensus methods used to diagnose MCI or dementia in large cohort studies written in English. From these results, we identified a framework for reporting standards and describe as an exemplar the clinical consensus procedure used in an ongoing study of elective surgery patients (the Successful Aging after Elective Surgery study).

RESULTS

Thirty-one articles representing unique cohorts were included. Among published methods, membership of experts panel varied significantly. There was more similarity in what types of information was use to ascertain disease status. However, information describing the diagnostic decision process and resolution of disagreements was often lacking.

CONCLUSIONS

Methods used for expert panel diagnosis of MCI and dementia in large cohort studies are widely variable, and there is a need for more standardized reporting of these approaches. By describing the procedure in which our expert panel achieved consensus diagnoses, we hope to encourage the development and publication of well-founded and reproducible methods for diagnosis of MCI and dementia in longitudinal studies.

Structural MRI markers of brain aging early after ischemic stroke

Objective:

To examine associations between ischemic stroke, vascular risk factors, and MRI markers of brain aging.

Methods:

Eighty-one patients (mean age 67.5 ± 13.1 years, 31 left-sided, 61 men) with confirmed first-ever (n = 66) or recurrent (n = 15) ischemic stroke underwent 3T MRI scanning within 6 weeks of symptom onset (mean 26 ± 9 days). Age-matched controls (n = 40) completed identical testing. Multivariate regression analyses examined associations between group membership and MRI markers of brain aging (cortical thickness, total brain volume, white matter hyperintensity [WMH] volume, hippocampal volume), normalized against intracranial volume, and the effects of vascular risk factors on these relationships.

Results:

First-ever stroke was associated with smaller hippocampal volume (p = 0.025) and greater WMH volume (p = 0.004) relative to controls. Recurrent stroke was in turn associated with smaller hippocampal volume relative to both first-ever stroke (p = 0.017) and controls (p = 0.001). These associations remained significant after adjustment for age, sex, education, and, in stroke patients, infarct volume. Total brain volume was not significantly smaller in first-ever stroke patients than in controls (p = 0.056), but the association became significant after further adjustment for atrial fibrillation (p = 0.036). Cortical thickness and brain volumes did not differ as a function of stroke type, infarct volume, or etiology.

Conclusions:

Brain structure is likely to be compromised before ischemic stroke by vascular risk factors. Smaller hippocampal and total brain volumes and increased WMH load represent proxies for underlying vascular brain injury.

The impact of cerebrovascular aging on vascular cognitive impairment and dementia

As human life expectancy rises, the aged population will increase. Aging is accompanied by changes in tissue structure, often resulting in functional decline. For example, aging within blood vessels contributes to a decrease in blood flow to important organs, potentially leading to organ atrophy and loss of function. In the central nervous system, cerebral vascular aging can lead to loss of the integrity of the blood-brain barrier, eventually resulting in cognitive and sensorimotor decline. One of the major of types of cognitive dysfunction due to chronic cerebral hypoperfusion is vascular cognitive impairment and dementia (VCID). In spite of recent progress in clinical and experimental VCID research, our understanding of vascular contributions to the pathogenesis of VCID is still very limited. In this review, we summarize recent findings on VCID, with a focus on vascular age-related pathologies and their contribution to the development of this condition.

Stroke injury, cognitive impairment and vascular dementia

The global burden of ischaemic strokes is almost 4-fold greater than haemorrhagic strokes. Current evidence suggests that 25–30% of ischaemic stroke survivors develop immediate or delayed vascular cognitive impairment (VCI) or vascular dementia (VaD). Dementia after stroke injury may encompass all types of cognitive disorders. States of cognitive dysfunction before the index stroke are described under the umbrella of pre-stroke dementia, which may entail vascular changes as well as insidious neurodegenerative processes. Risk factors for cognitive impairment and dementia after stroke are multifactorial including older age, family history, genetic variants, low educational status, vascular comorbidities, prior transient ischaemic attack or recurrent stroke and depressive illness. Neuroimaging determinants of dementia after stroke comprise silent brain infarcts, white matter changes, lacunar infarcts and medial temporal lobe atrophy. Until recently, the neuropathology of dementia after stroke was poorly defined. Most of post-stroke dementia is consistent with VaD involving multiple substrates. Microinfarction, microvascular changes related to blood–brain barrier damage, focal neuronal atrophy and low burden of co-existing neurodegenerative pathology appear key substrates of dementia after stroke injury. The elucidation of mechanisms of dementia after stroke injury will enable establishment of effective strategy for symptomatic relief and prevention. Controlling vascular disease risk factors is essential to reduce the burden of cognitive dysfunction after stroke. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

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Ischaemic injury is common among long-term stroke survivors

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About 25% stroke survivors develop dementia with a much greater proportion developing cognitive impairment

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Risk factors of dementia after stroke include older age, vascular comorbidities, prior stroke and pre-stroke impairment

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Current imaging and pathological studies suggest 70% of dementia after stroke is vascular dementia

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Severe white matter changes and medial temporal lobe atrophy as sequelae after ischaemic injury are substrates of dementia

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Controlling vascular risk factors and prevention strategies related to lifestyle factors would reduce dementia after stroke

Cognitive state following mild stroke: A matter of hippocampal mean diffusivity

The hippocampus is known to play a vital role in learning and memory and was demonstrated as an early imaging marker for Alzheimer's disease (AD). However, its role as a predictor for mild cognitive impairment and dementia following stroke is unclear. The main purpose of this study was to examine the associations between hippocampal volume, mean diffusivity (MD) and connectivity and cognitive state following stroke. Eighty three consecutive first ever mild to moderate stroke or transient ischemic attack (TIA) survivors from our ongoing prospective TABASCO (Tel Aviv Brain Acute Stroke Cohort) study underwent magnetic resonance imaging scans within 7 days of stroke onset. Hippocampal volume was measured from T1 weighted images, hippocampal mean diffusivity was calculated from diffusion tensor imaging and connectivity was calculated from resting state fMRI. Global cognitive assessments were evaluated during hospitalization and 6 and 12 months later using a computerized neuropsychological battery. Multiple linear regression analysis was used to test which of the hippocampi measurements best predict cognitive state. All three imaging parameters were significantly correlated to each other (|r's| >0.3, P's < 0.005), and with cognitive state 6 and 12 months after the event. Multiple regression analyses demonstrated the predictive role of hippocampal mean diffusivity (β = -0.382, P = 0.026) on cognitive state, above and beyond that of volume and connectivity of this structure. To our knowledge, the combination of hippocampal volume, mean diffusivity and connectivity in first ever post stroke or TIA patients has not yet been considered in relation to cognitive state. The results demonstrate the predictive role of hippocampal mean diffusivity, suggesting that these changes may precede and contribute to volumetric and connectivity changes in the hippocampi, potentially serving as a marker for early identification of patients at risk of developing cognitive impairment or dementia.

Post-stroke memory impairment among patients with vascular mild cognitive impairment

Background

The American Stroke Association/American Heart Association recommended the criteria for diagnosis of vascular cognitive impairment and memory impairment (MI) is a feature in the classification of vascular mild cognitive impairment (VaMCI). VaMCI patients with MI may differ in terms of infarct location or demographic features, so we evaluated the clinical characteristics associated with MI in patients with VaMCI.

Methods

A prospective multicenter study enrolled 353 acute ischemic stroke patients who underwent evaluation using the Korean Vascular Cognitive Impairment Harmonization Standard Neuropsychological Protocol at three months after onset. The association between MI and demographic features, stroke risk factors, and infarct location was assessed.

Results

VaMCI was diagnosed in 141 patients, and 58 (41.1%) exhibited MI. Proportions of men and of left side infarcts were higher in VaMCI with MI than those without (75.9 vs. 57.8%, P = 0.03, 66.7 vs. 47%, P = 0.02). Multiple logistic analyses revealed that male sex (odds ratio [OR] 3.07, 95% confidence interval [95% CI] 1.12-8.42), left-side infarcts (OR 3.14, 95% CI 1.37-7.20), and basal ganglia/internal capsule infarcts (OR 4.53, 95% CI 1.55-13.22) were associated with MI after adjusting other demographic variables, vascular risk factors, and subtypes of stroke.

Conclusions

MI is associated with sex and infarct location in VaMCI patients.

Pathogenesis and treatment of vascular cognitive impairment

SUMMARY 

Vascular cognitive impairment (VCI) defines a continuum of disorders ranging from mild cognitive impairment to full-blown dementia, attributable to cerebrovascular causes. Major morphological types – multi-infarct encephalopathy, strategic infarct type, subcortical arteriosclerotic leukoencephalopathy, multilacunar state, postischemic encephalopathy – result from systemic, cardiac and local large or small vessel disease. Cognitive decline is commonly caused by widespread small cerebrovascular lesions (CVLs) affecting regions/networks essential for cognition, memory and behavior. CVLs often coexist with Alzheimer-type and other pathologies, which interact in promoting dementia, but in many nondemented elderly individuals, mixed brain pathologies are also present. Due to the high variability of CVLs, no validated clinical and neuropathological criteria for VCI are available. Cholinesterase inhibitors and memantine produce small cognitive improvement but without essential effect. Antihypertensive treatment, cardiovascular control and lifestyle modifications reducing vascular risk factors are essential. Given its growing health, social and economic burden, prevention and treatment of VCI are a major challenge of neuroscience.

Understanding and preventing the development of post-stroke dementia

Post-stroke dementia (PSD) is a clinical entity but it now appears that most of PSD may be categorized as vascular dementia. The well-established relationship between vascular factors and dementia provides a rationale for the implementation of intervention and prevention efforts. Larger primary prevention trials related to lifestyle factors are warranted in association with dementia. Published clinical trials have not been promising and there is meager information on whether PSD can be prevented through the use of pharmacological agents. Control of vascular disease risk and prevention of recurrent strokes are obviously key to reducing the burden of cognitive decline and dementia after stroke. However, modern imaging and analysis techniques will help to elucidate the mechanism of PSD and establish better treatment.

Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence

Silent focal ischemic mini infarcts in the brain are thought to cause no clinically overt symptoms. Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemia-induced deficits. The present study investigated whether an otherwise silent ischemic mini infarct in the hippocampus (HPC) can produce impairments in spatial performance in rats. Spatial performance was assessed in the ziggurat task (ZT) using a 10-trial spatial learning protocol for 4 days prior to undergoing hippocampal ischemic lesion or sham surgery. Hippocampal silent ischemia was induced by infusion of endothelin-1 (ET-1), a potent vasoconstrictor, into either the dorsal or the ventral hippocampus (dHPC and vHPC). When tested postoperatively in the ZT using a standard testing protocol for 8 days, rats with hippocampal lesions exhibited no spatial deficit. Although spatial learning and memory in the ZT were not affected by the ET-1-induced silent ischemia, rats with dHPC stroke showed more returns when navigating the ZT as opposed to the vHPC rats. Comparison of region-specific HPC lesions in the present study indicated that dorsal hippocampal function is critically required for topographic orientation in a complex environment. Topographic disorientation as reflected by enhanced return behaviors may represent one of the earliest predictors of cognitive decline after silent ischemic insult that may be potentially traced with sensitive clinical examination in humans.

Alterations in the gray matter volume in transient ischemic attack: a voxel-based morphometry study

BACKGROUND

Several studies have emphasized that transient ischemic attack (TIA) patients suffered functional impairments, but whether underlying morphological alterations exist remains unclear. This study aims to detect possible gray matter volume (GMV) alterations in patients with TIA using voxel-based morphometry (VBM) method.

METHODS

High-resolution T1-weighted anatomical images of 21 patients were compared with 21 healthy controls of matching age, gender, and education. Changes in the GMV were observed using VBM technique, followed by two-sample t-test analysis to detect the differences in the GMV between TIA patients and healthy controls. Correlations between the clinical parameters and the Montreal cognitive assessment (MoCA) scores, and the altered GMV in TIAs, were investigated.

RESULTS

Two-sample t-test analysis revealed a significant GMV reduction in specific regions in the default mode network (DMN) in TIA patients, including the bilateral medial frontal gyrus, anterior cingulate cortex (ACC), and precuneus. No correlation was found between the reduced GMV and MoCA scores and clinical parameters.

CONCLUSION

Transient ischemic attack patients showed widespread morphology atrophy in DMN, suggesting that, despite the absence of a cerebral infarction, ischemic injury may induce structural abnormalities and eventually contribute to functional impairments in TIA patients. Our results may provide a valuable basis for the pathophysiological mechanism related to the cognitive dysfunction of TIA from the view of brain morphology.

Beyond the lesion: neuroimaging foundations for post-stroke recovery

A shift is emerging in the way in which we view post-stroke recovery. This shift, supported by evidence from neuroimaging studies, encourages us to look beyond the lesion and to identify viable brain networks with capacity for plasticity. In this article, the authors review current advances in neuroimaging techniques and the new insights that they have contributed. The ability to quantify salvageable tissue, evidence of changes in remote networks, changes of functional and structural connectivity, and alterations in cortical thickness are reviewed in the context of their impact on post-stroke recovery. The value of monitoring spared structural connections and functional connectivity of brain networks within and across hemispheres is highlighted.

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.

Post-stroke dementia: the contribution of thalamus and basal ganglia changes

BACKGROUND

The neurobiological basis of increased risk of dementia in stroke patients is unclear, though there are several related pathological changes, including white matter hyperintensities (WMH), and medial temporal atrophy. Subcortical gray matter structures have also been implicated in dementia resulting from vascular pathology, particularly vascular dementia. This study aimed to investigate the contribution of changes in subcortical gray matter structures to post-stroke dementia (PSD).

METHODS

T1- and T2-weighted images and T2-weighted fluid-attenuated inversion recovery (FLAIR) images were obtained on a 3-Tesla magnetic resonance (MR) system, in four groups aged over 75 years: post-stroke with dementia (PSD; 8), post-stroke no dementia (PSnoD; 33), Alzheimer's disease (AD; 26) and controls (30). Automated software was used to measure the volume of thalamus, putamen, caudate nucleus, and hippocampus as well as total WMH volume. The number of subcortical lacunes was also counted.

RESULTS

The number of caudate lacunes was higher in the PSnoD group, compared with AD (p = 0.029) and controls (p = 0.019). The putamen volume was smaller in the stroke and AD groups, when compared with controls. In the whole stroke group, putamen lacunes were correlated with impairment in memory (Rey test; ρ = -0.365; p = 0.031), while WMH and hippocampal volume both correlated with global dysfunction.

CONCLUSION

Our findings implicate a variety of neurobiological substrates of dementia, such as small vessel disease and Alzheimer pathology, which develop after stroke in an old older population, with a contribution from subcortical brain structures.

Autonomic responses to pain in aging and dementia

Increasing age and dementia are accompanied by an increased risk for undertreatment of pain owing to difficulty in assessing pain. Registration of autonomic responses to pain may contribute to a more reliable pain assessment. The aim of this review was to gain more insight into autonomic responses to pain in older persons with and without dementia. Literature searches were performed in the online databases MEDLINE and Web of Science. Seven studies on autonomic responses to pain in older people with or without dementia were included in the review. Autonomic responses to pain are present in older people with and without dementia, although they may be attenuated. Because no distinction could be made between different dementia subtypes based on these studies, predictions of changes in autonomic responses to pain have been made based on neuropathological changes. It can be concluded that autonomic responses to pain are attenuated in older people with and without dementia. Studies to specify the changes in the different autonomic responses for the different dementia subtypes are needed.

The more physical inactivity, the more agitation in dementia

Epidemiological studies show a close relationship between physical activity and cognition. A causal relationship between physical activity and cognition has been observed in children, adolescents, older people without dementia, and in older people in a very early stage of dementia. Considering these positive effects, we argue that a decline in physical activity has a detrimental effect on cognition and behavior in patients with dementia. Merely living in a nursing home reduces the level of physical activity. The level of physical activity may even be reduced to a minimum when physical restraints are applied. The use of physical restraints coincides with stress, further aggravating the already existing neuropathology, which may increase stress and agitation even more. Exercise may reduce stress and agitation.

Predictors and assessment of cognitive dysfunction resulting from ischaemic stroke

Stroke remains a primary cause of morbidity throughout the world mainly because of its effect on cognition. Individuals can recover from physical disability resulting from stroke, but might be unable to return to their previous occupations or independent life because of cognitive impairments. Cognitive dysfunction ranges from focal deficits, resulting directly from an area of infarction or from hypoperfusion in adjacent tissue, to more global cognitive dysfunction. Global dysfunction is likely to be related to other underlying subclinical cerebrovascular disease, such as white-matter disease or subclinical infarcts. Study of cognitive dysfunction after stroke is complicated by varying definitions and lack of measurement of cognition before stroke. Additionally, stroke can affect white-matter connectivity, so newer imaging techniques, such as diffusion-tensor imaging and magnetisation transfer imaging, that can be used to assess this subclinical injury are important tools in the assessment of cognitive dysfunction after stroke. As research is increasingly focused on the role of preventable risk factors in the development of dementia, the role of stroke in the development of cognitive impairment and dementia could be another target for prevention.

Prevalence of dementia disorders in the oldest-old: an autopsy study

The prevalence of Alzheimer disease (AD) and vascular dementia (VD) increases with advancing age, but less so after age 90 years. A retrospective hospital-based study of the relative prevalence of different disorders was performed in 1,110 consecutive autopsy cases of demented elderly in Vienna, Austria (66% females, MMSE <20; mean age 83.3 +/- 5.4 SD years). It assessed clinical, general autopsy data and neuropathology including immunohistochemistry. Neuropathologic diagnosis followed current consensus criteria. Four age groups (7-10th decade) were evaluated. In the total cohort AD pathology was seen in 82.9% ("pure" AD 42.9%; AD + other pathologies 39.9%), VD in 10.8% (mixed dementia, MIX, i.e. AD + vascular encephalopathy in 5.5%); other disorders in 5.7%, and negative pathology in 0.8%. The relative prevalence of AD increased from age 60 to 89 years and decreased slightly after age 90+, while "pure" VD diagnosed in the presence of vascular encephalopathy of different types with low neuritic AD pathology (Braak stages <3; mean 1.2-1.6) decreased progressively from age 60 to 90+; 85-95% of these patients had histories of diabetes, morphologic signs of hypertension, 65% myocardial infarction/cardiac decompensation, and 75% a history of stroke(s). Morphologic subtypes, subcortical arteriosclerotic (the most frequent), multi-infarct encephalopathy, and strategic infarct dementia showed no age-related differences. The relative prevalence of AD + Lewy pathology remained fairly constant with increasing age. Mixed dementia and AD with minor cerebrovascular lesions increased significantly with age, while other dementias decreased. This retrospective study using strict morphologic criteria confirmed increased prevalence of AD with age, but mild decline at age 90+, and progressive decline of VD, while AD + vascular pathologies including MIX showed considerable age-related increase, confirming that mixed pathologies account for most dementia cases in very old persons. A prospective clinicopathologic study in oldest-old subjects showed a significant increase in both AD and cerebral amyloid angiopathy (CAA), but decrease in VD over age 85, while in a small group of old subjects CAA without considerable AD pathology may be an independent risk factor for cognitive decline.