To report the clinical, neuropsychological, linguistic, imaging, and neuropathological features of a unique case of sporadic Jakob-Creutzfeldt disease in which the patient presented with a logopenic variant of primary progressive aphasia.
Large referral center for atypical memory and aging disorders, particularly Jakob-Creutzfeldt disease.
Patient presenting with logopenic variant primary progressive aphasia initially thought to be due to Alzheimer disease.
Despite the long, slow 3.5-year course, the patient was shown to have pathology-proven sporadic Jakob-Creutzfeldt disease.
These findings expand the differential of primary progressive aphasia to include prion disease.
Studying ethnically diverse groups is important for furthering our understanding of biological mechanisms of disease that may vary across human populations. The ε4 allele of apolipoprotein E (APOE ε4) is a well-established risk factor for Alzheimer’s disease (AD), and may confer anatomic and functional effects years before clinical signs of cognitive decline are observed. The allele frequency of APOE ε4 varies both across and within populations, and the size of the effect it confers for dementia risk may be affected by other factors. Our objective was to investigate the role APOE ε4 plays in moderating brain volume in cognitively normal Chinese older adults, compared to older white Americans. We hypothesized that carrying APOE ε4 would be associated with reduced brain volume and that the magnitude of this effect would be different between ethnic groups. We performed whole brain analysis of structural MRIs from Chinese living in America (n = 41) and Shanghai (n = 30) and compared them to white Americans (n = 71). We found a significant interaction effect of carrying APOE ε4 and being Chinese. The APOE ε4xChinese interaction was associated with lower volume in bilateral cuneus and left middle frontal gyrus (Puncorrected<0.001), with suggestive findings in right entorhinal cortex and left hippocampus (Puncorrected<0.01), all regions that are associated with neurodegeneration in AD. After correction for multiple testing, the left cuneus remained significantly associated with the interaction effect (PFWE = 0.05). Our study suggests there is a differential effect of APOE ε4 on brain volume in Chinese versus white cognitively normal elderly adults. This represents a novel finding that, if verified in larger studies, has implications for how biological, environmental and/or lifestyle factors may modify APOE ε4 effects on the brain in diverse populations.
Group comparisons demonstrate greater visuospatial and memory deficits and temporoparietal-predominant degeneration on neuroimaging in patients with corticobasal syndrome (CBS) found to have Alzheimer’s disease (AD) pathology versus those with underlying frontotemporal lobar degeneration (FTLD). The value of these features in predicting underlying AD pathology in individual patients is unknown. The goal of this study is to evaluate the utility of modified clinical criteria and visual interpretations of magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) for predicting amyloid deposition (as a surrogate of Alzheimer’s disease neuropathology) in patients presenting with CBS.
In total, 25 patients meeting CBS core criteria underwent amyloid (Pittsburgh compound B; PIB) PET scans. Clinical records, MRI, and FDG scans were reviewed blinded to PIB results. Modified clinical criteria were used to classify CBS patients as temporoparietal variant CBS (tpvCBS) or frontal variant CBS (fvCBS). MRI and FDG-PET were classified based on the predominant atrophy/hypometabolism pattern (frontal or temporoparietal).
A total of 9 out of 13 patients classified as tpvCBS were PIB+, compared to 2out of 12 patients classified as fvCBS (P < 0.01, sensitivity 82%, specificity 71% for PIB+ status). Visual MRI reads had 73% sensitivity and 46% specificity for PIB+ status with moderate intra-rater reliability (Cohen’s kappa = 0.42). Visual FDG reads had higher sensitivity (91%) for PIB+ status with perfect intra-rater reliability (kappa = 1.00), though specificity was low (50%). PIB results were confirmed in all 8 patients with available histopathology (3 PIB+ with confirmed AD, 5 PIB- with FTLD).
Splitting CBS patients into frontal or temporoparietal clinical variants can help predict the likelihood of underlying AD, but criteria require further refinement. Temporoparietal-predominant neuroimaging patterns are sensitive but not specific for AD.
Electronic supplementary material
The online version of this article (doi:10.1186/s13195-014-0093-y) contains supplementary material, which is available to authorized users.
Variants in transmembrane protein 106 B (TMEM106B) modify the disease penetrance of frontotemporal dementia (FTD) in carriers of progranulin (GRN) mutations. We investigated whether TMEM106B is also a genetic modifier of disease in carriers of chromosome 9 open reading frame 72 (C9ORF72) expansions. We assessed the genotype of 325 C9ORF72 expansion carriers (cohort 1), 586 FTD patients lacking C9ORF72 expansions (with or without motor neuron disease [MND]; cohort 2), and a total of 1,302 controls for TMEM106B variants (rs3173615 and rs1990622) using MassArray iPLEX and Taqman genotyping assays. For our primary analysis, we focused on functional variant rs3173615, and employed a recessive genotypic model. In cohort 1, patients with C9ORF72 expansions showed a significantly reduced frequency of carriers homozygous for the minor allele as compared to controls (11.9% versus 19.1%, odds ratio (OR): 0.57, p=0.014; same direction as carriers of GRN mutations). The strongest evidence was provided by FTD patients (OR: 0.33, p=0.009) followed by FTD/MND patients (OR: 0.38, p=0.017), whereas no significant difference was observed in MND patients (OR: 0.85, p=0.55). In cohort 2, the frequency of carriers homozygous for the minor allele was not significantly reduced in patients as compared to controls (OR: 0.77, p=0.079); however, a significant reduction was observed when focusing on those patients with frontotemporal lobar degeneration and TAR DNA-binding protein 43 inclusions (FTLD-TDP; OR: 0.26, p<0.001).
Our study identifies TMEM106B as the first genetic factor modifying disease presentation in C9ORF72 expansion carriers. Homozygosity for the minor allele protects carriers from developing FTD, but not from developing MND; similar effects are seen in FTLD-TDP patients with yet unknown genetic causes. These new findings show that the protective effects of TMEM106B are not confined to carriers of GRN mutations, and might be relevant for prognostic testing, and as a promising therapeutic target for the entire spectrum of FTLD-TDP.
C9ORF72; TMEM106B; frontotemporal dementia; motor neuron disease; amyotrophic lateral sclerosis; disease modifier
We investigated the viability of psychometrically robust executive function measures as markers for premanifest Huntington’s disease (HD).
Fifteen premanifest HD subjects and 42 controls were compared on the NIH EXAMINER executive function battery. This battery yields an overall Executive Composite score, plus Working Memory, Cognitive Control, and Fluency Scores that are measured on psychometrically matched scales. The scores were correlated with two disease markers, disease burden and striatal volumes, in the premanifest HD subjects.
The premanifest HD subjects scored significantly lower on the Working Memory Score. The Executive Composite positively correlated with striatal volumes, and Working Memory Score negatively correlated with disease burden. The Cognitive Control and Fluency Scores did not differ between the groups or correlate significantly with the disease markers.
The NIH EXAMINER Executive Composite and Working Memory Score are sensitive markers of cognitive dysfunction, striatal volume, and disease burden in premanifest HD.
Huntington’s disease; Executive function; Working memory; Striatal volume; Disease burden
Dementia is associated with disruptions in sleep and sleep quality for patients and their family caregivers. Little is known about the impact of frontotemporal dementia (FTD) on sleep.
The purpose of this study was to characterize sleep in patients with frontotemporal dementia and their family caregivers.
Twenty-two patient-caregiver dyads were enrolled: Thirteen behavioral variant FTD (bvFTD) and nine semantic dementia (SD). Sleep and sleep quality data were collected for two weeks using diaries and Actiwatches.
Patients with bvFTD and SD spent more time in bed at night compared to their caregivers. Nighttime behaviors were reported more frequently by caregivers for the bvFTD patients and strongly correlated with caregiver distress. Actigraphy data demonstrated normal sleep efficiency and timing of the nighttime sleep period for both patients and their caregivers. Caregivers of patients with bvFTD reported poorer sleep quality compared to the SD caregivers. A greater number of bvFTD caregivers compared to SD reported negative aspects of sleep quality for themselves and used sleep medications more frequently.
The clinical manifestations of bvFTD appear to be associated with different and more distressing impacts on the caregiver sleep quality than SD.
frontotemporal dementia; semantic dementia; caregiving; actigraphy; sleep; sleep quality
To assess consolidation in amnestic mild cognitive (aMCI) impairment, controlling for differences in initial learning and using a protracted delay period for recall.
Fifteen individuals with MCI were compared to fifteen healthy older adult controls on a story learning task. Subjects were trained to criteria to equalize initial learning across subjects. Recall was tested at both the 30-minute typically used delay and a 1-week delay used to target consolidation.
Using repeated measures ANOVAs adjusted for age, we found group × time point interactions across the entire task between the final trial and 30-minute delay, and again between the 30-minute and 1-week delay periods, with MCI having greater declines in recall as compared to controls. Significant group main effects were also found, with MCI recalling less than controls.
Consolidation was impaired in aMCI as compared to controls. Our findings indicate that MCI-related performance typically measured at 30 minutes underestimates MCI-associated memory deficits. This is the first study to isolate consolidation by controlling for initial learning differences and using a protracted delay period to target consolidation in an MCI sample.
consolidation; episodic learning; amnestic mild cognitive impairment; memory; cognitive aging
Elevated CSF tau is considered a biomarker of neuronal injury in newly developed Alzheimer’s disease (AD) and mild cognitive impairment (MCI) criteria. However, previous studies have failed to detect alterations of tau species in other primary tauopathies. We assessed CSF tau protein abnormalities in AD, a tauopathy with prominent Aβ pathology, and progressive supranuclear palsy (PSP), a primary tauopathy characterized by deposition of four microtubule binding repeat (4R) tau with minimal Aβ pathology.
26 normal control (NC), 37 AD, and 24 PSP patients participated in the study. AD and PSP were matched for severity using the clinical dementia rating sum of boxes (CDR-sb) scores. The INNO BIA AlzBio3 multiplex immunoassay was used to measure CSF Aβ, total tau, and ptau181. Additional, novel ELISAs targeting different N-terminal and central tau epitopes were developed to examine CSF tau components and to investigate interactions between diagnostic group, demographics, and genetic variables.
PSP had lower CSF N-terminal and C-terminal tau concentrations than NC and AD measured with both the novel tau ELISAs and the standard AlzBio3 tau and ptau assays. AD had higher total tau and ptau levels than NC and PSP. There was a gender by diagnosis interaction in both AD and PSP for most tau species, with lower concentrations for male compared to female patients.
CSF tau fragment concentrations are different in PSP compared with AD despite the presence of severe tau pathology and neuronal injury in both disorders. CSF tau concentration likely reflects multiple factors in addition to the degree of neuronal injury.
Alzheimer’s disease; Progressive supranuclear palsy; CSF; Tau
To investigate whether patients with behavioral variant frontotemporal dementia (bvFTD) have dysregulation in satiety-related hormonal signaling using a laboratory-based case-control study.
Fifty-four participants (19 patients with bvFTD, 17 patients with Alzheimer disease dementia, and 18 healthy normal controls [NCs]) were recruited from a tertiary-care dementia clinic. During a standardized breakfast, blood was drawn before, during, and after the breakfast protocol to quantify levels of peripheral satiety-related hormones (ghrelin, cortisol, insulin, leptin, and peptide YY) and glucose. To further explore the role of patients' feeding abnormalities on hormone levels, patients were classified into overeating and nonovereating subgroups based on feeding behavior during separate laboratory-based standardized lunch feeding sessions.
Irrespective of their feeding behavior in the laboratory, patients with bvFTD, but not patients with Alzheimer disease dementia, have significantly lower levels of ghrelin and cortisol and higher levels of insulin compared with NCs. Furthermore, while laboratory feeding behavior did not predict alterations in levels of ghrelin, cortisol, and insulin, only patients with bvFTD who significantly overate in the laboratory demonstrated significantly higher levels of leptin compared with NCs, suggesting that leptin may be sensitive to particularly severe feeding abnormalities in bvFTD.
Despite a tendency to overeat, patients with bvFTD have a hormonal profile that should decrease food intake. Aberrant hormone levels may represent a compensatory response to the behavioral or neuroanatomical abnormalities of bvFTD.
We present longitudinal clinical, cognitive and neuroimaging data from a 63-year-old woman who enrolled in research as a normal control and evolved posterior cortical atrophy (PCA) over five year follow-up. At baseline she reported only subtle difficulty driving and performed normally on cognitive tests, but already demonstrated atrophy in left visual association cortex. With follow-up she developed insidiously progressive visuospatial and visuoperceptual deficits, correlating with progressive atrophy in bilateral visual areas. Amyloid PET was positive. This case tracks the evolution of PCA from the prodromal stage, and illustrates challenges to early diagnosis as well as the utility of imaging biomarkers.
To assess the prevalence of geriatric depression in Chinese American patients with cognitive impairment and to compare the prevalence to that of cognitively normal elderly Chinese Americans and Caucasians.
We compared rates of depressive symptomatology in elderly Chinese Americans to a matched group of Caucasians, with and without dementia, and assessed rates of treatment for depression across all groups.
Academic subspecialty referral clinic.
Participants included a total of 137 elderly, cognitively impaired and cognitively normal Chinese Americans and 140 Caucasians with and without cognitive impairment.
Demographic (e.g. age, education, race, language ability), cognitive (MMSE score), medical (e.g. cardiovascular morbidity) and functional (Clinical Dementia Rating Scale) risk factors were assessed for association with depressive symptomatology as measured by the Geriatric Depression Scale (GDS).
Depression (GDS score ≥ 6 out of 15) was significantly more common in cognitively impaired Chinese Americans (35%) versus cognitively impaired Caucasians (15%, χ2 = 33.8, p<0.05), and Chinese Americans were less likely to be on treatment for depression (12%) than Caucasians (37%, χ2 = 41, p<0.05). Cognitive and functional impairment, age and education were all independent predictors of GDS score. Rates of depression were not significantly different in cognitively normal Chinese American (6%) and Caucasian (0%) groups.
These findings indicate that elderly Chinese Americans with cognitive impairment are at significantly increased risk for unrecognized depression and that education, and/or other cultural factors associated with education may contribute to this risk.
geriatric depression; dementia; Chinese American
Predicting the progression of dementia is a challenge for clinicians yet this information is highly valued by patients’ families. An informally observed 4-stage model of dementia can be helpful in educating caregivers and preparing them for what lies ahead. In the behavioral variant of frontotemporal dementia (bvFTD), this model describes the evolution of behavioral disturbances and is characterized by an inflection point between stage 2 (progressively severe behavioral aberration) and stage 3 (increasing apathy and remission of behavior problems). In this study we sought evidence for this model using a database of serial Neuropsychiatric Inventory (NPI) scores for 45 patients with FTD and 47 patients with Alzheimer’s disease (AD). We transformed the NPI scores into a single variable for each participant that represented the rate of change in NPI score over time (NPI slope) and used this as the dependent variable in a multivariate linear regression. Age at onset of dementia, NPI score at initial visit, and duration of illness at first NPI all contributed significantly to the regression model for NPI slope in the bvFTD group. Participants with an initial NPI acquired before 6 years of disease duration tended to have a more positive NPI slope (representing worsening behavioral disturbances) than those with an initial NPI performed after 6 years. None of the aforementioned variables were significantly associated with NPI slope in the AD group. These results support a crescendo-decrescendo trajectory of behavioral symptoms in bvFTD but do not suggest that there is a similar pattern in AD, and further longitudinal data collection is necessary.
Alzheimer’s disease; agitation; apathy; behavioral symptoms; disease progression; frontotemporal dementia; longitudinal study; neurobehavioral manifestations
In primary progressive aphasia (PPA), speech and language difficulties are caused by neurodegeneration of specific brain networks. In the nonfluent/agrammatic variant (nfvPPA), motor speech and grammatical deficits are associated with atrophy in a left fronto-insular-striatal network previously implicated in speech production. In vivo dissection of the crossing white matter (WM) tracts within this “speech production network” is complex and has rarely been performed in health or in PPA. We hypothesized that damage to these tracts would be specific to nfvPPA and would correlate with differential aspects of the patients' fluency abilities. We prospectively studied 25 PPA and 21 healthy individuals who underwent extensive cognitive testing and 3 T MRI. Using residual bootstrap Q-ball probabilistic tractography on high angular resolution diffusion-weighted imaging (HARDI), we reconstructed pathways connecting posterior inferior frontal, inferior premotor, insula, supplementary motor area (SMA) complex, striatum, and standard ventral and dorsal language pathways. We extracted tract-specific diffusion tensor imaging (DTI) metrics to assess changes across PPA variants and perform brain–behavioral correlations. Significant WM changes in the left intrafrontal and frontostriatal pathways were found in nfvPPA, but not in the semantic or logopenic variants. Correlations between tract-specific DTI metrics with cognitive scores confirmed the specific involvement of this anterior–dorsal network in fluency and suggested a preferential role of a posterior premotor-SMA pathway in motor speech. This study shows that left WM pathways connecting the speech production network are selectively damaged in nfvPPA and suggests that different tracts within this system are involved in subcomponents of fluency. These findings emphasize the emerging role of diffusion imaging in the differential diagnosis of neurodegenerative diseases.
diffusion tensor imaging; frontal tracts; primary progressive aphasia; speech production; tractography; white matter
An understanding of the anatomic distributions of major neurodegenerative disease lesions is important to appreciate the differential clinical profiles of these disorders and to serve as neuropathological standards for emerging molecular neuroimaging methods. To address these issues, here we present a comparative survey of the topographical distribution of the defining molecular neuropathological lesions among ten neurodegenerative diseases from a large and uniformly assessed brain collection. Ratings of pathological severity in sixteen brain regions from 671 cases with diverse neurodegenerative diseases were summarized and analyzed. These included: a) amyloid-β and tau lesions in Alzheimer’s disease, b) tau lesions in three other tauopathies including Pick’s disease, progressive supranuclear palsy and corticobasal degeneration, c) α-synuclein inclusion ratings in four synucleinopathies including Parkinson’s disease, Parkinson’s disease with dementia, dementia with Lewy bodies and multiple system atrophy, and d) TDP-43 lesions in two TDP-43 proteinopathies, including frontotemporal lobar degeneration associated with TDP-43 and amyotrophic lateral sclerosis. The data presented graphically and topographically confirm and extend previous pathological anatomic descriptions and statistical comparisons highlight the lesion distributions that either overlap or distinguish the diseases in each molecular disease category.
Alzheimer’s disease; Pick’s disease; corticobasal degeneration; progressive supranuclear palsy; Parkinson’s disease; Parkinson’s disease dementia; dementia with Lewy bodies; multiple system atrophy; frontotemporal lobar degeneration - TDP; amyotrophic lateral sclerosis; amyloid-β; Tau α-synuclein; TDP-43
Cross-sectional studies of normal aging indicate an association between memory and hippocampal volume, and between executive functioning and subcortical-frontal circuits. Much less is known, however, about the relationship between longitudinal MRI changes and cognitive decline. The authors hypothesized that longitudinal change in memory would be best predicted by change in hippocampal volumes, whereas change in executive functioning would be best predicted by cortical atrophy and progression of MRI markers of cerebrovascular disease. For this study, 50 healthy elderly subjects underwent structural MRI and cognitive testing at baseline and again at follow-up, with a mean follow-up interval of 45 months. Volumetric MRI measures were hippocampus, cortical gray matter, white matter signal hyperintensity (WMSH), and lacunae. Neuropsychological measures were psychometrically robust composite scores of episodic memory (MEM) and executive functioning (EXEC). Hierarchical multiple regression indicated that a decrease in hippocampus was associated with a decline in MEM, whereas decreased cortical gray matter and increased WMSH were independently associated with a decline in EXEC. Results suggest that in normal aging, cognitive functioning declines as cortical gray matter and hippocampus decrease, and WMSH increases. The association between WMSH and EXEC further highlights the cognitive sequealae associated with cerebrovascular disease in normal elderly.
normal aging; memory; executive function; hippocampal volumes; white matter signal hyperintensity
Sporadic Creutzfeldt-Jakob disease is considered primarily a disease of grey matter, although the extent of white matter involvement has not been well described. We used diffusion tensor imaging to study the white matter in sporadic Creutzfeldt-Jakob disease compared to healthy control subjects and to correlated magnetic resonance imaging findings with histopathology. Twenty-six patients with sporadic Creutzfeldt-Jakob disease and nine age- and gender-matched healthy control subjects underwent volumetric T1-weighted and diffusion tensor imaging. Six patients had post-mortem brain analysis available for assessment of neuropathological findings associated with prion disease. Parcellation of the subcortical white matter was performed on 3D T1-weighted volumes using Freesurfer. Diffusion tensor imaging maps were calculated and transformed to the 3D-T1 space; the average value for each diffusion metric was calculated in the total white matter and in regional volumes of interest. Tract-based spatial statistics analysis was also performed to investigate the deeper white matter tracts. There was a significant reduction of mean (P = 0.002), axial (P = 0.0003) and radial (P = 0.0134) diffusivities in the total white matter in sporadic Creutzfeldt-Jakob disease. Mean diffusivity was significantly lower in most white matter volumes of interest (P < 0.05, corrected for multiple comparisons), with a generally symmetric pattern of involvement in sporadic Creutzfeldt-Jakob disease. Mean diffusivity reduction reflected concomitant decrease of both axial and radial diffusivity, without appreciable changes in white matter anisotropy. Tract-based spatial statistics analysis showed significant reductions of mean diffusivity within the white matter of patients with sporadic Creutzfeldt-Jakob disease, mainly in the left hemisphere, with a strong trend (P = 0.06) towards reduced mean diffusivity in most of the white matter bilaterally. In contrast, by visual assessment there was no white matter abnormality either on T2-weighted or diffusion-weighted images. Widespread reduction in white matter mean diffusivity, however, was apparent visibly on the quantitative attenuation coefficient maps compared to healthy control subjects. Neuropathological analysis showed diffuse astrocytic gliosis and activated microglia in the white matter, rare prion deposition and subtle subcortical microvacuolization, and patchy foci of demyelination with no evident white matter axonal degeneration. Decreased mean diffusivity on attenuation coefficient maps might be associated with astrocytic gliosis. We show for the first time significant global reduced mean diffusivity within the white matter in sporadic Creutzfeldt-Jakob disease, suggesting possible primary involvement of the white matter, rather than changes secondary to neuronal degeneration/loss.
Sporadic Creutzfeldt-Jakob disease (sCJD) is considered primarily a disease of grey matter. However, Caverzasi et al. now show a global decrease in mean diffusivity in white matter. The changes appear to be associated with reactive astrocytic gliosis and activated microglia, and suggest primary involvement of the white matter in sCJD.
DTI; CJD; mean diffusivity; gliosis; microglia
Primary progressive aphasia is a neurodegenerative clinical syndrome that presents in adulthood with an isolated, progressive language disorder. Three main clinical/anatomical variants have been described, each associated with distinctive pathology. A high frequency of neurodevelopmental learning disability in primary progressive aphasia has been reported. Because the disorder is heterogeneous with different patterns of cognitive, anatomical and biological involvement, we sought to identify whether learning disability had a predilection for one or more of the primary progressive aphasia subtypes. We screened the University of California San Francisco Memory and Aging Center's primary progressive aphasia cohort (n = 198) for history of language-related learning disability as well as hand preference, which has associations with learning disability. The study included logopenic (n = 48), non-fluent (n = 54) and semantic (n = 96) variant primary progressive aphasias. We investigated whether the presence of learning disability or non-right-handedness was associated with differential effects on demographic, neuropsychological and neuroimaging features of primary progressive aphasia. We showed that a high frequency of learning disability was present only in the logopenic group (χ2 = 15.17, P < 0.001) and (χ2 = 11.51, P < 0.001) compared with semantic and non-fluent populations. In this group, learning disability was associated with earlier onset of disease, more isolated language symptoms, and more focal pattern of left posterior temporoparietal atrophy. Non-right-handedness was instead over-represented in the semantic group, at nearly twice the prevalence of the general population (χ2 = 6.34, P = 0.01). Within semantic variant primary progressive aphasia the right-handed and non-right-handed cohorts appeared homogeneous on imaging, cognitive profile, and structural analysis of brain symmetry. Lastly, the non-fluent group showed no increase in learning disability or non-right-handedness. Logopenic variant primary progressive aphasia and developmental dyslexia both manifest with phonological disturbances and posterior temporal involvement. Learning disability might confer vulnerability of this network to early-onset, focal Alzheimer’s pathology. Left-handedness has been described as a proxy for atypical brain hemispheric lateralization. As non-right-handedness was increased only in the semantic group, anomalous lateralization mechanisms might instead be related to frontotemporal lobar degeneration with abnormal TARDBP. Taken together, this study suggests that neurodevelopmental signatures impart differential trajectories towards neurodegenerative disease.
Alzheimer’s disease; frontotemporal dementia; dementia aphasia; case control study; risk factors in epidemiology
Recently, Coppola and colleagues demonstrated that a rare MAPT sequence variant, c.454G>A (p.A152T), significantly increases the risk of frontotemporal dementia (FTD) spectrum disorders and Alzheimer's disease (AD) in a screen of 15,369 subjects1. We describe clinical features of 9 patients with neurodegenerative disease (4 women) harboring p.A152T, aged 51 to 79 years at symptom onset. Seven developed FTD spectrum clinical syndromes, including progressive supranuclear palsy syndrome (PSP, n=2), behavioral variant FTD (bvFTD, n=1), nonfluent variant primary progressive aphasia (nfvPPA, n=2), and corticobasal syndrome (CBS, n=2); two patients were diagnosed with clinical AD. Thus, MAPT p.A152T is associated with a variety of FTD spectrum clinical presentations, although patients with clinical AD are also identified. These data warrant larger studies with clinicopathological correlation to elucidate the influence of this genetic variant on neurodegenerative disease.
All Cognitive Disorders/Dementia; Alzheimer's disease; Frontotemporal Dementia; Corticobasal degeneration; Progressive Supranuclear Palsy
The aims of this study were to examine executive dysfunction using an antisaccade (AS) task in normal elderly (NE) and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) as well as to evaluate the relationship between AS performance and cortical thinning within AD-associated regions.
We recorded eye movements in 182 subjects (NE: 118; MCI: 36; AD: 28) during an AS task. We also performed neuropsychological measures of executive function for comparison. Brain MRI scans were collected on most subjects, and cortical thickness was determined in 9 regions known to exhibit atrophy in AD dementia (“AD signature”). We investigated the relationships between AS and neuropsychological performance, as well as possible correlations between AS performance and cortical thickness.
AS performance in MCI resembled that in NE; subjects with AD were impaired relative to both MCI and NE. In all subjects, AS performance correlated with neuropsychological measures of executive function, even after controlling for disease severity. In the subjects with MCI but not in NE, cortical thickness in frontoparietal AD signature regions correlated with AS performance.
The AS task is a useful measure of executive function across the AD spectrum. In MCI, AS performance may reflect disease burden within cortical brain regions involved in oculomotor control; however, AS impairments in NE may have etiologies other than incipient AD.
The neural organization of semantic memory remains much debated. A ‘distributed-only’ view contends that semantic knowledge is represented within spatially distant, modality-selective primary and association cortices. Observations in semantic variant primary progressive aphasia have inspired an alternative model featuring the anterior temporal lobe as an amodal hub that supports semantic knowledge by linking distributed modality-selective regions. Direct evidence has been lacking, however, to support intrinsic functional interactions between an anterior temporal lobe hub and upstream sensory regions in humans. Here, we examined the neural networks supporting semantic knowledge by performing a multimodal brain imaging study in healthy subjects and patients with semantic variant primary progressive aphasia. In healthy subjects, the anterior temporal lobe showed intrinsic connectivity to an array of modality-selective primary and association cortices. Patients showed focal anterior temporal lobe degeneration but also reduced physiological integrity throughout distributed modality-selective regions connected with the anterior temporal lobe in healthy controls. Physiological deficits outside the anterior temporal lobe correlated with scores on semantic tasks and with anterior temporal subregion atrophy, following domain-specific and connectivity-based predictions. The findings provide a neurophysiological basis for the theory that semantic processing is orchestrated through interactions between a critical anterior temporal lobe hub and modality-selective processing nodes.
anterior temporal lobe; semantic dementia; cognition; semantics; functional neuroimaging
Aging is the primary risk factor for cognitive decline, an emerging health threat to aging societies worldwide. Whether anti-aging factors such as klotho can counteract cognitive decline is unknown. We show that a life span-extending variant of the human KLOTHO gene, KL-VS, is associated with enhanced cognition in heterozygous carriers. Because this allele increased klotho levels in serum, we analyzed transgenic mice with systemic overexpression of klotho. They performed better than controls in multiple tests of learning and memory. Elevating klotho in mice also enhanced long-term potentiation, a form of synaptic plasticity, and enriched synaptic GluN2B, an NMDA receptor subunit with key functions in learning and memory. Blockade of GluN2B abolished klotho-mediated effects. Surprisingly, klotho effects were evident also in young mice and did not correlate with age in humans, suggesting independence from the aging process. Augmenting klotho or its effects may enhance cognition at different life stages and counteract cognitive decline.
Hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9ORF72) are causative for frontotemporal dementia (FTD) and motor neuron disease (MND). Substantial phenotypic heterogeneity has been described in patients with these expansions. We set out to identify genetic modifiers of disease risk, age at onset, and survival after onset that may contribute to this clinical variability.
We examined a cohort of 330 C9ORF72 expansion carriers and 374 controls. In these individuals, we assessed variants previously implicated in FTD and/or MND; 36 variants were included in our analysis. After adjustment for multiple testing, our analysis revealed three variants significantly associated with age at onset (rs7018487 [UBAP1; p-value = 0.003], rs6052771 [PRNP; p-value = 0.003], and rs7403881 [MT-Ie; p-value = 0.003]), and six variants significantly associated with survival after onset (rs5848 [GRN; p-value = 0.001], rs7403881 [MT-Ie; p-value = 0.001], rs13268953 [ELP3; p-value = 0.003], the epsilon 4 allele [APOE; p-value = 0.004], rs12608932 [UNC13A; p-value = 0.003], and rs1800435 [ALAD; p-value = 0.003]).
Variants identified through this study were previously reported to be involved in FTD and/or MND, but we are the first to describe their effects as potential disease modifiers in the presence of a clear pathogenic mutation (i.e. C9ORF72 repeat expansion). Although validation of our findings is necessary, these variants highlight the importance of protein degradation, antioxidant defense and RNA-processing pathways, and additionally, they are promising targets for the development of therapeutic strategies and prognostic tests.
Electronic supplementary material
The online version of this article (doi:10.1186/1750-1326-9-38) contains supplementary material, which is available to authorized users.
C9ORF72; Frontotemporal dementia; Motor neuron disease; Genetic modifier; Repeat expansion
The contribution of inflammation to deleterious aging outcomes is increasingly recognized; however, little is known about the complex relationship between interleukin-6 (IL-6) and brain structure, or how this association might change with increasing age. We examined the association between IL-6, white matter integrity, and cognition in 151 community dwelling older adults, and tested whether age moderated these associations. Blood levels of IL-6 and vascular risk (e.g., homocysteine), as well as health history information, were collected. Processing speed assessments were administered to assess cognitive functioning, and we employed tract-based spatial statistics to examine whole brain white matter and regions of interest. Given the association between inflammation, vascular risk, and corpus callosum (CC) integrity, fractional anisotropy (FA) of the genu, body, and splenium represented our primary dependent variables. Whole brain analysis revealed an inverse association between IL-6 and CC fractional anisotropy. Subsequent ROI linear regression and ridge regression analyses indicated that the magnitude of this effect increased with age; thus, older individuals with higher IL-6 levels displayed lower white matter integrity. Finally, higher IL-6 levels were related to worse processing speed; this association was moderated by age, and was not fully accounted for by CC volume. This study highlights that at older ages, the association between higher IL-6 levels and lower white matter integrity is more pronounced; furthermore, it underscores the important, albeit burgeoning role of inflammatory processes in cognitive aging trajectories.
The aetiology and pathogenesis of non-genetic forms of frontotemporal dementia (FTD) is unknown and even with the genetic forms of FTD, pathogenesis remains elusive. Given the association between systemic inflammation and other neurodegenerative processes, links between autoimmunity and FTD need to be explored.
To describe the prevalence of systemic autoimmune disease in semantic variant primary progressive aphasia (svPPA), a clinical cohort, and in progranulin (PGRN) mutation carriers compared to neurologically healthy normal controls (NC) and Alzheimer’s disease (AD) as dementia controls.
Academic medical centres.
129 svPPA, 39 PGRN, 186 NC, and 158 AD patients underwent chart review for autoimmune conditions. A large subset of svPPA, PGRN, and NC cohorts underwent serum analysis for tumor necrosis factor α (TNF-α) levels.
Chi-square comparison of autoimmune prevalence and follow up logistic regression.
There was a significantly increased risk of autoimmune disorders clustered around inflammatory arthritides, cutaneous disorders, and gastrointestinal conditions in the svPPA and PGRN cohorts. Elevated TNF-α levels were observed in svPPA and PGRN compared to NC.
svPPA and PGRN are associated with increased prevalence of specific and related autoimmune diseases compared to NC and AD. These findings suggest a unique pattern of systemic inflammation in svPPA and PGRN and open new research avenues for understanding and treating disorders associated with underlying transactive response DNA-binding protein 43 (TDP-43) aggregation.