Self-conscious emotions such as embarrassment arise when one’s actions fail to meet salient social expectations and are accompanied by marked physiological and behavioral activation. We investigated the neural correlates of self-conscious emotional reactivity in 27 patients with behavioral variant frontotemporal dementia (bvFTD), a neurodegenerative disease that disrupts self-conscious emotion and targets brain regions critical for emotional functioning early in the disease course, and in 33 healthy older controls. Subjects participated in an embarrassing karaoke task in which they watched a video clip of themselves singing. They also watched a sad film clip; these data were used to control for non-self-conscious emotional reactivity in response to audiovisual stimuli. Using Freesurfer to quantify regional brain volumes from structural magnetic resonance imaging, right pregenual anterior cingulate cortex (pACC) gray matter volume was the only brain region that was a significant predictor of self-conscious emotion. Smaller pACC volume was associated with attenuated physiological and behavioral self-conscious emotional reactivity, and this relationship was not specific to diagnosis. We argue that these results reflect the significant role that right pACC plays in the visceromotor responding that accompanies self-conscious emotion and that neurodegeneration in this region may underlie the self-conscious emotional decline seen in bvFTD.
emotion; cingulate; autonomic nervous system; behavior; neurodegenerative disease
Post-translational modifications play a key role in tau protein aggregation and related neurodegeneration. Because hyperphosphorylation alone does not necessarily cause tau aggregation, other post-translational modifications have been recently explored. Tau acetylation promotes aggregation and inhibits tau’s ability to stabilize microtubules. Recent studies have shown co-localization of acetylated and phosphorylated tau in AD and some 4R tauopathies. We developed a novel monoclonal antibody against acetylated tau at lysine residue 274, which recognizes both 3R and 4R tau, and used immunohistochemistry and immunofluorescence to probe 22 cases, including AD and another eight familial or sporadic tauopathies. Acetylated tau was identified in all tauopathies except argyrophilic grain disease (AGD). AGD is an age-associated, common but atypical 4R tauopathy, not always associated with clinical progression. Pathologically, AGD is characterized by neuropil grains, pre-neurofibrillary tangles, and oligodendroglial coiled bodies, all recognized by phospho-tau antibodies. The lack of acetylated tau in these inclusions suggests that AGD represents a distinctive tauopathy. Our data converge with previous findings to raise the hypothesis that AGD could play a protective role against the spread of AD-related tau pathology. Tau acetylation as a key modification for the propagation tau toxicity deserves further investigation.
tau; pathology; autopsy; acetylation; immunohistochemistry; human
ApoE4 has been associated with an increased risk of Alzheimer’s disease (AD), amyloid deposition and hypometabolism. ApoE4 is less prevalent in non-amnestic AD variants suggesting a direct effect on the clinical phenotype. However, the impact of ApoE4 on amyloid burden and glucose metabolism across different clinical AD syndromes is not well understood. We aimed to assess the relationship between amyloid deposition, glucose metabolism and ApoE4 genotype in a clinically heterogeneous population of AD patients.
Fifty-two patients with probable AD (NIA-AA) underwent [11C]Pittsburgh compound B (PIB) and [18F]fluorodeoxyglucose (FDG) PET scans. All patients had positive PIB-PET scans. 23 were ApoE4+ (14 heterozygous, 9 homozygous) and 29 were ApoE4−. Groups consisted of language-variant AD, visual-variant AD, and AD patients with amnestic and dysexecutive deficits. 52 healthy controls were included for comparison. FDG and PIB uptake was compared between groups on a voxel-wise basis and in regions-of-interest.
Whilst PIB patterns were diffuse in both patient groups, ApoE4− patients showed higher PIB uptake than ApoE4+ patients across the cortex. Higher PIB uptake in ApoE4− patients was particularly significant in right lateral frontotemporal regions. In contrast, similar patterns of hypometabolism relative to controls were found in both patient groups, mainly involving lateral temporoparietal cortex, precuneus, posterior cingulate cortex, and middle frontal gyrus. Comparing patient groups, ApoE4+ subjects showed greater hypometabolism in bilateral medial temporal and right lateral temporal regions, and ApoE4− patients showed greater hypometabolism in cortical areas including supplementary motor cortex and superior frontal gyrus.
ApoE4+ AD patients showed lower global amyloid burden and greater medial temporal hypometabolism compared to matched ApoE4− patients. These findings suggest that ApoE4 may increase susceptibility to molecular pathology and modulate the anatomic pattern of neurodegeneration in AD.
Alzheimer’s disease; PET; amyloid; glucose metabolism; apolipoprotein E
The factors driving clinical heterogeneity in Alzheimer’s disease are not well understood. This study assessed the relationship between amyloid deposition, glucose metabolism and clinical phenotype in Alzheimer’s disease, and investigated how these relate to the involvement of functional networks. The study included 17 patients with early-onset Alzheimer’s disease (age at onset <65 years), 12 patients with logopenic variant primary progressive aphasia and 13 patients with posterior cortical atrophy [whole Alzheimer’s disease group: age = 61.5 years (standard deviation 6.5 years), 55% male]. Thirty healthy control subjects [age = 70.8 (3.3) years, 47% male] were also included. Subjects underwent positron emission tomography with 11C-labelled Pittsburgh compound B and 18F-labelled fluorodeoxyglucose. All patients met National Institute on Ageing–Alzheimer’s Association criteria for probable Alzheimer’s disease and showed evidence of amyloid deposition on 11C-labelled Pittsburgh compound B positron emission tomography. We hypothesized that hypometabolism patterns would differ across variants, reflecting involvement of specific functional networks, whereas amyloid patterns would be diffuse and similar across variants. We tested these hypotheses using three complimentary approaches: (i) mass-univariate voxel-wise group comparison of 18F-labelled fluorodeoxyglucose and 11C-labelled Pittsburgh compound B; (ii) generation of covariance maps across all subjects with Alzheimer’s disease from seed regions of interest specifically atrophied in each variant, and comparison of these maps to functional network templates; and (iii) extraction of 11C-labelled Pittsburgh compound B and 18F-labelled fluorodeoxyglucose values from functional network templates. Alzheimer’s disease clinical groups showed syndrome-specific 18F-labelled fluorodeoxyglucose patterns, with greater parieto-occipital involvement in posterior cortical atrophy, and asymmetric involvement of left temporoparietal regions in logopenic variant primary progressive aphasia. In contrast, all Alzheimer’s disease variants showed diffuse patterns of 11C-labelled Pittsburgh compound B binding, with posterior cortical atrophy additionally showing elevated uptake in occipital cortex compared with early-onset Alzheimer’s disease. The seed region of interest covariance analysis revealed distinct 18F-labelled fluorodeoxyglucose correlation patterns that greatly overlapped with the right executive-control network for the early-onset Alzheimer’s disease region of interest, the left language network for the logopenic variant primary progressive aphasia region of interest, and the higher visual network for the posterior cortical atrophy region of interest. In contrast, 11C-labelled Pittsburgh compound B covariance maps for each region of interest were diffuse. Finally, 18F-labelled fluorodeoxyglucose was similarly reduced in all Alzheimer’s disease variants in the dorsal and left ventral default mode network, whereas significant differences were found in the right ventral default mode, right executive-control (both lower in early-onset Alzheimer’s disease and posterior cortical atrophy than logopenic variant primary progressive aphasia) and higher-order visual network (lower in posterior cortical atrophy than in early-onset Alzheimer’s disease and logopenic variant primary progressive aphasia), with a trend towards lower 18F-labelled fluorodeoxyglucose also found in the left language network in logopenic variant primary progressive aphasia. There were no differences in 11C-labelled Pittsburgh compound B binding between syndromes in any of the networks. Our data suggest that Alzheimer’s disease syndromes are associated with degeneration of specific functional networks, and that fibrillar amyloid-β deposition explains at most a small amount of the clinico-anatomic heterogeneity in Alzheimer’s disease.
Alzheimer’s disease; posterior cortical atrophy; logopenic variant of PPA; positron emission tomography (PET); functional networks
Neuroimaging studies examining neural substrates of impaired self-awareness in patients with neurodegenerative diseases have shown divergent results depending on the modality (cognitive, emotional, behavioral) of awareness. Evidence is accumulating to suggest that self-awareness arises from a combination of modality-specific and large-scale supramodal neural networks.
We investigated the structural substrates of patients' tendency to overestimate or underestimate their own capacity to demonstrate empathic concern for others. Subjects' level of empathic concern was measured using the Interpersonal Reactivity Index, and subject-informant discrepancy scores were used to predict regional atrophy pattern, using voxel-based morphometry analysis. Of the 102 subjects, 83 were patients with neurodegenerative diseases such as behavioral variant frontotemporal dementia (bvFTD) or semantic variant primary progressive aphasia (svPPA); the other 19 were healthy older adults.
bvFTD and svPPA patients typically overestimated their level of empathic concern compared to controls, and overestimating one's empathic concern predicted damage to predominantly right-hemispheric anterior infero-lateral temporal regions, whereas underestimating one's empathic concern showed no neuroanatomical basis.
These findings suggest that overestimation and underestimation of one's capacity for empathic concern cannot be interpreted as varying degrees of the same phenomenon, but may arise from different pathophysiological processes. Damage to anterior infero-lateral temporal regions has been associated with semantic self-knowledge, emotion processing, and social perspective taking; neuropsychological functions partly associated with empathic concern itself. These findings support the hypothesis that—at least in the socioemotional domain—neural substrates of self-awareness are partly modality-specific.
Affective perspective taking; dementia; empathy; infero-lateral temporal cortex; neurodegeneration; semantic self-knowledge; unawareness; voxel-based morphometry
Frontotemporal dementia (FTD) has rarely been reported in Chinese populations. There are many potential reasons for this, including possible hesitancy on the part of patients or families to bring FTD-related symptoms to medical attention. Here, we present data on eight Chinese individuals, all of whom met criteria for the behavioral variant of FTD or the semantic variant of primary progressive aphasia. These patients presented for neurological evaluation at a relatively advanced stage. The mean MMSE score at initial presentation was 15. Behavioral symptoms were common and usually elicited during the medical history only after direct questioning. Delay in presentation was attributed to a variety of issues, including family disagreements about whether the symptoms represented a disease and lack of medical insurance. These cases illustrate that the symptoms of FTD in Chinese Americans are similar to those in Caucasians but various factors, some potentially culturally-relevant, may influence the likelihood and timing of clinical presentation for FTD, as well as other dementias. Additional study of FTD in diverse ethnic groups needs to address barriers to clinical presentation, including factors that may be culturally specific.
Frontotemporal dementia; Chinese; ethnic culture; pathology; cognitive impairment; behavior changes
We examined the relationship between a functional polymorphism of the serotonin transporter (5-HTTLPR) gene and individual differences in emotional reactivity in two laboratory studies. In study 1, empathic responding and physiological reactivity to viewing films of others in distress were assessed in healthy adults in three age groups. In study 2, emotional responding to watching oneself in an embarrassing situation was assessed in healthy adults and in patients with neurodegenerative diseases. In study 1, participants with two short alleles of 5-HTTLPR reported more personal distress and showed higher levels of physiological responses in response to the films than participants with long alleles. In study 2, participants with two short alleles reported more anger and amusement and displayed more emotional expressive behaviors in response to the embarrassing situation than participants with long alleles. These two findings from diverse samples of participants converge to indicate that individuals who are homozygous for the short allele variant of 5-HTTLPR have greater levels of emotional reactivity in two quite different socially-embedded contexts.
5-HTTLPR; empathy; self-conscious emotions; physiology; reactivity
This study characterized daytime activity and apathy in patients with behavioral variant frontotemporal dementia (bvFTD) and semantic dementia (SD) and their family caregivers. Twenty-two patient-caregiver dyads were enrolled,13 bvFTD and 9 SD.Data were collected on behaviors and movement. Patients and caregivers wore Actiwatches for 2 weeks to record activity. We predicted that bvFTD patients would show greater caregiver report of apathy and less daytime activity than patients diagnosed with SD. Findings: Patients with bvFTD spent 25% of their day immobile while patients with SD spent 16% of their day inactive. BvFTD caregivers spent 11% of their day immobile and SD caregivers 9%. Apathy was described as present in 100% of the patients with bvFTD and in all but one patient with SD, the severity of apathy was greater in bvFTD compared to SD. Apathy correlated with caregiver emotional distress in both groups. In conclusion, apathy has been defined as a condition of diminished motivation that is difficult to operationalize. Among patients with FTD, apathy was associated with lower levels of activity, greater number bouts of immobility and longer immobility bout duration. Apathy and diminished daytime activity appeared to have an impact on the caregiver. Objective measures of behavioral output may help in formulation of a more precise definition of apathy.
frontotemporal dementia; semantic dementia; activity; caregiving; actigraphy; apathy
Behavioral variant frontotemporal dementia and semantic dementia have been associated with striatal degeneration, but few studies have delineated striatal subregion volumes in vivo or related them to clinical phenotype. We traced caudate, putamen, and nucleus accumbens on MR images to quantify volumes of these structures in behavioral variant frontotemporal dementia, semantic dementia, Alzheimer’s disease, and healthy controls (n = 12 per group). We further related these striatal volumes to clinical deficits and neuropathological findings in a subset of patients. Behavioral variant frontotemporal dementia and semantic dementia showed significant overall striatal atrophy compared with controls. Moreover, behavioral variant frontotemporal dementia showed panstriatal degeneration whereas semantic dementia featured a more focal pattern involving putamen and accumbens. Right-sided striatal atrophy, especially in the putamen, correlated with overall behavioral symptom severity and with specific behavioral domains. At autopsy, patients with behavioral variant frontotemporal dementia and semantic dementia showed striking and severe tau or TAR DNA-binding protein of 43 kDa pathology, especially in ventral parts of the striatum. These results demonstrate that ventral striatum degeneration is a prominent shared feature in behavioral variant frontotemporal dementia and semantic dementia and may contribute to social-emotional deficits common to both disorders.
Many patients with primary progressive aphasia (PPA) are impaired in syntactic production. Because most previous studies of expressive syntax in PPA have relied on quantitative analysis of connected speech samples, which is a relatively unconstrained task, it is not well understood which specific syntactic structures are most challenging for these patients. We used an elicited syntactic production task to identify which syntactic structures pose difficulties for 31 patients with three variants of PPA: non-fluent/agrammatic, semantic and logopenic. Neurodegenerative and healthy age-matched participants were included as controls. As expected, non-fluent/agrammatic patients made the most syntactic errors. The structures that resulted in the most errors were constructions involving third person singular present agreement, and constructions involving embedded clauses. Deficits on this elicited production task were associated with atrophy of the left posterior inferior frontal gyrus.
syntax; production; primary progressive aphasia; voxel-based morphometry
Comprehension of insincere communication is an important aspect of social cognition requiring visual perspective taking, emotion reading, and understanding others’ thoughts, opinions, and intentions. Someone who is lying intends to hide their insincerity from the listener, while a sarcastic speaker wants the listener to recognize they are speaking insincerely. We investigated whether face-to-face testing of comprehending insincere communication would effectively discriminate among neurodegenerative disease patients with different patterns of real-life social deficits. We examined ability to comprehend lies and sarcasm from a third-person perspective, using contextual cues, in 102 patients with one of four neurodegenerative diseases (frontotemporal dementia [bvFTD], Alzheimer’s disease [AD], progressive supranuclear palsy [PSP], and vascular cognitive impairment) and 77 healthy older adults (NC). Participants answered questions about videos depicting social interactions involving deceptive, sarcastic, or sincere speech using The Awareness of Social Inference Test. All subjects equally understood sincere remarks, but bvFTD patients displayed impaired comprehension of lies and sarcasm compared with NCs. In other groups, impairment was not disease-specific but was proportionate to general cognitive impairment. Analysis of the task components revealed that only bvFTD patients were impaired on perspective taking and emotion reading elements and that both bvFTD and PSP patients had impaired ability to represent others’ opinions and intentions (i.e., theory of mind). Test performance correlated with informants’ ratings of subjects’ empathy, perspective taking and neuropsychiatric symptoms in everyday life. Comprehending insincere communication is complex and requires multiple cognitive and emotional processes vulnerable across neurodegenerative diseases. However, bvFTD patients show uniquely focal and severe impairments at every level of theory of mind and emotion reading, leading to an inability to identify obvious examples of deception and sarcasm. This is consistent with studies suggesting this disease targets a specific neural network necessary for perceiving social salience and predicting negative social outcomes.
social cognition; neurodegenerative disease; frontotemporal dementia; lies; sarcasm; theory of mind
High adiposity is deleteriously associated with brain health, and may disproportionately affect white matter integrity; however, limited information exists regarding the mechanisms underlying the association between body mass (BMI) and white matter integrity. The present study evaluated whether vascular and inflammatory markers influence the relationship between BMI and white matter in healthy aging. We conducted a cross-sectional evaluation of white matter integrity, BMI, and vascular/inflammatory factors in a cohort of 138 healthy older adults (mean age: 71.3 years). Participants underwent diffusion tensor imaging, provided blood samples, and participated in a health evaluation. Vascular risk factors and vascular/inflammatory blood markers were assessed. The primary outcome measure was fractional anisotropy (FA) of the genu, body, and splenium (corpus callosum); exploratory measures included additional white matter regions, based on significant associations with BMI. Regression analyses indicated that higher BMI was associated with lower FA in the corpus callosum, cingulate, and fornix (p<.001). Vascular and inflammatory factors influenced the association between BMI and FA. Specifically, BMI was independently associated with the genu [β=-.21; B=-.0024; 95% CI, -.0048 to -.0000; p=.05] and cingulate fibers [β=-.39; B=-.0035; 95% CI,-.0056 to -.0015; p<.001], even after controlling for vascular/inflammatory risk factors and blood markers. In contrast, BMI was no longer significantly associated with the fornix and middle/posterior regions of the corpus callosum after controlling for these markers. Results partially support a vascular/inflammatory hypothesis, but also suggest a more complex relationship between BMI and white matter characterized by potentially different neuroanatomic vulnerability.
Transactive response DNA-binding protein 43 (TDP-43) is a major pathological protein in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). There are many disease-associated mutations in TDP-43, and several cellular and animal models with ectopic overexpression of mutant TDP-43 have been established. Here we sought to study altered molecular events in FTD and ALS by using induced pluripotent stem cell (iPSC) derived patient neurons. We generated multiple iPSC lines from an FTD/ALS patient with the TARDBP A90V mutation and from an unaffected family member who lacked the mutation. After extensive characterization, two to three iPSC lines from each subject were selected, differentiated into postmitotic neurons, and screened for relevant cell-autonomous phenotypes. Patient-derived neurons were more sensitive than control neurons to 100 nM straurosporine but not to other inducers of cellular stress. Three disease-relevant cellular phenotypes were revealed under staurosporine-induced stress. First, TDP-43 was localized in the cytoplasm of a higher percentage of patient neurons than control neurons. Second, the total TDP-43 level was lower in patient neurons with the A90V mutation. Third, the levels of microRNA-9 (miR-9) and its precursor pri-miR-9-2 decreased in patient neurons but not in control neurons. The latter is likely because of reduced TDP-43, as shRNA-mediated TDP-43 knockdown in rodent primary neurons also decreased the pri-miR-9-2 level. The reduction in miR-9 expression was confirmed in human neurons derived from iPSC lines containing the more pathogenic TARDBP M337V mutation, suggesting miR-9 downregulation might be a common pathogenic event in FTD/ALS. These results show that iPSC models of FTD/ALS are useful for revealing stress-dependent cellular defects of human patient neurons containing rare TDP-43 mutations in their native genetic contexts.
To assess the neuropsychological and anatomical correlates of anti-saccade (AS) task performance in normal elders.
The AS task correlates with neuropsychological measures of executive function and frontal lobe volume in neurological diseases, but has not been studied in a well-characterized normal elderly population. Because executive dysfunction can indicate an increased risk for cognitive decline in cognitively normal elders, we hypothesized that AS performance might be a sensitive test of age-related processes that impair cognition.
The percentage of correct AS responses was evaluated in forty-eight normal elderly subjects and compared with neuropsychological test performance using linear regression analysis and gray matter volume measured on MRI scans using voxel-based morphometry.
The percentage of correct AS responses was associated with measures of executive function, including modified trails, design fluency, Stroop inhibition, abstraction, and backward digit span, and correlated with gray matter volume in two brain regions involved in inhibitory control: the left inferior frontal junction and the right supplementary eye field. The association of AS correct responses with neuropsychological measures of executive function was strongest in individuals with fewer years of education.
The AS task is sensitive to executive dysfunction and frontal lobe structural alterations in normal elders.
anti-saccade; normal aging; executive function; frontal lobe; cognitive reserve
Multiple neurodegenerative diseases are characterized by the abnormal accumulation of FUS protein including various subtypes of frontotemporal lobar degeneration with FUS inclusions (FTLD-FUS). These subtypes include atypical frontotemporal lobar degeneration with ubiquitin-positive inclusions (aFTLD-U), basophilic inclusion body disease (BIBD) and neuronal intermediate filament inclusion disease (NIFID). Despite considerable overlap, certain pathologic features including differences in inclusion morphology, the subcellular localization of inclusions, and the relative paucity of subcortical FUS pathology in aFTLD-U indicate that these three entities represent related but distinct diseases. In this study, we report the clinical and pathologic features of three cases of aFTLD-U and two cases of late-onset BIBD with an emphasis on the anatomic distribution of FUS inclusions.
The aFTLD-U cases demonstrated FUS inclusions in cerebral cortex, subcortical grey matter and brainstem with a predilection for anterior forebrain and rostral brainstem. In contrast, the distribution of FUS pathology in late-onset BIBD cases demonstrated a predilection for pyramidal and extrapyramidal motor regions with relative sparing of cerebral cortex and limbic regions.
The topography of FUS pathology in these cases demonstrate the diversity of sporadic FUS inclusion body diseases and raises the possibility that late-onset motor neuron disease with BIBD neuropathology may exhibit unique clinical and pathologic features.
Frontotemporal dementia; Frontotemporal lobar degeneration; Motor neuron disease; Amyotrophic lateral sclerosis
Frontotemporal lobar dementia (FTLD) is the most common cause of dementia in patients younger than 60 years of age, and causes progressive neurodegeneration of the frontal and temporal lobes usually accompanied by devastating changes in language or behavior in affected individuals. Mutations in the progranulin (GRN) gene account for a significant fraction of familial FTLD, and in the vast majority of cases, these mutations lead to reduced expression of progranulin via nonsense-mediated mRNA decay. Progranulin is a secreted glycoprotein that regulates a diverse range of cellular functions including cell proliferation, cell migration, and inflammation. Recent fundamental discoveries about progranulin biology, including the findings that sortilin and tumor necrosis factor receptor (TNFR) are high affinity progranulin receptors, are beginning to shed light on the mechanism(s) by which progranulin deficiency causes FTLD. This review will explore how alterations in basic cellular functions due to PGRN deficiency, both intrinsic and extrinsic to neurons, might lead to the development of FTLD.
Progranulin; Frontotemporal lobar dementia; Sortilin; Tumor necrosis factor receptor; TDP-43; Neuroinflammation
Tauopathies represent a group of neurodegenerative disorders characterized by the accumulation of pathological TAU protein in brains. We report a human neuronal model of tauopathy derived from induced pluripotent stem cells (iPSCs) carrying a TAU-A152T mutation. Using zinc-finger nuclease-mediated gene editing, we generated two isogenic iPSC lines: one with the mutation corrected, and another with the homozygous mutation engineered. The A152T mutation increased TAU fragmentation and phosphorylation, leading to neurodegeneration and especially axonal degeneration. These cellular phenotypes were consistent with those observed in a patient with TAU-A152T. Upon mutation correction, normal neuronal and axonal morphologies were restored, accompanied by decreases in TAU fragmentation and phosphorylation, whereas the severity of tauopathy was intensified in neurons with the homozygous mutation. These isogenic TAU-iPSC lines represent a critical advancement toward the accurate modeling and mechanistic study of tauopathies with human neurons and will be invaluable for drug-screening efforts and future cell-based therapies.
•A human neuron model of tauopathy using TAU-A152T-iPSCs•Correction of TAU-A152T mutation eliminates tauopathy•Engineered homozygous TAU-A152T mutation intensifies tauopathy•A152T mutation increases TAU proteolysis, leading to tauopathy
Brain magnetic resonance imaging (MRI) studies have demonstrated regional patterns of brain macrostructural atrophy and white matter microstructural alterations separately in the three major subtypes of frontotemporal lobar degeneration (FTLD), which includes behavioral variant frontotemporal dementia (bvFTD), semantic dementia (SD), and progressive nonfluent aphasia (PNFA). This study was to investigate to what extent the pattern of white matter microstructural alterations in FTLD subtypes mirrors the pattern of brain atrophy, and to compare the ability of various diffusion tensor imaging (DTI) indices in characterizing FTLD patients, as well as to determine whether DTI measures provide greater classification power for FTLD than measuring brain atrophy. Twenty-five patients with FTLD (13 with bvFTD, 6 with SD, and 6 with PNFA) and 19 healthy age-matched control subjects underwent both structural MRI and DTI scans. Measurements of regional brain atrophy were based on T1-weighted MRI data and voxel-based morphometry. Measurements of regional white matter degradation were based on voxelwise as well as regions-of-interest tests of DTI variations, expressed as fractional anisotropy, axial diffusivity, and radial diffusivity. Compared to controls, bvFTD, SD, and PNFA patients each exhibited characteristic regional patterns of brain atrophy and white matter damage. DTI overall provided significantly greater accuracy for FTLD classification than brain atrophy. Moreover, radial diffusivity was more sensitive in assessing white matter damage in FTLD than other DTI indices. The findings suggest that DTI in general and radial diffusivity in particular are more powerful measures for the classification of FTLD patients from controls than brain atrophy.
Behavioral variant frontotemporal dementia; diffusion tensor imaging; frontotemporal lobar degeneration; multimodality MRI; progressive nonfluent aphasia; semantic dementia
In 2009, inclusions containing the fused in sarcoma (FUS) protein were identified as a third major molecular class of pathology underlying the behavioral variant frontotemporal dementia (bvFTD) syndrome. Due to the low prevalence of FUS pathology, few clinical descriptions have been published and none provides information about specific social-emotional deficits despite evidence for severe behavioral manifestations in this disorder. We evaluated a patient with bvFTD due to FUS pathology using a comprehensive battery of cognitive and social-emotional tests. A structural MRI scan and genetic tests for tau, progranulin, and FUS mutations were also performed. The patient showed preserved general cognitive functioning and superior working memory, but severe deficits in emotion attribution, sensitivity to punishment, and the capacity for interpersonal warmth and empathy. The gray matter atrophy pattern corresponded to this focal deficit profile, with preservation of dorsolateral fronto-parietal regions associated with executive functioning but severe damage to right worse than left frontoinsula, temporal pole, subgenual anterior cingulate, medial orbitofrontal cortex, amygdala, and caudate. This patient demonstrates the striking focality associated with FUS neuropathology in patients with bvFTD.
behavioral variant frontotemporal dementia; FTLD-FUS; social emotional testing; voxel-based morphometry; FUS neuropathology
In comparison to late-onset Alzheimer’s disease (LO-AD, onset
> 65), early age-of-onset Alzheimer’s disease (EO-AD, onset<65
years) more often presents with language, visuospatial and/or executive
impairment, often occurring earlier than a progressive memory deficit. The
logopenic variant of primary progressive aphasia (lv-PPA) and the posterior
cortical atrophy (PCA) have recently been described as possible atypical
variants of EO-AD. Lv-PPA is characterized by isolated language deficit,
while PCA is characterized by predominant visuospatial deficits. Severe
hemispheric grey matter (GM) atrophy associated with EO-AD, lv-PPA and PCA
has been described, but regional patterns of white matter (WM) damage are
still poorly understood.
Using structural MRI and voxel-based morphometry, we investigated WM
damage in 16 EO-AD, 13 PCA, 10 lv-PPA, and 14 LO-AD patients at
presentation, and 72 age-matched controls.
In EO-AD, PCA and lv-PPA patients, WM atrophy was centered on lateral
temporal and parietal regions, including cingulum and posterior corpus
callosum. Compared to controls, lv-PPA patients showed a more severe left
parietal damage, and PCA showed a more severe occipital atrophy. Moreover,
EO-AD had greater cingulum atrophy compared with LO-AD. LO-AD showed WM
damage in medial temporal regions and less extensive hemispheric
Patterns of WM damage in EO-AD, lv-PPA and PCA are consistent with
the clinical syndromes and GM atrophy patterns. WM injury in AD atypical
variants may contribute to symptoms and disease pathogenesis.
Alzheimer’s disease; white matter damage; cerebral network; age of onset; VBM
The recently identified GGGGCC repeat expansion in the noncoding region of C9ORF72 is the most common pathogenic mutation in patients with frontotemporal dementia (FTD) or amyotrophic lateral sclerosis (ALS). We generated a human neuronal model and investigated the pathological phenotypes of human neurons containing GGGGCC repeat expansions. Skin biopsies were obtained from two subjects who had >1,000 GGGGCC repeats in C9ORF72 and their respective fibroblasts were used to generate multiple induced pluripotent stem cell (iPSC) lines. After extensive characterization, two iPSC lines from each subject were selected, differentiated into postmitotic neurons, and compared with control neurons to identify disease-relevant phenotypes. Expanded GGGGCC repeats exhibit instability during reprogramming and neuronal differentiation of iPSCs. RNA foci containing GGGGCC repeats were present in some iPSCs, iPSC-derived human neurons and primary fibroblasts. The percentage of cells with foci and the number of foci per cell appeared to be determined not simply by repeat length but also by other factors. These RNA foci do not seem to sequester several major RNA-binding proteins. Moreover, repeat-associated non-ATG (RAN) translation products were detected in human neurons with GGGGCC repeat expansions and these neurons showed significantly elevated p62 levels and increased sensitivity to cellular stress induced by autophagy inhibitors. Our findings demonstrate that key neuropathological features of FTD/ALS with GGGGCC repeat expansions can be recapitulated in iPSC-derived human neurons and also suggest that compromised autophagy function may represent a novel underlying pathogenic mechanism.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-013-1149-y) contains supplementary material, which is available to authorized users.
ALS; Autophagy; C9ORF72; FTD; Hexanucleotide repeats; iPSCs; Neurodegeneration; Neurons; p62; RAN translation; RNA foci
To compare music recognition in patients with frontotemporal dementia, semantic dementia, Alzheimer disease, and controls and to evaluate the relationship between music recognition and brain volume.
Recognition of familiar music depends on several levels of processing. There are few studies about how patients with dementia recognize familiar music.
Subjects were administered tasks that assess pitch and melody discrimination, detection of pitch errors in familiar melodies, and naming of familiar melodies.
There were no group differences on pitch and melody discrimination tasks. However, patients with semantic dementia had considerable difficulty naming familiar melodies and also scored the lowest when asked to identify pitch errors in the same melodies. Naming familiar melodies, but not other music tasks, was strongly related to measures of semantic memory. Voxel-based morphometry analysis of brain MRI showed that difficulty in naming songs was associated with the bilateral temporal lobes and inferior frontal gyrus, whereas difficulty in identifying pitch errors in familiar melodies correlated with primarily the right temporal lobe.
The results support a view that the anterior temporal lobes play a role in familiar melody recognition, and that musical functions are affected differentially across forms of dementia.
Pitch; Melody; temporal lobe; auditory perception
Frontotemporal lobar degeneration with motor neuron disease (FTLD-MND) is characterized by neuronal cytoplasmic inclusions containing TDP-43. Apolipoprotein E4 (apoE4), derived from the apoE ε4 allele, enhances brain atrophy in FTLD through unknown mechanisms. Here, we studied two siblings with C9ORF72-linked familial FTLD-MND, an apoE ε4 homozygote and an apoE ε3 homozygote. The apoE ε4 homozygote had more cognitive-behavioral symptoms, fronto-insulo-temporal atrophy, and apoE fragments and aggregates in the anterior cingulate cortex. ApoE formed complexes with TDP-43 that were more abundant in the apoE ε4 homozygote. Although differences seen in a sibling pair could arise due to chance, these findings raise the possibility that apoE4 exacerbates brain pathology in FTLD through formation of neurotoxic apoE fragments and interactions with TDP-43.
Apolipoprotein E; TDP-43; Frontotemporal dementia; Motor neuron disease; Neuropathology
Changes in personality differ qualitatively and quantitatively between patients with different neurodegenerative diseases, likely due to divergent patterns of regional neurodegeneration. Regional damage to circuits underlying various cognitive and emotional functions have been associated with interpersonal traits like dominance, extraversion, and warmth in patients with neurodegenerative diseases, suggesting that personality may in part be mediated by these more basic neuropsychological functions. In this study, we hypothesized that different combinations of cognitive, neuropsychiatric, and emotional measures would predict different interpersonal traits in patients with neurodegenerative diseases.
A battery of cognitive, neuropsychiatric, and emotional measures was administered to 286 patients with various neurodegenerative diseases such as Alzheimer’s disease, behavioral variant frontotemporal dementia, semantic dementia, and progressive supranuclear palsy, and informants described patients’ dominance, extraversion, and warmth using the Interpersonal Adjective Scales (IAS) personality questionnaire. Regression modeling was performed to identify which neuropsychological factors uniquely predicted current personality, controlling for age, gender, and premorbid personality.
Social dominance covaried with patients’ capacity for cognitive control and verbal fluency. Conversely, warmth did not rely on these executive or verbal skills, but covaried primarily with patients’ capacity for emotional responsiveness. Extraversion, representing a blend of dominance and warmth, demonstrated an intermediate degree of relationship to both executive/verbal and emotional functions.
These findings suggest that different personality traits are partly subserved by specific cognitive and emotional functions in neurodegenerative disease patients. While this study was performed in the context of brain damage, the results raise the question of whether individual differences in these neuropsychological abilities may also underlie variability in normal personality.
personality; neurodegenerative disease; cognition; emotion
Pathologic TAR-DNA-binding protein 43 (TDP-43) is a disease protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) and amyotrophic lateral sclerosis. We studied the presence, frequency, and distribution of TDP-43 pathology by immunohistochemistry and biochemistry in a series of clinically well-characterized tauopathy patient brains, including 182 Alzheimer disease (AD), 39 corticobasal degeneration, 77 progressive supranuclear palsy, and 12 Pick disease cases and investigated the clinical impact of concomitant TDP-43 pathology in these cases. TAR-DNA-binding protein 43 pathology was found in 25.8% of AD cases. It was restricted to the dentate gyrus and entorhinal cortex in approximately 75% of cases; approximately 25% showed more widespread TDP-43 pathology in frontal and temporal cortices, resembling the FTLD-U subtype associated with progranulin mutations. TAR-DNA-binding protein 43 pathology in AD was associated with significantly longer disease duration, but there was no association with the clinical presentation (148 cases diagnosed as AD and 34 cases diagnosed as frontotemporal lobar degeneration). Progressive supranuclear palsy and Pick disease cases showed no TDP-43 inclusions and no biochemical alterations of TDP-43. There was, however, a unique, predominantly glial TDP-43 pathology with staining of astrocytic plaque-like structures and coiled bodies in 15.4% of corticobasal degeneration cases; this was associated with biochemical TDP-43 changes similar to those in FTLD-U. These findings provide further insight into the burden and clinical significance of TDP-43 pathology in disorders other than FTLD-U and amyotrophic lateral sclerosis.
Alzheimer disease; Corticobasal degeneration; Frontotemporal dementia; Tauopathy; TDP-43