Brain : a journal of neurology
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Multicenter Study Comparative Study
Cognitive impairment, decline and fluctuations in older community-dwelling subjects with Lewy bodies.
Lewy bodies are common in the ageing brain and often co-occur with Alzheimer's disease pathology. There is little known regarding the independent role of Lewy body pathology in cognition impairment, decline and fluctuations in community-dwelling older persons. We examined the contribution of Lewy body pathology to dementia, global cognition, cognitive domains, cognitive decline and fluctuations in 872 autopsied subjects (mean age = 87.9 years) from the Rush Religious Order Study (n = 491) and Memory and Aging Project (n = 381) longitudinal community-based clinical-pathological studies. ⋯ Neocortical-type Lewy body pathology is associated with increased odds of dementia; lower and more rapid decline in all cognitive domains including episodic memory and fluctuations in decline in semantic and working memory. Limbic-type Lewy body pathology is specifically associated with lower and more rapid decline in visuospatial skills. The effect of Lewy body pathology on cognition appears to be independent of Alzheimer's disease pathology.
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Comparative Study
In vivo and post-mortem memory circuit integrity in frontotemporal dementia and Alzheimer's disease.
Behavioural variant frontotemporal dementia can present with episodic memory deficits as severe as those in Alzheimer's disease. Little is known of the integrity of grey matter areas and white matter tracts of the Papez memory circuit in these diseases. The integrity of the Papez circuit (hippocampus, fornix, mammillary bodies, anterior thalamus, cingulate cortex) was investigated in vivo and at post-mortem in behavioural variant frontotemporal dementia and Alzheimer's disease cohorts using voxel-based morphometry, diffusion tensor imaging and manual volumetric tracing. ⋯ Hippocampal atrophy does not appear to be an efficient diagnostic marker for underlying behavioural variant frontotemporal dementia or Alzheimer's disease pathology, although for behavioural variant frontotemporal dementia, episodic memory deficits in conjunction with marked hippocampal atrophy emerge as potential biomarkers for frontotemporal lobar degeneration with TDP-43 inclusions pathology. Sub-regions of the Papez circuit were differentially affected in behavioural variant frontotemporal dementia and Alzheimer's disease with subcortical regions determining the degree of episodic memory deficits in behavioural variant frontotemporal dementia. Subcortical atrophy should be taken into account when establishing whether the severe amnesia observed in a patient is likely to be due to behavioural variant frontotemporal dementia or Alzheimer's disease pathology.
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Temporal lobe seizures have a significant chance to induce impairment of normal brain functions. Even after the termination of ictal discharges, during the post-ictal period, loss of consciousness, decreased responsiveness or other cognitive dysfunctions can persist. Previous studies have found various anatomical and functional abnormalities accompanying temporal lobe seizures, including an abnormal elevation of cortical slow waves. ⋯ Secondarily generalized seizures and complex partial seizures exhibited increased slow waves distributed to frontal areas with spread to contralateral temporal and parietal regions than in simple partial seizures. These results revealed that a widespread cortical network including temporal and fronto-parietal cortex is involved in abnormal slow-wave activity following temporal lobe seizures. The differential spectral and spatial shifts of post-ictal electroencephalography activity in simple partial, complex partial and secondarily generalized seizures suggest a possible connection between cortical slow waves and behavioural and cognitive changes in a human epilepsy model.
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Comparative Study
Cortical lesion load associates with progression of disability in multiple sclerosis.
Cortical inflammatory lesions have been correlated with disability and cortical atrophy in multiple sclerosis. The extent to which cortical lesion load is associated with longer-term physical and cognitive disability in different multiple sclerosis phenotypes has not yet been investigated. Thus, a 5-year prospective longitudinal study was carried on in a large group of patients with multiple sclerosis. ⋯ Disease duration (β = 0.52, P < 0.001), cortical lesion volume (β = 0.67, P < 0.001), grey matter fraction (β = 0.56, P < 0.001) and T(2) white matter lesion volume (β = 0.31, P = 0.040) at baseline were found to be independent predictors of cognitive status at the end of the study. While confirming the relevance of cortical pathology in all multiple sclerosis phenotypes, but benign, our study suggests that grey matter and white matter changes in multiple sclerosis occur, at least, partly independently, and that grey matter, more than white matter, damage is associated with physical and cognitive disability progression. Thus, the combination of grey and white matter parameters gives a more comprehensive view of multiple sclerosis pathology and allows a better understanding of the progressive phase of the disease, which, however, seems more related to cortical damage than to subcortical white matter changes.
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Comparative Study
My belief or yours? Differential theory of mind deficits in frontotemporal dementia and Alzheimer's disease.
Theory of mind reasoning-the ability to understand someone else's mental states, such as beliefs, intentions and desires-is crucial in social interaction. It has been suggested that a theory of mind deficit may account for some of the abnormalities in interpersonal behaviour that characterize patients affected by behavioural variant frontotemporal dementia. However, there are conflicting reports as to whether understanding someone else's mind is a key difference between behavioural variant frontotemporal dementia and other neurodegenerative conditions such as Alzheimer's disease. ⋯ This finding suggests that self-perspective inhibition may depend on cognitive processes that are not specific to the social domain. Last, the severity of the deficit in inferring someone else's beliefs correlated significantly over all subjects with hypometabolism in the left temporoparietal junction, whereas the severity of the deficit in self-perspective inhibition correlated significantly with hypometabolism in the right lateral prefrontal cortex. In conclusion, our findings provided clinical and imaging evidence to support differential deficits in two components of theory of mind reasoning (subserved by distinct brain regions) in patients with Alzheimer's disease and patients with behavioural variant frontotemporal dementia.