Staging TDP-43 pathology in Alzheimer’s disease

Division of Behavioral Neurology, Department of Neurology, Mayo Clinic, Rochester, MN, 55905, USA, .
Acta Neuropathologica (Impact Factor: 10.76). 11/2013; 127(3). DOI: 10.1007/s00401-013-1211-9
Source: PubMed


TDP-43 immunoreactivity occurs in 19-57 % of Alzheimer's disease (AD) cases. Two patterns of TDP-43 deposition in AD have been described involving hippocampus (limbic) or hippocampus and neocortex (diffuse), although focal amygdala involvement has been observed. In 195 AD cases with TDP-43, we investigated regional TDP-43 immunoreactivity with the aim of developing a TDP-43 in AD staging scheme. TDP-43 immunoreactivity was assessed in amygdala, entorhinal cortex, subiculum, hippocampal dentate gyrus, occipitotemporal, inferior temporal and frontal cortices, and basal ganglia. Clinical, neuroimaging, genetic and pathological characteristics were assessed across stages. Five stages were identified: stage I showed scant-sparse TDP-43 in the amygdala only (17 %); stage II showed moderate-frequent amygdala TDP-43 with spread into entorhinal and subiculum (25 %); stage III showed further spread into dentate gyrus and occipitotemporal cortex (31 %); stage IV showed further spread into inferior temporal cortex (20 %); and stage V showed involvement of frontal cortex and basal ganglia (7 %). Cognition and medial temporal volumes differed across all stages and progression across stages correlated with worsening cognition and medial temporal volume loss. Compared to 147 AD patients without TDP-43, only the Boston Naming Test showed abnormalities in stage I. The findings demonstrate that TDP-43 deposition in AD progresses in a stereotypic manner that can be divided into five distinct topographic stages which are supported by correlations with clinical and neuroimaging features. Given these findings, we recommend sequential regional TDP-43 screening in AD beginning with the amygdala.

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    • "The selection of brain regions of interest was based on key brain regions routinely sampled for neuropathological assessment that are included in the three TDP-43 topographical staging schemes (Brettschneider et al., 2013, 2014; Josephs et al., 2014a) (Table 1). The following regions were included in the analyses: superior prefrontal cortex (Brodmann area 9), motor cortex (precentral gyrus, Brodmann area 4), anterior cingulate cortex (just posterior to genu of corpus callosum; Brodmann area 24), inferior temporal cortex (Brodmann area 20), entorhinal cortex, hippocampal dentate gyrus and CA1 region (at coronal level of lateral geniculate nucleus), amygdala, midbrain (including the substantia nigra and red nucleus), pontine tegmentum at the transverse brainstem level of the locus coeruleus , and medulla oblongata at the transverse level of the hypoglossal nucleus. "
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    ABSTRACT: The pathological sequestration of TAR DNA-binding protein 43 (TDP-43, encoded by TARDBP) into cytoplasmic pathological inclusions characterizes the distinct clinical syndromes of amyotrophic lateral sclerosis and behavioural variant frontotemporal dementia, while also co-occurring in a proportion of patients with Alzheimer's disease, suggesting that the regional concentration of TDP-43 pathology has most relevance to specific clinical phenotypes. This has been reflected in the three different pathological staging schemes for TDP-43 pathology in these different clinical syndromes, with none of these staging schemes including a preclinical phase similar to that which has proven beneficial in other neurodegenerative diseases. To apply each of these three staging schemes for TDP-43 pathology, the clinical phenotype must be known undermining the potential predictive value of the pathological examination. The present study set out to test whether a more unified approach could accurately predict clinical phenotypes based solely on the regional presence and severity of TDP-43 pathology. The selection of brain regions of interest was based on key regions routinely sampled for neuropathological assessment under current consensus criteria that have also been used in the three TDP-43 staging schemes. The severity of TDP-43 pathology in these regions of interest was assessed in four clinicopathological phenotypes: amyotrophic lateral sclerosis (n = 27, 47-78 years, 15 males), behavioural variant frontotemporal dementia (n = 15, 49-82 years, seven males), Alzheimer's disease (n = 26, 51-90 years, 11 males) and cognitively normal elderly individuals (n = 17, 80-103 years, nine males). Our results demonstrate that the presence of TDP-43 in the hypoglossal nucleus discriminates patients with amyotrophic lateral sclerosis with an accuracy of 98%. The severity of TDP-43 deposited in the anterior cingulate cortex identifies patients with behavioural variant frontotemporal dementia with an accuracy of 99%. This identification of regional pathology associated with distinct clinical phenotypes suggests key regions on which probabilistic pathological criteria, similar to those currently available for Alzheimer's disease and dementia with Lewy bodies, can be developed for TDP-43 proteinopathies. We propose and validate a simplified probabilistic statement that involves grading the presence of TDP-43 in the hypoglossal nucleus and the severity of TDP-43 in the anterior cingulate for the pathological identification of TDP-43 proteinopathy cases with clinical amyotrophic lateral sclerosis and behavioural variant frontotemporal dementia. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email:
    Brain 07/2015; DOI:10.1093/brain/awv220 · 9.20 Impact Factor
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    • "We were unable to include amygdala slides due to study tissue storage protocols. Amygdala TDP-43 positivity has been reported in AD [13] [16] and cognitively normal older adults [22] in the absence of positivity in other areas. We therefore likely underestimated the prevalence of TDP-43 pathology due to a lack of amygdala tissue. "
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    ABSTRACT: Background: The significance of TDP-43 pathology in relation to aging and dementia in the population is unclear. Objective: We aimed to determine the prevalence of transactive response DNA-binding protein of 43 kDA (TDP-43) neuronal inclusions in a population-based sample, and associations with age group at death (≤90 and >90 years) and clinical dementia status prior to death. Further, we investigate associations between TDP-43 inclusions and other key dementia-related neuropathologies (plaques, tangles, and neuronal loss) within the hippocampus and entorhinal and temporal cortices. Methods: All brain donors within the Cambridge City over-75 s Cohort (CC75C), which is population-based and longitudinally tracked (n = 228), were included. Age at death ranged from 78 to 106 years. TDP-43 neuronal inclusions were assessed in the hippocampus, entorhinal cortex, and temporal cortex. These data were combined with existing clinical and neuropathological data. Results: TDP-43 neuronal inclusions were present in 27% of the sample, 36% of those with clinical dementia and 18% without dementia. Individuals who died later (>90 years) or with clinical dementia were more likely to show TDP-43 inclusions. Hippocampal and entorhinal TDP-43 inclusions were significantly associated with dementia severity and increasing age, taking into account other neuropathologies. TDP-43 neuronal inclusions appeared to co-localized with severe neuronal loss. Conclusion: Findings indicate that hippocampal and entorhinal TDP-43 inclusions are important substrates of late onset dementia which appear to co-localize with severe neuronal loss, but not with Alzheimer's disease markers of amyloid and tau. This broadens the accepted view of TDP-43 pathology in dementias.
    Journal of Alzheimer's disease: JAD 06/2014; 42(2). DOI:10.3233/JAD-132351 · 4.15 Impact Factor
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    ABSTRACT: The aim of this study was to determine whether the TAR DNA-binding protein of 43 kDa (TDP-43) has any independent effect on the clinical and neuroimaging features typically ascribed to Alzheimer's disease (AD) pathology, and whether TDP-43 pathology could help shed light on the phenomenon of resilient cognition in AD. Three-hundred and forty-two subjects pathologically diagnosed with AD were screened for the presence, burden and distribution of TDP-43. All had been classified as cognitively impaired or normal, prior to death. Atlas-based parcellation and voxel-based morphometry were used to assess regional atrophy on MRI. Regression models controlling for age at death, apolipoprotein ε4 and other AD-related pathologies were utilized to explore associations between TDP-43 and cognition or brain atrophy, stratified by Braak stage. In addition, we determined whether the effects of TDP-43 were mediated by hippocampal sclerosis. One-hundred and ninety-five (57 %) cases were TDP-positive. After accounting for age, apolipoprotein ε4 and other pathologies, TDP-43 had a strong effect on cognition, memory loss and medial temporal atrophy in AD. These effects were not mediated by hippocampal sclerosis. TDP-positive subjects were 10× more likely to be cognitively impaired at death compared to TDP-negative subjects. Greater cognitive impairment and medial temporal atrophy were associated with greater TDP-43 burden and more extensive TDP-43 distribution. TDP-43 is an important factor in the manifestation of the clinico-imaging features of AD. TDP-43 also appears to be able to overpower what has been termed resilient brain aging. TDP-43 therefore should be considered a potential therapeutic target for the treatment of AD.
    Acta Neuropathologica 03/2014; 127(6). DOI:10.1007/s00401-014-1269-z · 10.76 Impact Factor
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