Frontotemporal lobar degeneration: demographic characteristics of 353 patients

Synaptopathy: presynaptic convergence in frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia and amyotrophic lateral sclerosis are common forms of neurodegenerative disease that share overlapping genetics and pathologies. Crucially, no significantly disease-modifying treatments are available for either disease. Identifying the earliest changes that initiate neuronal dysfunction is important for designing effective intervention therapeutics. The genes mutated in genetic forms of frontotemporal dementia and amyotrophic lateral sclerosis have diverse cellular functions, and multiple disease mechanisms have been proposed for both. Identification of a convergent disease mechanism in frontotemporal dementia and amyotrophic lateral sclerosis would focus research for a targetable pathway, which could potentially effectively treat all forms of frontotemporal dementia and amyotrophic lateral sclerosis (both familial and sporadic). Synaptopathies are diseases resulting from physiological dysfunction of synapses, and define the earliest stages in multiple neuronal diseases, with synapse loss a key feature in dementia. At the presynapse, the process of synaptic vesicle recruitment, fusion and recycling is necessary for activity-dependent neurotransmitter release. The unique distal location of the presynaptic terminal means the tight spatio-temporal control of presynaptic homeostasis is dependent on efficient local protein translation and degradation. Recently, numerous publications have shown that mutations associated with frontotemporal dementia and amyotrophic lateral sclerosis present with synaptopathy characterized by presynaptic dysfunction. This review will describe the complex local signalling and membrane trafficking events that occur at the presynapse to facilitate neurotransmission and will summarize recent publications linking frontotemporal dementia/amyotrophic lateral sclerosis genetic mutations to presynaptic function. This evidence indicates that presynaptic synaptopathy is an early and convergent event in frontotemporal dementia and amyotrophic lateral sclerosis and illustrates the need for further research in this area, to identify potential therapeutic targets with the ability to impact this convergent pathomechanism.

Identifying and Addressing Functional Communication Challenges in Patients With Behavioral Variant Frontotemporal Dementia

PURPOSE

We describe the communication challenges of four patients with a neurodegenerative disorder consistent with behavioral variant frontotemporal dementia (bvFTD), characterized by early behavioral and personality changes. By describing their clinical profiles, we identify common barriers to functional communication in this population and provide recommendations for how speech-language pathologists (SLPs) might contribute to minimizing them.

METHOD

Four patients with bvFTD were selected from a cohort of patients with progressive communication impairments. Three of them returned for at least one follow-up visit. Case histories are presented along with the results of comprehensive speech and language, neuropsychological, and neurological testing.

RESULTS

At the time of initial evaluation, patients were between the ages of 54 and 66 years and had been experiencing symptoms for 1.5-6 years. Consistent with their bvFTD diagnoses, all patients had prominent behavioral and personality changes that impacted communication. Patients 1 and 2 also had mild aphasia at enrollment, primarily characterized by anomia and loss of word meaning. Patients 3 and 4 both had apraxia of speech and moderate-to-severe aphasia at enrollment with prominent anomia and agrammatism. All four patients had impaired executive functioning and relative sparing of visuospatial skills; episodic memory was also impaired for Patients 2 and 4. Even though functional communication was progressively limited for all patients, none of them received regular support from an SLP.

CONCLUSIONS

This case series adds to a scant, but growing, literature demonstrating that patients with bvFTD have communication impairments. SLPs are uniquely positioned to identify barriers to functional communication and to provide tailored strategy training to the patients and their care partners over the course of their disease. Systematic evaluation of the efficacy of treatment in this population would be valuable.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25933762.

Case report: Assessing criminal responsibility and recidivism risk in the behavioral variant of frontotemporal dementia

Frontotemporal dementia (FTD) affects the frontal and temporal lobes of the brain, leading to personality changes, language impairments, and behavioral disturbances, including impulsivity and disinhibition. Assessing responsibility and recidivism risk in forensic evaluations is challenging due to the evolving nature of FTD. Despite limited literature, we present a case of a 45-year-old man with no prior legal or medical history, who committed criminal acts due to behavioral changes linked to the behavioral variant of frontotemporal dementia (bvFTD). Initial assessment found him irresponsible, with a non-evaluable risk of recidivism. Subsequent evaluation showed a low recidivism risk based on clinical evolution. We discuss these findings considering existing literature and Swiss jurisprudence.

Long-term, home-based transcranial direct current stimulation coupled with computerized cognitive training in frontotemporal dementia: A case report

We present the case of a 62-year-old woman with probable behavioral variant of frontotemporal dementia (bvFTD) with cognitive/language deficits who demonstrated improved performance on cognitive/language testing and in functional tasks following long-term, home-based transcranial direct current stimulation (tDCS) coupled with computerized cognitive training (CCT). The patient underwent home-based tDCS (anode on the left prefrontal cortex and cathode on the right homologue) for 46 sessions over 10 weeks along with CCT. On post-treatment testing, the patient improved by 3 points on the Mini-Mental State Exam (MMSE) (23 to 26). She also showed improvement on several cognitive/language tasks, such as immediate recall of single words and word pairs, total accurate words in sentence repetition, delayed recall, semantic processing, and sentence level comprehension. There was no decline in several other cognitive and language tasks. Family members reported subjective improvements in expressiveness, communication, and interaction with others as well as increased attention to grooming and style which contrasted with her pre-treatment condition. This report suggests that home-based tDCS combined with CCT for an extended period may slow decline, and improve cognitive/language performance and everyday function in FTD.

C9orf72 repeat expansions modify risk for secondary motor and cognitive-behavioral symptoms in behavioral-variant frontotemporal degeneration and amyotrophic lateral sclerosis

In behavioral-variant frontotemporal degeneration (bvFTD) and amyotrophic lateral sclerosis (ALS), the presence of secondary motor or cognitive-behavioral symptoms, respectively, is associated with shorter survival. However, factors influencing the risk and hazard of secondary symptom development remain largely unexplored. We performed a retrospective evaluation of the entire disease course of individuals with amyotrophic lateral sclerosis (n=172) and behavioral-variant frontotemporal degeneration (n=69). Only individuals who had neuropathological confirmation of a TDP-43 proteinopathy at autopsy or had a C9orf72 repeat expansion were included for analysis. We examined the odds and hazard of secondary symptom development and assessed whether they were modified by the presence of a C9orf72 repeat expansion or initial clinical syndrome. Binary logistic regression and Cox proportional hazard analyses revealed increased odds (OR=4.25 [1.97-9.14]; p<0.001) and an increased hazard (HR= 4.77 [2.33-9.79], p<0.001) for developing secondary symptoms in C9orf72 expansion carriers compared to noncarriers. Initial clinical syndrome (bvFTD or ALS), age at symptom onset, and sex were not associated with development of secondary motor or cognitive-behavioral symptoms. These findings highlight the need for clinician vigilance to detect the onset of secondary motor symptoms and cognitive-behavioral in patients carrying a C9orf72 repeat expansion, regardless of initial clinical syndrome, and may warrant dual referrals between cognitive and neuromuscular clinics in these cases.

Relationship between neuroimaging and cognition in frontotemporal dementia: An FDG-PET and structural MRI study

BACKGROUND AND PURPOSE

Frontotemporal dementia (FTD) is a clinically and pathologically heterogeneous neurodegenerative condition with a prevalence comparable to Alzheimer's disease for patients under 65 years of age. Limited studies have examined the association between cognition and neuroimaging in FTD using different imaging modalities.

METHODS

We examined the association of cognition using Montreal Cognitive Assessment (MoCA) with both gray matter (GM) volume and glucose metabolism using magnetic resonance imaging and fluorodeoxyglucose (FDG)-PET in 21 patients diagnosed with FTD. Standardized uptake value ratio (SUVR) using the brainstem as a reference region was the primary outcome measure for FDG-PET. Partial volume correction was applied to PET data to account for disease-related atrophy.

RESULTS

Significant positive associations were found between whole-cortex GM volume and MoCA scores (r = 0.46, p = .04). The association between whole-cortex FDG SUVR and MoCA scores was not significant (r = 0.37, p = .09). GM volumes of the frontal cortex (r = 0.54, p = .01), caudate (r = 0.62, p<.01), and insula (r = 0.57, p<.01) were also significantly correlated with MoCA, as were SUVR values of the insula (r = 0.51, p = .02), thalamus (r = 0.48, p = .03), and posterior cingulate cortex (PCC) (r = 0.47, p = .03).

CONCLUSIONS

Whole-cortex atrophy is associated with cognitive dysfunction, and this association is larger than for whole-cortex hypometabolism as measured with FDG-PET. At the regional level, focal atrophy and/or hypometabolism in the frontal cortex, insula, PCC, thalamus, and caudate seem to be important for the decline of cognitive function in FTD. Furthermore, these results highlight how functional and structural changes may not overlap and might contribute to cognitive dysfunction in FTD in different ways.

Examining the relation between bilingualism and age of symptom onset in frontotemporal dementia

Bilingualism is thought to confer advantages in executive functioning, thereby contributing to cognitive reserve and a later age of dementia symptom onset. While the relation between bilingualism and age of onset has been explored in Alzheimer's dementia, there are few studies examining bilingualism as a contributor to cognitive reserve in frontotemporal dementia (FTD). In line with previous findings, we hypothesized that bilinguals with behavioral variant FTD would be older at symptom onset compared to monolinguals, but that no such effect would be found in patients with nonfluent/agrammatic variant primary progressive aphasia (PPA) or semantic variant PPA. Contrary to our hypothesis, we found no significant difference in age at symptom onset between monolingual and bilingual speakers within any of the FTD variants, and there were no notable differences on neuropsychological measures. Overall, our results do not support a protective effect of bilingualism in patients with FTD-spectrum disease in a U.S. based cohort.

Fronto-striatal alterations correlate with apathy severity in behavioral variant frontotemporal dementia

Structural and functional changes in cortical and subcortical regions have been reported in behavioral variant frontotemporal dementia (bvFTD), however, a multimodal approach may provide deeper insights into the neural correlates of neuropsychiatric symptoms. In this multicenter study, we measured cortical thickness (CTh) and subcortical volumes to identify structural abnormalities in 37 bvFTD patients, and 37 age- and sex-matched healthy controls. For seed regions with significant structural changes, whole-brain functional connectivity (FC) was examined in a sub-cohort of N = 22 bvFTD and N = 22 matched control subjects to detect complementary alterations in brain network organization. To explore the functional significance of the observed structural and functional deviations, correlations with clinical and neuropsychological outcomes were tested where available. Significantly decreased CTh was observed in the bvFTD group in caudal middle frontal gyrus, left pars opercularis, bilateral superior frontal and bilateral middle temporal gyrus along with subcortical volume reductions in bilateral basal ganglia, thalamus, hippocampus, and amygdala. Resting-state functional magnetic resonance imaging showed decreased FC in bvFTD between: dorsal striatum and left caudal middle frontal gyrus; putamen and fronto-parietal regions; pallidum and cerebellum. Conversely, bvFTD showed increased FC between: left middle temporal gyrus and paracingulate gyrus; caudate nucleus and insula; amygdala and parahippocampal gyrus. Additionally, cortical thickness in caudal, lateral and superior frontal regions as well as caudate nucleus volume correlated negatively with apathy severity scores of the Neuropsychiatry Inventory Questionnaire. In conclusion, multimodal structural and functional imaging indicates that fronto-striatal regions have a considerable influence on the severity of apathy in bvFTD.

Relationship between Neuroimaging and Cognition in Frontotemporal Dementia: A [18 F]FDG PET and Structural MRI Study

Background

Frontotemporal dementia (FTD) is a clinically and pathologically heterogeneous condition with a prevalence comparable to Alzheimer's Disease for patients under sixty-five years of age. Gray matter (GM) atrophy and glucose hypometabolism are important biomarkers for the diagnosis and evaluation of disease progression in FTD. However, limited studies have systematically examined the association between cognition and neuroimaging in FTD using different imaging modalities in the same patient group.

Methods

We examined the association of cognition using Montreal Cognitive Assessment (MoCA) with both GM volume and glucose metabolism using structural magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose positron emission tomography scanning ([18F]FDG PET) in 21 patients diagnosed with FTD. Standardized uptake value ratio (SUVR) using the brainstem as a reference region was the primary outcome measure for [18F]FDG PET. Partial volume correction was applied to PET data to account for disease-related atrophy.

Results

Significant positive associations were found between whole-cortex GM volume and MoCA scores (r = 0.461, p = 0.035). The association between whole-cortex [18F]FDG SUVR and MoCA scores was not Significant (r = 0.374, p = 0.094). GM volumes of the frontal cortex (r = 0.540, p = 0.011), caudate (r = 0.616, p = 0.002), and insula (r = 0.568, p = 0.007) were also Significantly correlated with MoCA, as were SUVR values of the insula (r = 0.508, p = 0.018), thalamus (r = 0.478, p = 0.028), and posterior cingulate cortex (PCC) (r = 0.472, p = 0.030).

Discussion

Whole-cortex atrophy is associated with cognitive dysfunction, and this effect is larger than for cortical hypometabolism as measured with [18F]FDG PET. At the regional level, focal atrophy and/or hypometabolism in the frontal lobe, insula, PCC, thalamus, and caudate seem to imply the importance of these regions for the decline of cognitive function in FTD. Furthermore, these results highlight how functional and structural changes may not overlap and might contribute to cognitive dysfunction in FTD in different ways. Our findings provide insight into the relationships between structural, metabolic, and cognitive changes due to FTD.

Psychological and social impacts of frontotemporal dementia on caregivers and family members - A systematic review

INTRODUCTION

Frontotemporal dementia (FTD) may impose substantial psychological and social burdens on caregivers and family members that are unique from other forms of dementia due to its distinctive clinical characteristics. This systematic review investigated these impacts on caregivers and family members.

METHODS

A systematic search was conducted in the PubMed, Cochrane Library and Embase databases for relevant articles published from database inception to 23 March 2023. The methodological quality of the articles was evaluated using a checklist.

RESULTS

Thirty-six articles (six qualitative and thirty quantitative), including 5129 participants, were included in this review. Like other forms of dementia, FTD caregivers had significant caregiver burden levels and psychological impacts. Caregiver burden was associated with behavioural symptoms (e.g., apathy and disinhibition) and motor symptoms. The costs of caring for a patient with FTD were found to be higher than those for Alzheimer's disease. FTD patients often face challenges in obtaining a correct diagnosis and experience significant delays and multiple misdiagnoses. Healthcare professionals may also be less familiar with FTD than with Alzheimer's, leading to delayed diagnosis. This can cause considerable stress and deprive patients and caregivers of early intervention.

CONCLUSION

FTD is associated with significant costs and caregiver burden levels, and the difficulties faced by caregivers and family members can be unique and challenging in different aspects when compared to other forms of dementia. Better education about FTD for family members and healthcare professionals is required to improve the quality of life for both patients and caregivers, and more support needs to be provided at all stages of the disease.

Characterization of Progranulin Gene Mutations in Portuguese Patients with Frontotemporal Dementia

In Portugal, heterozygous loss-of-function mutations in the progranulin (GRN) gene account for approximately half of the genetic mediated forms of frontotemporal dementia (FTD). GRN mutations reported thus far cause FTD through a haploinsufficiency disease mechanism. Herein, we aim to unveil the GRN mutation spectrum, investigated in 257 FTD patients and 19 family members from the central/north region of Portugal using sequencing methods. Seven different pathogenic variants were identified in 46 subjects including 40 patients (16%) and 6 relatives (32%). bvFTD was the most common clinical presentation among the GRN mutation patients, who showed a global pattern of moderate-to-severe frontotemporoparietal deficits in the neuropsychological evaluation. Interestingly, two mutations were novel (p.Thr238Profs*18, p.Leu354Profs*16), and five were previously described, although three of them only in the Portuguese population, suggesting a population-specific GRN mutational spectrum. The subjects harboring a GRN mutation showed a significant reduction in serum PGRN levels, supporting the pathogenic nature of these variants. This work broadens the mutation spectrum of GRN and the identification of the underlying GRN mutations provided an accurate genetic counselling and allowed the enrolment of subjects with GRN mutations (both asymptomatic and symptomatic) in ongoing clinical trials, which is essential to test new drugs for the disease.

Semantic dementia in Arabic: An assessment of Arabic word reading within sentences

INTRODUCTION

Language impairments have not yet been fully explored in native Arabic speakers with semantic dementia (SD). The aim of this paper is to describe the impairments in language in two Saudi Arabians with SD and to determine if their word reading within a sentence context would result in incorrect responses.

METHODS

Two patients with semantic dementia (one with right > left and the other with left > right temporal involvement) underwent a reading assessment in Arabic. Patients were asked to read a series of words within a sentence context in which the correct reading of the word was dependent on the context of the sentence. Thirty-four sentences were designed in which 17 Arabic homographs were used. The same homograph would occur in two separate sentences, in which the pronunciation and meaning would differ between sentences. Patients were also assessed using five other sentences that contained irregular pronouns of high frequency. Eighteen healthy controls were used as reference.

RESULTS

Both patients made errors in reading the target Arabic homographs; this was more pronounced in the patient with left > right variant of SD. The patient with right > left variant of SD also suffered from prosopagnosia.

CONCLUSION

Correct reading of Arabic words within the sentence context may be impaired from semantic language impairments in semantic dementia. The role of comprehension in the correct reading of words in Arabic sentences is important.

Correlates of Functional Impairment in Patients with the Behavioral Variant of Frontotemporal Dementia: A PRISMA-Compliant Systematic Review

The behavioral variant of frontotemporal dementia (bvFTD) has a devastating effect on multiple domains of daily living. The purpose of this PRISMA-compliant systematic review is to summarize the most important factors associated with functional impairment in this clinical group by critically analyzing the existing literature spanning the period from 2000 to 2023. To be included in the review, a study had to investigate any kind of correlates of functional status in bvFTD patients, using a previously validated instrument of functional assessment. Out of 40 articles assessed for eligibility, 18 met the inclusion criteria. The anatomical pattern of cerebral atrophy at baseline appeared to be the strongest predictor of the rate of functional decline over time, with the frontal-dominant anatomical subtype being associated with a faster rate of functional impairment. Additionally, executive dysfunction as well as apathy appeared to contribute significantly to functional disability in bvFTD patients. A comparative examination of bvFTD in relation to other clinical subtypes of FTD and other types of dementia in general suggests that it is the predominant atrophy of the frontal lobes along with the subsequent unique combination of cognitive and neuropsychiatric manifestations that account for the pronounced functional limitations observed in these individuals, even from the early stages of the disease.

Sex influences clinical phenotype in valosin-containing protein mutations: A case family report and systematic literature review

OBJECTIVE

Mutations in the valosin-containing protein (VCP) gene cause autosomal dominant multisystem proteinopathy 1 (MSP1), characterized by a variable combination of inclusion body myopathy (IBM), Paget's disease of bone (PDB), and frontotemporal dementia (FTD). Here we report a novel VCP missense mutations in an Italian family with FTD as the prevalent manifestation and compare our results with those described in the literature.

METHODS

We described the clinical, molecular, and imaging data of the studied family. We also conducted a systematic literature search with the aim of comparing our findings with previously reported VCP-related phenotypes.

RESULTS

A novel heterozygous VCP missense mutation (c 0.473 T > C/p.Met158Thr) was found in all the affected family members. The proband is a 69-year-old man affected by progressive muscle weakness since the age of 49. Muscle MRI showed patchy fatty infiltration in most muscles, and STIR sequences revealed an unusual signal increase in distal leg muscles. At age 65, he presented a cognitive disorder suggestive of behavioral variant FTD. A bone scintigraphy also revealed PDB. The patient's mother, his maternal aunt and her daughter had died following a history of cognitive deterioration consistent with FTD; the mother also had PDB. No relatives had any muscular impairments. Reviewing the literature data, we observed a different sex distribution of VCP-related phenotypes, being FTD prevalence higher among women as compared to men (51.2 % vs 31.2 %) and IBM prevalence higher among men as compared to women (92.1 % vs 72.8 %).

DISCUSSION

This study broadened our clinical, genetic, and imaging knowledge of VCP-related disorders.

How Many Alzheimer-Perusini's Atypical Forms Do We Still Have to Discover?

Alzheimer-Perusini's (AD) disease represents the most spread dementia around the world and constitutes a serious problem for public health. It was first described by the two physicians from whom it took its name. Nowadays, we have extensively expanded our knowledge about this disease. Starting from a merely clinical and histopathologic description, we have now reached better molecular comprehension. For instance, we passed from an old conceptualization of the disease based on plaques and tangles to a more modern vision of mixed proteinopathy in a one-to-one relationship with an alteration of specific glial and neuronal phenotypes. However, no disease-modifying therapies are yet available. It is likely that the only way to find a few "magic bullets" is to deepen this aspect more and more until we are able to draw up specific molecular profiles for single AD cases. This review reports the most recent classifications of AD atypical variants in order to summarize all the clinical evidence using several discrimina (for example, post mortem neurofibrillary tangle density, cerebral atrophy, or FDG-PET studies). The better defined four atypical forms are posterior cortical atrophy (PCA), logopenic variant of primary progressive aphasia (LvPPA), behavioral/dysexecutive variant and AD with corticobasal degeneration (CBS). Moreover, we discuss the usefulness of such classifications before outlining the molecular-genetic aspects focusing on microglial activity or, more generally, immune system control of neuroinflammation and neurodegeneration.

Distinguishing Semantic Variant Primary Progressive Aphasia from Alzheimer’s Disease

The differentiation of semantic variant primary progressive aphasia from dementia and Alzheimer’s disease can be difficult, particularly when the semantic anomia is pronounced. This report describes a patient who presented with complaints of memory loss and proved to have prominent semantic loss of all types of nouns, common and proper, concrete and abstract, yet continued to live independently and maintain his activities of daily living. The evaluation was consistent for semantic variant primary progressive aphasia with degradation of semantic knowledge and focal anterior temporal atrophy and hypometabolism. This report summarizes the literature and discusses the differential diagnosis of this disorder from Alzheimer’s disease and related dementias.

Extremely Early-Onset Frontotemporal Dementia: A Case Report and Literature Review

BACKGROUND

In most cases, the onset of frontotemporal dementia (FTD) occurs between the ages of 45 and 65 years. However, some patients experience an extremely early disease onset.

OBJECTIVE

To investigate the clinical, genetic, and pathological features of extremely early-onset FTD.

METHODS

We conducted a comprehensive clinical, genetic, and neuropathological analysis of a 25-year-old patient experiencing the onset of behavioral variant frontotemporal dementia (bvFTD). In addition, we conducted a literature review and summarized the clinical, genetic, and pathological features of patients with FTD with onset age≤25 years.

RESULTS

The patient was diagnosed with bvFTD; however, there was no family history of FTD, no positive genetic test results and no deposition of TDP43, tau, ubiquitin, and synuclein in the brain. Literature screening identified 18 patients with onset age ≤25 years with FTD. The youngest patient was 14 years of age. Most patients (8/14) had a positive family history. The most common clinical phenotype was the behavioral variant (12/14). Genetic results were reported for 11 patients; the most common pathogenic gene was MAPT (10/12), with four cases of G389 R, two cases of P301 S, one case of G335 S, one case of G335A, one case of G335 V, and one case of L315 R. Pathological results were reported for 13 patients; the most common pathological subtype was tau (8/13).

CONCLUSION

FTD can start at an extremely early age. The most common phenotype of extremely early onset FTD was the behavioral variant, the most common pathogenic gene was MAPT, and the most common neuropathological type was tau.

Differences in Motor Features of C9orf72, MAPT, or GRN Variant Carriers With Familial Frontotemporal Lobar Degeneration

BACKGROUND AND OBJECTIVES

Familial frontotemporal lobar degeneration (f-FTLD) is a phenotypically heterogeneous spectrum of neurodegenerative disorders most often caused by variants within chromosome 9 open reading frame 72 (C9orf72), microtubule-associated protein tau (MAPT), or granulin (GRN). The phenotypic association with each of these genes is incompletely understood. We hypothesized that the frequency of specific clinical features would correspond with different genes.

METHODS

We screened the Advancing Research and Treatment in Frontotemporal Lobar Degeneration (ARTFL)/Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects (LEFFTDS)/ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration Consortium for symptomatic carriers of pathogenic variants in C9orf72, MAPT, or GRN. We assessed for clinical differences among these 3 groups based on data recorded as part of a detailed neurologic examination, the Progressive Supranuclear Palsy Rating Scale, Progressive Supranuclear Palsy-Quality of Life Rating Scale, Unified Parkinson's Disease Rating Scale Part III (motor items), and the Amyotrophic Lateral Sclerosis Functional Rating Scale, revised version. Data were analyzed using Kruskal-Wallis and Wilcoxon rank-sum tests and Fisher exact test.

RESULTS

We identified 184 symptomatic participants who had a single pathogenic variant in C9orf72 (n = 88), MAPT (n = 53), or GRN (n = 43). Motor symptom age at onset was earliest in the MAPT participants followed by C9orf72, whereas the GRN pathogenic variant carriers developed symptoms later. C9orf72 participants more often had fasciculations, muscle atrophy, and weakness, whereas parkinsonism was less frequent. Vertical oculomotor abnormalities were more common in the MAPT cohort, whereas apraxia and focal limb dystonia occurred more often in participants with GRN variants.

DISCUSSION

We present a large comparative study of motor features in C9orf72, MAPT, and GRN pathogenic variant carriers with symptomatic f-FTLD. Our findings demonstrate characteristic phenotypic differences corresponding with specific gene variants that increase our understanding of the genotype-phenotype relationship in this complex spectrum of neurodegenerative disorders.

TRIAL REGISTRATION INFORMATION

NCT02365922, NCT02372773, and NCT04363684.

Radiological assessment of dementia: the Italian inter-society consensus for a practical and clinically oriented guide to image acquisition, evaluation, and reporting

Background

Radiological evaluation of dementia is expected to increase more and more in routine practice due to both the primary role of neuroimaging in the diagnostic pathway and the increasing incidence of the disease. Despite this, radiologists often do not follow a disease-oriented approach to image interpretation, for several reasons, leading to reports of limited value to clinicians. In our work, through an intersocietal consensus on the main mandatory knowledge about dementia, we proposed a disease-oriented protocol to optimize and standardize the acquisition/evaluation/interpretation and reporting of radiological images. Our main purpose is to provide a practical guideline for the radiologist to help increase the effectiveness of interdisciplinary dialogue and diagnostic accuracy in daily practice.

Results

We defined key clinical and imaging features of the dementias (A), recommended MRI protocol (B), proposed a disease-oriented imaging evaluation and interpretation (C) and report (D) with a glimpse to future avenues (E). The proposed radiological practice is to systematically evaluate and score atrophy, white matter changes, microbleeds, small vessel disease, consider the use of quantitative measures using commercial software tools critically, and adopt a structured disease-oriented report.

Summary statement

In the expanding field of cognitive disorders, the only effective assessment approach is the standardized disease-oriented one, which includes a multidisciplinary integration of the clinical picture, MRI, CSF and blood biomarkers and nuclear medicine.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11547-022-01534-0.

Sex influences clinical phenotype in frontotemporal dementia

Introduction

Frontotemporal dementia (FTD) encompasses a wide spectrum of genetic, clinical, and histological findings. Sex is emerging as a potential biological variable influencing FTD heterogeneity; however, only a few studies explored this issue with nonconclusive results.

Objective

To estimate the role of sex in a single-center large cohort of FTD patients.

Methods

Five hundred thirty-one FTD patients were consecutively enrolled. Demographic, clinical, and neuropsychological features, survival rate, and serum neurofilament light (NfL) concentration were determined and compared between sex.

Results

The behavioral variant of FTD was more common in men, whereas primary progressive aphasia was overrepresented in women (p < 0.001). While global cognitive impairment was comparable, females had a more severe cognitive impairment, namely in Trail Making Test parts A and B (p = 0.003), semantic fluency (p = 0.03), Short Story Recall Test (p = 0.003), and the copy of Rey Complex Figure (p = 0.005). On the other hand, men exhibited more personality/behavioral symptoms (Frontal Behavior Inventory [FBI] AB, p = 0.003), displaying higher scores in positive FBI subscales (FBI B, p < 0.001). In particular, apathy (p = 0.02), irritability (p = 0.006), poor judgment (p = 0.033), aggressivity (p = 0.008), and hypersexuality (p = 0.006) were more common in men, after correction for disease severity. NfL concentration and survival were not statistically different between men and women (p = 0.167 and p = 0.645, respectively).

Discussion

The present study demonstrated that sex is a potential factor in determining FTD phenotype, while it does not influence survival. Although the pathophysiological contribution of sex in neurodegeneration is not well characterized yet, our findings highlight its role as deserving biological variable in FTD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-022-06185-7.

TMEM106B Acts as a Modifier of Cognitive and Motor Functions in Amyotrophic Lateral Sclerosis

The transmembrane protein 106B (TMEM106B) gene is a susceptibility factor and disease modifier of frontotemporal dementia, but few studies have investigated its role in amyotrophic lateral sclerosis. The aim of this work was to assess the impact of the TMEM106B rs1990622 (A–major risk allele; G–minor allele) on phenotypic variability of 865 patients with amyotrophic lateral sclerosis. Demographic and clinical features were compared according to genotypes by additive, dominant, and recessive genetic models. Bulbar onset was overrepresented among carriers of the AA risk genotype, together with enhanced upper motor neuron involvement and poorer functional status in patients harboring at least one major risk allele (A). In a subset of 195 patients, we found that the homozygotes for the minor allele (GG) showed lower scores at the Edinburgh Cognitive and Behavioral Amyotrophic Lateral Sclerosis Screen, indicating a more severe cognitive impairment, mainly involving the amyotrophic lateral sclerosis-specific cognitive functions and memory. Moreover, lower motor neuron burden predominated among patients with at least one minor allele (G). Overall, we found that TMEM106B is a disease modifier of amyotrophic lateral sclerosis, whose phenotypic effects encompass both sites of onset and functional status (major risk allele), motor functions (both major risk and minor alleles), and cognition (minor allele).

Sex and gender differences in dementia

The dementia landscape has undergone a striking paradigm shift. The advances in understanding of neurodegeneration and proteinopathies has changed our approach to patients with cognitive impairment. Firstly, it has recently been shown that the various proteinopathies that are the cause of the dementia begin to build up long before the appearance of any obvious symptoms. This has cemented the idea that there is an urgency in diagnosis as it occurs very late in the pathophysiology of these diseases. Secondly, that accurate diagnosis is required to deliver targeted therapies, that is precision medicine. With this latter point, the realization that various factors of a person need to be considered as they may impact the presentation and progression of disease has risen to the forefront. Two of these factors aside from race and age are biological sex and gender (social construct), as both can have tremendous impact on manifestation of disease. This chapter will cover what is known and remains to be known on the interaction of sex and gender with some of the major causes of dementia.

Locus Coeruleus Degeneration Differs Between Frontotemporal Lobar Degeneration Subtypes

Background:

There are few studies on the locus coeruleus (LC) in frontotemporal lobar degeneration (FTLD) and the potential differences in the LC related to the underlying proteinopathy.

Objective:

The aim of this study was to investigate the LC in FTLD subgroups.

Methods:

Neuropathological cases diagnosed with FTLD were included. The subgroups consisted of FTLD with tau, transactive response DNA-binding protein 43 (TDP) and fused in sarcoma (FUS). Micro- and macroscopical degeneration of the LC were assessed with respect to the number of neurons and the degree of depigmentation. A group of cognitively healthy subjects and a group with vascular cognitive impairment (VCI) served as comparison groups.

Results:

A total of 85 FTLD cases were included, of which 44 had FTLD-TDP, 38 had FTLD-tau, and three had FTLD-FUS. The groups were compared with 25 VCI cases and 41 cognitively healthy control cases (N = 151 for the entire study). All FTLD groups had a statistically higher microscopical degeneration of the LC compared to the controls, but the FTLD-tau group had greater micro- and macroscopical degeneration than the FTLD-TDP group. Age correlated positively with the LC score in the FTLD-tau group, but not in the FTLD-TDP group.

Conclusion:

A greater microscopical degeneration of the LC was observed in all FTLD cases compared to healthy controls and those with VCI. The LC degeneration was more severe in FTLD-tau than in FTLD-TDP. The macroscopically differential degeneration of the LC in FTLD subgroups may facilitate differential diagnostics, potentially with imaging.

Right Temporal Lobe Variant of Frontotemporal Dementia: Systematic Review

Frontotemporal dementia corresponds to a heterogenous group of syndromes characterized by progressive changes in behavior and/or language. Approximately 30% of patients with primary progressive aphasia, semantic variant (semantic dementia), present with atrophy in the right cerebral hemisphere, in a rare clinical condition called right temporal variant of frontotemporal dementia (rtvFTD). The objective of the study is to present the main demographic, clinical, neuropsychological, neuroimaging, and pathologic characteristics of rtvFTD patients. A systematic review of the literature was carried out in the PubMed, LILACS, and SCIELO databases between January and March 2022. After the evaluation process, 41 articles were selected, published between 1993 and 2021. We found that rtvFTD presents with severe and progressive prosopagnosia (related to anterior temporal lobe injury) associated with behavioral symptoms-desinibition (51%), apathy (39%), obsessive-compulsive symptoms (37%), changes in eating habits (33%), and depression (28%), which is different from semantic dementia. The most common pathologic pattern is TDP-43, type C. This field of knowledge has few studies (mainly reports and case series) and heterogenous nomenclature, which is a limitation. A multinational longitudinal registry of people with rtvFTD, with standardized assessment and description of symptoms, is necessary to elucidate the characteristics of this entity.

The Role of Graph Theory in Evaluating Brain Network Alterations in Frontotemporal Dementia

Frontotemporal dementia (FTD) is a spectrum of clinical syndromes that affects personality, behavior, language, and cognition. The current diagnostic criteria recognize three main clinical subtypes: the behavioral variant of FTD (bvFTD), the semantic variant of primary progressive aphasia (svPPA), and the non-fluent/agrammatic variant of PPA (nfvPPA). Patients with FTD display heterogeneous clinical and neuropsychological features that highly overlap with those presented by psychiatric syndromes and other types of dementia. Moreover, up to now there are no reliable disease biomarkers, which makes the diagnosis of FTD particularly challenging. To overcome this issue, different studies have adopted metrics derived from magnetic resonance imaging (MRI) to characterize structural and functional brain abnormalities. Within this field, a growing body of scientific literature has shown that graph theory analysis applied to MRI data displays unique potentialities in unveiling brain network abnormalities of FTD subtypes. Here, we provide a critical overview of studies that adopted graph theory to examine the topological changes of large-scale brain networks in FTD. Moreover, we also discuss the possible role of information arising from brain network organization in the diagnostic algorithm of FTD-spectrum disorders and in investigating the neural correlates of clinical symptoms and cognitive deficits experienced by patients.

Neuropsychiatric or Behavioral and Psychological Symptoms of Dementia (BPSD): Focus on Prevalence and Natural History in Alzheimer's Disease and Frontotemporal Dementia

Neuropsychiatric or behavioral and psychological symptoms of dementia (BPSD) represent a heterogeneous group of non-cognitive symptoms that are virtually present in all patients during the course of their disease. The aim of this study is to examine the prevalence and natural history of BPSD in a large cohort of patients with behavioral variant of frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) in three stages: (i) pre-T0 (before the onset of the disease); (ii) T0 or manifested disease (from the onset to 5 years); (iii) T1 or advanced (from 5 years onwards). Six hundred seventy-four clinical records of patients with bvFTD and 1925 with AD, from 2006 to 2018, were studied. Symptoms have been extracted from Neuropsychiatric Inventory (NPI) and from a checklist of BPSD for all periods observed. In our population, BPSD affect up to 90% of all dementia subjects over the course of their illness. BPSD profiles of the two dementia groups were similar but not identical. The most represented symptoms were apathy, irritability/affective lability, and agitation/aggression. Considering the order of appearance of neuropsychiatric symptoms in AD and bvFTD, mood disorders (depression, anxiety) come first than the other BPSD, with the same prevalence. This means that they could be an important “red flag” in detection of dementia. With the increase of disease severity, aberrant motor behavior and wandering were significantly more present in both groups. Differences between BPSD in AD and bvFTD resulted only in prevalence: Systematically, in bvFTD, all the symptoms were more represented than in AD, except for hallucinations, depression, anxiety, and irritability. Given their high frequency and impact on management and overall health care resources, BPSD should not be underestimated and considered as an additional important diagnostic and therapeutic target both in patients with AD and bvFTD.

The tauopathies: Neuroimaging characteristics and emerging experimental therapies

The tauopathies are a heterogeneous group of neurodegenerative disorders in which the prevailing underlying disease process is intracellular deposition of abnormal misfolded tau protein. Diseases often categorized as tauopathies include progressive supranuclear palsy, chronic traumatic encephalopathy, corticobasal degeneration, and frontotemporal lobar degeneration. Tauopathies can be classified through clinical assessment, imaging findings, histologic validation, or molecular biomarkers tied to the underlying disease mechanism. Many tauopathies vary in their clinical presentation and overlap substantially in presentation, making clinical diagnosis of a specific primary tauopathy difficult. Anatomic imaging findings are also rarely specific to a single tauopathy, and when present may not manifest until well after the point at which therapy may be most impactful. Molecular biomarkers hold the most promise for patient care and form a platform upon which emerging diagnostic and therapeutic applications could be developed. One of the most exciting developments utilizing these molecular biomarkers for assessment of tau deposition within the brain is tau‐PET imaging utilizing novel ligands that specifically target tau protein. This review will discuss the background, significance, and clinical presentation of each tauopathy with additional attention to the pathologic mechanisms at the protein level. The imaging characteristics will be outlined with select examples of emerging imaging techniques. Finally, current treatment options and emerging therapies will be discussed. This is by no means a comprehensive review of the literature but is instead intended for the practicing radiologist as an overview of a rapidly evolving topic.

Frontotemporal lobar degeneration with TAR DNA-binding protein 43 (TDP-43): its journey of more than 100 years

Frontotemporal lobar degeneration (FTLD) with TDP-43-immunoreactive inclusions (FTLD-TDP) is a neurodegenerative disease associated with clinical, genetic, and neuropathological heterogeneity. An association between TDP-43, FTLD and amyotrophic lateral sclerosis (ALS) was first described in 2006. However, a century before immunohistochemistry existed, atypical dementias displaying behavioral, language and/or pyramidal symptoms and showing non-specific FTLD with superficial cortical neuronal loss, gliosis and spongiosis were often confused with Alzheimer's or Pick's disease. Initially this pathology was termed dementia lacking distinctive histopathology (DLDH), but this was later renamed when ubiquitinated inclusions originally found in ALS were also discovered in (DLDH), thus warranting a recategorization as FTLD-U (ubiquitin). Finally, the ubiquitinated protein was identified as TDP-43, which aggregates in cortical, subcortical, limbic and brainstem neurons and glial cells. The topography and morphology of TDP-43 inclusions associate with specific clinical syndromes and genetic mutations which implies different pathomechanisms that are yet to be discovered; hence, the TDP-43 journey has actually just begun. In this review, we describe how FTLD-TDP was established and defined clinically and neuropathologically throughout the past century.

Site-specific mitochondrial dysfunction in neurodegeneration

Mitochondria are essential for neuronal survival and mitochondrial dysfunction is a hallmark of neurodegeneration. The loss in mitochondrial energy production, oxidative stress, and changes in calcium handling are associated with neurodegenerative diseases; however, different sites and types of mitochondrial dysfunction are linked to distinct neuropathologies. Understanding the causal or correlative relationship between changes in mitochondria and neuropathology will lead to new therapeutic strategies. Here, we summarize the evidence of site-specific mitochondrial dysfunction and mitochondrial-related clinical trials for neurodegenerative diseases. We further discuss potential therapeutic approaches, such as mitochondrial transplantation, restoration of mitochondrial function, and pharmacological alleviation of mitochondrial dysfunction.

The converging roles of sequestosome-1/p62 in the molecular pathways of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD)

Investigations into the pathogenetic mechanisms underlying amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have provided significant insight into the disease. At the cellular level, ALS and FTD are classified as proteinopathies, which is motor neuron degeneration and death characterized by pathological protein aggregates or dysregulated proteostasis. At both the clinical and molecular level there are common signaling pathways dysregulated across the ALS and FTD spectrum (ALS/FTD). Sequestosome-1/p62 is a multifunctional scaffold protein with roles in several signaling pathways including proteostasis, protein degradation via the ubiquitin proteasome system and autophagy, the antioxidant response, inflammatory response, and apoptosis. Notably these pathways are dysregulated in ALS and FTD. Mutations in the functional domains of p62 provide links to the pathogenetic mechanisms of p62 and dyshomeostasis of p62 levels is noted in several types of ALS and FTD. We present here that the dysregulated ALS and FTD signaling pathways are linked, with p62 converging the molecular mechanisms. This review summarizes the current literature on the complex role of p62 in the pathogenesis across the ALS/FTD spectrum. The focus is on the underlying convergent molecular mechanisms of ALS and FTD-associated proteins and pathways that dysregulate p62 levels or are dysregulated by p62, with emphasis on how p62 is implicated across the ALS/FTD spectrum.

Frontotemporal dementia: A unique window on the functional role of the temporal lobes

Frontotemporal dementia (FTD) is an umbrella term covering a plethora of progressive changes in executive functions, motor abilities, behavior, and/or language. Different clinical syndromes have been described in relation to localized atrophy, informing on the functional networks that underlie these specific cognitive, emotional, and behavioral processes. These functional declines are linked with the underlying neurodegeneration of frontal and/or temporal lobes due to diverse molecular pathologies. Initially, the accumulation of misfolded proteins targets specifically susceptible cell assemblies, leading to relatively focal neurodegeneration that later spreads throughout large-scale cortical networks. Here, we discuss the most recent clinical, neuropathological, imaging, and genetics findings in FTD-spectrum syndromes affecting the temporal lobe. We focus on the semantic variant of primary progressive aphasia and its mirror image, the right temporal variant of FTD. Incipient focal atrophy of the left anterior temporal lobe (ATL) manifests with predominant naming, word comprehension, reading, and object semantic deficits, while cases of predominantly right ATL atrophy present with impairments of socioemotional, nonverbal semantic, and person-specific knowledge. Overall, the observations in FTD allow for crucial clinical-anatomic inferences, shedding light on the role of the temporal lobes in both cognition and complex behaviors. The concerted activity of both ATLs is critical to ensure that percepts are translated into concepts, yet important hemispheric differences should be acknowledged. On one hand, the left ATL attributes meaning to linguistic, external stimuli, thus supporting goal-oriented, action-related behaviors (e.g., integrating sounds and letters into words). On the other hand, the right ATL assigns meaning to emotional, visceral stimuli, thus guiding socially relevant behaviors (e.g., integrating body sensations into feelings of familiarity).

Sex is a defining feature of neuroimaging phenotypes in major brain disorders

Sex is a biological variable that contributes to individual variability in brain structure and behavior. Neuroimaging studies of population-based samples have identified normative differences in brain structure between males and females, many of which are exacerbated in psychiatric and neurological conditions. Still, sex differences in MRI outcomes are understudied, particularly in clinical samples with known sex differences in disease risk, prevalence, and expression of clinical symptoms. Here we review the existing literature on sex differences in adult brain structure in normative samples and in 14 distinct psychiatric and neurological disorders. We discuss commonalities and sources of variance in study designs, analysis procedures, disease subtype effects, and the impact of these factors on MRI interpretation. Lastly, we identify key problems in the neuroimaging literature on sex differences and offer potential recommendations to address current barriers and optimize rigor and reproducibility. In particular, we emphasize the importance of large-scale neuroimaging initiatives such as the Enhancing NeuroImaging Genetics through Meta-Analyses consortium, the UK Biobank, Human Connectome Project, and others to provide unprecedented power to evaluate sex-specific phenotypes in major brain diseases.

Neuroinflammation in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia and the Interest of Induced Pluripotent Stem Cells to Study Immune Cells Interactions With Neurons

Inflammation is a shared hallmark between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). For long, studies were conducted on tissues of post-mortem patients and neuroinflammation was thought to be only bystander result of the disease with the immune system reacting to dying neurons. In the last two decades, thanks to improving technologies, the identification of causal genes and the development of new tools and models, the involvement of inflammation has emerged as a potential driver of the diseases and evolved as a new area of intense research. In this review, we present the current knowledge about neuroinflammation in ALS, ALS-FTD, and FTD patients and animal models and we discuss reasons of failures linked to therapeutic trials with immunomodulator drugs. Then we present the induced pluripotent stem cell (iPSC) technology and its interest as a new tool to have a better immunopathological comprehension of both diseases in a human context. The iPSC technology giving the unique opportunity to study cells across differentiation and maturation times, brings the hope to shed light on the different mechanisms linking neurodegeneration and activation of the immune system. Protocols available to differentiate iPSC into different immune cell types are presented. Finally, we discuss the interest in studying monocultures of iPS-derived immune cells, co-cultures with neurons and 3D cultures with different cell types, as more integrated cellular approaches. The hope is that the future work with human iPS-derived cells helps not only to identify disease-specific defects in the different cell types but also to decipher the synergistic effects between neurons and immune cells. These new cellular tools could help to find new therapeutic approaches for all patients with ALS, ALS-FTD, and FTD.

Risk factors to mortality and causes of death in frontotemporal dementia: An Australian perspective

OBJECTIVES

Frontotemporal dementia (FTD) is a common cause of dementia in younger people. There is less information known about risk factors to mortality such as the type of symptom onset and cause of death in this group.

METHOD

This was a retrospective file review of inpatients with FTD admitted to a tertiary neuropsychiatry unit located in Australia from 1992 to 2014. Mortality information including linkage of names and causes of death were obtained from the Australian Institute Health and Welfare National Death Index.

RESULTS

One hundred inpatients were diagnosed with FTD, including behavioural-variant, language-variant FTDs and FTD-motor neuron disease (FTD-MND). Mean age was 52.8 years (SD = 10, range 31-76 years). Sixty-seven of them had died at linkage. Median survival of the sample was 10.5 years and FTD-MND had the shortest survival, 3.5 years. Increasing age of onset and FTD-MND were found to be significant predictors of association for mortality. Compared to the general population, having a FTD had an 8× increased risk of death. Females had double the standardised mortality ratio compared to males.

DISCUSSION

This study provides important prognostic information for people diagnosed with FTD living in Australia. It highlights the importance of obtaining a definitive diagnosis as early as possible for future planning. More investigation into the relationship of symptom onset type and sex differences in FTD is required.

Research Criteria for the Behavioral Variant of Alzheimer Disease: A Systematic Review and Meta-analysis

Importance

The behavioral variant of Alzheimer disease (bvAD) is characterized by early and predominant behavioral deficits caused by AD pathology. This AD phenotype is insufficiently understood and lacks standardized clinical criteria, limiting reliability and reproducibility of diagnosis and scientific reporting.

Objective

To perform a systematic review and meta-analysis of the bvAD literature and use the outcomes to propose research criteria for this syndrome.

Data Sources

A systematic literature search in PubMed/MEDLINE and Web of Science databases (from inception through April 7, 2021) was performed in duplicate.

Study Selection

Studies reporting on behavioral, neuropsychological, or neuroimaging features in bvAD and, when available, providing comparisons with typical amnestic-predominant AD (tAD) or behavioral variant frontotemporal dementia (bvFTD).

Data Extraction and Synthesis

This analysis involved random-effects meta-analyses on group-level study results of clinical data and systematic review of the neuroimaging literature. The study was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.

Main Outcomes and Measures

Behavioral symptoms (neuropsychiatric symptoms and bvFTD core clinical criteria), cognitive function (global cognition, episodic memory, and executive functioning), and neuroimaging features (structural magnetic resonance imaging, [18F]fluorodeoxyglucose-positron emission tomography, perfusion single-photon emission computed tomography, amyloid positron emission tomography, and tau positron emission tomography).

Results

The search led to the assessment of 83 studies, including 13 suitable for meta-analysis. Data were collected for 591 patients with bvAD. There was moderate to substantial heterogeneity and moderate risk of bias across studies. Cases with bvAD showed more severe behavioral symptoms than tAD (standardized mean difference [SMD], 1.16 [95% CI, 0.74-1.59]; P < .001) and a trend toward less severe behavioral symptoms compared with bvFTD (SMD, -0.22 [95% CI, -0.47 to 0.04]; P = .10). Meta-analyses of cognitive data indicated worse executive performance in bvAD vs tAD (SMD, -1.03 [95% CI, -1.74 to -0.32]; P = .008) but not compared with bvFTD (SMD, -0.61 [95% CI, -1.75 to 0.53]; P = .29). Cases with bvAD showed a nonsignificant difference of worse memory performance compared with bvFTD (SMD, -1.31 [95% CI, -2.75 to 0.14]; P = .08) but did not differ from tAD (SMD, 0.43 [95% CI, -0.46 to 1.33]; P = .34). The neuroimaging literature revealed 2 distinct bvAD neuroimaging phenotypes: an AD-like pattern with relative frontal sparing and a relatively more bvFTD-like pattern characterized by additional anterior involvement, with the AD-like pattern being more prevalent.

Conclusions and Relevance

These data indicate that bvAD is clinically most similar to bvFTD, while it shares most pathophysiological features with tAD. Based on these insights, we propose research criteria for bvAD aimed at improving the consistency and reliability of future research and aiding the clinical assessment of this AD phenotype.

The Psychiatric Misdiagnosis of Behavioral Variant Frontotemporal Dementia in a Colombian Sample

Objective: To describe the demographic characteristics, initial psychiatric diagnoses, and the time to reach a diagnosis of probable behavioral variant frontotemporal dementia (bvFTD) in a public psychiatric hospital in Cali, Colombia. Methods: We retrospectively reviewed the medical records of 28 patients who were diagnosed with probable bvFTD based on a multidisciplinary evaluation that included a structural MRI, neuropsychological testing, functional assessment, and neurological exam. Prior to this evaluation, all patients were evaluated by a psychiatrist as part of their initial consultation at the hospital. The initial consultation included the Neuropsychiatric Inventory and diagnoses based on the DSM-V. Demographics, clinical features, and initial psychiatric misdiagnoses were extracted from clinical records and summarized in the full sample and by gender. Results: The study sample had a mean education of 10.0 years (SD = 4.9) and 68.0% were female. In the full sample, 28.6% were initially diagnosed with dementia, and 71.4% with a psychiatric disorder. The psychiatric diagnosis at initial consultation differed by gender. Women were most likely to be diagnosed with depression (26.3%) or bipolar disorder (26.3%), while the men were most likely to be diagnosed with anxiety (33.3%) or a psychotic disorder (22.2%). Psychotic symptoms were common (delusions, 60.7% and hallucinations, 39.3%), and the pattern of neuropsychiatric symptoms did not differ by gender. Conclusions: This is one of few case series of bvFTD in a Colombian population, where bvFTD is a recognizable and prevalent disorder. In this psychiatric hospital, the majority of patients with bvFTD were initially diagnosed with a primary psychiatric condition. There was a gender difference in psychiatric diagnosis, but not in neuropsychiatric symptoms. In this sample, the rate of psychiatric misdiagnosis, as well as the psychotic symptoms, were higher compared to rates described in other countries. These results highlight the need for interventions to improve bvFTD diagnosis in under-represented populations.

Premorbid de novo artistic creativity in frontotemporal dementia (FTD) syndromes

The emergence of new artistic activities or shifts in artistic style in patients with frontotemporal dementia (FTD) syndromes is well documented at or after disease onset. However, a closer look in the literature reveals emerging artistic creativity also before FTD onset, although the significance and underlying pathology of such creative endeavors remain elusive. Here, we systematically review relevant studies and report an additional FTD case to elaborate on artistic activities that developed years before disease manifestation by paying particular attention to the sequence of events in individual patients' biography and clinical history. We further discuss the FTD patient's creative activities in the context of their life events, other initial or "premorbid" dementia symptoms or risk factors described in the literature such as mental illness and mild behavioral impairment (MBI), as well as changes in neuronal systems (i.e., neuroimaging and neuropathology). In addition to our FTD patient, we identified five published cases with an FTD syndrome, including three with FTD, one with primary progressive aphasia (PPA), and one with the behavioral variant of PPA (bvPPA). Premorbid novel creativity emerged across different domains (visual, musical, writing), with the FTD diagnosis ensuing artistic productivity by a median of 8 years. Data on late-life and pre-dementia life events were available in four cases. The late creative phase in our case was accompanied by personality changes, accentuation of personality traits, and cessation of painting activities occurred with the onset of memory complaints. Thus, premorbid personality changes in FTD patients can be associated with de novo creative activity. Stressful life events may also contribute to the burgeoning of creativity. Moreover, primary neocortical areas that are largely spared by pathology at early FTD stages may facilitate the engagement in artistic activities, offering a window of opportunity for art therapy and other therapeutic interventions during the MBI stage or even earlier.

Global Prevalence of Young-Onset Dementia: A Systematic Review and Meta-analysis

Importance

Reliable prevalence estimates are lacking for young-onset dementia (YOD), in which symptoms of dementia start before the age of 65 years. Such estimates are needed for policy makers to organize appropriate health care.

Objective

To determine the global prevalence of YOD.

Data Sources

The PubMed, Embase, CINAHL, and PsycInfo databases were systematically searched for population-based studies on the prevalence of YOD published between January 1, 1990, and March 31, 2020.

Study Selection

Studies containing data on the prevalence of dementia in individuals younger than 65 years were screened by 2 researchers for inclusion in a systematic review and meta-analysis.

Data Extraction and Synthesis

Prevalence estimates on 5-year age bands, from 30 to 34 years to 60 to 64 years, were extracted. Random-effects meta-analyses were conducted to pool prevalence estimates. Results were age standardized for the World Standard Population. Heterogeneity was assessed by subgroup analyses for sex, dementia subtype, study design, and economic status based on the World Bank classification and by meta-regression.

Main Outcomes and Measures

Prevalence estimates of YOD for 5-year age bands.

Results

A total of 95 unique studies were included in this systematic review, of which 74 with 2 760 379 unique patients were also included in 5-year age band meta-analyses. Studies were mostly conducted in Europe and in older groups in Asia, North America, and Oceania. Age-standardized prevalence estimates increased from 1.1 per 100 000 population in the group aged 30 to 34 years to 77.4 per 100 000 population in the group aged 60 to 64 years. This gives an overall global age-standardized prevalence of 119.0 per 100 000 population in the age range of 30 to 64 years, corresponding to 3.9 million people aged 30 to 64 years living with YOD in the world. Subgroup analyses showed prevalence between men and women to be similar (crude estimates for men, 216.5 per 100 000 population; for women, 293.1 per 100 000 population), whereas prevalence was lower in high-income countries (crude estimate, 663.9 per 100 000 population) compared with upper-middle-income (crude estimate, 1873.6 per 100 000 population) and lower-middle-income (crude estimate, 764.2 per 100 000 population) countries. Meta-regression showed that age range (P < .001), sample size (P < .001), and study methodology (P = .02) significantly influenced heterogeneity between studies.

Conclusions and Relevance

This systematic review and meta-analysis found an age-standardized prevalence of YOD of 119.0 per 100 000 population, although estimates of the prevalence in low-income countries and younger age ranges remain scarce. These results should help policy makers organize sufficient health care for this subgroup of individuals with dementia.

Study Registration

PROSPERO CRD42019119288.

Identifying relevant outcomes in the progression of Alzheimer's disease; what do patients and care partners want to know about prognosis?

BACKGROUND

Prognostic studies in the context of Alzheimer's disease (AD) mainly predicted time to dementia. However, it is questionable whether onset of dementia is the most relevant outcome along the AD disease trajectory from the perspective of patients and their care partners. Therefore, we aimed to identify the most relevant outcomes from the viewpoint of patients and care partners.

METHODS

We used a two-step, mixed-methods approach. As a first step we conducted four focus groups in the Netherlands to elicit a comprehensive list of outcomes considered important by patients (n = 12) and care partners (n = 14) in the prognosis of AD. The focus groups resulted in a list of 59 items, divided into five categories. Next, in an online European survey, we asked participants (n = 232; 99 patients, 133 care partners) to rate the importance of all 59 items (5-point Likert scale). As participants were likely to rate a large number of outcomes as "important" (4) or "very important" (5), we subsequently asked them to select the three items they considered most important.

RESULTS

The top-10 lists of items most frequently mentioned as "most important" by patients and care partners were merged into one core outcome list, comprising 13 items. Both patients and care partners selected outcomes from the category "cognition" most often, followed by items in the categories "functioning and dependency" and "physical health." No items from the category "behavior and neuropsychiatry" and "social environment" ended up in our core list of relevant outcomes.

CONCLUSION

We identified a core list of outcomes relevant to patients and care partner, and found that prognostic information related to cognitive decline, dependency, and physical health are considered most relevant by both patients and their care partners.

Behavioral Variant Frontotemporal Dementia: Diagnosis and Treatment Interventions

Purpose of Review

The diagnosis and treatment of behavioral variant frontotemporal dementia is challenging and often delayed because of overlapping symptoms with more common dementia syndromes or primary psychiatric illnesses. The purpose of this paper is to explore the relevant presentation, diagnostic workup, pathophysiology, and both pharmacologic and non-pharmacologic management.

Recent Findings

Behavioral variant frontotemporal dementia is a highly heritable disorder. The gradual accumulation of diseased protein culminates in the destruction of those brain circuits responsible for much of one’s emotional and social functioning.

Summary

Behavioral variant frontotemporal dementia is a progressive neurodegenerative disorder with a far-reaching impact on patients and caregivers. Patients often present with emotional blunting, lack of empathy, apathy, and behavioral disinhibition. Non-pharmacologic interventions and caregiver support are the cornerstone of treatment. The use of cholinesterase inhibitors and memantine is not supported by the evidence. While current pharmacologic therapies target only certain symptoms, there are disease modifying agents currently in or nearing the clinical research stage.

Genetic testing in dementia-A medical genetics perspective

OBJECTIVE

When a genetic cause is suspected in a person with dementia, it creates unique diagnostic and management challenges to the treating clinician. Many clinicians may be unaware of the practicalities surrounding genetic testing for their patients, such as when to test and what tests to use and how to counsel patients and their families. This review was conducted to provide guidance to clinicians caring for patients with dementia regarding clinically relevant genetics.

METHODS

We searched PubMed for studies that involved genetics of dementia up to March 2020. Patient file reviews were also conducted to create composite cases.

RESULTS

In addition to families where a strong Mendelian pattern of family history is seen, people with younger age of onset, especially before the age of 65 years were found to be at an increased risk of harbouring a genetic cause for their dementia. This review discusses some of the most common genetic syndromes, including Alzheimer disease, frontotemporal dementia, vascular dementia, Parkinson disease dementia/dementia with Lewy bodies and some rarer types of genetic dementias, along with illustrative clinical case studies. This is followed by a brief review of the current genetic technologies and a discussion on the unique genetic counselling issues in dementia.

CONCLUSIONS

Inclusion of genetic testing in the diagnostic pathway in some patients with dementia could potentially reduce the time taken to diagnose the cause of their dementia. Although a definite advantage as an addition to the diagnostic repository, genetic testing has many pros and cons which need to be carefully considered first.

Lysosome dysfunction as a cause of neurodegenerative diseases: Lessons from frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are fatal neurodegenerative disorders that are thought to exist on a clinical and pathological spectrum. FTD and ALS are linked by shared genetic causes (e.g. C9orf72 hexanucleotide repeat expansions) and neuropathology, such as inclusions of ubiquitinated, misfolded proteins (e.g. TAR DNA-binding protein 43; TDP-43) in the CNS. Furthermore, some genes that cause FTD or ALS when mutated encode proteins that localize to the lysosome or modulate endosome-lysosome function, including lysosomal fusion, cargo trafficking, lysosomal acidification, autophagy, or TFEB activity. In this review, we summarize evidence that lysosomal dysfunction, caused by genetic mutations (e.g. C9orf72, GRN, MAPT, TMEM106B) or toxic-gain of function (e.g. aggregation of TDP-43 or tau), is an important pathogenic disease mechanism in FTD and ALS. Further studies into the normal function of many of these proteins are required and will help uncover the mechanisms that cause lysosomal dysfunction in FTD and ALS. Mutations or polymorphisms in genes that encode proteins important for endosome-lysosome function also occur in other age-dependent neurodegenerative diseases, including Alzheimer's (e.g. APOE, PSEN1, APP) and Parkinson's (e.g. GBA, LRRK2, ATP13A2) disease. A more complete understanding of the common and unique features of lysosome dysfunction across the spectrum of neurodegeneration will help guide the development of therapies for these devastating diseases.

Gene therapy for ALS: A review

Amyotrophic lateral sclerosis (ALS) has historically posed unique challenges for gene-therapy-based approaches, due to a paucity of therapeutic targets as well as the difficulty of accessing both the brain and spinal cord. Recent advances in our understanding of disease mechanism and ALS genetics, however, have combined with tremendous strides in CNS targeting, gene delivery, and gene editing and knockdown techniques to open new horizons of therapeutic possibility. Gene therapy clinical trials are currently underway for ALS patients with SOD1 mutations, C9orf72 hexanucleotide repeat expansions, ATXN2 trinucleotide expansions, and FUS mutations, as well as sporadic disease without known genetic cause. In this review, we provide an in-depth exploration of the state of ALS-directed gene therapy, including antisense oligonucleotides, RNA interference, CRISPR, adeno-associated virus (AAV)-mediated trophic support, and antibody-based methods. We discuss how each of these approaches has been implemented across known genetic causes as well as sporadic ALS, reviewing preclinical studies as well as completed and ongoing human clinical trials. We highlight the transformative potential of these evolving technologies as the gene therapy field advances toward a true disease-modifying treatment for this devastating illness.

Neuroimaging in Frontotemporal Dementia: Heterogeneity and Relationships with Underlying Neuropathology

Frontotemporal dementia encompasses a group of clinical syndromes defined pathologically by degeneration of the frontal and temporal lobes. Historically, these syndromes have been challenging to diagnose, with an average of about three years between the time of symptom onset and the initial evaluation and diagnosis. Research in the field of neuroimaging has revealed numerous biomarkers of the various frontotemporal dementia syndromes, which has provided clinicians with a method of narrowing the differential diagnosis and improving diagnostic accuracy. As such, neuroimaging is considered a core investigative tool in the evaluation of neurodegenerative disorders. Furthermore, patterns of neurodegeneration correlate with the underlying neuropathological substrates of the frontotemporal dementia syndromes, which can aid clinicians in determining the underlying etiology and improve prognostication. This review explores the advancements in neuroimaging and discusses the phenotypic and pathologic features of behavioral variant frontotemporal dementia, semantic variant primary progressive aphasia, and nonfluent variant primary progressive aphasia, as seen on structural magnetic resonance imaging and positron emission tomography.

Pharmacotherapy for Frontotemporal Dementia

Frontotemporal dementia is a heterogeneous spectrum of neurodegenerative disorders. The neuropathological inclusions are tau proteins, TAR DNA binding protein 43 kDa-TDP-43, or fused in sarcoma-ubiquitinated inclusions. Genetically, several autosomal mutations account for the heritability of the disorder. Phenotypically, frontotemporal dementia can present with a behavioral variant or a language variant called primary progressive aphasia. To date, there are no approved symptomatic or disease-modifying treatments for frontotemporal dementia. Currently used therapies are supported by low-level of evidence (mostly uncontrolled) studies. The off-label use of drugs is also limited by their side-effect profile including an increased risk of confusion, parkinsonian symptoms, and risk of mortality. Emerging disease-modifying treatments currently target the progranulin and the expansion on chromosome 9 open reading frame 72 genes as well as tau deposits. Advancing our understanding of the pathophysiology of the disease and improving the design of future clinical trials are much needed to optimize the chances to obtain positive outcomes.

Treating lexical retrieval using letter fluency and tDCS in primary progressive aphasia: a single-case study

Background

In early stages, individuals with Primary Progressive Aphasia (PPA) report language symptoms while scoring within norm in formal language tests. Early intervention is important due to the progressive nature of the disease.

Method

We report a single case study of an individual with logopenic variant PPA (lvPPA). We tested whether letter fluency, used as a therapy task, can improve lexical retrieval when combined with tDCS to either the left inferior-frontal gyrus (IFG) or the left inferior parietal lobe (IPL), administered in two separate therapy phases separated by a wash-out period of three months.

Outcomes and results

We observed increases in number of words retrieved during a letter fluency task in trained and untrained letters, when letter fluency therapy (LeFT) was administered with anodal tDCS. When LeFT was combined with left IFG stimulation, words produced in a letter fluency task were lower frequency and higher age of acquisition after treatment, compared to before treatment and there was also an increase in accuracy and response times in an untrained picture-naming task.

Conclusions

The results indicate that letter fluency therapy combined anodal tDCS is effective in improving lexical retrieval, particularly when left IFG stimulation was used. Effects generalize beyond the trained task, albeit slowing down of responses in picture naming. This task may provide a useful clinical intervention strategy for patients with mild anomia, who are not challenged enough by traditional naming therapies.

Comparison of Prodromal Symptoms of Patients with Behavioral Variant Frontotemporal Dementia and Alzheimer Disease

INTRODUCTION

Behavioral variant frontotemporal dementia (bvFTD) is the most common clinical subtype of frontotemporal lobar degeneration. bvFTD is often characterized by changes in behavior and personality, frequently leading to psychiatric misdiagnoses. On the other hand, substantial clinical overlap with other neurodegenerative diseases, such as Alzheimer disease (AD), further complicates the diagnostics.

OBJECTIVE

Our aim was to identify the main differences in early symptoms of bvFTD and AD in the prodromal stages of the diseases. In addition, patients with bvFTD were analyzed separately according to whether they carry the C9orf72repeat expansion or not.

METHODS

Patient records of bvFTD (n = 75) and AD (n = 83) patients were analyzed retrospectively for memory and neuropsychiatric symptoms, sleeping disorders, and somatic complaints before the setting of the accurate diagnosis.

RESULTS

A total of 84% of bvFTD patients (n = 63) and 98.8% of AD patients (n = 82) reported subjective memory disturbances in the prodromal phases of the disease. bvFTD patients presented significantly more often with sleeping disorders, headache, inexplicable collapses, transient loss of consciousness, somatization, delusions, and hallucinations, suicidality, changes in oral behaviors, and urinary problems. In addition, poor financial judgement was frequently detected in patients with prodromal bvFTD. Aberrant sensations in the nose and throat without any physical explanation, regarded as somatizations, emerged only in bvFTD patients with the C9orf72 repeat expansion.

CONCLUSIONS

Subjective reporting of impaired episodic memory is a poor indicator in differentiating bvFTD from AD. Sleeping disturbances, delusions, hallucinations, and unexplained somatic complaints in a patient with cognitive disturbances should prompt the clinicians to consider bvFTD as a possible diagnostic option behind these symptoms. The spectrum of symptoms in the prodromal stages of bvFTD may be more diverse than the latest criteria suggest.

Characteristics and progression of patients with frontotemporal dementia in a regional memory clinic network

Background

Due to heterogeneous clinical presentation, difficult differential diagnosis with Alzheimer’s disease (AD) and psychiatric disorders, and evolving clinical criteria, the epidemiology and natural history of frontotemporal lobar degeneration (FTD) remain elusive. In order to better characterize FTD patients, we relied on the database of a regional memory clinic network with standardized diagnostic procedures and chose AD patients as a comparator.

Methods

Patients that were first referred to our network between January 2010 and December 2016 and whose last clinical diagnosis was degenerative or vascular dementia were included. Comparisons were conducted between FTD and AD as well as between the different FTD syndromes, divided into language variants (lvFTD), behavioral variant (bvFTD), and FTD with primarily motor symptoms (mFTD). Cognitive progression was estimated with the yearly decline in Mini Mental State Examination (MMSE).

Results

Among the patients that were referred to our network in the 6-year time span, 690 were ultimately diagnosed with FTD and 18,831 with AD. Patients with FTD syndromes represented 2.6% of all-cause dementias. The age-standardized incidence was 2.90 per 100,000 person-year and incidence peaked between 75 and 79 years. Compared to AD, patients with FTD syndromes had a longer referral delay and delay to diagnosis. Patients with FTD syndromes had a higher MMSE score than AD at first referral while their progression was similar. mFTD patients had the shortest survival while survival in bvFTD, lvFTD, and AD did not significantly differ. FTD patients, especially those with the behavioral variant, received more antidepressants, anxiolytics, and antipsychotics than AD patients.

Conclusions

FTD syndromes differ with AD in characteristics at baseline, progression rate, and treatment. Despite a broad use of the new diagnostic criteria in an organized memory clinic network, FTD syndromes are longer to diagnose and account for a low proportion of dementia cases, suggesting persistent underdiagnosis. Congruent with recent publications, the late peak of incidence warns against considering FTD as being exclusively a young-onset dementia.