Medial temporal lobe atrophy in stroke patients: relation to pre-existing dementia

Neuroinflammation in Acute Ischemic and Hemorrhagic Stroke

PURPOSE OF REVIEW

This review aims to provide an overview of neuroinflammation in ischemic and hemorrhagic stroke, including recent findings on the mechanisms and cellular players involved in the inflammatory response to brain injury.

RECENT FINDINGS

Neuroinflammation is a crucial process following acute ischemic stroke (AIS) and hemorrhagic stroke (HS). In AIS, neuroinflammation is initiated within minutes of the ischemia onset and continues for several days. In HS, neuroinflammation is initiated by blood byproducts in the subarachnoid space and/or brain parenchyma. In both cases, neuroinflammation is characterized by the activation of resident immune cells, such as microglia and astrocytes, and infiltration of peripheral immune cells, leading to the release of pro-inflammatory cytokines, chemokines, and reactive oxygen species. These inflammatory mediators contribute to blood-brain barrier disruption, neuronal damage, and cerebral edema, promoting neuronal apoptosis and impairing neuroplasticity, ultimately exacerbating the neurologic deficit. However, neuroinflammation can also have beneficial effects by clearing cellular debris and promoting tissue repair. The role of neuroinflammation in AIS and ICH is complex and multifaceted, and further research is necessary to develop effective therapies that target this process. Intracerebral hemorrhage (ICH) will be the HS subtype addressed in this review. Neuroinflammation is a significant contributor to brain tissue damage following AIS and HS. Understanding the mechanisms and cellular players involved in neuroinflammation is essential for developing effective therapies to reduce secondary injury and improve stroke outcomes. Recent findings have provided new insights into the pathophysiology of neuroinflammation, highlighting the potential for targeting specific cytokines, chemokines, and glial cells as therapeutic strategies.

Temporal lobe atrophy as a potential predictor of functional outcome in older adults with acute ischemic stroke

BACKGROUND

To explore whether temporal lobe atrophy predicts 3-month functional outcome in a population of patients with anterior circulation acute ischemic stroke (AIS) treated with mechanical thrombectomy (MT).

METHODS

We retrospectively selected patients > 65 years from our prospective endovascular stroke registry between June 2013 and August 2018. According to 3-month modified Rankin Scale (mRS), patients were divided in two groups, named good (mRS ≤ 2) and poor (mRS > 2) outcome. Measures of temporal lobe atrophy (i.e., interuncal distance [IUD], medial temporal lobe thickness [mTLT] and radial width of temporal horn [rWTH]) were assessed on pre-treatment CT scan. Cutoff values for good outcome were obtained for IUD, mTLT and rWTH by means of non-parametric ROC curve analysis. Multivariate analysis was performed to identify predictors of outcome. Ordinal shift analysis based on cutoff values was built to evaluate differences in 3-month mRS.

RESULTS

Among 340 patients, 130 (38.2%) had good and 210 (61.8%) had poor outcome. We found the following cutoff values for good outcome: < 25 mm for IUD, > 15 mm for mTLT and < 4 mm for rWTH. Lower IUD (OR 0.71; 95% CI 0.63-0.80; p < 0.0001) and rWTH (OR 0.73; 95% CI 0.61-0.87; p < 0.0001) and higher mTLT (OR 1.30; 95% CI 1.14-1.49; p < 0.0001) were independently associated with good outcome. Ordinal shift analysis based on cutoff values revealed significant differences in the rate of good outcome for rWTH (49 vs 27%; p < 0.0001), mTLT (52 vs 21%; p < 0.0001) and IUD (57 vs 17%; p < 0.0001).

CONCLUSIONS

Assessment of temporal lobe atrophy may predict functional outcome in patients with AIS treated with MT.

APOE ɛ4 Carriers Show Delayed Recovery of Verbal Memory and Smaller Entorhinal Volume in the First Year After Ischemic Stroke

BACKGROUND

The apolipoprotein E (APOE) gene ɛ4 allele is a risk factor for Alzheimer's disease and cardiovascular disease. However, its relationship with cognition and brain volume after stroke is not clear.

OBJECTIVE

We compared cognition and medial temporal lobe volumes in APOEɛ4 carriers and non-carriers in the first year after ischemic stroke.

METHODS

We sampled 20 APOEɛ4 carriers and 20 non-carriers from a larger cohort of 135 ischemic stroke participants in the longitudinal CANVAS study. Participants were matched on a range of demographic and stroke characteristics. We used linear mixed-effect models to compare cognitive domain z-scores (attention, processing speed, executive function, verbal and visual memory, language, visuospatial function) and regional medial temporal lobe volumes (hippocampal, entorhinal cortex) between groups at each time-point (3, 12-months post-stroke), and within groups across time-points. APOE gene single nucleotide polymorphisms (SNPs; rs7412, rs429358) were genotyped on venous blood.

RESULTS

APOEɛ4 carriers and non-carriers did not differ on any demographic, clinical, or stroke variable. Carriers performed worse than non-carriers in verbal memory at 3 months post-stroke (p = 0.046), but were better in executive function at 12 months (p = 0.035). Carriers demonstrated a significant improvement in verbal memory (p = 0.012) and executive function (p = 0.015) between time-points. Non-carriers demonstrated a significant improvement in visual memory (p = 0.0005). Carriers had smaller bilateral entorhinal cortex volumes (p < 0.05), and larger right sided and contralesional hippocampal volumes, at both time-points (p < 0.05).

CONCLUSION

APOE ɛ4 is associated with delayed recovery of verbal memory function and reduced entorhinal cortex volumes in the first year after ischemic stroke.

Cognitive Impairment Before Atrial Fibrillation-Related Ischemic Events: Neuroimaging and Prognostic Associations

Background

It is likely that a proportion of poststroke cognitive impairment is sometimes attributable to unidentified prestroke decline; prestroke cognitive function is also clinically relevant because it is associated with poor functional outcomes, including death. We investigated the radiological and prognostic associations of preexisting cognitive impairment in patients with ischemic stroke or transient ischemic attack associated with atrial fibrillation.

Methods and Results

We included 1102 patients from the prospective multicenter observational CROMIS‐2 (Clinical Relevance of Microbleeds in Stroke 2) atrial fibrillation study. Preexisting cognitive impairment was identified using the 16‐item Informant Questionnaire for Cognitive Decline in the Elderly. Functional outcome was measured using the modified Rankin scale. Preexisting cognitive impairment was common (n=271; 24.6%). The presence of lacunes (odds ratio [OR], 1.50; 95% CI, 1.03–1.05; P=0.034), increasing periventricular white matter hyperintensity grade (per grade increase, OR, 1.38; 95% CI, 1.17–1.63; P<0.0001), deep white matter hyperintensity grade (per grade increase, OR, 1.26; 95% CI, 1.05–1.51; P=0.011), and medial temporal atrophy grade (per grade increase, OR, 1.61; 95% CI, 1.34–1.95; P<0.0001) were independently associated with preexisting cognitive impairment. Preexisting cognitive impairment was associated with poorer functional outcome at 24 months (mRS >2; adjusted OR, 2.43; 95% CI, 1.42–4.20; P=0.001).

Conclusions

Preexisting cognitive impairment in patients with atrial fibrillation–associated ischemic stroke or transient ischemic attack is common, and associated with imaging markers of cerebral small vessel disease and neurodegeneration, as well as with longer‐term functional outcome.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02513316.

The new insights into human brain imaging after stroke

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

Hippocampal Neurodegenerative Pathology in Post-stroke Dementia Compared to Other Dementias and Aging Controls

Neuroimaging evidence from older stroke survivors in Nigeria and Northeast England showed medial temporal lobe atrophy (MTLA) to be independently associated with post-stroke cognitive impairment and dementia. Given the hypothesis ascribing MTLA to neurodegenerative processes, we assessed Alzheimer pathology in the hippocampal formation and entorhinal cortex of autopsied brains from of post-stroke demented and non-demented subjects in comparison with controls and other dementias. We quantified markers of amyloid β (total Aβ, Aβ-40, Aβ-42, and soluble Aβ) and hyperphosphorylated tau in the hippocampal formation and entorhinal cortex of 94 subjects consisting of normal controls (n = 12), vascular dementia, VaD (17), post-stroke demented, PSD (n = 15), and post-stroke non-demented, PSND (n = 23), Alzheimer's disease, AD (n = 14), and mixed AD and vascular dementia, AD_VAD (n = 13) using immunohistochemical techniques. We found differential expression of amyloid and tau across the disease groups, and across hippocampal sub-regions. Among amyloid markers, the pattern of Aβ-42 immunoreactivity was similar to that of total Aβ. Tau immunoreactivity showed highest expression in the AD and mixed AD and vascular dementia, AD_VaD, which was higher than in control, post - stroke and VaD groups (p < 0.05). APOE ε4 allele positivity was associated with higher expression of amyloid and tau pathology in the subiculum and entorhinal cortex of post-stroke cases (p < 0.05). Comparison between PSND and PSD revealed higher total Aβ immunoreactivity in PSND compared to PSD in the CA1, subiculum and entorhinal cortex (p < 0.05) but no differences between PSND and PSD in Aβ-42, Aβ-40, soluble Aβ or tau immunoreactivities (p > 0.05). Correlation of MMSE and CAMCOG scores with AD pathological measures showed lack of correlation with amyloid species although tau immunoreactivity demonstrated correlation with memory scores (p < 0.05). Our findings suggest hippocampal AD pathology does not necessarily differ between demented and non-demented post-stroke subjects. The dissociation of cognitive performance with hippocampal AD pathological burden suggests more dominant roles for non-Alzheimer neurodegenerative and / or other non-neurodegenerative substrates for dementia following stroke.

Stroke occurring in patients with cognitive impairment or dementia

Objective

To determine how pre-stroke cognitive impairment can be detected, its mechanism, and influence on outcome and management.

Methods

Literature search.

Results

(i) A systematic approach with the Informant Questionnaire of Cognitive Decline in the Elderly is recommended; (ii) Pre-stroke cognitive impairment may be due to brain lesions of vascular, degenerative, or mixed origin; (iii) Patients with pre-stroke dementia, have worse outcomes, more seizures, delirium, and depression, and higher mortality rates; they often need to be institutionalised after their stroke; (iv) Although the safety profile of treatment is not as good as that of cognitively normal patients, the risk:benefit ratio is in favour of treating these patients like others.

Conclusion

Patients with cognitive impairment who develop a stroke have worse outcomes, but should be treated like others.

Cerebral small vessel disease, medial temporal lobe atrophy and cognitive status in patients with ischaemic stroke and transient ischaemic attack

BACKGROUND AND PURPOSE

Small vessel disease (SVD) and Alzheimer's disease (AD) are two common causes of cognitive impairment and dementia, traditionally considered as distinct processes. The relationship between radiological features suggestive of AD and SVD was explored, and the association of each of these features with cognitive status at 1 year was investigated in patients with stroke or transient ischaemic attack.

METHODS

Anonymized data were accessed from the Virtual International Stroke Trials Archive (VISTA). Medial temporal lobe atrophy (MTA; a marker of AD) and markers of SVD were rated using validated ordinal visual scales. Cognitive status was evaluated with the Mini Mental State Examination (MMSE) 1 year after the index stroke. Logistic regression models were used to investigate independent associations between (i) baseline SVD features and MTA and (ii) all baseline neuroimaging features and cognitive status 1 year post-stroke.

RESULTS

In all, 234 patients were included, mean (±SD) age 65.7 ± 13.1 years, 145 (62%) male. Moderate to severe MTA was present in 104 (44%) patients. SVD features were independently associated with MTA (P < 0.001). After adjusting for age, sex, disability after stroke, hypertension and diabetes mellitus, MTA was the only radiological feature independently associated with cognitive impairment, defined using thresholds of MMSE ≤ 26 (odds ratio 1.94; 95% confidence interval 1.28-2.94) and MMSE ≤ 23 (odds ratio 2.31; 95% confidence interval 1.48-3.62).

CONCLUSION

In patients with ischaemic cerebrovascular disease, SVD features are associated with MTA, which is a common finding in stroke survivors. SVD and AD type neurodegeneration coexist, but the AD marker MTA, rather than SVD markers, is associated with post-stroke cognitive impairment.

The Combined Effect of Neuropsychological and Neuropathological Deficits on Instrumental Activities of Daily Living in Older Adults: a Systematic Review

To date, studies have consistently demonstrated associations between either neuropsychological deficits or neuroanatomical changes and instrumental activities of daily living (IADL) in aging. Only a limited number of studies have evaluated morphological brain changes and neuropsychological test performance concurrently in relation to IADL in this population. As a result, it remains largely unknown whether these factors independently predict functional outcome. The current systematic review intended to address this lack of information by reviewing the literature on older adults, incorporating studies that examined e.g., normal aging, but also stroke or dementia patients. A comprehensive search of databases (Pubmed, Embase, Medline, Web of Science, PsycINFO) and reference lists was performed, focusing on papers in the English language that examined the combined effect of neuropsychological and neuroanatomical factors on IADL in samples of adults with an average age above 50. In total, 58 potential articles were identified; 20 were included in the review. The results show that especially neuropsychological variables (primarily memory and executive functions) independently predict IADL. Although some unique predictive value of brain morphological changes, such as hippocampal atrophy, was found, support for the importance of white matter changes was limited. However, the results of the studies reviewed are diverse, and appear to be at least partially determined by the variables included. For example, studies were less likely to find an independent effect of cognition if they solely employed a cognitive screening instrument. This indicates that a structured examination of neuroanatomical and neuropsychological correlates of IADL in different patient populations is warranted.

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.

Ipsilateral hippocampal atrophy is associated with long-term memory dysfunction after ischemic stroke in young adults

Memory impairment after stroke in young adults is poorly understood. In elderly stroke survivors memory impairments and the concomitant loss of hippocampal volume are usually explained by coexisting neurodegenerative disease (e.g., amyloid pathology) in interaction with stroke. However, neurodegenerative disease, such as amyloid pathology, is generally absent at young age. Accumulating evidence suggests that infarction itself may cause secondary neurodegeneration in remote areas. Therefore, we investigated the relation between long-term memory performance and hippocampal volume in young patients with first-ever ischemic stroke. We studied all consecutive first-ever ischemic stroke patients, aged 18-50 years, admitted to our academic hospital center between 1980 and 2010. Episodic memory of 173 patients was assessed using the Rey Auditory Verbal Learning Test and the Rey Complex Figure and compared with 87 stroke-free controls. Hippocampal volume was determined using FSL-FIRST, with manual correction. On average 10 years after stroke, patients had smaller ipsilateral hippocampal volumes compared with controls after left-hemispheric stroke (5.4%) and right-hemispheric stroke (7.7%), with most apparent memory dysfunctioning after left-hemispheric stroke. A larger hemispheric stroke was associated with a smaller ipsilateral hippocampal volume (b=-0.003, P<0.0001). Longer follow-up duration was associated with smaller ipsilateral hippocampal volume after left-hemispheric stroke (b=-0.028 ml, P=0.002) and right-hemispheric stroke (b=-0.015 ml, P=0.03). Our results suggest that infarction is associated with remote injury to the hippocampus, which may lower or expedite the threshold for cognitive impairment or even dementia later in life.

Prevalence and cognitive impact of medial temporal atrophy in a hospital stroke service: retrospective cohort study

BACKGROUND

Cerebrovascular disease and neurodegeneration cause cognitive impairment and frequently coexist.

AIMS

Our objectives were to investigate the prevalence and cognitive impact of medial temporal lobe atrophy - a radiological marker often associated with Alzheimer's disease - in a hospital stroke service.

METHODS

Retrospective cohort study of patients from a hospital stroke service. Patients assessed for suspected ischemic stroke or transient ischemic attack, irrespective of final diagnosis, underwent neuropsychological testing and magnetic resonance imaging. medial temporal lobe atrophy, white matter hyperintensities, lacunes, and cerebral microbleeds were rated using established criteria and validated scales. The associations between medial temporal lobe atrophy and cognition were tested using multivariable logistic regression analyses, adjusted for age and imaging markers of cerebrovascular disease.

RESULTS

Three hundred and ninety-three patients were included, of whom 169 (43%; 95% confidence interval: 38·1-48·1%) had medial temporal lobe atrophy; in 38 patients (9·7%), medial temporal lobe atrophy was severe (mean score ≥2). In unadjusted logistic regression analyses in the whole cohort, mean medial temporal lobe atrophy score was associated with verbal memory, nominal and perceptual skills, executive function, and speed and attention. After adjustment for age, white matter hyperintensities, number of lacunes, presence of cerebral microbleeds, previous ischemic stroke or transient ischemic attack, and premorbid intelligence quotient, mean medial temporal lobe atrophy score remained associated with impairment in verbal memory (odds ratio: 1·64; 95% confidence interval 1·04-2·58) and nominal skills (odds ratio: 1·61; 95% confidence interval 1·04-2·48).

CONCLUSIONS

Medial temporal lobe atrophy is common and has an independent impact on cognitive function in a stroke service population, independent of confounding factors including age and magnetic resonance imaging markers of cerebrovascular disease. Medial temporal lobe atrophy is independently related to verbal memory and nominal skills, while small vessel pathology also contributes to speed and attention, and executive and perceptual functions.

Profile and determinants of vascular cognitive impairment in African stroke survivors: the CogFAST Nigeria Study

OBJECTIVE

Sub-Saharan Africa faces a potential epidemic of non-communicable diseases including stroke and dementia but little is known about the burden of stroke-related cognitive dysfunction. We assessed the baseline profile and factors associated with vascular cognitive impairment (VCI) in stroke survivors participating in the Cognitive Function After STroke (CogFAST) Nigeria Study.

METHODS

We recruited 217 subjects (>45 years old) comprising 143 stroke survivors and 74 demographically matched stroke-free healthy controls. We obtained demographic, clinical and lifestyle information and assessed the cognitive status of the subjects at baseline three months after stroke. Standard neuropsychological tests included the Vascular Neuropsychological Battery, which assessed executive function/mental speed, memory, language, and visuospatial/visuoconstructive functioning. Cognitive impairment and dementia were defined based on the AHA/ASA VCI guidelines and the DSM IV criteria.

RESULTS

Among the stroke survivors (mean ag e= 60.4+9.5 years, 43.4% female, mean number of years of education = 9.4+5.6 years, median modified Rankin score = 2), 57 (39.9%) had cognitive impairment no dementia while 12 (8.4%) were demented at baseline. Multivariate analysis revealed that older age [OR = 1.05 (1.00-1.09)], low education [OR = 5.09 (2.17-11.95)], pre-stroke cognitive decline [OR = 4.51 (1.20-16.88)] and medial temporal lobe atrophy [OR = 2.25 (1.16-4.35)] were independently associated with cognitive dysfunction whereas pre-stroke daily intake of fish [p = 0.022, OR = 0.39 (0.15-0.89)] was inversely associated.

CONCLUSIONS

These results suggest a high frequency of early VCI in older Nigerian stroke survivors. Apart from aging, associated neurodegeneration and cognitive decline, educational level and pre-stroke diet particularly fish consumption were identified as modifiable factors. This emphasizes the vital role of education and healthy nutrition in building reserves to ameliorate cognitive dysfunction after stroke.

The association between brain volumes, delirium duration, and cognitive outcomes in intensive care unit survivors: the VISIONS cohort magnetic resonance imaging study*

OBJECTIVE

Delirium duration is predictive of long-term cognitive impairment in intensive care unit survivors. Hypothesizing that a neuroanatomical basis may exist for the relationship between delirium and long-term cognitive impairment, we conducted this exploratory investigation of the associations between delirium duration, brain volumes, and long-term cognitive impairment.

DESIGN, SETTING, AND PATIENTS

A prospective cohort of medical and surgical intensive care unit survivors with respiratory failure or shock.

MEASUREMENTS

Quantitative high resolution 3-Tesla brain magnetic resonance imaging was used to calculate brain volumes at discharge and 3-month follow-up. Delirium was evaluated using the confusion assessment method for the intensive care unit; cognitive outcomes were tested at 3- and 12-month follow-up. Linear regression was used to examine associations between delirium duration and brain volumes, and between brain volumes and cognitive outcomes.

RESULTS

A total of 47 patients completed the magnetic resonance imaging protocol. Patients with longer duration of delirium displayed greater brain atrophy as measured by a larger ventricle-to-brain ratio at hospital discharge (0.76, 95% confidence intervals [0.10, 1.41]; p = .03) and at 3-month follow-up (0.62 [0.02, 1.21], p = .05). Longer duration of delirium was associated with smaller superior frontal lobe (-2.11 cm(3) [-3.89, -0.32]; p = .03) and hippocampal volumes at discharge (-0.58 cm(3) [-0.85, -0.31], p < .001)--regions responsible for executive functioning and memory, respectively. Greater brain atrophy (higher ventricle-to-brain ratio) at 3 months was associated with worse cognitive performances at 12 months (lower Repeatable Battery for the Assessment of Neuropsychological Status score -11.17 [-21.12, -1.22], p = .04). Smaller superior frontal lobes, thalamus, and cerebellar volumes at 3 months were associated with worse executive functioning and visual attention at 12 months.

CONCLUSIONS

These preliminary data show that longer duration of delirium is associated with smaller brain volumes up to 3 months after discharge, and that smaller brain volumes are associated with long-term cognitive impairment up to 12 months. We cannot, however, rule out that smaller preexisting brain volumes explain these findings.

Medial temporal atrophy and memory dysfunction in poststroke cognitive impairment-no dementia

Background and Purpose

It was recently reported that the prevalence of poststroke memory dysfunction might be higher than previously thought. Stroke may exist concomitantly with underlying Alzheimer's disease (AD), and so we determined whether post-stroke memory dysfunction indicates manifestation of underlying subclinical AD.

Methods

Of 1201 patients in a prospective cognitive assessment database, we enrolled subjects with poststroke amnestic vascular cognitive impairment-no dementia (aVCIND; n=48), poststroke nonamnestic vascular cognitive impairment-no dementia (naVCIND; n=50), and nonstroke amnestic mild cognitive impairment (aMCI; n=65). All subjects had cognitive deficits, but did not meet the criteria for dementia. A standardized neuropsychological test battery and magnetic resonance imaging were performed at least 90 days after the index stroke (mean, 473 days). Visual assessment of medial temporal atrophy (MTA) was used as a measure of underlying AD pathology.

Results

The MTA score was significantly lower in the naVCIND group (0.64±0.85, mean±SD) than in the aVCIND (1.10±1.08) and aMCI (1.45±1.13; p<0.01) groups. Multivariable ordinal logistic regression analysis revealed that compared with naVCIND, aVCIND [odds ratio (OR)=2.69; 95% confidence interval (CI)=1.21-5.99] and aMCI (OR=5.20; 95% CI=2.41-11.23) were significantly associated with increasing severity of MTA.

Conclusions

Our findings show that compared with poststroke naVCIND, the odds of having more-severe MTA were increased for poststroke aVCIND and nonstroke aMCI.

Vascular basis for brain degeneration: faltering controls and risk factors for dementia

The integrity of the vascular system is essential for the efficient functioning of the brain. Aging-related structural and functional disturbances in the macro- or microcirculation of the brain make it vulnerable to cognitive dysfunction, leading to brain degeneration and dementing illness. Several faltering controls, including impairment in autoregulation, neurovascular coupling, blood-brain barrier leakage, decreased cerebrospinal fluid, and reduced vascular tone, appear to be responsible for varying degrees of neurodegeneration in old age. There is ample evidence to indicate vascular risk factors are also linked to neurodegenerative processes preceding cognitive decline and dementia. The strongest risk factor for brain degeneration, whether it results from vascular or neurodegenerative mechanisms or both, is age. However, several modifiable risks such as cardiovascular disease, hypertension, dyslipidemia, diabetes, and obesity enhance the rate of cognitive decline and increase the risk of Alzheimer's disease in particular. The ultimate accumulation of brain pathological lesions may be modified by genetic influences, such as the apolipoprotein E ε4 allele and the environment. Lifestyle measures that maintain or improve cardiovascular health, including consumption of healthy diets, moderate use of alcohol, and implementation of regular physical exercise are important factors for brain protection.

Functional correlates of instrumental activities of daily living in mild Alzheimer's disease

Instrumental activities of daily living (IADL) includes the integration of task-initiation, -planning, and -performance. Little is known on the cerebral perfusion correlates of these subcomponents of IADL in Alzheimer's disease (AD). In 121 AD patients, cerebral perfusion, using single-photon emission computed tomography, in 13 bilateral regions of interest (ROI) and the perfusion correlates of IADL subcomponents, rated on the Disability Assessment in Dementia scale, were explored. Significant correlations were observed between IADL initiation and multiple bilateral prefrontal-striatal-anterior cingulate ROI (p < 0.01), IADL planning and right occipital ROI (p < 0.05), and IADL performance and right parietal ROI (p < 0.05). Multiple regression, accounting for age, cognitive impairment, and depression severity, revealed significant relationship between right basal ganglia perfusion and IADL-initiation (R = 0.6, R(2) = 0.39, F(4,117) = 17.8, SE = 1.56; p < 0.001) and right occipital perfusion and IADL-planning (R = 0.6, R(2) = 0.34, F(4,117) = 19.5, SE = 1.47; p < 0.001). In AD, perfusion correlates of these subcomponents may be linked to the heterogenous cognitive processes involved in IADL.

Relationship between lesion location and cognitive domains in acute ischemic stroke patients

Localization of brain lesions in acute ischemic stroke has a significant effect on performance in various cognitive domains. The aim of the study was to determine whether there is association between different locations of ischemic brain lesions and different cognitive domains. The study included 40 acute ischemic stroke patients (26 male and 14 female, aged 45-78 years, with 8-16 years of education). Lesion location was visualized using brain computerized tomography, whereas performance in different cognitive domains was assessed using an extensive neuropsychological test battery. The following domains were evaluated: executive function, language, immediate recall, delayed recall, attention, divergent reasoning, and visual-constructive performance in two dimensions. A series of categorical regression analyses were applied. The results showed a significant association between the domains of executive function and language and a set of predictors related to lesion location. Global brain atrophy was found to be a significant partial predictor of performance in all cognitive domains, with higher degrees of global brain atrophy correlating with poorer performance in each of the studied domains. Combined (cortical-subcortical) lesions and unilateral lesions were both found to be significant partial predictors for language, with a higher lesion load being associated with poorer language performance. Combined lesions were also a significant partial predictor for delayed recall, with a higher lesion load correlating with poorer performance in the delayed recall domain.

Medial temporal lobe atrophy in vascular dementia: visual temporal lobe rating scale

Medial temporal lobe atrophy (MTA) as assessed by magnetic resonance imaging (MRI) can be measured in several ways. First of all, visual rating scale is a quick and easy measurement. MTA is a sensitive marker for Alzheimer's disease (AD), but not specific. It has been documented in other dementias including vascular dementia (VD). This study is to evaluate the degree of MTA in VD patients using a standardized visual rating scale and to suggest the importance of the possible role of MTA in VD. Twenty-five VD, 33 AD and 27 non-demented patients underwent a coronal three-dimensional magnetization prepared rapid gradient echo brain MRI sequence. MTA was rated visually using a 5-point rating scale from 0 (no atrophy) to 4 (severe atrophy). The mean summed MTA score was 5.39 in AD, 2.16 in VD and 0.56 in non-demented patients. Most of the VD patients (80%) showed MTA. They were greater in bilateral sides compared with the non-demented group, but milder than in AD. Additionally, MTA of left side score was significantly associated with age. Medial temporal lobe volumes measured visually are smaller in size in patients with VD, although not to the same extent as in AD. This suggests that MTA in VD patients may be associated with pre-existing AD.

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

BACKGROUND

Hippocampal atrophy is an early feature of Alzheimer's disease (AD) but it has also been reported in vascular dementia (VaD). It is uncertain whether hippocampal size can help differentiate the two disorders.

METHODS

We assessed 90 stroke/TIA patients 3-6 months after the event, and 75 control subjects, with neuropsychological tests, medical and psychiatric examination and brain MRI scans. A diagnosis of VaD, vascular mild cognitive impairment (VaMCI) or no cognitive impairment (NCI) was reached by consensus on agreed criteria. T1-weighted MRI was used to obtain total intracranial volume (TICV), gray and white matter volume, CSF volume, hippocampus and amygdala volumes, and T2-weighted scans for white matter hyperintensity (WMH) ratings.

RESULTS

Stroke/TIA patients had more white matter hyperintensities (WMHs), larger ventricle-to-brain ratios and smaller amygdalae than controls, but hippocampus size and gray and white matter volumes were not different. WMHs and amygdala but not hippocampal volume distinguished stroke/TIA patients with VaD and VaMCI and without NCI and amygdala volumes. Right hippocampus volume significantly correlated with new visual learning.

CONCLUSIONS

Stroke/TIA patients and patients with post-stroke VaMCI or mild VaD do not have hippocampal atrophy. The amygdala is smaller in stroke/TIA patients, especially in those with cognitive impairment, and this may be accounted for by white matter lesions. The hippocampus volume relates to episodic memory, especially right hippocampus and new visual learning. A longitudinal study of these subjects will determine whether hippocampal atrophy is a late development in VaD.

Influence of cognitive impairment on the institutionalisation rate 3 years after a stroke

BACKGROUND AND PURPOSE

Pre-existing cognitive decline and new-onset dementia are common in patients with stroke, but their influence on institutionalisation rates is unknown.

OBJECTIVE

To evaluate the influence of cognitive impairment on the institutionalisation rate 3 years after a stroke.

DESIGN

(1) The previous cognitive state of 192 consecutive patients with stroke living at home before the stroke (with the Informant Questionnaire on COgnitive Decline in the Elderly (IQCODE)), (2) new-onset dementia occurring within 3 years and (3) institutionalisation rates within 3 years in the 165 patients who were discharged alive after the acute stage were prospectively evaluated.

RESULTS

Independent predictors of institutionalisation over a 3-year period that were available at admission were age (adjusted odds ratio (adjOR) for 1-year increase = 1.08; 95% confidence interval (CI) 1.03 to 1.15), severity of the neurological deficit (adjOR for 1-point increase in Orgogozo score = 0.97; 95% CI 0.96 to 0.99) and severity of cognitive impairment (adjOR for 1-point increase in IQCODE score = 1.03; 95% CI 1 to 1.06). Factors associated with institutionalisation at 3 years that were present at admission or occurred during the follow-up were age (adjOR for 1-year increase = 1.17; 95% CI 1.07 to 1.27) and any (pre-existing or new) dementia (adjOR = 5.85; 95% CI 1.59 to 21.59), but not the severity of the deficit of the neurological deficit.

CONCLUSION

Age and cognitive impairment are more important predictors of institutionalisation 3 years after a stroke than the severity of the physical disability.

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.

Épidémiologie de la maladie d’Alzheimer et des syndromes apparentés

Alzheimer's disease and related disorders (dementia) are a major public health problem due to the number of cases in the general population, the projections for the future, and the consequences of these diseases. We can estimate that about 850 000 cases of dementia were present in France in 2005 and this number will increase to 1,200,000 in 2020 and 2,100,000 in 2040 if the incidence and the duration of the disease did not change. The development of prevention is therefore necessary. Four ways of prevention are credible. The most important is the treatment of vascular risk factors and particularly hypertension. Other ways are nutritional factors, stimulating leisure activities and depression.

Pathological aging of the brain: an overview

The number of elderly people is increasing rapidly and, therefore, an increase in neurodegenerative and cerebrovascular disorders causing dementia is expected. Alzheimer disease (AD) is the most common cause of dementia. Vascular dementia, dementia with Lewy bodies, and frontotemporal dementia are the most frequent causes after AD, but a large proportion of patients have a combination of degenerative and vascular brain pathology. Characteristic magnetic resonance (MR) imaging findings can contribute to the identification of different diseases causing dementia. The MR imaging protocol should include axial T2-weighted images (T2-WI), axial fluid-attenuated inversion recovery (FLAIR) or proton density-weighted images, and axial gradient-echo T2*-weighted images, for the detection of cerebrovascular pathology. Structural neuroimaging in dementia is focused on detection of brain atrophy, especially in the medial temporal lobe, for which coronal high resolution T1-weighted images perpendicular to the long axis of the temporal lobe are extremely important. Single photon emission computed tomography and positron emission tomography may have added value in the diagnosis of dementia and may become more important in the future, due to the development of radioligands for in vivo detection of AD pathology. New functional MR techniques and serial volumetric imaging studies to identify subtle brain abnormalities may also provide surrogate markers for pathologic processes that occur in diseases causing dementia and, in conjunction with clinical evaluation, may enable a more rigorous and early diagnosis, approaching the accuracy of neuropathology.

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.

Medial temporal lobe atrophy and memory deficits in elderly stroke patients

Medial temporal lobe atrophy (MTA) and its role in memory deficits have been studied extensively in patients with various dementias and non-degenerative neurologic diseases. In stroke patients MTA is a significant risk factor for dementia. However, its role in memory decline in non-demented stroke patients is not yet known. Our aim was to evaluate the relationship between MTA and cognitive functions in a large cohort of elderly patients, who underwent a comprehensive neuropsychologic examination and magnetic resonance imaging 3 months after an ischemic stroke. The study sample (n = 260) was divided into three groups according to the severity of MTA. After adjusting for age, volume of infarcts and cortical atrophy, we found that patients with moderate to severe MTA performed significantly worse in tests of learning, story recall, visual reproduction, block design and mental speed. In contrast, the groups did not differ in tests of digit span, flexibility, verbal fluency and conceptualization. Our conclusion is that in aged stroke patients, MTA is associated with poor performance in specific cognitive domains. The most vulnerable domains are memory and visuospatial functions, whereas verbal and executive functions seem to be unrelated to MTA.

Poststroke Dementia in the Elderly

Risk of dementia increases after stroke, and poststroke dementia (PSD) is an important cause of disability in the elderly. The prevalence rates of PSD vary from 12.2% to 31.8% within 3 months to 1 year after stroke, depending on patient populations and the diagnostic criteria used in the numerous studies. Incidence rates of PSD increase with time after the stroke. Although vascular lesions and white matter changes can explain the cognitive disorders seen in stroke patients, an underlying neurodegenerative disorder may contribute to the development of PSD. Cognitive decline may pre-date the stroke and follow a progressive course after the stroke. The vascular and degenerative processes involved share common environmental and genetic risk factors. This review explains the mechanisms of dementia in stroke patients and identifies predictive factors for PSD. The following points are successively considered: (i) demographic characteristics of the patients, including age and level of education; (ii) prestroke cognitive decline; (iii) vascular risk factors, including diabetes mellitus and prior strokes; (iv) stroke characteristics, including severity and location of the vascular lesion; (v) co-morbid disorders; and (vi) abnormalities on brain imaging, including location, size and number of vascular lesions, white matter changes and cerebral atrophy. Older age, prestroke cognitive decline, stroke recurrence, hypoxic-ischaemic disorders, left-side infarcts, strategic infarcts and white matter lesions appear to be the main predictive factors of PSD. Prevention of stroke should reduce the morbidity and mortality associated with PSD. In addition, management of PSD with secondary prevention treatments could reduce occurrence of further strokes. Cholinesterase inhibitors may be beneficial not only in Alzheimer's disease associated with cerebrovascular lesions, but also for the treatment of cholinergic dysfunction arising from pure vascular dementia. Better knowledge of the risk factors for PSD, including environmental and genetic factors, should increase the effectiveness of preventive strategies in patients with this condition.

Demographic and CT scan features related to cognitive impairment in the first year after stroke

OBJECTIVE

Little is known about the relation between stroke related features and cognitive performance over time when stroke patients with dementia or less severe cognitive disorders are considered separately. We aimed to study the features (computed tomography (CT) scan and demographic) that could be related to vascular cognitive impairment one, six, and 12 months after stroke.

METHODS

A total of 176 patients with a first-ever brain infarct, a Mini Mental State Examination score > or = 15, age older than 40 years, and without pre-stroke dementia and other neurological or psychiatric disorders participated in this study. The following CT scan features were recorded: side of infarct, lacunar or territorial infarct, white matter lesions, silent infarcts, and brain atrophy. The demographic features studied were: age, level of education, and sex. Univariate and multivariate logistic regression analyses were performed to compare the three groups of patients (patients with dementia, patients with vascular cognitive impairment (VCI), and patients with vascular mild cognitive impairment (MCI)) with patients without cognitive disorders.

RESULTS

At one month none of the variables were predictors of dementia; at six months older age (odds ratio (OR) 9.4), low education (OR 14.7), and territorial infarct (OR 10.6) predicted dementia; and at 12 months low education (OR 8.7) and pre-stroke cerebrovascular damage (OR 7.4) predicted dementia. Predictors of VCI were low education (OR 3.4) and territorial infarct (OR 2.4) at one month post stroke; older age (OR 4.3) and low education (OR 4.1) at six months; and older age (OR 3.5) at 12 months. Predictors of vascular MCI were low education (OR 4.96) and territorial infarct (OR 3.58) at one month; and older age and lower education at six months (OR 3.4 and 3.7, respectively) and at 12 months (OR 3.5 and 2.28, respectively).

CONCLUSIONS

Territorial infarct, older age, and low educational level are predictors of cognitive disorders after stroke.

Everyday functioning in relation to cognitive functioning and neuroimaging in community-dwelling Hispanic and non-Hispanic older adults

The purpose of this study was to examine how a specific informant-based measure of everyday functioning, the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE; Jorm & Korten, 1988) relates to cognition and structural neuroimaging in a large multicultural, multilingual sample of Caucasians and Hispanics. Cognitive variables included selected subtests from the Spanish and English Neuropsychological Assessment Scales (SENAS; Mungas et al., 2000): Verbal Memory, Object Naming, Verbal Attention Span, Verbal Conceptual Thinking, and Pattern Recognition. The association between the IQCODE and selected neuroimaging variables, hippocampal volume and white matter hyperintensity, was evaluated in a subsample of English- and Spanish-speaking Hispanic individuals. The cognitive variables showed strong bivariate relationships with the IQCODE, although only Verbal Memory and Object Naming independently predicted level of functional ability. Verbal Memory was the strongest predictor of functional status, accounting for 23% of the variance in the IQCODE. White matter hyperintensity was also independently related to the IQCODE, accounting for 18% of the variance. Hippocampal volume was related to the IQCODE in a simple bivariate analysis, but was not an independent predictor of reported functional status after controlling for age. The relationships between cognitive variables and functional status, as well as between the imaging variables and the IQCODE, did not differ across language-ethnic groups.

Frequency and Determinants of Poststroke Dementia in Chinese

BACKGROUND AND PURPOSE

Both dementia and stroke are major health problems in Chinese societies. Stroke is a frequent cause of dementia. Only a few studies have been published on poststroke dementia (PSDE), none of which has investigated a consecutive stroke cohort in Asian patient populations. The objective of this study was to examine the prevalence and clinical correlates of PSDE in Chinese stroke patients in Hong Kong.

METHODS

Two hundred eighty stroke patients consecutively admitted to the medical wards of a university-affiliated regional hospital were interviewed by a psychiatrist 3 months after stroke. The presence of dementia and vascular dementia was diagnosed according to the Diagnostic and Statistical Manual, 4th edition. In addition, a wide range of demographic and clinical variables were examined.

RESULTS

Fifty-five participants (20%) had PSDE. Univariate analysis found that PSDE was associated with age; level of education; prestroke Rankin Scale score; prestroke Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) score; National Institutes of Health Stroke Scale (NIHSS) best language score, dysarthria score, and total score; urinary incontinence; cortical infarct; leukoaraiosis; bilateral lesions; number of lesions; involvement of middle cerebral artery circulation; and cerebral atrophy index. Multivariate logistic regression suggested that prestroke IQCODE score, NIHSS total score, leukoaraiosis, involvement of middle cerebral artery territory, and cerebral atrophy index were independent risk factors of PSDE. After removal of 22 patients with prestroke dementia, which was defined as a prestroke IQCODE score > or =4.0, the frequency of PSDE dropped to 15.5%. Furthermore, involvement of the middle cerebral artery territory and cerebral atrophy index were replaced by level of education and bilateral lesions as independent predictors in the final logistic model.

CONCLUSIONS

PSDE is common among Chinese stroke patients in Hong Kong. Its frequency is comparable to that in white populations. The clinical determinants of PSDE, after the exclusion of patients with prestroke dementia, include premorbid level of cognitive function, severity of stroke, leukoaraiosis, level of education, and bilateral lesions.

Can IQCODE detect poststroke dementia?

BACKGROUND

Little is known about the performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) in the screening of post-stroke dementia (PSDE).

METHODS

At 3 months after the index stroke, a research assistant administered the IQCODE to relatives of 189 Chinese patients with acute stroke who were consecutively admitted to a general hospital. A psychiatrist, who was blind to the IQCODE scores, interviewed all 189 patients and made DSM-IV diagnosis of dementia, which served as the benchmark for judging the performance of IQCODE in screening PSDE.

RESULTS

The optimal cut-off point of IQCODE was 3.40. The sensitivity, specificity, and positive and negative predictive values of IQCODE, and the area under the receiver operating characteristic curve, were 88%, 75%, 33%, 98%, and 0.88, respectively.

CONCLUSIONS

When used as a sole instrument, IQCODE does not appear to be useful in screening PSDE in Chinese elderly.

Neuroimaging predictors of dementia in stroke patients

The risk of dementia is increased in stroke patients. Dementia syndromes associated with cerebrovascular diseases were commonly recognized as an immediate consequence of stroke. However, more and more data suggest that degenerative pathology and white matter changes (WMC) may play a role in the development of dementia in stroke patients. The aim of this paper was to review the literature concerning the neuroimaging predictors of dementia in stroke patients. From the literature data, it appears that although vascular lesions alone may lead to dementia, in stroke patients, no clear association between stroke location and size has yet been identified, even if the role of the left hemisphere has been suggested. The influence of silent infarcts remains undetermined while more and more data suggest that global cerebral atrophy and WMC are predictive factors of post-stroke dementia (PSD). The influence of medial temporal lobe atrophy on the risk of PSD has until now never been evaluated.

Stroke and cognition

Several studies confirm cognitive impairment and dementia to be increased after stroke in the elderly. Although not necessarily involving memory deficits, the frequency of cognitive impairments may occur in up to 30% of stroke survivors at 3 months. This impairment may be confounded by preexisting cognitive decline or dementia. By contrast, cognitive changes and dementia are widely recognized in familial forms of stroke, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Several factors, including type of stroke, recurrent episodes, the site and laterality of the lesion(s), volume of cerebral infarction, medial temporal lobe atrophy, and coexistent neurodegenerative pathology predict the degree of impairment. Aphasia, diabetes mellitus, atrial fibrillation, and depression are listed among other biologic factors that further exacerbate cognition and affect long-term survival. There is no clear consensus whether genetic factors, such as the apolipoprotein E e4 allele or angiotensin converting enzyme gene polymorphisms, modify cognitive changes or stroke outcome. Although several neurotransmitter systems may be affected in post-stroke dementia, the amelioration of cholinergic function is a worthy target.

Synaptic deprivation and age-related vulnerability to hypoxic-ischemic neuronal injury. A hypothesis

Advanced age is associated with physiological changes, such as cerebral autoregulation dysfunction, atrial fibrillation, reduced cerebral blood flow, elevated blood pressure, and other changes. Stroke-related dementia is associated with brain loss principally due to strokes, and neuropathological examination of the brains of old people shows a direct correlation between the extent of brain loss and dementia. However, the exact mechanism of the age related vulnerability to hypoxic-ischemic neuronal injury remains unknown. The majority of synapses in the brain use excitatory amino acids as their neurotransmitter. Glutamate, a major endogenous excitatory amino acid required for normal physiological excitation, is also involved in the pathophysiology of hypoxic-ischemic neuronal injury. The N-methyl-D-aspartate (NMDA) glutamate receptor subtype plays a major role in mediating hypoxic-ischemic neuronal injury. NMDA receptors also mediate adaptive responses important for synaptic plasticity. This report explores the possible role of synaptic activity as a protective mechanism against neuronal cell death. Specifically, the role of NMDA receptors in neuronal plasticity by upregulating a survival pathway is discussed. Loss of a neuronal population that uses glutamate as its neurotransmitter leads to a loss of activity on the postsynaptic neurons or synaptic deprivation. Deprivation of excitatory amino acids on the postsynaptic neurons results in the failure of activity-dependent induced intrinsic survival pathways induced by NMDA receptors. The loss of neuroprotective intrinsic survival pathways increases the vulnerability of these neurons to more hypoxic-ischemic neuronal damage. Since cerebral infarction is also age related, this hypothesis provides a plausible explanation of how we become more vulnerable to hypoxic-ischemic neuronal injury as a function of age.

How can cerebral infarcts and hemorrhages lead to dementia?

The incidence of new onset dementias is increased after stroke. The objective of this review is to investigate how cerebral infarcts and hemorrhages can lead to dementia. Stroke subtypes, total volume of cerebral lesion and functional tissue loss, and location of the lesions are the major determinant of dementia in stroke patients. The causal relationship between stroke and dementia is clear: (1) in young patients who are unlikely to have associated Alzheimer pathology; (2) when the cognitive functioning was normal before stroke, impaired immediately after, and does not worsen over time; (3) when the lesions are located in strategic areas; and (4) when a well-defined vasculopathy known to be associated with dementia is proven. However, white matter changes and associated Alzheimer pathology may also contribute to the dementia syndrome in stroke patients.

MRI correlates of dementia after first clinical ischemic stroke

BACKGROUND AND PURPOSE

Dementia after first clinical stroke frequently has been found, but the clinical and radiological correlates have not been fully detailed. We examined magnetic resonance imaging (MRI) correlates of dementia in a large well-defined series of patients with first clinical ischemic stroke.

METHODS

Detailed medical, neurological and neuropsychological examination was conducted 3 months after ischemic stroke for 273 patients with first clinical stroke from a consecutive series of 486 patients aged 55-85 years. MRI of the head categorised infarcts (type, site, side, number, volume), extent of white matter lesions (WMLs) and degree of atrophy. The DSM-III definition for dementia was used.

RESULTS

Dementia was diagnosed in 79 (28.9%) of the patients with first clinical stroke. Volumes, numbers, distinct sites of infarcts, extent of WMLs and degree of atrophy were different for the demented and nondemented subjects. Logistic regression analysis showed that the correlates of dementia included the combination of infarct features (volume of infarcts in left-sided anterior corona radiata; OR 1.86), extent of WMLs (OR 1. 37), medial temporal lobe atrophy (OR 3.4) and host factors (low education; OR 1.11). The additive effect of having more than one correlate was detected (OR 2.53).

CONCLUSIONS

Dementia occurring after first clinical stroke is frequent and not solely due to a single stroke, but contain a combination of infarcts features, extent of WMLs, medial temporal lobe atrophy and host factors reflecting more than one underlying pathology.

Visual rating and volumetry of the medial temporal lobe on magnetic resonance imaging in dementia: a comparative study

OBJECTIVES

It has been shown that atrophy of medial temporal lobe structures such as the hippocampus and entorhinal cortex shown on MRI may distinguish patients with Alzheimer's disease from healthy controls. However, the diagnostic value of visual inspection and volumetry of medial temporal lobe atrophy (MTA) on MRI in a clinical setting is insufficiently known.

METHODS

Medial temporal lobe atrophy in 143 patients was visually rated from hard copies, using a 0-4 rating scale and a comparison was made with the volumes (cm(3)) of the medial temporal lobe as estimated with volumetry, using a stereological method. All patients were recruited in an unselected way in a clinical setting in the centre for memory impairments at the Huddinge University Hospital. Patients with Alzheimer's disease (n=41), patients with other dementias (vascular dementia, frontotemporal dementia, and unspecified dementia; n=36) as well as non-demented subjects (n=66) were included. Medial temporal atrophy and volumetry were evaluated as a diagnostic tool by performing logistic regression analysis including age, sex, and mini mental state examination (MMSE) score and calculating the sensitivity and specificity and percentage correct classification.

RESULTS

Visual and volumetric analysis yielded statistically significant differences between patients with Alzheimer's disease and non-demented subjects, as well as between those with other dementias and non-demented subjects. Combining MMSE scores and visually rated MTA ratings yielded a sensitivity of 95% for Alzheimer's disease, 85% for other dementias. Non-demented subjects were identified with a specificity of 96%. Volumetry did not have an added value over the MMSE score alone.

CONCLUSIONS

Visual rating of MTA is a clinically useful method for differentiating Alzheimer's disease from controls and is both quicker and more accurate than volumetry.

Clinical and radiological determinants of prestroke cognitive decline in a stroke cohort

OBJECTIVES

Stroke seems to be related to dementia more often than previously assumed and vascular factors are also related to Alzheimer's disease. The pathophysiology of poststroke dementia includes ischaemic changes in the brain, a combination of degenerative and vascular changes, and changes only related to Alzheimer's disease. Some cognitive decline recognised after a stroke may be due to pre-existing cognitive decline. The aim of this study was to determine the clinical and radiological determinants of prestroke cognitive decline.

METHODS

The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischaemic stroke completed a comprehensive neuropsychological test battery; structured medical, neurological, and mental status examination; interview of a knowledgeable informant containing structured questions on abnormality in the cognitive functions; assessment of social functions before the index stroke; and MRI.

RESULTS

Frequency of prestroke cognitive decline including that of dementia was 9.2% (31/337). The patients with prestroke cognitive decline were older, more often had less than 6 years of education, and had history of previous stroke. Vascular risk factors did not differ significantly between these two groups. White matter changes (p=0.004), cortical entorhinal, hippocampal, and medial temporal atrophy (p<0.001), cortical frontal atrophy (p=0.008); and any central atrophy (p<0.01), but not the frequencies or volumes of old, silent, or all infarcts on MRI differentiated those with and without prestroke cognitive decline. The correlates of prestroke cognitive decline in logistic regression analysis were medial temporal cortical atrophy (odds ratio (OR) 7.5, 95% confidence interval (95%CI) 3.2-18.2), history of previous ischaemic stroke (OR 4.4, 95% CI 1.8-10.6), and education (OR 0.9, 95% CI 0.8-0.9).

CONCLUSIONS

History of previous stroke, but not volumes or frequencies was found to correlate with prestroke cognitive decline. Other associating factors were rather those usually associated with degenerative dementia: white matter changes and cerebral atrophy; and in multiple models medial temporal cortical atrophy and education. The possible overlap between two or more underlying diseases must be remembered in diagnosis and treatment of patients with vascular cognitive impairment.