Positron emission tomography in vascular dementia

BACKGROUND

Vascular dementia (VaD) is an ill-defined entity. It is not known how acute brain failure related to stroke becomes chronic leading to dementia.

PURPOSE

The present study investigates whether positron emission tomography (PET) can detect different metabolic patterns in VaD.

PATIENTS AND METHODS

Four groups of stroke patients were selected. The PET findings of 14 stroke patients with multiple large infarcts and dementia (MID) and 14 without dementia (MS) were compared. Sixteen stroke patients with lacunes, leukoaraiosis and dementia (LD) were assessed against nine without dementia (LS). The PET examination utilised the 15-O-steady-state technique in order to determine regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional cerebral metabolic rate for oxygen (rCMRO2) in different pre-established cortical, subcortical and cerebellar regions.

RESULTS

Decreased coupled mean rCBF and rCMRO2 with comparable rOER values were observed in all cerebral regions except in the cerebellum of the MID compared to the MS group. In the LD group mean rCBF and rCMRO2 were decreased with increased rOER in all cerebral regions except in the cerebellum compared to the LS group.

CONCLUSIONS

The PET findings in demented patients with multiple large infarcts are in agreement with the concept of multi-infarct dementia. In demented patients with lacunes and leukoaraiosis, the PET pattern suggests a state of misery perfusion not only in the deep structures but also in the whole cerebral cortex. The present PET study argues that there are at least two possible mechanisms that can explain the occurrence of VaD in stroke patients.

[Ultrastructure of the blood-brain barrier in the cerebral cortex in atherosclerotic dementia]

Ultrastructural changes of blood-brain barrier elements were studied in the cortex of cerebral superior frontal and medial temporal gyri in atherosclerotic dementia. Destructive changes in endotheliocytes, pericytes, basement membrane and increase in number, swelling and edema of astrocyte peduncles with the inconstant approximation of astrocyte body to the capillary basement membrane were demonstrated along with signs of blood circulation decline in cortical capillaries. Lipofuscin and lipids accumulation and aggregation of homogenous material of high electron density, probably plasma proteins, were characteristic for changes in blood-brain barrier in atherosclerotic dementia, which is important in pathogenesis of this type of the disease.

Delirium in dementia

Delirium is a common mental disorder in the elderly with old age being a major risk factor for delirium. Another major risk factor is dementia. The aim of the present study was to identify differences in occurrence of episodes of delirium between the most common dementia diagnoses and the possible importance of age, gender, severity and duration of dementia for the development of delirium. Included in the study were 175 consecutive patients with probable Alzheimer's disease, vascular dementia (VAD) or frontotemporal dementia (FTD) who were admitted to a neuropsychiatric diagnostic unit. There were no significant differences in sex distribution or duration of dementia between the delirious and non delirious patients. The rate of delirium was higher in late onset Alzheimer's disease (LAD) than in early onset Alzheimer's disease (EAD) and FTD. It was also higher in VAD than in EAD. The differences in occurrence of delirium between the diagnostic groups in this sample could not be explained by differences in age. It seems that delirium is more common in brain disorders such as LAD and VAD in which the damage to the brain is more widespread. In the two brain disorders that are predominantly cortical, EAD and FTD, the occurrence of delirium was comparatively low.

Neuropathological assessment of the lesions of significance in vascular dementia

OBJECTIVES

To better define the neuropathology of vascular dementia.

METHODS

The neuropathological findings in 18 elderly, undemented subjects free of cerebrovascular disease were compared with 19 elderly undemented subjects who had cerebrovascular disease (many of whom had had a "stroke") and 24 elderly demented subjects who had cerebrovascular disease, but no other pathology to account for dementia. Cases in all groups were selected for absence or no more than very mild Alzheimer type pathology.

RESULTS

Microvascular brain damage in the form of severe cribriform change and associated subcortical white matter damage and microinfarction were correlated with a history of dementia. Severe cribriform change was much more common and microinfarction somewhat more common in the demented group with vascular disease than the undemented group with vascular disease (P=0.0006 and P=0.031 respectively). Other findings of note were that congophilic angiopathy had a greater prevalence in the vascular dementia group than the control group, single cerebral infarcts were more common in the group who were undemented with vascular disease than in the group with dementia and vascular disease (P=0.0028), and the last group lacked evidence of macroscopic infarction more often than the first (P=0.034). There was a non-significant trend for the ratio of infarcted:uninfarcted tissue in one cerebral hemisphere to be higher in the group with dementia and vascular disease than in the group with vascular disease but no dementia.

CONCLUSIONS

Microvascular disease, not macroscopic infarction, was the chief substrate of vascular dementia in this series of cases.

Fluency and memory differences between ischemic vascular dementia and Alzheimer's disease

This study compared 32 patients with ischemic vascular dementia (IVD) to 32 patients with probable Alzheimer's disease (AD) on select language and verbal memory tests. The IVD and AD patients were individually matched on the basis of age, dementia severity, years of education, and gender. The IVD patients had poorer verbal fluency, but better free recall, fewer recal intrusions, and better recognition memory than the AD patients. Relationships between the neuropsychological measures and radiological indexes of cortical and subcortical pathology were also examined. Number of infarcts, white-matter lucency, and ventricular enlargement correlated with some of the neuropsychological measures; cortical atrophy correlated with most of the measures. The findings suggest that neuropsychological deficits in IVD may be related to dysfunction of frontal-subcortical circuits, although an associated degenerative cortical process may also be involved.

Brain microvascular changes in Alzheimer's disease and other dementias

Vasculopathy in Alzheimer's disease (AD) may represent an important pathogenetic factor of this disorder. In the present study, microvasculature was studied by immunohistochemistry using a monoclonal antibody against a vascular heparan sulfate proteoglycan. Vascular changes were consistently observed in AD and included decrease in vascular density, presence of atrophic and coiling vessels, and glomerular loop formations. The laminar and regional distribution of these vascular alterations was correlated with the presence of neurofibrillary tangles. However, vascular changes may also follow neuronal loss. Vascular density may be related to a decrease in brain metabolism. Furthermore, one of the main features of AD is the presence of amyloid deposits within brain parenchyma and blood vessel walls. It is not yet clear whether amyloid components are derived from the blood or the central nervous system. Because AD is clearly heterogeneous, based on clinical and genetic data, evidence for either a brain or peripheral origin is discussed. Microvasculature was also analyzed in other neurodegenerative disorders devoid of amyloid deposits including amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam and Pick's disease. In conclusion, if vasculopathy in neurodegenerative disorders is not directly involved in pathogenesis, it may act synergistically with other pathogenetic mechanisms including genetic and environmental factors. This aspect of pathology is particularly interesting in view of its accessibility to therapeutic interventions.

Sensitivity and specificity of newly proposed clinical criteria for possible vascular dementia

The objective of this study was to determine the sensitivity and specificity of clinical criteria for possible vascular dementia (VaD) recently developed independently by two groups: the State of California Alzheimer's Disease Diagnostic and Treatment Centers (ADDTC) and the National Institute for Neurological Disorders and Stroke with the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN). We also wished to compare the performance of the new criteria to that of the Hachinski Ischemic Score (HIS). The study was comprised of a retrospective chart review and clinicopathologic correlation, and took place in 304-bed acute-care geriatric hospital. The subjects were 113 autopsied elderly patients with dementia, who were assessed to determine sensitivity and specificity of the ADDTC and NINDS-AIREN criteria for possible VaD. Sensitivity and specificity were calculated using the neuropathologic diagnosis as a gold standard. Sensitivity was 0.63, and specificity was 0.64 for the ADDTC, 0.58 sensitivity and 0.80 specificity for the NINDS, and 0.43 sensitivity and 0.88 specificity for the HIS. Test combinations did not lead to substantial gains in sensitivity or specificity. The majority of patients with Alzheimer's disease were successfully excluded by the ADDTC (87%), the NINDS-AIREN (91%), and the HIS (97%). The proportion of mixed dementia cases clinically misclassified as VaD was 54% for the ADDTC, 29% for the NINDS-AIREN, and 18% for the HIS. Low sensitivity is the main weakness of the above clinical criteria for possible VaD. Mixed dementia is better excluded by the NINDS-AIREN than the ADDTC. Data from this validation study should provide valuable information to clinicians and researchers who wish to apply these criteria to the diagnosis of VaD.

[Progressive cerebral parenchyma damage caused by recurrent arterial hypotension]

To date clinical and experimental investigations have focused on acute strokes and complete infarctions. Histological and immunological staining in animal experiments and improved imaging techniques in patients suggest that selective or incomplete infarction is a common pathomechanism. Incomplete infarction can manifest as laminar necrosis at autopsy and as leukoaraiosis in imaging studies. An important mechanism in the genesis of leukoaraiosis is vascular pathology of the long penetrating arteries of the deep white matter combined with episodes of decreased perfusion pressure or hypotension. We demonstrate that the cumulative effect of repetitive, moderate hypotensive episodes on cognitive performance or cerebral tissue has not been adequately studied and appreciated.

[Dementia. Outlook on current developments]

The results of recent neuropathologic and genetic studies in Alzheimer's disease led to a renewed interest in differentiations within the dementia syndrome. New disease-entities can be distinguished (Lewy Body Dementia, Frontal Lobe Dementia) and other criteria have been put forward for vascular dementia. Hachinski's Ischemic Score, for many years the diagnostic criterium for vascular dementia, has been cancelled. Instead a CT- or MRI scan must demonstrate the vascular pathology in the brain. For clinical practice, the differentiation between cortical and subcortical dementia is still important. For reasons of management it appears useful to distinguish between early-onset and late-onset Alzheimer's disease. The amyloid cascade hypothesis for the pathogenesis of Alzheimer's disease is credible for the early-onset as well as the late-onset type, because results from epidemiological as well as from neurobiological studies might be fit in. Moreover, this hypothesis is promising from the point of view of developing specific therapies. Finally, the breakdown of the dementia syndrome in separate disease-entities stimulated interest in the psychiatric symptoms in these patients and activated the development of rational and symptomatic therapeutics.

The vascular dementia of Fabry's disease

Fabry's disease, a rare X-linked disorder of glycosphingolipid metabolism, can present as an insidious dementia in middle or later life. This genetic disorder produces a deficiency of alpha-galactosidase A which results in the deposition of glycosphingolipids in blood vessel walls in the brain as well as in the kidney, heart, peripheral nerves, and other organs. Among the cerebrovascular manifestations of this disorder is a vascular dementia from involvement of multiple small penetrating blood vessels. Fabry's disease is a consideration in the workup of an otherwise unexplained vascular dementia, particularly in males less than 65 years of age.

Alterations in glia and axons in the brains of Binswanger's disease patients

BACKGROUND AND PURPOSE

Although increasing attention is being paid to Binswanger's disease, a form of vascular dementia characterized by diffuse white matter lesions, only limited information is available on the pathological changes that occur in the glia and axons in the white matter. We therefore investigated the brains of patients with Binswanger's disease to gain further insight into its pathophysiology.

METHODS

Autopsied brains from patients with Binswanger's disease (group 3; n = 17) were compared with those of nonneurological controls (group 1; n = 5) and controls with large cortical infarcts but without significant white matter lesions (group 2; n = 5). Glial fibrillary acidic protein (GFAP) was used as an immunohistochemical marker for astroglia, leukocyte common antigen (LCA) was used as a marker for microglia, and HLA-DR was used as a marker for activated microglia. Axonal damage was assessed by the accumulation of proteins, which are transported by fast axonal flow, amyloid protein precursor (APP), synaptophysin, and chromogranin A.

RESULTS

Although there was no difference in numerical density of GFAP-immunoreactive astroglia in each group, regressive astroglia were observed in 7 of 17 patients with Binswanger's disease. LCA-immunoreactive microglia were 1.7 times more numerous in Binswanger's disease than in group 1 (P < .05). HLA-DR-immunoreactive-activated microglia were 3.4 times and 2.1 times more numerous in Binswanger's disease as compared with group 1 (P < .01) and group 2 (P < .05), respectively. There was frequent perivascular lymphocyte cuffing, and clusters of macrophages with a decreased number of oligodendroglia were observed in the rarefied white matter. The grading scores for the number of axons immunoreactive for either APP, synaptophysin, or chromogranin A were significantly higher in Binswanger's disease than in group 1 or 2.

CONCLUSIONS

The pathological alterations in Binswanger's diseased brains include regressive changes in the astroglia and activation of the microglia with a decrease in the oligodendroglia, which were associated with the degradation of both myelin and axonal components. These results indicate that an inflammatory reaction and compromised axonal transport, mediated by chronic ischemia, may play an important role in the pathophysiology of Binswanger's disease.

[The Zurich prospective dementia study 1987-1993]

1987-1993 the Zurich prospective dementia study examined twice yearly 308 nursing-home patients: 192 with senile dementia of Alzheimer-type, 18 with Parkinsonism, 20 with Parkinson dementia and 78 controls, with the Zurich variant of the mini-mental state and rated their dementia state by CDR, activities of daily living with ADL and social behavior with an SVS-scale. At the end of the study or at death the average age was 86.2 years (range 63-103 and 159 autopsies were performed which confirmed the clinical diagnoses at least partly in 70%. Of the 62 cases with autopsies who had been studied more than two years 25 showed M.Alzheimer, 8 M, Parkinson, 7 vascular dementia and 13 a combination of those three diagnoses 40% of these Alzheimer patients exhibited no deterioration in the SVS for two years, 40% respectively 30% during one, resp. two years in the CDR, 20% resp. 40% in the ADL and 23% resp. 5% in the MMS. This demonstrates that good nursing-home care can stabilize behaviour and to a lesser extent even cognitive abilities of a large minority of patients with a pathologically confirmed progressive dementing illness.

MRI-defined vascular depression

OBJECTIVE

The authors' goal was to characterize the clinical and demographic features of vascular depression.

METHOD

They classified 89 depressed patients into two groups-those with vascular (N = 32) and nonvascular (N = 57) depression-on the basis of examination of brain magnetic resonance images. All of the patients were enrolled in the National Institute of Mental Health Clinical Research Center for the Study of Depression in Later Life, located at Duke University. The patients with vascular and nonvascular depression were compared on several clinical and demographic risk factors.

RESULTS

Bivariate analyses and a fully adjusted logistic regression model revealed that older age, late age at onset, and nonpsychotic subtype occurred more often in patients with vascular depression than in those with nonvascular depression. A family history of mental illness was found somewhat less often, and anhedonia and functional disability were seen somewhat more often in patients with vascular depression.

CONCLUSIONS

The profile of patients with vascular depression needs to be developed further. This is likely to have important therapeutic and theoretical implications for the management of these patients.

Quantitative magnetic resonance analysis in vascular dementia

The potential role of magnetic resonance imaging (MRI) in differentiating between specific causes of cognitive decline in patients with vascular dementia (VD) has not yet been fully established. We therefore decided to assess the supratentorial cerebral contents in 24 patients with a diagnosis of probable VD and in 24 normal subjects, matched for age and education level, using MRI volumetric parameters obtained by means of a quantitative method. The volumes of subarachnoid and ventricular spaces, cerebral tissue, and hyperintense areas on T2-weighted images were calculated. In order to reduce interindividual variability caused by differences in intracranial size, each absolute measurement was normalized to the relative size of the intracranial volume. In addition, we calculated the ratio between the areas of the corpus callosum (CC) and supratentorial brain at the same level on the T1-weighted image midsagittal plane. The MRI data were correlated with the deterioration of cognitive functions. Patients with VD showed significantly lower cerebral tissue volume and CC area, and higher ventricular space volume than normal subjects. Furthermore, the total volume of the T2 signal alterations was higher in VD patients than in normal subjects. In VD patients, this volume was found to be proportional to the increase in the volume of the ventricular space. On the other hand, no correlation was found between the volume of the T2 signal alterations and the area of the CC. The degree of global cognitive dysfunction and the score of each neuropsychological test did not show any correlation with the MRI data. Our results suggest that ventricular enlargement in VD patients is correlated with the increase in volume of the T2 signal abnormalities, but that the degree of global cognitive dysfunction is not influenced by the volume of these T2 signal abnormalities. Furthermore, the CC atrophy does not influence the score of any neuropsychological test or the degree of global cognitive dysfunction.

[Epidemiologic autopsy of Binswanger's disease]

BACKGROUND

Binswanger's disease is the most substantial part of the continuum of ischemic vascular dementia (IVD). IVD is the second most frequent cause of dementia in industrialised countries. The frequency of IVD generally, and of the Binswanger's disease especially, is due to the method of statistical data collection, in the Czech republic not known.

METHODS AND RESULTS

The crude rate of Binswanger's disease diagnosed histologically among the autopsies of 132 men and 212 woman aged 60-99 yr. performed at Thomayer's University Hospital from 1. 7. 1995 to 1. 7. 1996 by use of by principle of "epidemiologic" autopsy was estimated at 7.9%. This is about a half of the crude rate of Alzheimer's disease found in the same cohort. By estimating of histological "ischemic score", which is independent on clinical data, it is possible to diagnose the Binswanger's disease with high probability.

CONCLUSIONS

The sensitivity and specificity of clinical diagnosis IVD generally and of BN in particular is low. IVD/BN is one of the most frequent and consequential ailment in higher age groups. IVD/BN is preventable and curable at earlier stages of development. Knowledge and precise and timely diagnosis of IVD/BN is fundamentally important for patients.

Neuropathological brain mapping

Neuropathological brain mapping is enabled by extensive semiserial sectioning with whole brain coronal microscopical sections prepared from every 5 to 15 mm. By this method not only type of change but also distribution and regional severity can be assessed, which is fundamental for a correct neuropathological diagnosis. This has proved to be of vital importance for the correlation and validation of the clinical symptoms and brain imaging findings in cases of organic dementia, and vice versa for the interpretation of the neuropathological findings. Different patterns for the distribution and types of changes have been revealed for Alzheimer's disease and frontal lobe degeneration, as well as in vascular dementia where pure subgroups could be identified. In the very aged, the mapping of several types of mild lesions have been shown to cooperate to cause a summational dementia.

Modulation of neuronal and glial cell function by adenosine and neuroprotection in vascular dementia

Dementia is one of the major medical challenges in the industrialized countries. An increasing number of demented patients shows ischemic brain lesions. One strategy to treat dementia could be the reinforcement of the multifarious neuroprotective actions of the endogenous cell modulator adenosine. This involves the modulation of neuronal and glial cell functions. Adenosine appears to raise the threshold for the initiation of the pathophysiological cascade of ischemic neuronal death by counteracting ischemic membrane depolarization and the successive disturbance of intracellular Ca2+ homeostasis. When this threshold is overcome, adenosine seems to stimulate astrocyte differentiation and reinforce important protective astrocyte functions, e.g., synthesis and release of neurotrophic factors such as NGF and the clearance of abnormal neurotoxic levels of K+ and glutamate from the extracellular space. Propentofylline, a combined inhibitor of adenosine reuptake and cAMP phosphodiesterases, reinforces the actions of endogenous adenosine and cAMP. One important action of propentofylline is the inhibition of potentially neurotoxic functions of activated microglia (free radical formation and transformation into brain macrophages). Such drugs may help to inhibit the progressive neurodegenerative process in dementia.

Fundamental pathological lesions in vascular dementia

This review concerns the fundamental cerebral lesions in cases of vascular dementia. Extracerebral vascular alterations are dominated by atherosclerosis with or without thrombosis. In addition, occlusion of extracerebral arteries can be induced by thrombo-embolism and in rare cases by other vascular diseases, chiefly arteritis. Intracerebral microangiopathies are usually of arteriolosclerotic or hyalinotic types in which there is degeneration of smooth muscle cells of the media and deposition of components of extracellular matrix, chiefly collagens. Ageing, chronic hypertension, hyperlipidemias and diabetes are important factors inducing vascular lesions. The vascular lesions, often combined with systemic factors, may produce various ischemic and edematous alterations of the brain parenchyma. Occlusion and obliteration of arteries (macroangiopathy) are associated with large infarcts, whereas microangiopathy may cause lacunar infarcts and some forms of white matter degeneration. Cases of vascular dementia usually present many types of lesions in the brain parenchyma and its arterial supply. The extent and location of the injuries differ considerably from case to case. Location of the lesions, volume of destroyed tissue, multiplicity and bilateral occurrence are most important parameters underlying the clinical manifestations in vascular dementia. A strategic location of a small injury is in some cases of particular importance.

APOE-related frequency of cognitive and noncognitive symptoms in dementia

Although memory disorders and the aphaso-apraxo-agnosic syndrome are the most relevant clinical symptoms in dementia, behavioral changes, mood-related disturbances and sleep disorders are the major cause of institutionalization and caregiver concern. In the present study we have investigated the frequency and progression of cognitive and noncognitive symptoms in Alzheimer's disease (AD) as well as the APOE-related frequency of clinical symptoms in dementia. Memory decline (100%), aphasia (94%), apraxia (99%), agnosia (94%) and motor dysfunction (90%) appeared in practically all cases with mild (GDS-3), moderate (GDS 3-4) and severe (GDS 6-7) dementia. The most frequent noncognitive symptoms include anxiety (76%), depression (68%), behavioral changes (67%), psychotic symptoms (43%), sleep disorders (43%), incontinence (23%) and cerebrovascular symptoms (75%). Anxiety, depression, behavioral changes, psychotic symptoms, motor dysfunction and cognitive deterioration paralleled the severity of dementia, increasing their frequency from mild to severe dementia. The most important sleep disorders were irregular sleep-wake pattern (67%) and insomnia (47%). Disorientation (90%) and drug administration (88%) appeared to be the most important factors in causing sleep disorders in dementia. Disorientation, agitation and motor disorders were slightly more frequent in patients with APOE-4/4, while anxiety and sleep disorders appeared more frequently in APOE-3/4. Behavioral changes and psychotic symptoms did not show any clear association with specific APOE subtypes. In conclusion, our results suggest that noncognitive symptoms are very important clinical events in the disease progression and in decision making for therapeutic intervention and institutionalization. Furthermore, it is likely that some brain dysfunctions leading to particular clinical symptoms might be associated with specific AD genotypes.

The first Italian report on "Binswanger's disease"

The eponym "Binswanger's disease" is frequently used to indicate a form of vascular dementia characterized by white matter rarefaction and lacunar infarcts; however, it is difficult to find any consistency between this picture and the single case reported by Binswanger in 1894, which was vaguely defined both clinically and pathologically, and was probably a case of neurosyphilis. The first Italian report of a case of "Binswanger's disease" was published in 1958 by Donegani and Grattarola, who described a patient with a history of manic episodes followed by progressive mental deterioration. Pathological examination revealed changes mainly located in the hemispheric white matter, and the authors defined the patient as being affected by Binswanger's encephalopathy. Re-evaluation of this report indicates that the term "Binswanger's disease" has been applied to cases with non-specific clinical and pathological characteristics in the past. In this paper, we briefly compare Binswanger's original and the 1958 Italian case report, and discuss the current use of the term "Binswanger's disease".

Evidence for chronic ischaemia in the pathogenesis of vascular dementia: from neuroPATH to neuroPET

Vascular dementia is actually considered as a ill-defined entity. The clinical and neuropathologic criteria of this multifactorial disorder remain uncertain. Although not widely accepted, the introduction of the concept of incomplete infarction in the brain can help to explain some particular types of vascular dementia. In the hypoxic-hypoperfusion dementia syndromes of cerebral cortex and white matter and in lacunar state dementia, which are the most common types of vascular dementia, areas of incomplete infarction co-exist with regions of complete infarction. Although initially rejected by early positron emission tomographic studies, it can now be demonstrated that these incomplete infarction areas reflect chronic ischaemia of the brain and that they are relevant to the pathogenesis of vascular dementia.

Intact brain serotonin system in vascular dementia

Pre- and postsynaptic elements of the 5-hydroxytryptamine (5-HT, serotonin) system were studied in a control group and in patients with vascular dementia (VAD). The 5-HT uptake site was used as a presynaptic marker for 5-HT terminals and 5-HT1A and 5HT2 receptors were used as postsynaptic markers. The binding sites were quantified with radioligand binding techniques, where the radioligands used were [3H]paroxetine, [3H]8-OH-DPAT and [3H]ketanserin, respectively. The presynaptic uptake site was studied in frontal and temporal cortices and caudate nucleus. 5-HT1A and 5-HT2 receptors were studied only in frontal and temporal cortices. There were no differences between control and VAD groups in any of the regions investigated with respect to the number of binding sites (Bmax) and binding affinity (Kd). This indicates that both pre- and postsynaptic parts of the 5-HT system are intact in these brain areas in VAD.

MRI and neuropsychological differences in early- and late-life-onset geriatric depression

We sought to determine whether geriatric patients with late-life-onset major depression have more subcortical hyperintensities on MRI and greater cognitive impairment than age-matched geriatric patients with early-life-onset major depression, suggesting that subcortical disease may be etiologic in late-life depression. Most negative studies of the clinical significance of subcortical hyperintensities on MRI in geriatric patients have sampled from a restricted range of subjects, have employed limited batteries of neuropsychological tests, or have not quantified MRI changes; the present study attempted to address these limitations. Thirty subjects from a geriatric psychiatry inpatient service who were over 60 years of age and presented with major depression were divided into groups with onset of first depression after age 60 (mean = 72.4 years, 15 women, 0 men), and onset of first depression before age 60 (mean = 35.8 years, 12 women, 3 men). Quantitative analysis of MRI yielded the volume of: periventricular hyperintensities (PVH) and deep white-matter hyperintensities (DWMH). Subjects were administered a neuropsychological battery and measures of depression by raters blind to age of onset. The late-onset group had significantly more PVH and DWMH. They were also more impaired on executive and verbal and nonverbal memory tasks. Discriminant analysis using the severity or subcortical signal hyperintensities on MRI, cognitive index, and depression scores correctly predicted late versus early onset of depression in 87% of the early-onset group and 80% of the late-onset group. These findings suggest that late-life-onset depression may be associated with an increased severity of subcortical vascular disease and greater impairment of cognitive performance.

Diffuse vacuolization (spongiosis) and arteriolosclerosis in the frontal white matter occurs in vascular dementia

OBJECTIVE

To examine quantitatively white-matter changes at different sites in patients with definite vascular dementia and Alzheimer's disease.

DESIGN

Prospective clinical and neuropathological series.

SETTING

University Hospital clinics (Helsinki, Finland and London, Ontario).

SUBJECTS

Twenty-two patients with a clinical and neuropathological diagnosis of vascular dementia and 20 patients with Alzheimer's disease.

MEASURES

The frequencies of focal white-matter lesions, arteriolosclerosis, and cerebral amyloid angiopathy were assessed. Validated ratings and cell counts were done in the subcortical U-fiber, centrum semiovale, and periventricular areas of the frontal white matter. Degrees of abnormality (none, mild, moderate, severe) were rated for spongiosis (vacuolization of white matter), état criblé (widening of perivascular spaces), myelin loss, oligodendrocyte density, axonal loss, and overall. Densities of oligodendrocytes and astrocytes (cells per square millimeter) were determined.

RESULTS

Patients with vascular dementia showed focal white-matter lesions and arteriolosclerosis more often than patients with Alzheimer's disease. The patients with vascular dementia also had significantly greater spongiosis (P<.001), état criblé (P=.004), myelin loss (P<.005) and overall white-matter abnormality (P<.001). Arteriolosclerosis was found in association with spongiosis but not with état criblé. Cerebral amyloid angiopathy did not appear to be related to any of the white-matter changes in patients with either vascular dementia or Alzheimer's disease. The U-fiber area showed fewer changes, and the periventricular area tended to be most affected.

CONCLUSION

In addition to focal infarcts, patients with vascular dementia showed widespread diffuse changes, including spongiosis and arteriolosclerosis, along with état criblé and myelin loss. White-matter changes in patients with Alzheimer's disease could not be related to infarction. Pathologic changes in small blood vessels are associated with diffuse white-matter changes and may have a distinct role in the genesis of vascular dementia.