Frontotemporal dementia

Explorative genetic study of UBQLN2 and PFN1 in an extended Flanders-Belgian cohort of frontotemporal lobar degeneration patients

UBQLN2 and PFN1 were recently associated with amyotrophic lateral sclerosis (ALS). We investigated a role for these ALS genes in frontotemporal lobar degeneration (FTLD). We screened 328 FTLD, 17 FTLD-ALS, and 157 ALS patients. Patients originated from Flanders-Belgium except for 26 Bulgarian ALS patients. The frequency of UBQLN2 and PFN1 genetic variants in the FTLD patients was low at 0.30% and 0.91% respectively. Moreover, the biological relevance to disease of the variants was questionable. In UBQLN2, we identified p.S346C outside of the PXX domain in 1 FTLD patient. Yet, a closely located serine substitution, p.S340I, was observed in a neurologically healthy control individual. In PFN1, we observed the previously reported p.E117G mutation in 3 FTLD patients and in 3 control individuals. In the ALS patient cohort, we detected UBQLN2 variants in 1.27% of patients. These involved 2 novel UBQLN2 missense mutations, p.S400G and p.P440L, that were also present in unaffected relatives (i.e., the p.S400G carrier's son [70 years] and daughter [65 years]) and the p.P440L carrier's mother (67 years). No mutations were observed in PFN1. In summary, we conclude that genetic variations in UBQLN2 and PFN1 in a predominantly Flanders-Belgian cohort of FTLD and ALS patients are extremely rare.

Mechanisms of granulin deficiency: lessons from cellular and animal models

The identification of causative mutations in the (pro)granulin gene (GRN) has been a major breakthrough in the research on frontotemporal dementia (FTD). So far, all FTD-associated GRN mutations are leading to neurodegeneration through a “loss-of-function” mechanism, encouraging researchers to develop a growing number of cellular and animal models for GRN deficiency. GRN is a multifunctional secreted growth factor, and loss of its function can affect different cellular processes. Besides loss-of-function (i.e., mostly premature termination codons) mutations, which cause GRN haploinsufficiency through reduction of GRN expression, FTD-associated GRN missense mutations have also been identified. Several of these missense mutations are predicted to increase the risk of developing neurodegenerative diseases through altering various key biological properties of GRN-like protein secretion, proteolytic processing, and neurite outgrowth. With the use of cellular and animal models for GRN deficiency, the portfolio of GRN functions has recently been extended to include functions in important biological processes like energy and protein homeostasis, inflammation as well as neuronal survival, neurite outgrowth, and branching. Furthermore, GRN-deficient animal models have been established and they are believed to be promising disease models as they show accelerated aging and recapitulate at least some neuropathological features of FTD. In this review, we summarize the current knowledge on the molecular mechanisms leading to GRN deficiency and the lessons we learned from the established cellular and animal models. Furthermore, we discuss how these insights might help in developing therapeutic strategies for GRN-associated FTD.

The low-frequency blood oxygenation level-dependent functional connectivity signature of the hippocampal-prefrontal network in the rat brain

Interactions between the hippocampus and the prefrontal cortex (PFC) are of major interest in the neurobiology of psychiatric and neurodegenerative disorders and are central to many experimental rodent models. Non-invasive imaging techniques offer a translatable approach to probing this system if homologous features can be identified across species. The objective of the present study was to systematically characterize the rat brain connectivity signature derived from low-frequency resting blood oxygenation level-dependent (BOLD) oscillations associated with and within the hippocampal-prefrontal network, using an array of small seed locations within the relatively large anatomical structures comprising this system. A heterogeneous structure of functional connectivity, both between and within the hippocampal-prefrontal brain structures, was observed. In the hippocampal formation, the posterior (subiculum) region correlated more strongly than the anterior dorsal hippocampus with the PFC. A homologous relationship was found in the human hippocampus, with differential functional connectivity between hippocampal locations proximal to the fornix body relative to locations more distal being localized to the medial prefrontal regions in both species. The orbitofrontal cortex correlated more strongly with sensory cortices and a heterogeneous dependence of functional coupling on seed location was observed along the midline cingulate and retrosplenial cortices. These findings are all convergent with known anatomical connectivity, with stronger BOLD correlations corresponding to known monosynaptic connections. These functional connectivity relationships may provide a useful translatable probe of the hippocampal-prefrontal system for the further study of rodent models of disease and potential treatments, and inform electrode placement in electrophysiology to yield more precise descriptors of the circuits at risk in psychiatric disease.

Genetics of dementia

Neurodegenerative adult-onset dementias are complex and multifactorial diseases that are most commonly caused by environmental, genetic, or mixed environmental and genetic factors. Regarding the genetic causes, a variety of phenotypes may present. This article reviews several of the genetic risk factors for the most common dementias encountered in neurology. Practical implications of genetic testing and pharmacogenomic considerations for clinical practice are also discussed.

Frontotemporal dementia, manifested as schizophrenia, with decreased heterochromatin on chromosome 1

Introduction. Frontotemporal dementia is a disorder of complex etiology, with genetic components contributing to the disease. The aim of this report is to describe a young patient suffering from frontotemporal dementia, misdiagnosed as schizophrenia, related to a genetic defect on chromosome 1. Case Presentation. A 29-year-old female patient, previously diagnosed as having schizophrenia, was hospitalized with severe behavioural disturbances. She demonstrated severe sexual disinhibition, hyperphagia, lack of motivation, apathy, psychotic symptoms, suicidal thoughts, and cognitive deterioration. Focal atrophy of frontal and anterior temporal structures bilaterally was found on brain MRI, as well as bifrontal hypo perfusion of the brain on SPECT scan. The diagnosis of frontotemporal dementia was made clinically, according to Lund and Manchester groups and Neary diagnostic criteria. Chromosomal analysis was conducted and revealed decrease in length of heterochromatin on the long arm of chromosome 1 (46, XX, 1qh-). Parental karyotypes were normal. Discussion. Frontotemporal dementia, and particularly early-onset cases, can be often misdiagnosed as schizophrenia, with negative impact on case management. Genetic testing could be an aid to the correct diagnosis, which is crucial for optimal patient care.

Identifying the neural correlates of executive functions in early cerebral microangiopathy: a combined VBM and DTI study

Cerebral microangiopathy (CMA) has been associated with executive dysfunction and fronto-parietal neural network disruption. Advances in magnetic resonance imaging allow more detailed analyses of gray (e.g., voxel-based morphometry-VBM) and white matter (e.g., diffusion tensor imaging-DTI) than traditional visual rating scales. The current study investigated patients with early CMA and healthy control subjects with all three approaches. Neuropsychological assessment focused on executive functions, the cognitive domain most discussed in CMA. The DTI and age-related white matter changes rating scales revealed convergent results showing widespread white matter changes in early CMA. Correlations were found in frontal and parietal areas exclusively with speeded, but not with speed-corrected executive measures. The VBM analyses showed reduced gray matter in frontal areas. All three approaches confirmed the hypothesized fronto-parietal network disruption in early CMA. Innovative methods (DTI) converged with results from conventional methods (visual rating) while allowing greater spatial and tissue accuracy. They are thus valid additions to the analysis of neural correlates of cognitive dysfunction. We found a clear distinction between speeded and nonspeeded executive measures in relationship to imaging parameters. Cognitive slowing is related to disease severity in early CMA and therefore important for early diagnostics.

The genetics and neuropathology of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is a heterogeneous group of disorders characterized by disturbances of behavior and personality and different types of language impairment with or without concomitant features of motor neuron disease or parkinsonism. FTLD is characterized by atrophy of the frontal and anterior temporal brain lobes. Detailed neuropathological studies have elicited proteinopathies defined by inclusions of hyperphosphorylated microtubule-associated protein tau, TAR DNA-binding protein TDP-43, fused-in-sarcoma or yet unidentified proteins in affected brain regions. Rather than the type of proteinopathy, the site of neurodegeneration correlates relatively well with the clinical presentation of FTLD. Molecular genetic studies identified five disease genes, of which the gene encoding the tau protein (MAPT), the growth factor precursor gene granulin (GRN), and C9orf72 with unknown function are most frequently mutated. Rare mutations were also identified in the genes encoding valosin-containing protein (VCP) and charged multivesicular body protein 2B (CHMP2B). These genes are good markers to distinguish underlying neuropathological phenotypes. Due to the complex landscape of FTLD diseases, combined characterization of clinical, imaging, biological and genetic biomarkers is essential to establish a detailed diagnosis. Although major progress has been made in FTLD research in recent years, further studies are needed to completely map out and correlate the clinical, pathological and genetic entities, and to understand the underlying disease mechanisms. In this review, we summarize the current state of the rapidly progressing field of genetic, neuropathological and clinical research of this intriguing condition.

Montreal Cognitive Assessment (MoCA): validation study for frontotemporal dementia

The Montreal Cognitive Assessment (MoCA) is a brief instrument developed for the screening of milder forms of cognitive impairment, having surpassed the well-known limitations of the Mini-Mental State Examination (MMSE). The aim of the present study was to validate the MoCA as a cognitive screening test for behavioral-variant frontotemporal dementia (bv-FTD) by examining its psychometric properties and diagnostic accuracy. Three matched subgroups of participants were considered: bv-FTD (n = 50), Alzheimer disease (n = 50), and a control group of healthy adults (n = 50). Compared with the MMSE, the MoCA demonstrated consistently superior psychometric properties and discriminant capacity, providing comprehensive information about the patients' cognitive profiles. The diagnostic accuracy of MoCA for bv-FTD was extremely high (area under the curve AUC [MoCA] = 0.934, 95% confidence interval [CI] = 0.866-.974; AUC [MMSE] = 0.772, 95% CI = 0.677-0.850). With a cutoff below 17 points, the MoCA results for sensitivity, specificity, positive predictive value, negative predictive value, and classification accuracy were significantly superior to those of the MMSE. The MoCA is a sensitive and accurate instrument for screening the patients with bv-FTD and represents a better option than the MMSE.

Study protocol: EXERcise and cognition in sedentary adults with early-ONset dementia (EXERCISE-ON)

Background

Although the development of early-onset dementia is a radical and invalidating experience for both patient and family there are hardly any non-pharmacological studies that focus on this group of patients. One type of a non-pharmacological intervention that appears to have a beneficial effect on cognition in older persons without dementia and older persons at risk for dementia is exercise. In view of their younger age early-onset dementia patients may be well able to participate in an exercise program. The main aim of the EXERCISE-ON study is to assess whether exercise slows down the progressive course of the symptoms of dementia.

Methods/Design

One hundred and fifty patients with early-onset dementia are recruited. After completion of the baseline measurements, participants living within a 50 kilometre radius to one of the rehabilitation centres are randomly assigned to either an aerobic exercise program in a rehabilitation centre or a flexibility and relaxation program in a rehabilitation centre. Both programs are applied three times a week during 3 months. Participants living outside the 50 kilometre radius are included in a feasibility study where participants join in a daily physical activity program set at home making use of pedometers. Measurements take place at baseline (entry of the study), after three months (end of the exercise program) and after six months (follow-up). Primary outcomes are cognitive functioning; psychomotor speed and executive functioning; (instrumental) activities of daily living, and quality of life. Secondary outcomes include physical, neuropsychological, and rest-activity rhythm measures.

Discussion

The EXERCISE-ON study is the first study to offer exercise programs to patients with early-onset dementia. We expect this study to supply evidence regarding the effects of exercise on the symptoms of early-onset dementia, influencing quality of life.

Trial registration

The present study is registered within The Netherlands National Trial Register (ref: NTR2124)

ALS and Frontotemporal Dysfunction: A Review

Though once believed to be a disease that was limited to the motor system, it is now apparent that amyotrophic lateral sclerosis (ALS) may be associated with cognitive changes in some patients. Changes are consistent with frontotemporal dysfunction, and may range from mild abnormalities only recognized with formal neuropsychological testing, to profound frontotemporal dementia (FTD). Executive function, behavior, and language are the most likely areas to be involved. Screening helpful in detecting abnormalities includes verbal or categorical fluency, behavioral inventories filled out by the caregiver, and evaluation for the presence of depression and pseudobulbar affect. Patients with cognitive dysfunction have shortened survival and may be less compliant with recommendations regarding use of feeding tubes and noninvasive ventilation. Evolving knowledge of genetic and pathological links between ALS and FTD has allowed us to better understand the overlapping spectrum of ALS and FTD.

Structural brain changes in First Episode Schizophrenia compared with Fronto-Temporal Lobar Degeneration: a meta-analysis

BACKGROUND

The authors sought to compare gray matter changes in First Episode Schizophrenia (FES) compared with Fronto-Temporal Lobar Degeneration (FTLD) using meta-analytic methods applied to neuro-imaging studies.

METHODS

A systematic search was conducted for published, structural voxel-based morphometric MRI studies in patients with FES or FTLD. Data were combined using anatomical likelihood estimation (ALE) to determine the extent of gray matter decreases and analysed to ascertain the degree of overlap in the spatial distribution of brain changes in both diseases.

RESULTS

Data were extracted from 18 FES studies (including a total of 555 patients and 621 comparison subjects) and 20 studies of FTLD or related disorders (including a total of 311 patients and 431 comparison subjects). The similarity in spatial overlap of brain changes in the two disorders was significant (p = 0.001). Gray matter deficits common to both disorders included bilateral caudate, left insula and bilateral uncus regions.

CONCLUSIONS

There is a significant overlap in the distribution of structural brain changes in First Episode Schizophrenia and Fronto-Temporal Lobar Degeneration. This may reflect overlapping aetiologies, or a common vulnerability of these regions to the distinct aetio-pathological processes in the two disorders.

Cognitive correlates of cerebrospinal fluid biomarkers in frontotemporal dementia

OBJECTIVE

In this study we investigated the relationships between cerebrospinal fluid (CSF) biomarkers (tau and amyloid-β1-42 [Aβ1-42]) and cognition or behavior in patients with frontotemporal dementia (the behavioral variant, bvFTD).

METHODS

We included 58 patients with bvFTD. All patients underwent a neuropsychological assessment and lumbar puncture. Relationships between CSF biomarkers and cognition or behavior were assessed with linear regression analysis.

RESULTS

After correction for age, sex, and education, CSF tau levels were found to be negatively related to the Visual Association Test (standardized β = -0.3, P < .05), whereas CSF Aβ1-42 levels were found to be positively related to the Mini-Mental State Examination (β = 0.3, P < .05), the frontal assessment battery (β = 0.5, P < .05), and digit span backwards test (β = 0.3, P = .01). We did not find relations between CSF biomarkers and behavior (measured by the neuropsychiatric inventory). After excluding all patients with a CSF biomarker profile often seen in Alzheimer's disease (high levels of tau and low levels of Aβ1-42), we still found relations between CSF Aβ1-42 levels and Visual Association Test object naming (β = 0.4, P < .05), as well as between CSF Aβ1-42 levels and the frontal assessment battery (β = 0.5, P < .05, but there was no relation between CSF tau and cognition.

CONCLUSION

Low CSF Aβ1-42 levels are associated with worse general cognitive function and worse executive function in patients with bvFTD. Our results provide circumstantial evidence for a pathophysiological role of Aβ1-42 in bvFTD.

Familial frontotemporal dementia-associated presenilin-1 c.548G>T mutation causes decreased mRNA expression and reduced presenilin function in knock-in mice

Mutations in the presenilin-1 (PSEN1) gene are associated with familial Alzheimer's disease and frontotemporal dementia (FTD). Interestingly, neuropathological analysis of a Belgian FTD family carrying a PSEN1 c.548G>T mutation confirmed neurodegeneration in the absence of amyloid plaques. To investigate the impact of the c.548G>T mutation on presenilin-1 (PS1) function in vivo, we introduced this mutation into the genomic Psen1 locus. The resulting c.548G>T knock-in (KI) mice are viable but express markedly lower levels of Psen1 mRNA and protein in the brain. This reduction is due to production of aberrantly spliced transcripts lacking either exon 6 or exons 6 and 7 and their subsequent degradation via non-sense-mediated decay (NMD); inhibition of NMD by cycloheximide treatment stabilized these transcripts and restored the level of Psen1 mRNA in KI/KI brains. Interestingly, the reduction of Psen1 mRNA expression and the degradation of aberrant Psen1 splice products occur exclusively in the brain but not in other tissues. Consistent with decreased Psen1 expression, γ-secretase activity was strongly reduced in the cerebral cortex of KI mice, as measured by de novo γ-secretase-mediated cleavage of APP and Notch. Moreover, PS1 expressed from Psen1 cDNA carrying the c.548G>T mutation displayed normal γ-secretase activity in cultured cells, indicating that the corresponding p.183G>V amino acid substitution does not affect γ-secretase activity. Finally, Psen1 c.548G>T(KI/KI);Psen2(-/-) mice exhibited mild spatial memory deficits in the Morris water maze task. Together, our findings demonstrate that the c.548G>T mutation results in a brain-specific loss of presenilin function due to decreased Psen1 mRNA expression.

Behavioral and psychological symptoms of dementia

Behavioral and psychological symptoms of dementia (BPSD), also known as neuropsychiatric symptoms, represent a heterogeneous group of non-cognitive symptoms and behaviors occurring in subjects with dementia. BPSD constitute a major component of the dementia syndrome irrespective of its subtype. They are as clinically relevant as cognitive symptoms as they strongly correlate with the degree of functional and cognitive impairment. BPSD include agitation, aberrant motor behavior, anxiety, elation, irritability, depression, apathy, disinhibition, delusions, hallucinations, and sleep or appetite changes. It is estimated that BPSD affect up to 90% of all dementia subjects over the course of their illness, and is independently associated with poor outcomes, including distress among patients and caregivers, long-term hospitalization, misuse of medication, and increased health care costs. Although these symptoms can be present individually it is more common that various psychopathological features co-occur simultaneously in the same patient. Thus, categorization of BPSD in clusters taking into account their natural course, prognosis, and treatment response may be useful in the clinical practice. The pathogenesis of BPSD has not been clearly delineated but it is probably the result of a complex interplay of psychological, social, and biological factors. Recent studies have emphasized the role of neurochemical, neuropathological, and genetic factors underlying the clinical manifestations of BPSD. A high degree of clinical expertise is crucial to appropriately recognize and manage the neuropsychiatric symptoms in a patient with dementia. Combination of non-pharmacological and careful use of pharmacological interventions is the recommended therapeutic for managing BPSD. Given the modest efficacy of current strategies, there is an urgent need to identify novel pharmacological targets and develop new non-pharmacological approaches to improve the adverse outcomes associated with BPSD.

Clinico-pathological correlations of the most common neurodegenerative dementias

Neurodegenerative dementias are a group of neurological disorders characterized by deterioration in several cognitive domains in which there is selective and progressive loss of specific populations of neurons. The precise neurobiological basis for the different neurodegenerative dementias remains unknown. It is expected that different pathologies reflect different mechanisms, at least early in the neurodegeneration process. The next decades promise treatments directed to causes and mechanisms, bringing an outstanding challenge to clinicians due to heterogeneous clinical presentations with the same molecular pathology. The purpose of this brief review is to describe the key neuropathological features of the most common neurodegenerative dementias (Alzheimer disease, dementia with Lewy bodies and Parkinson’s disease dementia, and frontotemporal lobar degeneration) and the relationship with the clinical syndromes described in clinico-pathological studies. We expect this overview contributes for the understanding of this broad topic integrating the two ends of the spectrum: clinical and pathological.

Frontotemporal dementia and neurocysticercosis: a case report

We report a case of a 67-year-old woman with frontotemporal dementia (FTD) and a history of neurocysticercosis. After her retirement she showed progressive behavioral changes and neuropsychiatric symptoms with relative preservation of cognitive functioning. During the next three years, the patient manifested progressive deterioration of verbal communication gradually evolving to mutism, a hallmark of cases of progressive nonfluent aphasia.

Diminished disgust reactivity in behavioral variant frontotemporal dementia

Frontotemporal dementia is a neurodegenerative disease that impacts emotion and social behavior. Using laboratory measures of emotional reactivity, our past work has found that reactivity to loud noises and to thematically simple happy and sad emotional films are preserved in the early stages of the disease while other emotional responses (e.g., embarrassment) are severely compromised. In the present study we examined disgust, an emotion whose function is to distance us from offending objects and situations. We measured disgust reactivity in 21 patients with behavioral variant frontotemporal dementia (bvFTD, a subtype of frontotemporal dementia characterized by emotional blunting) and 25 neurologically healthy controls. Disgust is an emotion of particular interest in bvFTD, due to caregiver and clinician reports that patients engage in acts that suggest this emotion may be compromised; in addition, the pattern of neurodegeneration in bvFTD includes atrophy of key frontotemporal structures (e.g., anterior insula) with known roles in visceral emotions such as disgust. In the present study, participants had their emotional facial behavior, physiology, and self-reported emotional experience measured while watching a disgust-eliciting film. We found that behavioral, physiological, and self-reported experiential responses were all reduced in bvFTD patients compared to controls (with behavioral and physiological differences still found after controlling for patients' cognitive deficits). We discuss the implications of these findings for bvFTD patients' problems in social functioning and their typical patterns of neurodegeneration.

Quantitative EEG and LORETA: valuable tools in discerning FTD from AD?

Drawing a clinical distinction between frontotemporal dementia (FTD) and Alzheimer's disease (AD) is tricky, particularly at the early stages of disease. This study evaluates the possibility in differentiating 39 FTD, 39 AD, and 39 controls (CTR) by means of power spectral analysis and standardized low resolution brain electromagnetic tomography (sLORETA) within delta, theta, alpha 1 and 2, beta 1, 2, and 3 frequency bands. Both analyses revealed in AD patients, relative to CTR, higher expression of diffuse delta/theta and lower central/posterior fast frequency (from alpha1 to beta2) bands. FTD patients showed diffuse increased theta power compared with CTR and lower delta relative to AD patients. Compared with FTD, AD patients showed diffuse higher theta power at spectral analysis and, at sLORETA, decreased alpha2 and beta1 values in central/temporal regions. Spectral analysis and sLORETA provided complementary information that might help characterizing different patterns of electroencephalogram (EEG) oscillatory activity in AD and FTD. Nevertheless, this differentiation was possible only at the group level because single patients could not be discerned with sufficient accuracy.

Perseverations and non-verbal confabulations on the Rey-Osterrieth Complex Figure Test in a fronto-temporal dementia single case study

We describe the case of a patient with late onset fronto-temporal dementia (FTD), who presented with typical personality changes, but also perseverative and confabulatory behaviors while performing the Rey-Osterrieth Complex Figure Test. We hypothesize that the progressive atrophy of orbitobasal, medial, and dorsolateral frontal cortices may give rise to both confabulations and perseverations in the non-verbal domain. In agreement with previous studies, reporting atypical profiles, this case report underlines the clinical heterogeneity of FTD. Authors declare that they have no conflicts of interest.

Executive deficits are related to the inferior frontal junction in early dementia

Executive functions describe a wide variety of higher order cognitive processes that allow the flexible modification of thought and behaviour in response to changing cognitive or environmental contexts. Their impairment is common in neurodegenerative disorders. Executive deficits negatively affect everyday activities and hamper the ability to cope with other deficits, such as memory impairment in Alzheimer's disease or behavioural disorders in frontotemporal lobar degeneration. Our study aimed to characterize the neural correlates of executive functions by relating respective deficits to regional hypometabolism in early dementia. Executive functions were assessed with two classical tests, the Stroop and semantic fluency test and various subtests of the behavioural assessment of the dysexecutive syndrome test battery capturing essential aspects of executive abilities relevant to daily living. Impairments in executive functions were correlated with reductions in brain glucose utilization as measured by [(18)F]fluorodeoxyglucose positron emission tomography and analysed voxelwise using statistical parametric mapping in 54 subjects with early dementia, mainly Alzheimer's disease and frontotemporal lobar degeneration, and its prodromal stages: subjective and mild cognitive impairment. Although the analysis revealed task-specific frontoparietal networks, it consistently showed that hypometabolism in one region in the left lateral prefrontal cortex-the inferior frontal junction area-was related to performance in the various neuropsychological tests. This brain region has recently been related to the three component processes of cognitive control-working memory, task switching and inhibitory control. Group comparisons additionally showed hypometabolism in this area in Alzheimer's disease and frontotemporal lobar degeneration. Our study underlines the importance of the inferior frontal junction area for cognitive control in general and for executive deficits in early dementia.

Aberrant septin 11 is associated with sporadic frontotemporal lobar degeneration

Background

Detergent-insoluble protein accumulation and aggregation in the brain is one of the pathological hallmarks of neurodegenerative diseases. Here, we describe the identification of septin 11 (SEPT11), an enriched component of detergent-resistant fractions in frontotemporal lobar degeneration with ubiquitin-immunoreactive inclusions (FTLD-U), using large-scale unbiased proteomics approaches.

Results

We developed and applied orthogonal quantitative proteomic strategies for the unbiased identification of disease-associated proteins in FTLD-U. Using these approaches, we proteomically profiled detergent-insoluble protein extracts prepared from frontal cortex of FTLD-U cases, unaffected controls, or neurologic controls (i.e. Alzheimer's disease; AD). Among the proteins altered specifically in FTLD-U, we identified TAR DNA binding protein-43 (TDP-43), a known component of ubiquitinated inclusions. Moreover, we identified additional proteins enriched in detergent-resistant fractions in FTLD-U, and characterized one of them, SEPT11, in detail. Using independent highly sensitive targeted proteomics approaches, we confirmed the enrichment of SEPT11 in FTLD-U extracts. We further showed that SEPT11 is proteolytically cleaved into N-terminal fragments and, in addition to its prominent glial localization in normal brain, accumulates in thread-like pathology in affected cortex of FTLD-U patients.

Conclusions

The proteomic discovery of insoluble SEPT11 accumulation in FTLD-U, along with novel pathological associations, highlights a role for this cytoskeleton-associated protein in the pathogenesis of this complex disorder.

Regional brain atrophy and impaired decision making on the balloon analog risk task in behavioral variant frontotemporal dementia

OBJECTIVE

The goal of this study was 2-fold, first, to compare decision making in behavioral variant frontotemporal dementia (bvFTD) patients and healthy adults using the Balloon Analog Risk Task (BART), and, second, to identify the regions of gray matter atrophy associated with bvFTD patients' BART performance.

BACKGROUND

Stimulus-reinforcement learning is required to evaluate the results of previously chosen actions to improve future decisions. Although there is a well established literature suggesting altered decision making in FTD patients and data from lesion studies suggest orbitofrontal cortex (OFC) involvement in decision making, there is very little research looking at the brain correlates of decision making in FTD populations specifically.

METHOD

Twenty-seven bvFTD patients and 19 age-matched and education-matched normal controls completed the BART. Voxel-based morphometry analysis was performed on the magnetic resonance imaging scans of a subset of patients.

RESULTS

Compared with healthy controls, the bvFTD patients did not learn and pumped less to inflate a balloon to receive a reward, indicating altered stimulus-reinforcement learning. The voxel-based morphometry analysis indicated that bvFTD patients' impaired BART performance was related to atrophy in the right lateral OFC.

CONCLUSIONS

The right lateral OFC is crucial for stimulus-reinforcement learning required for the adjustment of behavior under changing reward contingencies.

Clinical amyloid imaging in Alzheimer's disease

BACKGROUND

The hypothesis that amyloid deposition is the leading cause of Alzheimer's disease (AD) is supported by findings in transgenic animal models and forms the basis of clinical trials of anti-amyloid agents. According to this theory, amyloid deposition causes severe damage to neurons many years before onset of dementia via a cascade of several downstream effects. This hypothesis has, however, not yet been directly tested in human beings because of the very limited possibility of diagnosing amyloid deposition in vivo, which until recently required either brain biopsy or PET imaging with an on-site cyclotron and radiochemistry laboratory. Moreover, a clinical diagnosis of AD requires that patients have dementia, at which stage any effective treatment aimed at reducing amyloid deposition will probably be too late.

RECENT DEVELOPMENTS

The amyloid imaging tracers flutemetamol, florbetapir, and florbetaben labelled with (18)F have been developed for PET; they can be produced commercially at central cyclotron sites and subsequently delivered to clinical PET scanning facilities. These tracers are currently undergoing formal clinical trials to establish whether they can be used to accurately image fibrillary amyloid and to distinguish patients with AD from normal controls and those with other diseases that cause dementia. They might also be used as biomarkers to predict development of AD before onset of dementia and to assess the effect of anti-amyloid therapy. Negative amyloid scans indicate absence of AD with a high level of accuracy, but healthy elderly volunteers might have positive amyloid scans, so their predictive value in isolation is less clear. Close association of in-vivo amyloid imaging results with post-mortem histopathological findings was shown with florbetapir in a phase 3 study. WHERE NEXT?: Therapeutic studies of anti-amyloid agents that include amyloid tracers as biomarkers are expected to be useful for drug development and to clarify the relation between amyloid removal and clinical effects. Once the (18)F tracers become available for diagnostic use, large-scale longitudinal studies will be needed to clarify their prognostic and diagnostic power in relation to age, risk factors, and AD subtypes. Ultimately, these tracers will hopefully clarify the pathophysiological role of amyloid in AD and contribute to development of new treatments.

The clinical diagnosis of early-onset dementias: diagnostic accuracy and clinicopathological relationships

Accuracy of clinical diagnosis of dementia is increasingly important for therapeutic and scientific investigations. In this study, we examine diagnostic accuracy in a consecutive series of 228 patients referred to a specialist early-onset dementia clinic, whose brains were subsequently examined at post-mortem. Diagnosis was based on structured history, neurological examination and neuropsychological assessment, with emphasis on qualitative as well as quantitative aspects of performance. Neuroimaging provided support for but did not alter the clinical diagnosis. We set out the principles that guided diagnosis: (i) time course of illness; (ii) weighting of physical, behavioural and cognitive symptoms and signs; (iii) 'anterior' versus 'posterior' hemisphere character of cognitive change; and (iv) specificity of deficit, paying attention to the differentiation between syndromes of frontotemporal lobar degeneration and focal forms of Alzheimer's disease. Forty-two per cent of the patients had clinical diagnoses of one of the syndromes of frontotemporal lobar degeneration, the high proportion reflecting the research interests of the group. Forty-six per cent were diagnosed with Alzheimer's disease and the remaining patients, dementia with Lewy bodies, Creutzfeldt-Jakob disease, vascular or unclassified dementia. Frontotemporal lobar degeneration was identified with 100% sensitivity and 97% specificity and Alzheimer's disease with 97% sensitivity and 100% specificity. Patients with other pathologies were accurately identified on clinical grounds. Examination of subsyndromes of frontotemporal lobar degeneration showed a relatively predictable relationship between clinical diagnosis and pathological subtype. Whereas the behavioural disorder of frontotemporal dementia was associated with tau, transactive response DNA binding protein 43 and fused-in-sarcoma pathology, cases of frontotemporal dementia with motoneuron disease, semantic dementia and, with one exception, progressive non-fluent aphasia were associated with transactive response DNA binding protein 43 pathology, distinguished by ubiquitin subtyping (types B, C and A, respectively). Clinical diagnoses of progressive apraxia, corticobasal degeneration and progressive supranuclear palsy were, with one exception, associated with Pick, corticobasal and progressive supranuclear palsy subtypes of tau pathology, respectively. Unanticipated findings included Alzheimer pathology in two patients presenting with the behavioural syndrome of frontotemporal dementia and corticobasal pathology in four others with clinical frontotemporal dementia. Notwithstanding such anomalies, which serve as a reminder that there is not an absolute concordance between clinical phenotype and underlying pathology, the findings show that dementias can be distinguished in life with a high level of accuracy. Moreover, careful clinical phenotyping allows prediction of histopathological subtype of frontotemporal lobar degeneration. The principles guiding diagnosis provide the foundation for future prospective studies.

Anomia as a marker of distinct semantic memory impairments in Alzheimer's disease and semantic dementia

OBJECTIVE

Many neurologically constrained models of semantic memory have been informed by two primary temporal lobe pathologies: Alzheimer's disease (AD) and Semantic Dementia (SD). However, controversy persists regarding the nature of the semantic impairment associated with these patient populations. Some argue that AD presents as a disconnection syndrome in which linguistic impairment reflects difficulties in lexical or perceptual means of semantic access. In contrast, there is a wider consensus that SD reflects loss of core knowledge that underlies word and object meaning. Object naming provides a window into the integrity of semantic knowledge in these two populations.

METHOD

We examined naming accuracy, errors and the correlation of naming ability with neuropsychological measures (semantic ability, executive functioning, and working memory) in a large sample of patients with AD (n = 36) and SD (n = 21).

RESULTS

Naming ability and naming errors differed between groups, as did neuropsychological predictors of naming ability. Despite a similar extent of baseline cognitive impairment, SD patients were more anomic than AD patients.

CONCLUSIONS

These results add to a growing body of literature supporting a dual impairment to semantic content and active semantic processing in AD, and confirm the fundamental deficit in semantic content in SD. We interpret these findings as supporting of a model of semantic memory premised upon dynamic interactivity between the process and content of conceptual knowledge.

The most common type of FTLD-FUS (aFTLD-U) is associated with a distinct clinical form of frontotemporal dementia but is not related to mutations in the FUS gene

Frontotemporal lobar degeneration (FTLD) is clinically, pathologically and genetically heterogeneous. Recent descriptions of a pathological sub-type that is ubiquitin positive, TDP-43 negative and immunostains positive for the Fused in Sarcoma protein (FUS) raises the question whether it is associated with a distinct clinical phenotype identifiable on clinical grounds, and whether mutations in the Fused in Sarcoma gene (FUS) might also be associated with FTLD. Examination of a pathological series of 118 cases of FTLD from two centres, showing tau-negative, ubiquitin-positive pathology, revealed FUS pathology in five patients, four classified as atypical FTLD with ubiquitin inclusions (aFTLD-U), and one as neuronal intermediate filament inclusion disease (NIFID). The aFTLD-U cases had youthful onset (22-46 years), an absence of strong family history, a behavioural syndrome consistent with frontotemporal dementia (FTD) and severe caudate atrophy. Their cognitive/behavioural profile was distinct, characterised by prominent obsessionality, repetitive behaviours and rituals, social withdrawal and lack of engagement, hyperorality with pica, and marked stimulus-bound behaviour including utilisation behaviour. They conformed to the rare behavioural sub-type of FTD identified previously by us as the "stereotypic" form, and linked to striatal pathology. Cognitive evaluation revealed executive deficits in keeping with subcortical-frontal dysfunction, but no cortical deficits in language, perceptuospatial skills or praxis. The patient with NIFID was older and exhibited aphasia and dyspraxia. No patient had clinical evidence of motor neurone disease during life, or a mutation in the FUS gene. In the complementary clinical study of 312 patients with clinical syndromes of FTLD, genetic analysis revealed a 6 bp deletion in FUS in 3 patients, of questionable significance. One presented a prototypical picture of FTD, another expressive language disorder, and the third semantic dementia. None showed the early onset age or distinctive 'stereotypic' picture of patients with aFTLD-U. We conclude that aFTLD-U is associated with a distinct clinical form of frontotemporal dementia, potentially allowing identification of such patients in life with a high degree of precision. Whether mutations in the FUS gene cause some cases of FTLD remains unresolved.

C-terminus of progranulin interacts with the beta-propeller region of sortilin to regulate progranulin trafficking

Progranulin haplo-insufficiency is a main cause of frontotemporal lobar degeneration (FTLD) with TDP-43 aggregates. Previous studies have shown that sortilin regulates progranulin trafficking and is a main determinant of progranulin level in the brain. In this study, we mapped the binding site between progranulin and sortilin. Progranulin binds to the beta-propeller region of sortilin through its C-terminal tail. The C-terminal progranulin fragment is fully sufficient for sortilin binding and progranulin C-terminal peptide displaces progranulin binding to sortilin. Deletion of the last 3 residues of progranulin (QLL) abolishes its binding to sortilin and also sortilin dependent regulation of progranulin trafficking. Since progranulin haplo-insufficiency results in FTLD, these results may provide important insights into future studies of progranulin trafficking and signaling and progranulin based therapy for FTLD.

Cellular effects of progranulin in health and disease

Progranulin is a fascinating multifunctional protein, which has been implicated in cell growth, wound repair, tumorigenesis, inflammation, neurodevelopment, and more recently in neurodegeneration. The mechanism of action of this protein is still largely unknown, but the knowledge about the cellular effects on various cell types is expanding. In the current review, we will summarize what is known about the cell biology of progranulin. A better understanding of the biology of progranulin will impact diverse areas of research.

Proteomic analysis of hippocampal dentate granule cells in frontotemporal lobar degeneration: application of laser capture technology

Frontotemporal lobar degeneration (FTLD) is the most common cause of dementia with pre-senile onset, accounting for as many as 20% of cases. A common subset of FTLD cases is characterized by the presence of ubiquitinated inclusions in vulnerable neurons (FTLD-U). While the pathophysiological mechanisms underlying neurodegeneration in FTLD-U have not yet been elucidated, the presence of inclusions in this disease indicates enhanced aggregation of one or several proteins. Moreover, these inclusions suggest altered expression, processing, or degradation of proteins during FTLD-U pathogenesis. Thus, one approach to understanding disease mechanisms is to delineate the molecular changes in protein composition in FTLD-U brain. Using a combined approach consisting of laser capture microdissection (LCM) and high-resolution liquid chromatography-tandem mass spectrometry (LC–MS/MS), we identified 1252 proteins in hippocampal dentate granule cells excised from three post-mortem FTLD-U and three unaffected control cases processed in parallel. Additionally, we employed a labeling-free quantification technique to compare the abundance of the identified proteins between FTLD-U and control cases. Quantification revealed 54 proteins with selective enrichment in FTLD-U, including TAR–DNA binding protein 43 (TDP-43), a recently identified component of ubiquitinated inclusions. Moreover, 19 proteins were selectively decreased in FTLD-U. Subsequent immunohistochemical analysis of TDP-43 and three additional protein candidates suggests that our proteomic profiling of FTLD-U dentate granule cells reveals both inclusion-associated proteins and non-aggregated disease-specific proteins. Application of LCM is a valuable tool in the molecular analysis of complex tissues, and its application in the proteomic characterization of neurodegenerative disorders such as FTLD-U may be used to identify proteins altered in disease.

TMEM106B is associated with frontotemporal lobar degeneration in a clinically diagnosed patient cohort

In a genome-wide association study of frontotemporal lobar degeneration with pathological inclusions of TAR DNA-binding protein, significant association was obtained with three single nucleotide polymorphisms at 7p21.3, in a region encompassing the gene TMEM106B. This study also suggested a potential modifying effect of TMEM106B on disease since the association was strongest in progranulin mutation carriers. Further, the risk effect seemed to correlate with increased TMEM106B expression in patients. In the present study, we sought to replicate these three findings using an independent Flanders–Belgian cohort of primarily clinically diagnosed patients with frontotemporal lobar degeneration (n = 288). We were able to confirm the association with TMEM106B with a P-value of 0.008 for rs1990622, the top marker from the genome-wide association study [odds ratio 0.75 (95% confidence interval 0.61–0.93)]. Further, high-density single nucleotide polymorphism mapping suggested that the association was solely driven by the gene TMEM106B. Homozygous carriers of the TMEM106B protective alleles had a 50% reduced risk of developing frontotemporal lobar degeneration. However, we were unable to detect a modifying effect of the TMEM106B single nucleotide polymorphisms on onset age in progranulin mutation carriers belonging to an extended, clinical and pathological well-documented founder family segregating a progranulin null mutation. Also, we could not observe significant differences in messenger RNA expression between patients and control individuals in lymphoblast cell lines and in brain frontal cortex. In conclusion, we replicated the genetic TMEM106B association in a primarily clinically diagnosed cohort of patients with frontotemporal lobar degeneration from Flanders–Belgium. Additional studies are needed to unravel the molecular role of TMEM106B in disease onset and pathogenesis.

Mutations in CHMP2B are not a cause of frontotemporal lobar degeneration in Finnish patients

BACKGROUND

Frontotemporal lobar degeneration (FTLD) is a genetically complex disorder. The majority of mutations linked to FTLD families are found in the microtubule-associated protein tau (MAPT) and progranulin (PGRN) genes. Mutations in the chromatin-modifying protein 2B gene (CHMP2B) have been identified in a few families. However, CHMP2B has been showed to be a rare cause of FTLD. Our aim was to determine the frequency of CHMP2B mutations in a clinical series of patients with FTLD in Northern Finland.

PATIENTS AND METHODS

We examined 72 (36 men) Finnish patients with FTLD. The mean age at onset was 58.9 (range 43–80). Symptoms of motor neuron disease (FTLDMND) were present in 12 patients (17%). Positive family history was detected in 28% of the patients. Mutations in MAPT and PGRN were excluded from these patients. All exons and exon–intron boundaries of the CHMP2B gene were sequenced.

RESULTS

No pathogenic CHMP2B mutations were found. A rare polymorphism in the non-coding region of exon 1 (rs36098294) and three other previously reported polymorphisms were detected.

CONCLUSIONS

Our results confirm that mutations in CHMP2B are not a common cause of FTLD. MAPT and PGRN mutations are also rare in Finnish population, suggesting that other, still unknown genetic factors may play a role in the pathogenesis of FTLD in Finnish population.

Molecular pathways of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is a neurodegenerative condition that predominantly affects behavior, social awareness, and language. It is characterized by extensive heterogeneity at the clinical, pathological, and genetic levels. Recognition of these levels of heterogeneity is important for proper disease management. The identification of progranulin and TDP-43 as key proteins in a significant proportion of FTLD patients has provided the impetus for a wealth of studies probing their role in neurodegeneration. This review highlights the most recent developments and future directions in this field and puts them in perspective of the novel insights into the neurodegenerative process, which have been gained from related disorders, e.g., the role of FUS in amyotrophic lateral sclerosis.

Brain morphometry and functional imaging techniques in dementia: methods, findings and relevance in forensic neurology

PURPOSE OF REVIEW

The ability to predict what people perceive from patterns of brain activity raises futuristic questions. Amongst these are questions about the role of brain activity in predicting misdemeanours or preventing them. Two obvious cases in point are the tendency of some patients with fronto-temporal lobar degeneration to become aggressive and the difficulty deciding when Alzheimer patients need to stop driving for reasons of safety. These two situations will be used to structure a review of the literature in this general area.

RECENT FINDINGS

Multivariate classification techniques (MCT) improve early accurate diagnosis of dementia. Given the known frequency of behavioural abnormalities, this information allows better prediction of the future frequency of such behaviour. In addition, MCT could prove suitable for providing reasonably accurate information of relevance to individuals about the combination of future symptoms. However, no study has applied MCT to the prediction of future behavioural problems or to assessments of road safety in dementia.

SUMMARY

MCT could improve the prediction of offensive or risky behaviour in which standard neuropsychological testing is less than conclusive. Cognitive function in multiple domains, as required for driving, is likely to be best examined using well established neuropsychological tests and possibly driving simulators.

Advanced practice nursing: meeting the caregiving challenges for families of persons with frontotemporal dementia

Frontotemporal dementia (FTD), once thought to be a rare cause for dementia, is now acknowledged to be the most common presenile (before age 65 years) cause of dementia. Frontotemporal dementia is associated with profound changes in behavior, personality, emotions, and cognition. The purpose of this article is to describe 2 cases of patients with FTD to illustrate salient aspects of the caregiving experience. Issues faced by caregivers are organized into 6 categories: diagnosis, behavioral symptoms, function, communication, long-term management and care, and maintenance of the caregiver's emotional and physical health. Examples of interventions directed by advanced practice nurses are described. We suggest that management of FTD requires expertise as scientific advances and discoveries about FTD continually change the landscape of care.

Relation between frontal lobe symptoms and dementia severity within and across diagnostic dementia categories

BACKGROUND

To study frontal lobe symptoms in relation to dementia severity within and across diagnostic dementia categories, a cross-sectional analysis of behavioural data was performed.

METHODS

Patients with probable Alzheimer's disease (AD) (n = 456), frontotemporal dementia (FTD) (n = 55) and dementia with Lewy bodies (DLB) (n = 48) were included. Dementia severity and frontal lobe symptoms were assessed by means of the global deterioration scale and the Middelheim frontality score (MFS).

RESULTS

In FTD, no difference in MFS total scores between patients belonging to the mild and severe dementia stages was found (p = 0.828). In AD and DLB groups, significantly higher MFS total scores were found in severe dementia stages compared to mild dementia stages (p < 0.001). Comparing MFS total scores between FTD and AD patients, significantly higher scores were achieved in FTD patients, irrespective of dementia severity (p < 0.001).

CONCLUSIONS

In FTD patients, frontal lobe symptoms were severe in the mild, moderate and severe dementia stages although the nature of frontal lobe symptoms depended on disease severity. AD and DLB patients displayed more frontal lobe symptoms in the advanced disease stages as compared to disease onset, suggesting gradual frontal lobe involvement as the disease progresses. The nature of frontal lobe symptoms related to dementia severity differed between AD, DLB and FTD patients, suggesting different patterns of frontal lobe involvement. Last but not the least, these data point to the potential diagnostic value of behavioural observation of frontal lobe symptoms for (differential) dementia diagnosis, especially at the earliest disease stages. These findings await confirmation through a prospective, longitudinal study.

Cognition, language, and clinical pathological features of non-Alzheimer's dementias: an overview

There are many distinct forms of dementia whose pharmacological and behavioral management differ. Differential diagnosis among the dementia variants currently relies upon a weighted combination of genetic and protein biomarkers, neuroanatomical integrity, and behavior. Diagnostic specificity is complicated by a high degree of overlap in the initial presenting symptoms across dementia subtypes. For this reason, reliable markers are of considerable diagnostic value. Communication disorders have proven to be among the strongest predictors for discriminating among dementia subtypes. As such, speech-language pathologists may be poised to make an increasingly visible contribution to dementia diagnosis and its ongoing management. The value and durability of this potential contribution, however, demands an improved discipline-wide knowledge base about the unique features associated with different dementia variants. To this end we provide an overview of cognition, language, and clinical pathological features of four of the most common non-Alzheimer's dementias: frontotemporal dementia, vascular dementia, Lewy body disease dementia, and Parkinson's disease dementia.

LEARNING OUTCOMES

Readers will learn characteristics and distinguishing features of several non-Alzheimer's dementias, including Parkinson's disease dementia, frontotemporal dementia, vascular dementia, and Lewy body dementia. Readers will also learn to distinguish between several variants of frontotemporal dementia. Finally, readers will gain knowledge of the term primary progressive aphasia as it relates to the aforementioned dementia etiologies.

CHMP2B mutations are rare in French families with frontotemporal lobar degeneration

Two C-truncating CHMP2B (chromatin modifying protein 2B) mutations were recently found in Danish and Belgian families with autosomal dominant forms of frontotemporal lobar degeneration (FTLD). In addition, few CHMP2B missense mutations of uncertain pathogenic role were reported in several families with FTLD or FTLD associated with motoneuron disease (FTLD-MND). In order to determine the genetic contribution of CHMP2B mutations in FTLD and FTLD-MND families, we analyzed the CHMP2B gene in 198 French probands with familial FTLD and FTLD-MND. One CHMP2B missense variant was found in a proband with familial FTLD (0.8%). The pathogenic role of CHMP2B missense variants is unclear, however the pSer194Leu substitution, located in the C-terminal domain of the protein, was predicted to alter the stability of the protein by in silico analyses. We conclude that CHMP2B mutations represent a rare cause of familial FTLD and they are not implicated in familial FTLD-MND in French patients. The previously reported C-truncating CHMP2B mutations may be private to the Danish and Belgian pedigrees.

Morbid risk for schizophrenia in first-degree relatives of people with frontotemporal dementia

BACKGROUND

Familial co-occurrence of frontotemporal dementia and schizophrenia has never been investigated.

AIMS

To test the hypothesis that frontotemporal dementia and schizophrenia might have a common aetiology in some families in which both syndromes coexist (mixed families).

METHOD

The morbid risk for schizophrenia, calculated in first-degree relatives of 100 frontotemporal dementia probands, was compared with that calculated in first-degree relatives of 100 Alzheimer's disease probands. In mixed families, sequencing analysis of known frontotemporal dementia genes and detailed phenotype characterisation of individuals with frontotemporal dementia and schizophrenia were performed.

RESULTS

The morbid risk for schizophrenia was significantly higher in relatives of frontotemporal dementia probands (1.35, s.e. = 0.45) than in relatives of Alzheimer's disease probands (0.32, s.e. = 0.22). Ten mixed families were characterised. In three of them a frontotemporal dementia causal mutation was identified that was present in individuals with schizophrenia. Several specific clinical features were noted in people with schizophrenia and frontotemporal dementia in mixed families.

CONCLUSIONS

Co-occurrence of schizophrenia and frontotemporal dementia could indicate, in some families, a common aetiology for both conditions.