Advances in vascular cognitive impairment 2005

Review of cerebral microangiopathy and Alzheimer's disease: relation between white matter hyperintensities and microbleeds

Although Alzheimer's disease (AD) is basically considered to be a neurodegenerative disorder, cerebrovascular disease is also involved. The role of vascular risk factors and vascular disease in the progression of AD remains incompletely understood. With the development of brain MRI, it is now possible to detect small-vessel disease, whose prevalence and severity increase with age. The first types of small-vessel disease to be described were white matter hyperintensities (WMHs). More recently, small areas of signal loss on T(2)*-weighted images, also called microbleeds (MBs), have been reported. Cerebral MBs are focal deposits of hemosiderin that indicate prior microhemorrhages around small vessels, related to either ruptured atherosclerotic microvessels or amyloid angiopathy. Consequently, using brain MRI for the detection of microangiopathy may prove useful to improve our understanding of the impact of the vascular burden in AD pathology. The relationship between microangiopathy and the clinical course of AD or the conversion of mild cognitive impairment to AD remains questionable in terms of cognitive or affective symptoms, particularly if we consider MBs.

Cognitive functioning and chronic heart failure: a review of the literature (2002-July 2007)

PURPOSE

The purposes of this article are to (1) summarize the state of the science about cognitive impairment and heart failure (HF) using the results of a literature search of publications from 2002 through July 2007; (2) provide a focused review of the studies that used a prospective, longitudinal design with measurement at 2 or more time points in order to identify change in cognitive functioning; and (3) identify gaps and priorities for future studies.

METHODS

A computer search of the literature from 2002 through July 2007 was conducted. All of the resulting 97 references were reviewed, categorized into 8 groups, and evaluated.

RESULTS

The 97 studies were categorized as follows: those not directly related to cognitive impairment (n = 15); comments, letters to the editor, and brief summaries (n = 11); reviews (n = 15); data-based publications using screening measures (n = 14); data-based publications using neuropsychological tests (n = 10); data-based publications assessing brain structure and functioning (n = 22); and data-based publications of populations other than HF in which HF emerged as a correlate/predictor of cognitive impairment (n = 10). Many investigators have reported that patients with HF had cognitive impairments compared with healthy persons without HF; approximately 25% to 50% of HF patients experience cognitive impairments. Patients with HF have been found to have structural and functional brain changes, including losses in gray matter in specific areas, areas of silent stroke, and decreased cerebral perfusion. Gaps in our knowledge and future research priorities are proposed.

CONCLUSIONS

Future studies are urgently needed to identify mechanisms of cognitive impairment in HF, prospectively identify changes in cognitive functioning that occur over time, and evaluate screening measures for use in clinical settings.

Cognitive-behavioral profiles of neurodegenerative dementias: beyond Alzheimer's disease

The neurocognitive and behavioral profiles of vascular dementia and vascular cognitive impairment, dementia with Lewy bodies and Parkinson's disease with dementia, and dementia syndromes associated with frontotemporal lobar degenerations are compared and contrasted with Alzheimer's dementia (AD). Vascular dementia/vascular cognitive impairment is characterized by better verbal memory performance, worse quantitative executive functioning, and prominent depressed mood. Dementia with Lewy bodies and Parkinson's disease with dementia are equally contrasted with AD by defective processing of visual information, better performance on executively supported verbal learning tasks, greater attentional variability, poorer qualitative executive functioning, and the presence of mood-congruent visual hallucinations. The frontal variant of frontotemporal lobar degeneration (frontotemporal dementia) differs from AD by better multimodal retention on learning tasks, different patterns of generative word fluency, defective qualitative executive functioning, and by markedly impairment of comportment. For temporal variants of frontotemporal lobar degenerations, progressive aphasia and semantic dementia, worse language performance relative to AD is typically characteristic.

Clinicopathologic correlations in a large Alzheimer disease center autopsy cohort: neuritic plaques and neurofibrillary tangles "do count" when staging disease severity

There is uncertainty regarding the association of cognitive decline in Alzheimer disease (AD) with classic histopathologic features- neurofibrillary tangles (NFTs) and "neuritic" amyloid plaques (NPs). This uncertainty fuels doubts about the diagnostic importance of NFTs and NPs and leads to confusion regarding hypotheses of AD pathogenesis. Three hundred ninety subjects who underwent longitudinal premortem clinical workup and postmortem quantitative neuropathologic assessment served as the group to address this issue. Subjects with concomitant brain disease(s) were analyzed independently to more accurately assess the contribution of distinct pathologies to cognitive decline. More than 60% of patients of all age groups had important non-AD brain pathologies. However, subjects without superimposed brain diseases showed strong correlations between AD-type pathology counts (NFTs > NPs) and premortem Mini-Mental State Examination scores. The observed correlation was stronger in isocortex than in allocortex and was maintained across age groups including patients older than 90 years. A theoretical model is proposed in which our results are interpreted to support the "amyloid cascade hypothesis" of AD pathogenesis. Our data show that there are many important contributory causes to cognitive decline in older persons. However, NFTs and NPs should not be dismissed as irrelevant in AD based on clinicopathologic correlation.

Distinguishing delirium and dementia

Delirium and dementia are syndromes with multiple cognitive impairments common to the elderly and to medically ill patients. While strides have been made in recognition of both delirium and dementia, underdiagnosis is common. Delirium and dementia cause great suffering in patients, families and caregivers. Both necessitate further advancement in assessment methods and treatment, especially when they overlap. Differentiating delirium and dementia requires recognizing that both may present with cognitive, behavioral and neuropsychiatric symptoms, but attentional disturbance and acute onset are cardinal discriminators in delirium. Superimposed delirium on dementia presents a particularly vexing problem in terms of recognition, treatment and prognosis. The pathophysiology of delirium results from diffuse cortical dysfunction or impairment in susceptible areas of the cortex and the reticular activating system. The pathophysiology of dementia is varied across dementias although several share histolological features. Treatment for both delirium and dementia includes antipsychotic medications and cholinesterase inhibitors, among others, although the disadvantages of pharmacological treatment are becoming better understood and demand caution. Nevertheless, there is an array of treatments and preventive strategies being explored for dementia, and to a lesser degree for delirium, that hold promise for the future.

Dementia with cerebrovascular disease

In this case study, we review the symptoms, cognitive testing, brain imaging, and brain pathology of a woman with dementia, for whom the neuropathological findings suggest a prominent contribution of cerebrovascular disease. Vascular dementia is the term commonly used for persons with dementia resulting from strokes, either clinically evident or subclinical "silent" events. "Mixed dementia" is the term used when there is an admixture of pathological findings related to Alzheimer's disease (AD) and cerebrovascular disease, as in this situation. In some cases of mixed dementia, the pathological involvement of AD may be the principal contributory cause of the cognitive symptoms, and in others, the vascular changes may give the greater contribution.