Clinical determinants of dementia related to stroke

Symptomatic carotid artery occlusion. A reappraisal of hemodynamic factors

BACKGROUND

Over the last several years evidence has accumulated that in addition to embolism, a compromised cerebral blood flow may play an important role in causing transient ischemic attacks and ischemic stroke in patients with occlusion of the internal carotid artery. This evidence is found in both clinical features and ancillary investigations, particularly measurements of cerebral blood flow.

SUMMARY OF REVIEW

On the basis of 20 follow-up studies in patients with transient ischemic attacks or minor ischemic stroke associated with an occluded carotid artery, the annual risk of stroke was 5.5% (95% confidence interval [CI], 5.0% to 6.0%), and that of ipsilateral stroke (distinguished in 11 of the 20 studies) was 2.1% (95% CI, 1.6% to 2.8%). Patients with a compromised cerebral blood flow as measured by positron emission tomography, single-photon emission CT, transcranial Doppler, or stable xenon CT (six studies) have an even higher annual risk of stroke (all strokes: 12.5%; 95% CI, 8.9% to 17.6%; ipsilateral stroke: 9.5%; 95% CI, 6.4% to 14.0%).

CONCLUSIONS

Because a compromised cerebral blood flow may be an important causal factor in patients with symptomatic carotid artery occlusion, medical and surgical options for treatment are reviewed in this light.

Dementia three months after stroke. Baseline frequency and effect of different definitions of dementia in the Helsinki Stroke Aging Memory Study (SAM) cohort

BACKGROUND AND PURPOSE

Vascular dementia is a common cause of dementia, and cerebrovascular disease is related to a higher risk of dementia. The frequency of dementia associated with ischemic stroke and the effects of different definitions of dementia in the diagnosis are still incompletely known. We evaluated the frequency of cognitive decline and dementia 3 months after ischemic stroke in a large stroke cohort.

METHODS

Our cohort consisted of consecutively admitted ischemic stroke patients (n = 486) aged 55 to 85 years in the Helsinki (Finland) Stroke Aging Memory Study (SAM). Subjects were assessed by structured medical, neurological, and radiological examinations and interview with a close informant, as well as by the Mini-Mental State Examination and detailed clinical mental status examination of defined cognitive domains. The criteria for dementia were those of the Diagnostic and Statistical Manual of Mental Disorders (DSM) (DSM-III, DSM-III-R, and DSM-IV), the National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN), and the International Classification of Diseases, 10th Revision (ICD-10).

RESULTS

We found that 451 (92.8%) of the patients were testable, 239 (49.2%) of the patients were women, and the mean age was 71.2 years. Any cognitive decline was present in 61.7%. In the groups aged 55 to 64, 65 to 74, and 75 to 85 years, the frequency of any cognitive decline was 45.7%, 53.8%, and 74.1% (P = .0008), respectively. The frequency of dementia was 25.5% by DSM-III, 20.0% by DSM-III-R, 18.4% by DSM-IV, 21.1% by NINDS-AIREN, and 6.0% by ICD-10 criteria. The frequency increased with increasing age: by the DSM-III definition, frequency in the aforementioned age groups was 19.3%, 23.7%, and 25.5%, respectively (P = .014). There was an overlap in the cases diagnosed as demented according to the different guidelines. Compared with standard diagnosis, the DSM-III was the most sensitive and ICD-10 the most specific. Concordance was moderate between the DSM criteria and NINDS-AIREN criteria but was poor between ICD-10 and the other criteria.

CONCLUSIONS

Cognitive decline and dementia were frequent in the cohort of ischemic stroke patients, and the frequency increased with increasing age. Different definitions gave different frequency estimates, and overlap in the cases was observed. Our findings question the validity of current criteria for dementia in the setting of cerebrovascular disease and emphasize the need for further debate and studies to refine the categories of cognitive impairment related to cerebrovascular disease.

Status of risk factors for dementia associated with stroke

BACKGROUND

Cognitive impairment associated with vascular disease may be the only preventable form of dementia of late life. Identification of risk factors for dementia associated with stroke may be a prelude to improved intervention.

SUMMARY OF REVIEW

I reviewed putative risk factors for dementia associated with stroke. These included demographic, atherogenic, stroke-related, and genetic factors. Key studies from the English literature were reviewed and graded according to quality of evidence ratings (classes I, II, and III). Although many of the cardiovascular disease risk factors are logical antecedents of dementia associated with stroke, age was the only factor that could be considered a well-documented risk factor.

CONCLUSIONS

We should continue to support efforts directed at primary stroke prevention and the brain-at-risk and predementia stages. Additional rigorous epidemiological study is needed to clarify risk factors for dementia associated with stroke.

Blood pressure and dementia in the elderly: epidemiologic perspectives

High blood pressure is associated with an increased risk of vascular dementia as a result of ischemic stroke and other cerebrovascular events or lesions. However, there is insufficient epidemiologic evidence indicating that blood pressure is involved in the etiology of Alzheimer's disease. Clinical studies suggest that episodes of hypotension may cause cerebral hypoperfusion and play a role in the development of dementia. Lowering of blood pressure in dementia, especially Alzheimer's disease, may be due to the dementia process itself or to the characteristics of the disease. Recent large clinical trials have shown that antihypertensive drugs may not significantly affect cognitive performance, but no data are available regarding their potential effects in decreasing the risk of dementia by lowering the incidence of cerebrovascular events. Some data suggest that the blood pressure-dementia relationship may be age-dependent.

Dementia: diagnostics, early treatment, and assistance from family members

This state of the art document is the result of the conference held in Stockholm on March 9-10, 1995, initiated by the Swedish Medical Research Council. The conference brought together researchers from basic science and clinic to different disciplines. Response to questions was given in small groups and the answers were presented and discussed with all the participants. The final consensus was formulated in this larger group and comprises the state of the art document.

Recovery of cognitive function after stroke

BACKGROUND AND PURPOSE

Previous studies have suggested that recovery of cognitive function after stroke is maximal within the first 3 months after onset. We performed the present study to investigate the long-term course and clinical correlates of improvement in generalized cognitive function after ischemic stroke.

METHODS

We administered a battery of neuropsychological tests to 151 patients (age, 70.4 +/- 7.7 years; education, 10.4 +/- 4.6 years) at 3 months and then annually after stroke. We transformed their test results into z scores based on the performance of a stroke-free normative group, averaged those scores to create a summary score, and defined improvement in annual examinations as an increase in that summary score greater than two standard deviations above the mean first annual change of the normative group. We then used logistic regression to determine whether stroke location, syndrome, or recurrence; vascular risk factors; dementia status; depression; or demographic variables were associated with improvement.

RESULTS

We found that 19 of the 151 patients exhibited improvement, which was evident only at the first annual examination in most cases. Logistic regression determined that improvement was significantly related to left hemisphere infarction relative to brain stem/cerebellar infarction (odds ratio [OR], 5.57), while the presence of a major hemispheral stroke syndrome showed a trend toward significance (OR, 3.32). Diabetes mellitus was significantly associated with a failure to exhibit improvement (OR, 0.12). Based on the logistic model, the probability of long-term improvement would be 54.0% for a patient with a left hemisphere infarct and a major hemispheral syndrome but only 11.9% if diabetes was also present.

CONCLUSIONS

Long-term improvement in generalized cognitive function may be evident after stroke in association with left hemisphere infarction and severe hemispheral syndromes, while it may be compromised by diabetes, possibly because of an increased burden of cerebrovascular disease.

Risk factors for incident dementia after stroke. Role of hypoxic and ischemic disorders

BACKGROUND AND PURPOSE

Stroke significantly increases the risk of dementia in the elderly, yet the risk factors for incident dementia after ischemic stroke are not well understood. We attempted to determine whether hypoxic-ischemic (HI) disorders, which may result from comorbid medical conditions (eg. seizures, cardiac arrhythmias, pneumonia), would be an independent risk factor for the development of new dementia after stroke.

METHODS

We prospectively followed 185 initially nondemented patients with ischemic stroke (age, 70.3 +/- 7.7 years) for a maximum of 52.8 months. We diagnosed the presence of dementia at annual examinations based on neuropsychological testing and modified DSM-III-R criteria. HI disorders were identified by record review or examination during hospitalization. We used Kaplan-Meier analysis to determine the cumulative proportion of patients with and without HI disorders who survived free of dementia and used Cox models to estimate the relative risk of dementia associated with HI disorders.

RESULTS

The cumulative proportion (+/- SE) surviving without dementia was 51.7 +/- 10.9% in the HI group versus 78.2 +/- 4.3% in the non-HI group after 52.8 months of observation. The relative risk of incident dementia associated with HI events was 4.3 (95% confidence interval = 1.9 to 9.6) after we adjusted for demographic factors, recurrent stroke, and baseline cognitive function.

CONCLUSIONS

We conclude that HI disorders may be a significant independent risk factor for incident dementia after stroke, even after adjustment for other recognized predictors of cognitive decline. Recognition of HI cerebral damage as a possible pathogenic mechanism for dementia after stroke may allow targeted therapeutic interventions to prevent subsequent cognitive deterioration.

Dementia after first stroke

BACKGROUND AND PURPOSE

Cognitive deficits may significantly worsen the quality of life after stroke. Our aim was to determine the frequency of dementia in a consecutive series of previously nondemented patients between the ages of 40 and 79 years at 3 months after a first ischemic stroke.

METHODS

All patients admitted to our department during an 18-month period who met the above criteria were visited and tested and underwent a CT scan 3 months after their stroke. Dementia was diagnosed according to criteria of the National Institute of Neurological Disorders and Stroke and AIREN, but cases with aphasia were not excluded.

RESULTS

Of 304 patients admitted for stroke, 146 were eligible for study. Eleven refused to participate, 25 were dead at 3 months, and 110 were tested. Fifteen patients were demented (13.6%; 95% confidence interval [CI], 7.8% to 21.5%), and six had severe isolated aphasia, neglect, or memory deficit (5.4%). Excluding patients with aphasia, 5.0% of cases showed dementia (95% CI, 1.6% to 11.3%). The frequency of dementia was 24.6% (95% CI, 14.5% to 37.3%), considering only patients with supratentorial lesions and with residual deficits of elementary functions (paresis, sensory deficits) at the time of examination. Demented patients had significantly more diabetes (P<.029), atrial fibrillation (P=.032), aphasia at entry (P<.001), large middle cerebral artery infarctions (P=.001), and a more severe neurological deficit at entry (P=.003) and at 3 months (P=.001). At CT scan, demented patients had a larger mean volume of the recent lesion (P<.001) and more lesions in the frontal lobe (P=.041). An exploratory multivariate analysis selected age between 60 and 69 years (odds ratio [OR], 45.8; 95% CI, 2.9 to 726.0), diabetes (OR 59.4; 95% CI, 4.3 to 821.0), aphasia (OR, 14.8; 95% CI, 2.0 to 111.0), a large middle cerebral artery infarction (OR, 30.0; 95% CI, 2.7 to 334.0), and lesions of the frontal lobe (OR, 9.8; 95% CI, 1.3 to 72.8) as significant independent correlates of poststroke dementia.

CONCLUSIONS

Dementia is relatively frequent after a clinical first stroke in persons younger than 80 years, and aphasia is very often associated with poststroke dementia. If aphasic patients are not considered, it may be necessary to screen a very large number of subjects to collect an adequate sample of demented cases.

Vascular dementia

Images

Prospective CT confirms differences between vascular and Alzheimer's dementia

BACKGROUND AND PURPOSE

Cognitive test performances were correlated prospectively with changes in cerebral CT measurements of atrophy, infarct volume, ventricular enlargement, local tissue density, and local perfusion to contrast annual rates of changes among patients with ischemic vascular dementia (IVD) or dementia of the Alzheimer type (DAT).

METHODS

The cerebral atrophic index (ATI; ratio of cerebrospinal fluid or infarcted brain to intracranial volume), infarct volume ratio, ventricular volume ratio (VVR; ventricular volume/intracranial volume), cortical and subcortical gray and white matter local perfusion (local cerebral blood flow [LCBF]), and local Hounsfield unit (HU) density were measured concurrently and compared longitudinally with Cognitive Capacity Screening Examinations (CCSE) scores among 24 treated IVD (age, 68.2 +/- 9.7 years; follow-up, 42 +/- 27 months) and 24 DAT patients (age, 74.2 +/- 6.2 years; follow-up, 30 +/- 19 months).

RESULTS

IVD annual changes were as follows: CCSE, +1.2 +/- 5.9; ATI, +2.1%/y; VVR, +3.2%/y; and LCBF in the subcortical basal ganglia, -0.74 mL.100 g-1.min-1.y-1 (-1.8%/y). DAT annual changes were as follows: CCSE, -1.8/y; ATI, +8.1%/y; VVR, +9.6%/y; cortical LCBF, -2.0 mL.100 g-1.min-1.y-1 (-5.2%/y); LCBF in the basal ganglia, -3.0 mL.100 g-1.min-1.y-1 (-6.7%/y); white matter LCBF, -0.75 mL.100 g-1.min-1.y-1 (-4.1%/y); and all cortical tissue densities, -0.83 HU/y (-2.1%/y). In IVD, multiple regression analyses correlated cognitive changes directly with (1) recurrent silent infarctions and (2) bidirectional changes of perfusions within frontal white matter, thalamus, and internal capsules. In DAT, cognitive declines correlated with cerebral atrophy and cortical hypoperfusion related to frontotemporal and parietal cortical polioaraiosis (decreased gray matter tissue densities).

CONCLUSIONS

In IVD, recurrent strokes were not observed clinically during risk factor control, and antiplatelet therapy and cognitive impairments improved or stabilized. In DAT, cognitive performance relentlessly declined. Ischemic pathogenesis for vascular dementia is supported by the following: (1) cognitive declines correlate directly with recurrent "silent" strokes, and (2) bidirectional cognitive changes correlate directly with frontal white matter, thalamic, and internal capsular perfusional changes.

Dementia after stroke is a predictor of long-term survival

BACKGROUND AND PURPOSE

The aim of this study was to determine whether dementia after stroke adversely influences long-term survival.

METHODS

Subjects were 251 patients > or = 60 years of age with ischemic stroke who were given neurological, neuropsychological, and functional examinations 3 months after hospitalization and were followed up prospectively. Using criteria modified from the Diagnostic and Statistical Manual of Mental Disorders-III-R, dementia was found in 66 (26.3%) patients at the 3-month baseline examination. Life-table methods were used to estimate mortality rates in the groups with and without dementia after 1 to 5 years of follow-up, Kaplan-Meier curves to estimate the cumulative proportion surviving with and without dementia, and Cox proportional-hazards analysis to compute the relative risk of mortality associated with dementia at baseline, after adjusting for other potential predictors of stroke mortality.

RESULTS

The mortality rate was 19.8 deaths per 100 person-years with dementia compared with 6.9 deaths per 100 person-years without dementia. The cumulative proportion surviving after a median follow-up of 58.6 months was 38.9 +/- 0.08% for those with dementia and 74.5 +/- 0.04% for those without dementia. The relative risk associated with dementia was 3.11 (95% confidence interval, 1.79 to 5.41) after adjusting for the effects of demographic factors, cardiac disease, severity of stroke (Barthel Index), stroke type (lacunar versus nonlacunar), and recurrent stroke (examined as a time-dependent variable). When the Mini-Mental State Examination score at baseline was examined instead of the diagnosis of dementia, the results of the model were similar.

CONCLUSION

Our study is the first to demonstrate that dementia or cognitive impairment adversely influences long-term survival after stroke, even after adjusting for other commonly accepted predictors of stroke mortality. Impairment in intellectual function after stroke, independent of physical disability, has a significant impact on prognosis. Both cognitive and physical functions should be assessed in clinical studies of stroke outcome.