Clinical and genetic analyses of a Swedish patient series diagnosed with ataxia.

Hereditary ataxia is a heterogeneous group of complex neurological disorders. Next-generation sequencing methods have become a great help in clinical diagnostics, but it may remain challenging to determine if a genetic variant is the cause of the patient's disease. We compiled a consecutive single-center series of 87 patients from 76 families with progressive ataxia of known or unknown etiology. We investigated them clinically and genetically using whole exome or whole genome sequencing. Test methods were selected depending on family history, clinical phenotype, and availability. Genetic results were interpreted based on the American College of Medical Genetics criteria. For high-suspicion variants of uncertain significance, renewed bioinformatical and clinical evaluation was performed to assess the level of pathogenicity. Thirty (39.5%) of the 76 families had received a genetic diagnosis at the end of our study. We present the predominant etiologies of hereditary ataxia in a Swedish patient series. In two families, we established a clinical diagnosis, although the genetic variant was classified as "of uncertain significance" only, and in an additional three families, results are pending. We found a pathogenic variant in one family, but we suspect that it does not explain the complete clinical picture. We conclude that correctly interpreting genetic variants in complex neurogenetic diseases requires genetics and clinical expertise. The neurologist's careful phenotyping remains essential to confirm or reject a diagnosis, also by reassessing clinical findings after a candidate genetic variant is suggested. Collaboration between neurology and clinical genetics and combining clinical and research approaches optimizes diagnostic yield.

Exonic trinucleotide repeat expansions in ZFHX3 cause spinocerebellar ataxia type 4: A poly-glycine disease.

Autosomal-dominant ataxia with sensory and autonomic neuropathy is a highly specific combined phenotype that we described in two Swedish kindreds in 2014; its genetic cause had remained unknown. Here, we report the discovery of exonic GGC trinucleotide repeat expansions, encoding poly-glycine, in zinc finger homeobox 3 (ZFHX3) in these families. The expansions were identified in whole-genome datasets within genomic segments that all affected family members shared. Non-expanded alleles carried one or more interruptions within the repeat. We also found ZFHX3 repeat expansions in three additional families, all from the region of Skåne in southern Sweden. Individuals with expanded repeats developed balance and gait disturbances at 15 to 60 years of age and had sensory neuropathy and slow saccades. Anticipation was observed in all families and correlated with different repeat lengths determined through long-read sequencing in two family members. The most severely affected individuals had marked autonomic dysfunction, with severe orthostatism as the most disabling clinical feature. Neuropathology revealed p62-positive intracytoplasmic and intranuclear inclusions in neurons of the central and enteric nervous system, as well as alpha-synuclein positivity. ZFHX3 is located within the 16q22 locus, to which spinocerebellar ataxia type 4 (SCA4) repeatedly had been mapped; the clinical phenotype in our families corresponded well with the unique phenotype described in SCA4, and the original SCA4 kindred originated from Sweden. ZFHX3 has known functions in neuronal development and differentiation n both the central and peripheral nervous system. Our findings demonstrate that SCA4 is caused by repeat expansions in ZFHX3.

[18F]RO948 tau positron emission tomography in genetic and sporadic frontotemporal dementia syndromes.

PURPOSE: To examine [18F]RO948 retention in FTD, sampling the underlying protein pathology heterogeneity. METHODS: A total of 61 individuals with FTD (n = 35), matched cases of AD (n = 13) and Aß-negative cognitively unimpaired individuals (n = 13) underwent [18F]RO948PET and MRI. FTD included 21 behavioral variant FTD (bvFTD) cases, 11 symptomatic C9orf72 mutation carriers, one patient with non-genetic bvFTD-ALS, one individual with bvFTD due to a GRN mutation, and one due to a MAPT mutation (R406W). Tracer retention was examined using a region-of-interest and voxel-wise approaches. Two individuals (bvFTD due to C9orf72) underwent postmortem neuropathological examination. Tracer binding was additionally assessed in vitro using [3H]RO948 autoradiography in six separate cases. RESULTS: [18F]RO948 retention across ROIs was clearly lower than in AD and comparable to that in Aß-negative cognitively unimpaired individuals. Only minor loci of tracer retention were seen in bvFTD; these did not overlap with the observed cortical atrophy in the cases, the expected pattern of atrophy, nor the expected or verified protein pathology distribution. Autoradiography analyses showed no specific [3H]RO948 binding. The R406W MAPT mutation carriers were clear exceptions with AD-like retention levels and specific in-vitro binding. CONCLUSION: [18F]RO948 uptake is not significantly increased in the majority of FTD patients, with a clear exception being specific MAPT mutations.

Prenatal gyrification pattern affects age at onset in frontotemporal dementia.

The paracingulate sulcus is a tertiary sulcus formed during the third trimester. In healthy individuals paracingulate sulcation is more prevalent in the left hemisphere. The anterior cingulate and paracingulate gyri are focal points of neurodegeneration in behavioral variant frontotemporal dementia (bvFTD). This study aims to determine the prevalence and impact of paracingulate sulcation in bvFTD. Structural magnetic resonance images of individuals with bvFTD (n = 105, mean age 66.9 years), Alzheimer's disease (n = 92, 73.3), and healthy controls (n = 110, 62.4) were evaluated using standard protocol for hemispheric paracingulate sulcal presence. No difference in left hemisphere paracingulate sulcal frequency was observed between groups; 0.72, 0.79, and 0.70, respectively, in the bvFTD, Alzheimer's disease, and healthy control groups, (P = 0.3). A significant impact of right (but not left) hemispheric paracingulate sulcation on age at disease onset was identified in bvFTD (mean 60.4 years where absent vs. 63.8 where present [P = 0.04, Cohen's d = 0.42]). This relationship was not observed in Alzheimer's disease. These findings demonstrate a relationship between prenatal neuronal development and the expression of a neurodegenerative disease providing a gross morphological example of brain reserve.

Plasma neurofilament light protein correlates with diffusion tensor imaging metrics in frontotemporal dementia.

Neurofilaments are structural components of neurons and are particularly abundant in highly myelinated axons. The levels of neurofilament light chain (NfL) in both cerebrospinal fluid (CSF) and plasma have been related to degeneration in several neurodegenerative conditions including frontotemporal dementia (FTD) and NfL is currently considered as the most promising diagnostic and prognostic fluid biomarker in FTD. Although the location and function of filaments in the healthy nervous system suggests a link between increased NfL and white matter degeneration, such a claim has not been fully elucidated in vivo, especially in the context of FTD. The present study provides evidence of an association between the plasma levels of NfL and white matter involvement in behavioral variant FTD (bvFTD) by relating plasma concentration of NfL to diffusion tensor imaging (DTI) metrics in a group of 20 bvFTD patients. The results of both voxel-wise and tract specific analysis showed that increased plasma NfL concentration is associated with a reduction in fractional anisotropy (FA) in a widespread set of white matter tracts including the superior longitudinal fasciculus, the fronto-occipital fasciculus the anterior thalamic radiation and the dorsal cingulum bundle. Plasma NfL concentration also correlated with cortical thinning in a portion of the right medial prefrontal cortex and of the right lateral orbitofrontal cortex. These results support the hypothesis that blood NfL levels reflect the global level of neurodegeneration in bvFTD and help to advance our understanding of the association between this blood biomarker for FTD and the disease process.

Clinicopathological concordance in cognitive disease diagnostics.

Neurocognitive disorder encompasses many separate diagnoses, such as frontotemporal dementia (FTD), Alzheimer's disease (AD), Lewy body dementia (LBD), vascular dementia (VaD), and mixed dementia (MD). Because of the many variations between and within each subtype, it may be a challenge to clinically diagnose each condition. In a previous study on 176 dementia patients in a university hospital cohort between the years 1996 and 2006, a full diagnostic concordance of 49% was demonstrated between clinical diagnoses and pathological morphology [1]. The aims of this study were to do a follow-up on diagnostic concordance from the subsequent 10 years (2007 - 2016) and to compare the results with the previous study from 2009. In all cases of neuropathologically diagnosed dementia disorders (n = 324), the clinical records were searched for information on the clinical diagnosis of dementia, including on subtype. All individuals who had been diagnosed by a specialist were selected (n = 210). In this study, a full concordance between clinical diagnoses and neuropathological morphology was found in 61% of individuals, with marked variations between subgroups, including the lowest (31%) in the group of VaD. Vigilance in clinicopathological concordance is important for quality maintenance as well as the improvement of skills in diagnostic work. In light of the previous study, VaD one decade later remains elusive. The unmasking of this complicated and multifaceted disorder may be beneficial to the overall diagnostic accuracy in cognitive disease investigations.
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CSF placental growth factor - a novel candidate biomarker of frontotemporal dementia.

OBJECTIVE: Diagnosis of frontotemporal dementia (FTD) is complicated by the overlap of clinical symptoms with other dementia disorders. Development of robust fluid biomarkers is critical to improve the diagnostic work-up of FTD. METHODS: CSF concentrations of placental growth factor (PlGF) were measured in the discovery cohort including patients with FTD (n = 27), Alzheimer disease (AD) dementia (n = 75), DLB or PDD (n = 47), subcortical vascular dementia (VaD, n = 33), mild cognitive impairment that later converted to AD (MCI-AD, n = 34), stable MCI (sMCI, n = 62), and 50 cognitively healthy controls from the Swedish BioFINDER study. For validation, CSF PlGF was measured in additional independent cohort of FTD patients (n = 22) and controls (n = 18) from the Netherlands. RESULTS: In the discovery cohort, MCI, MCI-AD, AD dementia, DLB-PDD, VaD, and FTD patients all showed increased CSF levels of PlGF compared with controls (sMCI P = 0.019; MCI-AD P = 0.005; AD dementia, DLB-PDD, VaD, and FTD all P < 0.001). PlGF levels were 1.8-2.1-fold higher in FTD than in AD, DLB-PDD and VaD (all P < 0.001). PlGF distinguished with high accuracy FTD from controls and sMCI performing better than tau/Aß42 (AUC 0.954-0.996 versus 0.564-0.754, P < 0.001). A combination of PlGF, tau, and Aß42 (tau/Aß42/PlGF) was more accurate than tau/Aß42 when differentiating FTD from a group of other dementias (AUC 0.972 vs. 0.932, P < 0.01). Increased CSF levels of PlGF in FTD compared with controls were corroborated in the validation cohort. INTERPRETATION: CSF PlGF is increased in FTD compared with other dementia disorders, MCI, and healthy controls and might be useful as a diagnostic biomarker of FTD.

Association of Neuropathologically Confirmed Frontotemporal Dementia and Alzheimer Disease With Criminal and Socially Inappropriate Behavior in a Swedish Cohort.

Importance: Criminal and socially inappropriate behavior is encountered among patients with dementia, and it is sometimes the first sign of a dementing disorder. This behavior constitutes a significant burden to society, patients' relatives, and patients themselves. Objectives: To investigate and compare the prevalence and type of criminal and socially inappropriate behavior, as well as recurrence of criminal behavior, associated with Alzheimer disease (AD) and frontotemporal dementia (FTD) neuropathologically verified post mortem, and to assess whether there is a specific type of protein pathology more closely associated with criminal behavior in patients with FTD. Design, Setting, and Participants: Cohort study using medical record review of 220 Swedish patients with a postmortem neuropathologic diagnosis of AD (n = 101) or frontotemporal lobar degeneration (n = 119) (hereinafter referred to as FTD) diagnosed between January 1, 1967, and December 31, 2017. Main Outcomes and Measures: Patient notes containing reports of criminal and socially inappropriate behavior, as well as data on dominant protein pathology for patients with FTD, were duly reviewed and recorded. The Fisher exact test or logistic regression was used to assess possible differences between groups. Results: Of the 220 patients studied, 128 (58.2%) were female, the median (range) age at disease onset was 63 (30-88) years and at death was 72 (34-96) years, and the median (range) disease duration was 9 (1-28) years. Instances of criminal behavior were found in 65 of the 220 patients (29.5%): in 15 of the 101 patients (14.9%) with AD and 50 of the 119 patients (42.0%) with FTD (P < .001). Recurrence of criminal behavior was significantly higher in the FTD group (89.0%) than in the AD group (53.3%) (P = .04). Instances of socially inappropriate behavior were found in 57 patients (56.4%) with AD and 89 (74.8%) with FTD (P = .004). An expression of non-tau pathology increased the odds for criminal behavior by a factor of 9.0 (95% CI, 3.4-24.0) among patients with FTD. Conclusions and Relevance: These results suggest that criminal and socially inappropriate behaviors may be more prevalent and criminal behaviors may be more recurrent in patients with FTD than in those with AD. Non-tau pathology, but not tau pathology, appears to be associated with criminal behavior. These findings may help with the clinical diagnostic process.

Police Interactions Among Neuropathologically Confirmed Dementia Patients: Prevalence and Cause.

OBJECTIVE: The aim of this study was to investigate and compare the prevalence and recurrence of police interaction (PI) with patients diagnosed with dementia. We also aimed to study the reason behind the PI, the time of occurrence of PI, and potential consequences of the PI. METHODS: For this retrospective medical records' review, we included 281 cases with a neuropathologic dementia diagnosis from the Department of Pathology, Region Skane/Lund University, between 1967 and 2013. The diagnoses were Alzheimer disease, frontotemporal lobar degeneration, vascular dementia, and mixed dementia. A prerequisite was that extensive clinical investigation and follow-up had been conducted at the Department of Geriatric Psychiatry in Lund. RESULTS: Of the 281 patients studied, 50 (18%) had a history of interacting with the police during the course of their disease. Frontotemporal dementia patients had a relatively higher prevalence of PI and more often due to criminal behavior. The recurrence of PIs differed among the groups; frontotemporal dementia patients exhibited a higher PI recurrence compared with the other groups. CONCLUSIONS: The patterns of PIs differ between the frontotemporal dementia and Alzheimer disease patients. Knowledge about such differences may be of value for the police, the judiciary system, and the society in general.

Slowly progressive dementia caused by MAPT R406W mutations: longitudinal report on a new kindred and systematic review.

BACKGROUND: The MAPT c.1216C > T (p.Arg406Trp; R406W) mutation is a known cause of frontotemporal dementia with Parkinsonism linked to chromosome 17 tau with Alzheimer's disease-like clinical features. METHODS: We compiled clinical data from a new Swedish kindred with R406W mutation. Seven family members were followed longitudinally for up to 22 years. Radiological examinations were performed in six family members and neuropathological examinations in three. We systematically reviewed the literature and compiled clinical, radiological, and neuropathological data on 63 previously described R406W heterozygotes and 3 homozygotes. RESULTS: For all cases combined, the median age of onset was 56 years and the median disease duration was 13 years. Memory impairment was the most frequent symptom, behavioral disturbance and language impairment were less common, and Parkinsonism was rare. Disease progression was most often slow. The most frequent clinical diagnosis was Alzheimer's disease. R406W homozygotes had an earlier age at onset and a higher frequency of behavioral symptoms and Parkinsonism than heterozygotes. In the new Swedish kindred, a consistent imaging finding was ventromedial temporal lobe atrophy, which was evident also in early disease stages as a widening of the collateral sulcus with ensuing atrophy of the parahippocampal gyrus. Unlike previously published R406W carriers, all three autopsied patients from the novel family showed neuropathological similarities with progressive supranuclear palsy, with predominant four-repeat (exon 10+) tau isoform (4R) tauopathy and neurofibrillary tangles accentuated in the basal-medial temporal lobe. Amyloid-ß pathology was absent. CONCLUSIONS: Dominance of 4R over three-repeat (exon 10-) tau isoforms contrasts with earlier reports of R406W patients and was not sufficiently explained by the presence of H1/H2 haplotypes in two of the autopsied patients. R406W patients often show a long course of disease with marked memory deficits. Both our neuropathological results and our imaging findings revealed that the ventromedial temporal lobes were extensively affected in the disease. We suggest that this area may represent the point of origin of tau deposition in this disease with relatively isolated tauopathy.

Physical aggression among patients with dementia, neuropathologically confirmed post-mortem.

OBJECTIVE: To investigate the prevalence of physical aggression among patients with dementia of different types and to analyze potential differences in clinical traits, in terms of singular or repetitive behavior and occurrence in early or late stage of the disease. We also aimed at examining against whom the physical aggression was exerted. METHODS: We included 281 cases with a neuropathological dementia diagnosis from the brain bank at the Department of Pathology, Lund University, for this retrospective medical records review. The study covers cases with a post-mortem examination performed between 1967 and 2013. RESULTS: Of the 281 patients studied, 97 (35%) patients had a history of exerting physical aggression during the course of their disease. The patients with frontotemporal dementia exerted physical aggression earlier in the course of their disease than Alzheimer's disease patients. The most frequent victims of the patients' physical aggression were health staff and other patients. The aggression also affected family members as well as (to the demented patient) unknown people. The frequency of the physical aggression differed among the different diagnostic groups; frontotemporal dementia patients exhibiting a higher physical aggression frequency score than did Alzheimer's disease patients. CONCLUSIONS: The patterns of manifested physical aggression thus differ between the frontotemporal dementia and Alzheimer's disease patient groups in this study. Knowledge about such differences may be of value in decision making in patient care.

Grey and White Matter Clinico-Anatomical Correlates of Disinhibition in Neurodegenerative Disease.

Disinhibition is an important symptom in neurodegenerative diseases. However, the clinico-anatomical underpinnings remain controversial. We explored the anatomical correlates of disinhibition in neurodegenerative disease using the perspective of grey and white matter imaging. Disinhibition was assessed with a neuropsychological test and a caregiver information-based clinical rating scale in 21 patients with prefrontal syndromes due to behavioural variant frontotemporal dementia (n = 12) or progressive supranuclear palsy (n = 9), and healthy controls (n = 25). Cortical thickness was assessed using the Freesurfer software on 3T MRI data. The integrity of selected white matter tracts was determined by the fractional anisotropy (FA) from Diffusion Tensor Imaging. Disinhibition correlated with the cortical thickness of the right parahippocampal gyrus, right orbitofrontal cortex and right insula and the FA of the right uncinate fasciculus and right anterior cingulum. Notably, no relationship was seen with the thickness of ventromedial prefrontal cortex. Our results support an associative model of inhibitory control, distributed in a medial temporal lobe-insular-orbitofrontal network, connected by the intercommunicating white matter tracts. This reconciles some of the divergences among previous studies, but also questions the current conceptualisation of the "prefrontal" syndrome and the central role attributed to the ventromedial prefrontal cortex in inhibitory control.

Cerebrospinal fluid neurogranin and YKL-40 as biomarkers of Alzheimer's disease.

OBJECTIVE: Widespread implementation of cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) in clinical settings requires improved accuracy for diagnosis of prodromal disease and for distinguishing AD from non-AD dementias. Novel and promising CSF biomarkers include neurogranin, a marker of synaptic degeneration, and YKL-40, a marker of neuroinflammation. METHODS: CSF neurogranin and YKL-40 were measured in a cohort of 338 individuals including cognitively healthy controls and patients with stable mild cognitive impairment (sMCI), MCI who later developed AD (MCI-AD), AD dementia, Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), vascular dementia (VaD), and frontotemporal dementia (FTD). The diagnostic accuracy of neurogranin and YKL-40 were compared with the core AD biomarkers, ß-amyloid (Aß42 and Aß40) and tau. RESULTS: Neurogranin levels were increased in AD and decreased in non-AD dementia compared with healthy controls. As a result, AD patients showed considerably higher CSF levels of neurogranin than DLB/PDD, VaD and FTD patients. CSF YKL-40 levels were increased in AD compared with DLB/PDD but not with VaD or FTD. Neither CSF neurogranin nor YKL-40 levels differed significantly between sMCI patients and MCI-AD patients. Both biomarkers correlated positively with CSF Aß40 and tau. CSF neurogranin and YKL-40 could separate AD dementia from non-AD dementias (neurogranin, area under the curve [AUC] = 0.761; YKL-40, AUC = 0.604; Aß42/neurogranin, AUC = 0.849; Aß42/YKL-40, AUC = 0.785), but the diagnostic accuracy was not better compared to CSF Aß and tau (Aß42, AUC = 0.755; tau AUC = 0.858; Aß42/tau, AUC = 0.895; Aß42/Aß40, AUC = 0.881). Similar results were obtained when separating sMCI from MCI-AD cases. INTERPRETATION: CSF neurogranin and YKL-40 do not improve the diagnostic accuracy of either prodromal AD or AD dementia when compared to the core CSF AD biomarkers. Nevertheless, the CSF level of neurogranin is selectively increased in AD dementia, whereas YKL-40 is increased in both AD and FTD suggesting that synaptic degeneration and glial activation may be important in these neurodegenerative conditions.

Psychotic symptoms in frontotemporal dementia: a diagnostic dilemma?

BACKGROUND: Frontotemporal dementia (FTD) constitutes a spectrum of neurodegenerative disorders associated with degeneration of, predominantly, the frontal and temporal lobes. The clinical heterogeneity is evident, and early diagnosis is a challenge. The primary objectives were to characterize psychotic symptoms, initial clinical diagnoses and family history in neuropathologically verified FTD-patients and to analyze possible correlations with different neuropathological findings. METHODS: The medical records of 97 consecutive patients with a neuropathological diagnosis of frontotemporal lobar degeneration (FTLD) were reevaluated. Psychotic symptoms (hallucinations, delusions, paranoid ideas), initial diagnosis and family history for psychiatric disorders were analyzed. RESULTS: Psychotic symptoms were present in 31 patients (32%). There were no significant differences in age at onset, disease duration or gender between patients with and without psychotic symptoms. Paranoid ideas were seen in 20.6%, and hallucinations and delusions in 17.5% in equal measure. Apart from a strong correlation between psychotic symptoms and predominantly right-sided brain degeneration, the majority of patients (77.4%) were tau-negative. Only 14.4% of the patients were initially diagnosed as FTD, while other types of dementia were seen in 34%, other psychiatric disorders in 42%, and 9.2% with other cognitive/neurological disorders. The patients who were initially diagnosed with a psychiatric disorder were significantly younger than the patients with other initial clinical diagnoses. A positive heredity for dementia or other psychiatric disorder was seen in 42% and 26% of the patients respectively. CONCLUSIONS: Psychotic symptoms, not covered by current diagnostic criteria, are common and may lead to clinical misdiagnosis in FTD.

Somatic complaints in frontotemporal dementia.

Frontotemporal dementia (FTD) is associated with a broad spectrum of clinical characteristics. The objective of this study was to analyze the prevalence of unexplained somatic complaints in neuropathologically verified FTD. We also examined whether the somatic presentations correlated with protein pathology or regional brain pathology and if the patients with these somatic features showed more depressive traits. Ninety-seven consecutively neuropathologically verified FTLD patients were selected. All 97 patients were part of a longitudinal study of FTD and all medical records were systematically reviewed. The somatic complaints focused on were headache, musculoskeletal, gastro/urogenital and abnormal pain response. Symptoms of somatic character (either somatic complaints and/or abnormal pain response) were found in 40.2%. These patients did not differ from the total group with regard to gender, age at onset or duration. Six patients showed exaggerated reactions to sensory stimuli, whereas three patients showed reduced response to pain. Depressive traits were present in 38% and did not correlate with somatic complaints. Suicidal behavior was present in 17 patients, in 10 of these suicidal behavior was concurrent with somatic complaints. No clear correlation between somatic complaints and brain protein pathology, regional pathology or asymmetric hemispherical atrophy was found. Our results show that many FTD patients suffer from unexplained somatic complaints before and/or during dementia where no clear correlation can be found with protein pathology or regional degeneration. Somatic complaints are not covered by current diagnostic criteria for FTD, but need to be considered in diagnostics and care. The need for prospective studies with neuropathological follow up must be stressed as these phenomena remain unexplained, misinterpreted, bizarre and, in many cases, excruciating.

Age-related incidence and family history in frontotemporal dementia: data from the Swedish Dementia Registry.

OBJECTIVES: Frontotemporal dementia (FTD) is considered to be a mainly early-onset neurodegenerative disorder with a strong hereditary component. The aim of the study was to investigate age-related incidence and family history in FTD compared to other dementia disorders, especially Alzheimer's disease (AD). METHODS: The Swedish Dementia Registry (SveDem) registers all new cases of dementia diagnosed by the participating centres, including data on demographics, diagnosis, and investigations used. Data for the period 2008-2011 were extracted and compared with age-related population data on a regional and national level. RESULTS: There were 20 305 patients registered in SveDem during 2008-2011, whereof 352 received a diagnosis of FTD. Mean age at diagnosis for FTD was 69.6 years and almost 70% of FTD cases were 65 years or older at the time of diagnosis. Both FTD and AD showed an increased incidence with age, which reached a maximum in the age group 80-84 years at 6.04 and 202 cases per 100 000 person-years, respectively. The proportion of cases with a positive family history was significantly lower in FTD than in AD. CONCLUSIONS: Contrary to general opinion within the field, data from SveDem show that the incidence of FTD increases with age, and that the majority of cases are diagnosed after the age of 65 years. In addition, data from SveDem might suggest that the importance of hereditary factors in general is similar in FTD and AD. The recognition of these findings has important consequences for the diagnosis, treatment and care of patients with FTD.

Frontotemporal dementia with a C9ORF72 expansion in a Swedish family: clinical and neuropathological characteristics.

BACKGROUND: In 2011 the C9ORF72 repeat expansion was identified as the most frequent genetic mutation underlying FTD and ALS. The main aim of this study was to investigate clinical characteristics in a large C9ORF72-positive FTD family, and to compare these with the neuropathological findings. METHODS: The clinical records of 12 related FTD patients were thoroughly evaluated. The five neuropathologically examined cases were revised using additional TDP-43 immuno-stainings. Four cases were screened for the C9ORF72 expansion. RESULTS: All 12 patients fulfilled the criteria for bvFTD. Restlessness and social neglect were often among the first reported symptoms. Psychotic symptoms were reported in 8 patients. Somatic complaints were seen in 7 cases. All the neuropathologically examined cases were TDP-43 positive. CONCLUSIONS: The phenotype of this C9ORF72 hexanucleotide expansion carrier family was bvFTD. The clinical symptom profile was strikingly homogenous. Psychotic symptoms and somatic complaints were observed in most of the cases.

Diffusion tensor tractography versus volumetric imaging in the diagnosis of behavioral variant frontotemporal dementia.

MRI diffusion tensor imaging (DTI) studies of white matter integrity in behavioral variant frontotemporal dementia have consistently shown involvement of frontal and temporal white matter, corresponding to regional loss of cortical volume. Volumetric imaging has a suboptimal sensitivity as a diagnostic tool and thus we wanted to explore if DTI is a better method to discriminate patients and controls than volumetric imaging. We examined the anterior cingulum bundle in 14 patients with behavioral variant frontotemporal dementia and 22 healthy controls using deterministic manual diffusion tensor tractography, and compared DTI parameters with two measures of cortical atrophy, VBM and cortical thickness, of the anterior cingulate cortex (ACC). Statistically significant changes between patients and controls were detected in all DTI parameters, with large effect sizes. ROC-AUC was for the best DTI parameters: 0.92 (fractional anisotropy) to 0.97 (radial diffusivity), 0.82 for the best cortical parameter, VBM of the ACC. Results from the AUC were confirmed with binary logistic regression analysis including demographic variables, but only for fractional anisotropy and mean diffusivity. Ability to classify patient/nonpatient status was significantly better for mean diffusivity vs. VBM (p=0.031), and borderline significant for fractional anisotropy vs. VBM (p=0.062). The results indicate that DTI could offer advantages in comparison with the assessment of cortical volume in differentiating patients with behavioral variant frontotemporal dementia and controls.

Cerebrospinal fluid neurofilament light chain protein levels in subtypes of frontotemporal dementia.

BACKGROUND: Frontotemporal dementia (FTD) is recognised as a clinically and morphologically heterogeneous group of interrelated neurodegenerative conditions. One of the subtypes within this disease spectrum is the behavioural variant FTD (bvFTD). This is known to be a varied disorder with a mixture of tau-positive and tau-negative underlying pathologies. The other subtypes include semantic dementia (SD), which generally exhibits tau-negative pathology, and progressive non-fluent aphasia (PNFA), which is usually tau-positive. As the clinical presentation of these subtypes may overlap, a specific diagnosis can be difficult to attain and today no specific biomarker can predict the underlying pathology. Neurofilament light chain protein (NFL), a cytoskeletal constituent of intermediate filaments, is thought to reflect neuronal and axonal death when appearing in the cerebrospinal fluid (CSF). NFL has been shown to be elevated in CSF in patients with FTD compared with AD and controls. Our hypothesis was that the levels of NFL also differ between the subtypes of FTD and may indicate the underlying pathological subtype. METHODS: We retrospectively analysed data from previous CSF analyses in 34 FTD cases (23 bvFTD, seven SD, four PNFA), 20 AD cases, and 26 healthy controls. A separate group of 10 neuropathologically verified and subtyped FTD cases (seven tau-negative, three tau-positive) were also analysed. RESULT: NFL levels were significantly higher in FTD compared with both AD (p<0.001) and controls (p<0.001). The NFL levels of SD and bvFTD were significantly higher (p<0.001) compared with AD. The biomarker profiles of PNFA and AD were similar. In the neuropathologically verified FTD cases, NFL was higher in the tau-negative than in the tau-positive cases (exact p=0.017). CONCLUSIONS: The marked NFL elevation in some but not all FTD cases is likely to reflect the different underlying pathologies. The highest NFL values found in the SD group as well as in the neuropathologically verified tau-negative cases may be of subtype diagnostic value, if corroborated in larger patient cohorts. In bvFTD, a mixture of tau-positive and tau-negative underlying pathologies could possibly explain the intermediate NFL values.