Cerebral hypoperfusion correlates with mild and parenchymal loss with severe multi-infarct dementia

Mitochondrial Protection and Against Glutamate Neurotoxicity via Shh/Ptch1 Signaling Pathway to Ameliorate Cognitive Dysfunction by Kaixin San in Multi-Infarct Dementia Rats

Multi-infarct dementia (MID), a prominent subtype of vascular dementia (VD), is responsible for at least 15 to 20 percent of dementia in the elderly. Mitochondrial dysfunctions and glutamate neurotoxicity due to chronic hypoperfusion and oxidative stress were regarded as the major risk factors in the pathogenesis. Kaixin San (KXS), a classic prescription of Beiji Qianjin Yaofang, was applied to treatment for "amnesia" and has been demonstrated to alleviate the cognitive deficit in a variety of dementias, including MID. However, little is known whether mitochondria and glutamate are associated with the protection of KXS in MID treatment. The aim of this study was to investigate the role of KXS in improving the cognitive function of MID rats through strengthening mitochondrial functions and antagonizing glutamate neurotoxicity via the Shh/Ptch1 signaling pathway. Our data showed that KXS significantly ameliorated memory impairment and hippocampal neuron damage in MID rats. Moreover, KXS improved hippocampal mitochondrial functions by reducing the degree of mitochondrial swelling, increasing the mitochondrial membrane potential (MMP), and elevating the energy charge (EC) and ATP content in MID rats. As expected, the concentration of glutamate and the expression of p-NMDAR1 were significantly reduced by KXS in the brain tissue of MID rats. Furthermore, our results showed that KXS noticeably activated the Shh/Ptch1 signaling pathway which was demonstrated by remarkable elevations of Ptch1, Smo, and Gli1 protein levels in the brain tissue of MID rats. Intriguingly, the inhibition of the Shh signaling pathway with cyclopamine significantly inhibited the protective effects of KXS on glutamate-induced neurotoxicity in PC12 cells. To sum up, these findings suggested that KXS protected MID rats from memory loss by rescuing mitochondrial functions as well as against glutamate neurotoxicity through activating Shh/Ptch1 signaling pathway.

Cerebral atrophy is an independent risk factor for unfavorable outcome after spontaneous supratentorial intracerebral hemorrhage

BACKGROUND AND PURPOSE

To investigate the influence of cerebral atrophy on clinical outcome in patients with supratentorial intracerebral hemorrhage.

METHODS

Computed tomography scans of 320 patients included in a prospective, multicenter trial were used for a segmentation analysis to determine the supratentorial cerebral volume. A logistic regression analysis was used to explore its effect on outcome after 90 days in addition to other clinical and imaging parameters.

RESULTS

Cerebral volume loss significantly reduced the odds for favorable outcome after 90 days (odds ratio=0.91; confidence interval, 0.85-0.99; P=0.02).

CONCLUSIONS

Cerebral atrophy is an independent predictor of unfavorable outcome after intracerebral hemorrhage, indicating reduced functional recovery potential in these individuals.

Lacune-associated cerebral hypoperfusion correlates with cognitive testing

The hypothesis was tested among 83 patients with multiple lacunar infarctions that cerebral hypoperfusion will correlate with cognitive impairments. Patients were subdivided according to Cognitive Capacity Screening Examination (CCSE) scores into a cognitively impaired group (Group D, n = 40; mean age, 68.2 years) with CCSE scores between 6 and 25 (mean, 19.9) and a cognitively intact group (Group I, n = 43; mean age, 66.0) with normal scores (mean, 29.4). Gray and white matter tissue densities were measured by plain computed tomography (CT), and their compartmental perfusions were estimated during stable xenon inhalation. Eighty infarcts in basal ganglia and white matter were detected in Group D and 62 in Group I. Cognitive impairments correlated with (a) multiplicity and bilaterality of lacunes; (b) hypertension, diabetes mellitus, and multiplicity of risk factors for stroke; (c) hypoperfusion of white and gray matter, but particularly of frontal white matter; (d) leuko-araiosis; (e) aging; and (f) lower education. The conclusion was that hypertension and diabetes mellitus are potent risk factors for cerebral small vessel disease or arteriolosclerosis ultimately resulting in lacunar infarcts, leuko-araiosis, white matter hypoperfusion, and impaired cognitive test performance.

Does perfusion CT enable differentiating Alzheimer's disease from vascular dementia and mixed dementia? A preliminary report

The purpose of the study was to evaluate the usefulness of perfusion CT (pCT) in differentiating Alzheimer's disease (AD) from vascular dementia (VaD) and mixed dementia (MixD). pCT was performed in 41 patients (mean age, 68.3 years): 24 with AD, 8 with VaD, and 9 with MixD. Regional perfusion parameters (rCBF, rCBV, and rMTT) were calculated from 31 ROIs in the grey and white matter of the frontal and temporal lobes, basal ganglia, and internal capsules bilaterally. The obtained data for the subgroups of AD, VaD, and MixD patients were compared statistically.

CONCLUSIONS

On the basis of rCBF and rCBV values, pCT may be a valuable method of distinguishing between AD and VaD but it seems to be of little significance in differentiating MixD from VaD and of no usefulness in distinguishing between AD and MixD.

Progressive expression of vascular endothelial growth factor (VEGF) and angiogenesis after chronic ischemic hypoperfusion in rat

Cerebrovascular stenosis caused by arteriosclerosis induces failure of the cerebral circulation. Even if chronic cerebral hypoperfusion does not induce acute neuronal cell death, cerebral hypoperfusion may be a risk factor for neurodegenerative diseases. The purpose of this study was to determine if vasodilation, expression of VEGF, and neovascularization are homeostatic signs of cerebral circulation failure after permanent common carotid artery occlusion (CCAO) in the rat. Neuronal cell death in neocortex was observed 2 weeks after CCAO and gradually increased in a time-dependent manner. The diameter of capillaries and expression of VEGF also increased progressively after CCAO. Moreover, we observed unusual irregular angiogenic vasculature at 4 weeks. In conclusion, chronic hypoperfusion results in mechanisms to compensate for insufficiency in blood flow including vasodilation, VEGF expression, and neovascularization in the ischemic region. These results suggest that angiogenesis might be induced in adult brain through the support of growth factors and transplantation of vascular progenitor cells, and that neovascularization might be a therapeutic strategy for children and adults with diseases such as vascular dementia.

Frequency and clinical determinants of poststroke cognitive impairment in nondemented stroke patients

The objective of this study was to examine the prevalence and clinical correlates of poststroke cognitive impairment in Chinese stroke patients in Hong Kong. One hundred seventy-nine stroke patients were interviewed by a psychiatrist 3 months after their stroke. Cognitive impairment was determined according to the Mini-Mental State Examination score. Thirty-nine participants (21.8%) had cognitive impairment. Univariate analysis found that cognitive impairment was associated with age, female sex, level of education, previous stroke, prestroke Rankin score, National Institutes of Health Stroke Scale dysarthria and total scores, urinary incontinence, and cerebral atrophy index. Multivariate logistic regression suggested that female sex, education, National Institutes of Health Stroke Scale dysarthria score, urinary incontinence, and atrial fibrillation were independent risk factors of poststroke cognitive impairment. After removal of 54 patients with previous stroke from the sample, the frequency of cognitive impairment decreased to 18.4%. It was concluded that cognitive impairment is common among nondemented Chinese stroke patients in Hong Kong.

Determinants of prestroke cognitive impairment in stroke associated with small vessel disease

Understanding the determinants of prestroke cognitive impairment (PCI) in stroke associated with small vessel disease (SVD) may shed light on how to prevent further cognitive deterioration after stroke. We administered the Informant Questionnaire on Cognitive Decline (IQCODE) to close informants of 78 consecutive stroke patients who had SVD. PCI, as defined by an average score of IQCODE > or =3.4 was found in 19 (24%) patients. Regression analyses were performed on the following risk factors for PCI: age, years of education, gender, previous stroke, volume of white matter changes, measures of silent lacunes, cerebral atrophy index, medial temporal lobe atrophy and frontal lobe atrophy. Multivariate regression analyses revealed that only cerebral atrophy index (OR 1.5, CI 1.2-1.9, p < 0.001) predicted PCI among patients with SVD.

Impact of Applying NINDS-AIREN Criteria of Probable Vascular Dementia to Clinical and Radiological Characteristics of a Stroke Cohort with Dementia

BACKGROUND

There are no data concerning the relative representation of clinical vascular risk factors and radiological lesions in cases that have been ruled in and ruled out for probable vascular dementia (VaD) according to NINDS-AIREN criteria.

METHODS

Three months after their index stroke, a psychiatrist interviewed patients and made a diagnosis of VaD according to both DSM-IV and NINDS-AIREN criteria for probable VaD. Patients who fulfilled the DSM-IV criteria for VaD were divided into two groups: those who were ruled in and ruled out according to NINDS-AIREN criteria as probable VaD. Demographic characteristics, vascular risk factors, clinical features of the index stroke and radiological findings were then compared between the two groups.

RESULTS

Of the 297 patients screened, 56 (18.8%) had a DSM-IV diagnosis of dementia. Among these demented patients, 55 (98.2%) and 22 (39.3%) fulfilled DSM-IV and NINDS-AIREN diagnosis of VaD, respectively. The concordance and level of agreement (kappa statistic) between DSM-IV and NINDS-AIREN diagnoses were 40% and 0.02, respectively. Reasons of failure to meet NINDS-AIREN criteria included the lack of temporal relationship between dementia and stroke (n = 20), the absence of focal neurological signs and/or radiological evidence of stroke (n = 6) and both of the above (n = 7). There was no significant difference between the above two groups in terms of demographic data, features of index stroke, vascular risk factors and CT scan findings, except that leukoaraiosis (p = 0.021) and bilateral lesions (p = 0.015) were more frequent in subjects diagnosed according to NINDS-AIREN criteria of probable VaD. The difference between these two groups with respect to the number of lesions was borderline for significance (p = 0.052).

CONCLUSIONS

The use of NINDS-AIREN criteria for VaD for case selection in poststroke dementia research may exclude a number of subjects with VaD.

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.

Correlations between P300 components and regional cerebral blood flows

To evaluate the diagnostic importance of event-related potential P300, the correlation between P300 and regional cerebral blood flow (rCBF) was investigated in various brain regions in patients with multiple cerebral infarction (16 cases), chronic alcoholism (11 cases) and Alzheimer's disease (5 cases) and in seven healthy people. Cognitive function was also evaluated by mini-mental state examination. P300 latency and rCBF was measured by recording of evoked potentials using an oddball paradigm and stable xenon computed tomographic scanning, respectively. A significant (P<0.05) negative correlation between P300 and rCBF was observed in the thalamus in patients with multiple cerebral infarction and chronic alcoholism. In addition, a significant (P<0.01) negative correlation between P300 latency and the mini-mental state examination score and positive correlation between rCBF in the thalamus and the mini-mental state examination score were observed. These findings suggest that P300 latency is associated with rCBF in the thalamus and cognitive function.

Hippocampal and cortical atrophy predict dementia in subcortical ischemic vascular disease

BACKGROUND

The cause of dementia in subcortical ischemic vascular disease (SIVD) is controversial.

OBJECTIVES

To determine whether cognitive impairment in SIVD 1) correlates with measures of ischemic brain injury or brain atrophy, and/or 2) is due to concomitant AD.

METHODS

Volumetric MRI of the brain was performed in 1) elderly subjects with lacunes (L) and a spectrum of cognitive impairment-normal cognition (NC+L, n = 32), mild cognitive impairment (CI+L, n = 26), and dementia (D+L, n = 29); 2) a comparison group with probable AD (n = 28); and 3) a control group with normal cognition and no lacunes (NC). The authors examined the relationship between the severity of cognitive impairment and 1) volume, number, and location of lacunes; 2) volume of white matter signal hyperintensities (WMSH); and 3) measures of brain atrophy (i. e., hippocampal, cortical gray matter, and CSF volumes).

RESULTS

Among the three lacune groups, severity of cognitive impairment correlated with atrophy of the hippocampus and cortical gray matter, but not with any lacune measure. Although hippocampal atrophy was the best predictor of severity of cognitive impairment, there was evidence for a second, partially independent, atrophic process associated with ventricular dilation, cortical gray matter atrophy, and increase in WMSH. Eight autopsied SIVD cases showed variable severity of ischemic and neurofibrillary degeneration in the hippocampus, but no significant AD pathology in neocortex. The probable AD group gave evidence of only one atrophic process, reflected in the severity of hippocampal atrophy. Comparison of regional neocortical gray matter volumes showed sparing of the primary motor and visual cortices in the probable AD group, but relatively uniform atrophy in the D+L group.

CONCLUSIONS

Dementia in SIVD, as in AD, correlates best with hippocampal and cortical atrophy, rather than any measure of lacunes. In SIVD, unlike AD, there is evidence for partial independence between these two atrophic processes. Hippocampal atrophy may result from a mixture of ischemic and degenerative pathologies. The cause of diffuse cortical atrophy is not known, but may be partially indexed by the severity of WMSH.

Central motor conduction time and regional cerebral blood flow in patients with leuko-araiosis

Central motor conduction time (CMCT) and regional cerebral blood flow were investigated in 21 patients with leuko-araiosis. The severity of dementia was examined using mini-mental state examination. The head magnetic stimulation was performed using an SMN-1100 magnetic stimulator and a round coil with a diameter of 17 cm. The regional cerebral blood flow was measured using the stable xenon computed tomography method. The CMCT was significantly longer in the patients with dementia than in the patients without dementia. The blood flows in the parietal cortex, frontal white matter and thalamus were significantly lower in the patients with dementia than in the patients without dementia. There were significant negative correlations between the CMCT and the blood flows in the frontal cortex, temporal cortex, frontal white matter and thalamus. The significant negative correlations suggest that the prolongation of CMCT in patients with leuko-araiosis is related to the decrease in regional cerebral blood flows.

Vascular dementia: still a debatable entity?

Vascular dementia (VAD) is currently considered to be the second most common cause of dementia in Europe and the USA, second to dementia of the Alzheimer's type (DAT). However, in Asia and many developing countries the incidence of VAD exceeds that of DAT. The positive clinical diagnostic workup for VAD requires six steps: (1) clear-cut quantitative assessment of cognitive deficits utilizing standard neuropsychological tests to establish and quantify the dementia syndrome and rule out pseudo-dementia OF depression; (2) ascertaining the presence of risk factors for stroke; (3) identifying cerebral vascular lesions by neuroimaging (MRI, Iodine or Xenon contrasted CT, PET and SPECT); (4) exclusion of other causes of dementia; (5) differential diagnosis of possible, probable or definite VAD versus DAT and ascertaining when there are mixtures of the two; and (6) temporal identification of causality between onset and progression of the dementia with identified cerebral vascular lesions. There are eight subtypes of VAD: (1) multi-infarct dementias. These are due to large cerebral emboli, and are usually readily identifiable; (2) strategically placed infarctions causing dementia; (3) multiple subcortical lacunar lesions. Patients with these develop VAD at least five to twenty-five times more frequently than those in age-matched general population samples; (4) Binswanger's disease (arteriosclerotic subcortical leuko-encephalopathy). This form is rare. Neuroimaging confirms the diagnosis during life but the diagnosis can not be made by neuroimaging alone; (5) mixtures of two or more of above VAD subtypes; (6) hemorrhagic lesions causing dementia; (7) subcortical dementias due to cerebral autosomally dominant arteriolopathy with subcortical infarcts and leuko-encephalopathy (CADASIL), or to familial amyloid angiopathies and coagulopathies all of which present with multiple subcortical lacunar lesions similar to Binswanger's disease; (8) mixtures of DAT and VAD. The clinical significance of leukoaraiosis and its suspected relationships to VAD remains to be better established. The presence of ischemic infarctions, single or multiple large or multiple small (lacunar) by neuroimaging are necessary for the diagnosis of VAD, but identifying their presence, by neuroimaging alone, does not permit the diagnosis of dementia which can only be established by neuropsychological assessments. VAD is a clinical entity, identifiable in at least 30-70% of patients after strokes but mechanisms responsible for the cognitive impairments are complex. Some of these mechanisms are incompletely understood but provide subjects for important future research.

Vascular dementia of Binswanger's type: clinical, neuroradiological and 99mTc-HMPAO SPET study

In 24 patients with vascular dementia of Binswanger's type (VDBT) and 14 age-matched neurologically normal volunteers, we investigated the relationship between clinical features, white matter lesions (leuco-araiosis) and cerebral atrophy on computed tomographic (CT) scan, and regional cerebral blood flow. All subjects underwent the Mini-Mental State Examination of Taiwan, version 1 (MMSE-T1), for assessing the severity of cognitive impairment. The patients were subdivided into two groups, one with mild to moderate (group I, MMSE-T1 scores: 11-24, n=11), and the other with severe dementia (group II, MMSE-T1 scores: below 10, n=13). White matter degeneration was evaluated with densitometric methods. Loss of brain parenchyma was estimated with seven linear measurements (Evan's ratio, third ventricle ratio, width of temporal horn tip, anterior-posterior length of temporal horn, anterior-posterior length of Sylvian fissure and width of frontal interhemispheric fissure) by CT scans. Regional cerebral blood flow was determined with technetium-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission tomography (SPET). In neuroimaging studies, subcortical leuco-araiosis was localized at the frontal region in group I patients and scattered diffusely in group II patients. 99mTc-HMPAO SPET analysis revealed reduction of regional cerebral blood flow in the frontal lobe in group I patients and widespread reduction of regional cerebral blood flow in group II patients. A correlation between frontal leuco-araiosis and perfusion defect of the frontal pole was demonstrated in group I patients, showing findings typical of subcortical dementia. There was no difference in frontal atrophic measurements between group I patients and controls. Ratios of volumes of lost brain parenchyma and leuco-araiosis were significantly higher in group II patients than in the age-matched controls, corresponding to a diffuse cerebral perfusion defect. These results suggest that patients with VDBT have early frontal lobe involvement with posterior progression. Patients with mild VDBT are more likely to show reduction of frontal cerebral blood flow and leuco-araiosis, while those with severe VDBT are more likely to have diffuse leuco-araiosis, cerebral hypoperfusion and brain atrophy.

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.

CT changes associated with normal aging of the human brain

CT was used to measure changes in cerebral gray and white matter tissue densities associated with normal aging, using a cross-sectional design, in order to provide normative data for comparisons with abnormal aging such as dementias of Alzheimer's and vascular types. Cerebral compartmental densities were measured using plain CT, and their perfusion values were recorded during stable xenon inhalation (CT-CBF), among 81 neurologically and cognitively normal volunteers of different ages. Results led to the conclusion that cortical gray matter tissue densities progressively decline (polio-araiosis) after age 60. Cortical polio-araiosis is coupled with regional hypoperfusion but not with cortical atrophy. It is speculated that the cortical hypodensity identified by CT imaging parallels declines in cortical synaptic density, as reported from autopsy studies using anti-synaptophysin staining of cerebral cortex obtained from normal people above and below age 60. The coupling of cortical hypoperfusion with polio-araiosis is believed to reflect age-related reductions of cortical metabolic demands as reported by PET. During normal aging leuko-araiosis correlates directly with cortical atrophy, suggesting that anterograde axonal degeneration resulting from cortical neuronal dearborization play a role in its causation.

Correlations of leuko-araiosis with cerebral atrophy and perfusion in elderly normal subjects and demented patients

CT images of leuko-araiosis in brain slices were quantified according to volumes of reduced Hounsfield units in frontal periventricular white matter in groups of elderly patients with multi-infarct dementia (MID, n = 23) and dementia of the Alzheimer type (DAT, n = 16). Volumes of leuko-araiosis, estimates of atrophic cerebral tissue, and local cerebral perfusion utilising inhalation of xenon gas as the indicator were correlated on the same CT slices. Ratios of frontal leuko-araiosis to total brain tissue volume were similar for patients with MID and DAT (mean 5.7 (SD 2.1)% v 6.5 (3.2%)), and both were significantly greater than ratios in elderly normal volunteers (3.1(1.3)%, 0 < 0.001). Cerebral atrophy (measured as the ratio of volumes of cerebrospinal fluid to total brain area) for DAT patients was 17.0 (6.7)%, which was greater than for MID patients (12.5 (5.4)%; p < 0.05) and both types of patients showed more cerebral atrophy than did age matched, elderly normal subjects. Cerebral perfusion was decreased in all regions measured in patients with MID and DAT compared with elderly normal subjects. Multi variate regression analyses correlated frontal leuko-araiosis with reductions of local cerebral blood flow in subcortical grey matter (p < 0.025) in patients with vascular dementia but not in those with DAT. These quantitative measures implicate decreased perfusion due to atherosclerosis in territories supplied by the deep penetrating cerebral arteries in the pathogenesis of leuko-araiosis in patients with vascular dementia, but suggest a different pathogenesis for leuko-araiosis in Alzheimer's disease.

Dementia associated with lacunar infarction

BACKGROUND AND PURPOSE

The purpose of this study was to assess the number of patients with lacunar lesions who develop dementia and to evaluate in patients with and without dementia the relevance of risk factors for cerebrovascular disease, the occurrence of leukoaraiosis, the volume and location of vascular lesions, the size of ventricular and subarachnoid spaces, and stroke recurrence.

METHODS

One hundred eight patients in whom computed tomograms revealed lacunar lesions that could account for their clinical neurological pictures were followed up for an average of 4 years after their first lacunar stroke.

RESULTS

Twenty-five patients (23.1%) developed dementia. The prognosis regarding occurrence of dementia during the follow-up period, evaluated by the Kaplan-Meier method, was significantly worse in subjects with the greatest evidence of cerebral atrophy (p less than 0.009) and in subjects who underwent new focal cerebrovascular episodes (p less than 0.000001). No differences were seen in the frequency of vascular risk factors or the site or volume of lesions between the demented and nondemented groups.

CONCLUSIONS

Patients with lacunar infarcts suffer from dementia 4-12 times more frequently than the normal population. Cerebral atrophy and recurrent stroke, as well as other as-yet unclarified factors, are involved in producing dementia.

White matter lesions in the elderly

The advent of neuroimaging has brought medical attention to the frequency of unsuspected white matter lesions in the brains of elderly people. In 1987 Hachinski suggested the term "leuko-araiosis" to identify such white matter abnormalities detected by computed tomography and magnetic resonance imaging to emphasize that their etiology and clinical relevance require clarification. Since then, leuko-araiosis has been recognized among approximately ten percent of apparently normal, elderly people over age sixty-five. The severity and frequency of leuko-araiosis increases with advancing age, risk factors for stroke, history of strokes particularly of the lacunar type and dementia of both the vascular and Alzheimer type. Current concepts concerning the pathogenesis and neurological concomitants of leuko-araiosis are reviewed. The etiology of leuko-araiosis may be heterogeneous but is most likely ischemic in nature. However, as white matter lesions progress among the elderly they are likely to become associated with cognitive impairments and motor dyspraxias presumably resulting from cortico-subcortical disconnections, particularly involving the frontal cortex and basal ganglia and may themselves be considered a radiological "risk factor" or precursor for dementia.

Patterns of cerebral hypoperfusion compared among demented and nondemented patients with stroke

BACKGROUND AND PURPOSES

No reports are available that compare local cerebral perfusion among groups of patients suffering from multiple cerebral infarctions with and without cognitive impairments. The present study was designed to correlate changes in regional cerebral perfusion that may lead to dementia among patients with multiple cerebral infarctions by comparing measurements of local cerebral blood flow.

METHODS

Local perfusion was measured using xenon-contrasted computed tomographic scanning among two groups of patients who had suffered from multiple cerebral infarctions: Group D (n = 12) were demented and had severe cognitive impairments, and group I (n = 11) were cognitively intact. Results were compared with similar measurements among neurologically and cognitively normal, age-matched volunteers (group N, n = 16).

RESULTS

Mean local perfusion values were reduced among both groups with cerebral infarctions but to a more marked degree in group D (p less than 0.05). Perfusion of cerebral white matter was diffusely and severely reduced in group D (p less than 0.05) but was mildly reduced only in frontal and capsular white matter in group I (p less than 0.05). Perfusion of cerebral cortex was reduced in frontal (p less than 0.01) and temporal (p less than 0.01) regions among both groups but to a significantly greater degree in group D subjects (frontal, p less than 0.05; temporal, p less than 0.01), who also showed hypoperfusion of the occipital cortex (p less than 0.05), apparently because of underlying leukoaraiosis and cortical disconnections. Perfusion of the basal ganglia was reduced to the same degree among both groups of stroke patients (p less than 0.01).

CONCLUSIONS

Leukoaraiosis with white matter hypoperfusion appears to be an important determinant for cognitive impairments among patients with multiple cerebral infarctions.