Necrosome-positive granulovacuolar degeneration is associated with TDP-43 pathological lesions in the hippocampus of ALS/FTLD cases.

AIM: Granulovacuolar degeneration (GVD) in Alzheimer's disease (AD) involves the necrosome, which is a protein complex consisting of phosphorylated receptor-interacting protein kinase 1 (pRIPK1), pRIPK3 and phosphorylated mixed lineage kinase domain-like protein (pMLKL). Necrosome-positive GVD was associated with neuron loss in AD. GVD was recently linked to the C9ORF72 mutation in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with transactive response DNA-binding protein (TDP-43) pathology (FTLD-TDP). Therefore, we investigated whether GVD in cases of the ALS-FTLD-TDP spectrum (ALS/FTLD) shows a similar involvement of the necrosome as in AD, and whether it correlates with diagnosis, presence of protein aggregates and cell death in ALS/FTLD. METHODS: We analysed the presence and distribution of the necrosome in post-mortem brain and spinal cord of ALS and FTLD-TDP patients (n = 30) with and without the C9ORF72 mutation, and controls (n = 22). We investigated the association of the necrosome with diagnosis, the presence of pathological protein aggregates and neuronal loss. RESULTS: Necrosome-positive GVD was primarily observed in hippocampal regions of ALS/FTLD cases and was associated with hippocampal TDP-43 inclusions as the main predictor of the pMLKL-GVD stage, as well as with the Braak stage of neurofibrillary tangle pathology. The central cortex and spinal cord, showing motor neuron loss in ALS, were devoid of any accumulation of pRIPK1, pRIPK3 or pMLKL. CONCLUSIONS: Our findings suggest a role for hippocampal TDP-43 pathology as a contributor to necrosome-positive GVD in ALS/FTLD. The absence of necroptosis-related proteins in motor neurons in ALS argues against a role for necroptosis in ALS-related motor neuron death.

Increased expression of BIN1 mediates Alzheimer genetic risk by modulating tau pathology.

Genome-wide association studies (GWAS) have identified a region upstream the BIN1 gene as the most important genetic susceptibility locus in Alzheimer's disease (AD) after APOE. We report that BIN1 transcript levels were increased in AD brains and identified a novel 3 bp insertion allele ∼28 kb upstream of BIN1, which increased (i) transcriptional activity in vitro, (ii) BIN1 expression levels in human brain and (iii) AD risk in three independent case-control cohorts (Meta-analysed Odds ratio of 1.20 (1.14-1.26) (P=3.8 × 10(-11))). Interestingly, decreased expression of the Drosophila BIN1 ortholog Amph suppressed Tau-mediated neurotoxicity in three different assays. Accordingly, Tau and BIN1 colocalized and interacted in human neuroblastoma cells and in mouse brain. Finally, the 3 bp insertion was associated with Tau but not Amyloid loads in AD brains. We propose that BIN1 mediates AD risk by modulating Tau pathology.

Alzheimer risk associated with a copy number variation in the complement receptor 1 increasing C3b/C4b binding sites.

Two multicentre genome-wide association (GWA) studies provided substantial evidence, implicating the complement receptor 1 gene (CR1) in Alzheimer disease (AD) genetic etiology. CR1 encodes a large transmembrane receptor with a crucial role in the immune complement cascade. We performed a genetic follow-up of the GWA CR1 association in a Flanders-Belgian cohort (n=1883), and investigated the effect of single-nucleotide polymorphisms (SNPs) located in the CR1 locus on AD risk and cerebrospinal fluid (CSF) biomarker levels. We obtained significant association (P(adj)<0.03; odds ratio (OR)=1.24 (95% confidence interval (CI): 1.02-1.51)) for one CR1 risk haplotype, and haplotype association was strongest in individuals carrying apolipoprotein E (APOE) ɛ4 alleles (P(adj)<0.006; OR=1.50 (95% CI: 1.08-2.09)). Also, four SNPs correlated with increased CSF amyloid Aß1₋42 levels, suggesting a role for the CR1 protein in Aß metabolism. Moreover, we quantified a low-copy repeat (LCR)-associated copy number variation (CNV) in CR1, producing different CR1 isoforms, CR1-F and CR1-S, and obtained significant association in carriers of CR1-S. We replicated the CR1 CNV association finding in a French cohort (n=2003) and calculated in the combined cohorts, an OR of 1.32; 95% CI: 1.10-1.59 (P=0.0025). Our data showed that the common AD risk association may well be explained by the presence of CR1-S increasing the number of C3b/C4b and cofactor activity sites and AD risk with 30% in CR1-S carriers. How precisely the different functional role of CR1-S in the immune complement cascade contributes to AD pathogenesis will need additional functional studies.

[Imaging of language and communication in dementia]. / Beeldvorming van taal en communicatie bij dementie.

BACKGROUND: Social interaction in patients with dementia is compromised by language problems and impairment of other cognitive domains involved in communication. AIM: To describe language and communication problems in patients with dementia and to provide insight into the neurological basis of these problems. METHOD: Our study is based on some of our own research findings and on relevant literature concerning the imaging of language and communication in patients with Alzheimer's disease and frontotemporal degeneration. RESULTS: Imaging revealed that the clinical expression of communicative disorders in patients with cortical neurodegeneration depends on regional brain atrophy and a possible functional reorganisation triggered by neuropathological changes. CONCLUSION: Brain imaging increases our knowledge about the pathogenesis of communicative disorders in dementia.

Functional specialisation within the cortical language network: effects of cortical dysfunction.

In the 1990's neuroanatomical models of language and semantic memory have been mainly based on functional neuroimaging studies of brain activity in healthy volunteers and correlational studies between structural lesions in patients and behavioral deficits. In this paper we present a novel approach where we test models that have been developed in healthy volunteers by means of functional imaging in patients in combination with behavioral studies. Study populations consist of patients with focal cortical stroke (n = 2), amnestic mild cognitive impairment (n = 14) and primary progressive aphasia (n = 18). The experiments provide converging evidence that 1. the integrity of the right mid- and anterior fusiform gyrus is required for full and detailed retrieval of knowledge of visual attributes of concrete entities 2. the left posterior superior temporal sulcus is critically involved in lexical-semantic retrieval 3. the anterior temporal pole to the left functions as an associative structure that links the representations of meaning that are distribured over the cortical brain surface. Our experiments also provide us with new insight into the degradation and re-organisation of the language system in cortical neurodegenerative disease.

Alzheimer dementia caused by a novel mutation located in the APP C-terminal intracytosolic fragment.

Since the first report showing that Alzheimer disease (AD) might be caused by mutations in the amyloid precursor protein gene (APP), 20 different missense mutations have been reported. The majority of early-onset AD mutations alter processing of APP increasing relative levels of Abeta42 peptide, either by increasing Abeta42 or decreasing Abeta40 peptide levels or both. In a diagnostic setting using direct sequence analysis, we identified in one patient with familial early-onset AD a novel mutation in APP (c.2172G>C), predicting a K724N substitution in the intracytosolic fragment. The mutation is located downstream of the epsilon-cleavage site of APP and is the furthermost C-terminal mutation reported to date. In vitro expression of APP K724N cDNA showed an increase in Abeta42 and a decrease in Abeta40 levels resulting in a near three-fold increase of the Abeta42/Abeta40 ratio. Further, in vivo amyloid positron emission tomography (PET) imaging revealed significantly increased cortical amyloid deposits, supporting that in human this novel APP mutation is likely causing disease.

Attentional responses to unattended stimuli in human parietal cortex.

Right-sided parietal lesions lead to lateralized attentional deficits which are most prominent with bilateral stimulation. We determined how an irrelevant stimulus in the unattended hemifield alters attentional responses in parietal cortex during unilateral orienting. A trial consisted of a central spatial cue, a delay and a test phase during which a grating was presented at 9 degrees eccentricity. Subjects had to discriminate the orientation of the grating. The unattended hemifield was either empty or contained a second, irrelevant grating. We carried out a series of functional MRI (fMRI) studies in 35 healthy volunteers (13 men and 22 women, aged between 19 and 30 years) as well as a behavioural and structural lesion mapping study in 17 right-hemispheric lesion patients, 11 of whom had neglect. In the patients with but not in those without neglect, the addition of a distractor in the unattended hemifield significantly impaired performance if attention was directed contralesionally but not if it was directed ipsilesionally. In the healthy volunteers, we discerned two functionally distinct areas along the posterior-anterior axis of the intraparietal sulcus (IPS). The posterior, descending IPS segment in both hemispheres showed attentional enhancement of responses during contralateral attentional orienting and was unaffected by the presence of an irrelevant stimulus in the ignored hemifield. In contrast, the right-sided horizontal IPS segment showed a strong attentional response when subjects oriented to a stimulus in the relevant hemifield and an irrelevant stimulus was simultaneously present in the ignored hemifield, compared with unilateral stimulation. This effect was independent of the direction of attention. The symmetrical left-sided horizontal IPS segment showed the highest responses under the same circumstances, in combination with a contralateral bias during unilateral stimulation conditions. None of the six patients without neglect had a lesion of the horizontal IPS segment. In four of the 11 neglect patients, the lesion overlapped with the horizontal IPS activity cluster and lay in close proximity to it in another four. The remaining three patients had a lesion at a distance from the parietal cortex. Our findings reconcile the role of the IPS in endogenous attentional control with the clinically significant interaction between direction of attention and bilateral stimulation in right parietal lesion patients. Functional imaging in neglect patients will be necessary to assess IPS function in those cases where the structural lesion spares the middle IPS segment.

Cognitive aging and Alzheimer's disease.

Cognitive aging and clinically probable Alzheimer's disease can be discriminated by means of clinical and neuropsychological testing, and structural and functional imaging techniques. Research at the level of cognitive brain systems and at the molecular level provides exciting new insights into the relation between aging and neurodegeneration. The advances at the clinical and at the basic research levels are necessary if we wish to meet the formidable challenge that the increasing prevalence of Alzheimer's disease poses to the medical community.

Visualisation of loss of 5-HT2A receptors with age in healthy volunteers using [18F]altanserin and positron emission tomographic imaging.

We used [18F]altanserin and positron emission tomography (PET) to image serotonin 5-HT2A receptors in humans. The highest [18F]altanserin uptake is found in the cerebral cortex, with specific-to-nonspecific binding ratios varying from 0.53 to 1.91 in humans between 24 and 48 years of age. In all neocortical regions studied, [18F]altanserin uptake correlates negatively with age. No correlations were found between age and uptake in the cerebellum, the regional cerebral blood flow, or the time course of metabolization of [18F]altanserin. The reduction in cerebral 5-HT2A receptor binding thus directly reflects the loss of specific 5-HT2A receptors with age.

Language, ageing and neurodegenerative disease.

UNLABELLED: Until recently brain-behavior relationships in healthy ageing and neurodegenerative disease were based on studies of the state of the brain after its final outcome, death. Direct in vivo imaging of dynamic cognitive systems at different disease stages offers an unprecedented opportunity to gain insight into evolving cognitive dysfunctions and changing brain systems. In this talk we will present new data on how this semantic system is affected by healthy ageing, lesions and neurodegenerative disease. 1. Age: One of the principal cognitive consequences of normal ageing is a decline of episodic memory while semantic memory is preserved. Despite the fact that semantic task performance remains at equal levels, the underlying semantic brain network shows clear alterations: The gradient between left and right prefrontal cortex is significantly decreased, principally due to a decrease of left prefrontal activation. 2. Focal brain lesions: In a patient who suffered from an ischemic lesion that is confined to the right anterior fusiform gyrus, associative semantics were still performed at a high level while drawing from memory and pseudo-object decision task were severely impaired. The right anterior fusiform group activation coincided with the lesion. In this patient the mirror left fusiform region was significantly more active during picture semantics than under normal circumstances. A case with a lesion in the mirror left fusiform region will also be discussed. 3. Neurodegenerative disease: We will contrast two patient groups: Patients with a progressive word finding and semantic memory deficit (primary progressive aphasia, most often due to frontotemporal degeneration) and patients with an isolated episodic memory deficit (incipient Alzheimer's disease, mild cognitive impairment). In patients with primary progressive aphasia different components of the semantic network, i.e. inferior frontal sulcus, superior temporal sulcus and anterior temporal pole, show less activity than in healthy controls. The activity levels correlate with performance on off-line picture naming tasks. Interestingly, the right medial temporal lobe, classically implicated in episodic memory functions, shows higher activity in primary progressive aphasics than in healthy controls, suggesting that patients make use of non-verbal episodic memory strategies to compensate for their semantic deficit. In contrast, patients with mild cognitive impairment clinically have only an isolated episodic memory deficit and perform within the normal range on semantic tasks. Despite normal performance the semantic system for words and pictures show profound alterations, including among other differences decreased activity in Wernicke's area (posterior middle temporal gyrus) on the left compared to age-matched controls. CONCLUSION: cognitive brain systems for semantic memory change with increasing age. These changes are qualitatively different from those found in incipient Alzheimer's disease or in primary progressive aphasia. The degree to which brain systems adapt in a plastic way to pathogenetic processes at multiple levels, is a determinant of disease manifestation and an important target for current and future therapies.

Classification of primary progressive aphasia and its variants.

This article provides a classification of primary progressive aphasia (PPA) and its 3 main variants to improve the uniformity of case reporting and the reliability of research results. Criteria for the 3 variants of PPA--nonfluent/agrammatic, semantic, and logopenic--were developed by an international group of PPA investigators who convened on 3 occasions to operationalize earlier published clinical descriptions for PPA subtypes. Patients are first diagnosed with PPA and are then divided into clinical variants based on specific speech and language features characteristic of each subtype. Classification can then be further specified as "imaging-supported" if the expected pattern of atrophy is found and "with definite pathology" if pathologic or genetic data are available. The working recommendations are presented in lists of features, and suggested assessment tasks are also provided. These recommendations have been widely agreed upon by a large group of experts and should be used to ensure consistency of PPA classification in future studies. Future collaborations will collect prospective data to identify relationships between each of these syndromes and specific biomarkers for a more detailed understanding of clinicopathologic correlations.

Genetic contribution of FUS to frontotemporal lobar degeneration.

BACKGROUND: Recently, the FUS gene was identified as a new causal gene for amyotrophic lateral sclerosis (ALS) in approximately 4% of patients with familial ALS. Since ALS and frontotemporal lobar degeneration (FTLD) are part of a clinical, pathologic, and genetic disease spectrum, we investigated a potential role of FUS in FTLD. METHODS: We performed mutational analysis of FUS in 122 patients with FTLD and 15 patients with FTLD-ALS, as well as in 47 patients with ALS. Mutation screening was performed by sequencing of PCR amplicons of the 15 FUS exons. RESULTS: We identified 1 patient with FTLD with a novel missense mutation, M254V, that was absent in 638 control individuals. In silico analysis predicted this amino acid substitution to be pathogenic. The patient did not have a proven family history of neurodegenerative brain disease. Further, we observed the known R521H mutation in 1 patient with ALS. No FUS mutations were detected in the patients with FTLD-ALS. While insertions/deletions of 2 glycines (G) were suggested to be pathogenic in the initial FUS reports, we observed an identical GG-deletion in 2 healthy individuals and similar G-insertions/deletions in 4 other control individuals, suggesting that G-insertions/deletions within this G-rich region may be tolerated. CONCLUSIONS: In a first analysis of FUS in patients with frontotemporal lobar degeneration (FTLD), we identified a novel FUS missense mutation, M254V, in 1 patient with pure FTLD. At this point, the biologic relevance of this mutation remains elusive. Screening of additional FTLD patient cohorts will be needed to further elucidate the contribution of FUS mutations to FTLD pathogenesis.

Clinical heterogeneity in 3 unrelated families linked to VCP p.Arg159His.

BACKGROUND: Families associated with missense mutations in the valosin-containing protein (VCP) present with a rare autosomal dominant multisystem disorder of frontotemporal lobar degeneration (FTLD), inclusion body myopathy (IBM), and Paget disease of bone (PDB), referred to as IBMPFD. METHODS: We used exon-based genomic DNA sequencing to test for VCP mutations in 123 unrelated Belgian patients with FTLD and their relatives, and the absence of such mutations in 157 control individuals. We analyzed haplotype sharing among mutation carriers by genotyping 8 microsatellite markers in the VCP locus. We obtained family history and clinical and pathologic data using established diagnostic instruments. RESULTS: Mutation analysis of VCP identified 2 Belgian patients with FTLD carrying the p.Arg159His mutation, which segregated in their families. In one family, patients presented with FTLD only, whereas in the other family, patients developed FTLD, PDB, or both without signs of IBM for any of the mutation carriers. We had previously identified p.Arg159His in an Austrian family with patients exhibiting both IBM and PDB. Haplotype sharing analysis indicated that the 3 p.Arg159His families are unrelated. Clinical follow-up of the Austrian family identified dementia symptoms in 1 patient. Autopsy data of 3 patients of the 2 Belgian families revealed FTLD pathology with numerous ubiquitin-immunoreactive, intranuclear inclusions and dystrophic neurites staining positive for TDP-43 protein. CONCLUSIONS: In 3 unrelated families with IBMPFD segregating VCP p.Arg159His, we observed a high degree of clinical heterogeneity and variable penetrance of the 3 cardinal clinical phenotypes: inclusion body myopathy, Paget disease of bone, and frontotemporal lobar degeneration. In contrast, the neuropathologic phenotype was consistent with FTLD-TDP type 4.

Orchiectomy for suspected microscopic tumor in patients with anti-Ma2-associated encephalitis.

OBJECTIVE: To report the presence of microscopic neoplasms of the testis in men with anti-Ma2-associated encephalitis (Ma2-encephalitis) and to discuss the clinical implications. METHODS: Orchiectomy specimens were examined using immunohistochemistry with Ma2 and Oct4 antibodies. RESULTS: Among 25 patients with Ma2-encephalitis younger than 50 years, 19 had germ-cell tumors, and 6 had no evidence of cancer. These 6 patients underwent orchiectomy because they fulfilled five criteria: 1) demonstration of anti-Ma2 antibodies in association with MRI or clinical features compatible with Ma2-encephalitis, 2) life-threatening or progressive neurologic deficits, 3) age < 50 years, 4) absence of other tumors, and 5) new testicular enlargement or risk factors for germ-cell tumors, mainly cryptorchidism or ultrasound evidence of testicular microcalcifications. All orchiectomy specimens showed intratubular-germ cell neoplasms unclassified type (IGCNU) and other abnormalities including microcalcifications, atrophy, fibrosis, inflammatory infiltrates, or hypospermatogenesis. Ma2 was expressed by neoplastic cells in three of three patients examined. Even though most patients had severe neurologic deficits at the time of orchiectomy (median progression of symptoms, 10 months), 4 had partial improvement and prolonged stabilization (8 to 84 months, median 22.5 months) and two did not improve after the procedure. CONCLUSIONS: In young men with Ma2-encephalitis, 1) the disorder should be attributed to a germ-cell neoplasm of the testis unless another Ma2-expressing tumor is found, 2) negative tumor markers, ultrasound, body CT, or PET do not exclude an intratubular germ-cell neoplasm of the testis, and 3) if no tumor is found, the presence of the five indicated criteria should prompt consideration of orchiectomy.

Invasion of a subcutaneous Aspergillus abscess into the brain.

We present the case of a 57 year old woman with contiguous infection by Aspergillus fumigatus. The lesion started subcutaneously, forming an abscess. Seventeen days later we observed an intracranial abscess, infection of the frontal sinus and destruction of the frontal bone between the subcutaneous abscess and the sinus.

The response of left temporal cortex to sentences.

The meaning of a sentence differs from the sum of the meanings of its constituents. Left anterior temporal cortex responds to sentences more strongly than to unconnected words. We hypothesized that the anterior temporal response to sentences is due to this difference in meaning (compositional semantics). Using positron emission tomography (PET), we studied four experimental conditions (2 x 2 factorial design): In one condition, subjects read normal sentences. In a second condition, they read grammatically correct sentences containing numerous semantic violations (semantically random sentences). In a third condition, we scrambled the word order within the normal sentences, and, in a fourth condition, the word order was scrambled within the semantically random sentences. The left anterior temporal pole responded strongly to sentences compared to scrambled versions of sentences. A similar although weaker response occurred in the left anterior superior temporal sulcus and the left posterior middle temporal gyrus. A subset of voxels within the left anterior temporal pole responded more to semantically random sentences and their scrambled versions than to normal sentences and the corresponding scrambled versions (main effect of semantic randomness). Finally, the grammatical and the semantic factor interacted in a subset of voxels within the anterior temporal pole: Activity was higher when subjects read normal sentences compared to their scrambled versions but not for semantically random sentences compared to their corresponding scrambled versions. The effects of grammar and meaning and, most importantly, the interaction between grammatical and semantic factors are compatible with the hypothesis that the left anterior temporal pole contributes to the composition of sentence meaning.

A motion area in human visual cortex.

We have localized an area in the human brain involved in the processing of contours defined by motion differences (kinetic contours) by comparing with positron emission tomography the regional cerebral blood flow in tasks performed with kinetic and luminance-defined gratings. These tasks included passive viewing, counting the total number of grating stimuli, and counting the number of gratings of a given orientation. Comparison between the counting tasks and passive viewing with a given type of contour revealed a set of active areas that were similar for both luminance-defined and kinetic contours. Comparisons between these two types of contours revealed a single focus in the right hemisphere that did not overlap with the many regions activated by uniform motion. In particular this "kinetic focus" was clearly separated from the area previously defined as the human homologue of V5/middle temporal. Activity in this kinetic focus was stronger when orientation had to be processed than in the other two tasks. These results and control experiments with uniformly moving random dot patterns suggest the existence of an area in the human visual system that is activated much more by kinetic contours than by luminance contours or uniformly moving random dots. Up to now, such an area has not been described in the monkey visual system.

Blood flow in human anterior temporal cortex decreases with stimulus familiarity.

In this positron emission tomography investigation of human nonverbal visual memory, we determined the anatomical distribution of changes in regional cerebral blood flow (rCBF) reflecting familiarity of visual shapes. All stimuli consisted of relatively simple, abstract outlines generated by Fourier expansions. Subjects performed the same task twice, once using unfamiliar and once using familiar stimuli. The task was a modified version of delayed nonmatching-to-sample, consisting of one sample presentation prior to tracer injection and a sequence of test trials during which images were acquired. When this task was performed with familiar instead of unfamiliar stimuli, only decreases in rCBF were observed, which were localized to the left lateral anterior temporal neocortex, the left medial temporal pole, and the rostral anterior cingulate. The correlates of familiarity measured in this human brain mapping experiment may correspond with what has been measured in single neurons in monkeys. This correspondence holds both for the type and for the localization of changes.

Functional anatomy of a common semantic system for words and pictures.

The relationship between the semantic processing of words and of pictures is a matter of debate among cognitive scientists. We studied the functional anatomy of such processing by using positron-emission tomography (PET). We contrasted activity during two semantic tasks (probing knowledge of associations between concepts, and knowledge of the visual attributes of these concepts) and a baseline task (discrimination of physical stimulus size), performed either with words or with pictures. Modality-specific activations unrelated to semantic processing occurred in the left inferior parietal lobule for words, and the right middle occipital gyrus for pictures. A semantic network common to both words and pictures extended from the left superior occipital gyrus through the middle and inferior temporal cortex to the inferior frontal gyrus. A picture-specific activation related to semantic tasks occurred in the left posterior inferior temporal sulcus, and word-specific activations related to semantic tasks were localized to the left superior temporal sulcus, left anterior middle temporal gyrus, and left inferior frontal sulcus. Thus semantic tasks activate a distributed semantic processing system shared by both words and pictures, with a few specific areas differentially active for either words or pictures.