'Communication is difficult': Speech, language and communication needs of people with young onset or rarer forms of non-language led dementia

BACKGROUND

People with behavioural variant frontotemporal dementia, Lewy body dementia, posterior cortical atrophy and young onset Alzheimer's disease may experience language and communication difficulties. However, the role of speech and language interventions for people with these non-language led dementias has received little attention.

AIMS

This study aimed to explore the experiences and perspectives of people living with these conditions, and their families, regarding their language and communication difficulties and how speech and language therapy could address these needs.

METHODS

This study employed a qualitative design to explore the experiences of people living with or caring for somebody with behavioural variant frontotemporal dementia, Lewy body dementia, posterior cortical atrophy or young onset Alzheimer's disease, and to understand their opinions about speech and language therapy. Participants were recruited from a support service connected to a dementia clinic to attend one of five focus group meetings. Videorecorded focus groups and interviews were transcribed, and reflexive thematic analysis was used to analyse data from people affected by each type of dementia.

RESULTS

A total of 25 participants were recruited to the study, with representation across the different forms of non-language led dementias. The four main themes identified were: (1) communication difficulties as a key difficulty, (2) loss and loneliness, (3) speech and language therapy, and (4) the role of the caregiver. Sixteen subthemes were also identified which highlighted individual issues across disease types.

DISCUSSION

Although all the forms of dementia studied here are not considered to be language-led, people with these conditions and/or their care partners identified speech, language and communication as common challenges. These communication difficulties were reported to have a negative impact on their social participation and mental health and participants felt speech and language interventions could help. There is a need for research exploring speech and language interventions developed for and with people with non-language led dementias and their care partners, to ensure they meet the needs of the people they are designed for.

WHAT THIS PAPER ADDS

What is already known on the subject People with primary progressive aphasia present with speech, language and communication difficulties, and several speech and language interventions have been developed to meet the needs of this population. However, people with non-language led dementias may also experience speech, language and communication difficulties, and little is known about interventions that may address these difficulties. What this paper adds to existing knowledge People living with or caring for somebody with behavioural variant frontotemporal dementia, Lewy body dementia, posterior cortical atrophy and young onset Alzheimer's disease report experiencing speech, language and communication difficulties that impact on the person with dementia's social participation and mood. Participants in this study also shared their opinions about how speech and language interventions could help, from the earliest stages of the disease. What are the potential or actual clinical implications of this work? Speech and language therapists need to address the individual speech, language and communication needs of people with dementias, even those that are not thought to be language-led. Current speech and language therapy service provision does not meet the needs of people with non-language led dementias and further research is required to develop interventions and services to meet these needs.

Symptom-led staging for semantic and non-fluent/agrammatic variants of primary progressive aphasia

INTRODUCTION

Here we set out to create a symptom-led staging system for the canonical semantic and non-fluent/agrammatic variants of primary progressive aphasia (PPA), which present unique diagnostic and management challenges not well captured by functional scales developed for Alzheimer's disease and other dementias.

METHODS

An international PPA caregiver cohort was surveyed on symptom development under six provisional clinical stages and feedback was analyzed using a mixed-methods sequential explanatory design.

RESULTS

Both PPA syndromes were characterized by initial communication dysfunction and non-verbal behavioral changes, with increasing syndromic convergence and functional dependency at later stages. Milestone symptoms were distilled to create a prototypical progression and severity scale of functional impairment: the PPA Progression Planning Aid ("PPA-Squared").

DISCUSSION

This work introduces a symptom-led staging scheme and functional scale for semantic and non-fluent/agrammatic variants of PPA. Our findings have implications for diagnostic and care pathway guidelines, trial design, and personalized prognosis and treatment for PPA.

HIGHLIGHTS

We introduce new symptom-led perspectives on primary progressive aphasia (PPA). The focus is on non-fluent/agrammatic (nfvPPA) and semantic (svPPA) variants. Foregrounding of early and non-verbal features of PPA and clinical trajectories is featured. We introduce a symptom-led staging scheme for PPA. We propose a prototype for a functional impairment scale, the PPA Progression Planning Aid.

Adaptation of an eHealth Intervention: iSupport for Carers of People with Rare Dementias

'iSupport' is an online psychoeducation and skills development intervention created by the World Health Organisation to support people with dementia. This project adapted iSupport for carers of people with rare dementias (iSupport RDC), creating a new resource to support the health and wellbeing of this underserved population. The adaptation involved three phases: (1) Co-design methods to generate preliminary adaptations; (2) Analysis of phase one findings informing adaptations to iSupport to develop; iSupport RDC; (3) Post-adaptation survey to ascertain participant agreement with the adaptations in iSupport RDC. Fourteen participants contributed, resulting in 212 suggested adaptations, of which 94 (92%) were considered practical, generalisable, and aligned with iSupport principles. These adaptations encompassed content and design changes, including addressing the challenges of rare dementias (PCA, PPA, LBD, and FTD). iSupport RDC represents a significant adaptation of the WHO iSupport intervention. Its tailored nature acknowledges the unique needs of people caring for someone with a rare dementia, improving their access to specialised resources and support. By extending iSupport to this population, it contributes to advancing dementia care inclusivity and broadening the understanding of rare dementias. A feasibility study is underway to assess iSupport RDCs acceptability, with prospects for cultural adaptations to benefit carers globally.

'I have never bounced back': resilience and living with dementia

OBJECTIVE

This work responds to the limited research about resilience when living with dementia and develops a conceptual model to inform service development and healthcare practices for this population.

METHODS

An iterative process of theory building across four phases of activity (scoping review n = 9 studies), stakeholder engagement (n = 7), interviews (n = 11) generated a combined sample of 87 people living with dementia and their carers, including those affected by rare dementias to explore their lived experiences. An existing framework of resilience developed in other populations served as the starting point to analyse and synthesise the findings, inspiring a new conceptual model of resilience unique to the experience of living with dementia.

RESULTS

The synthesis suggests resilience encompasses the daily struggles of living with a dementia; people are not flourishing, thriving or 'bouncing back', but are managing and adapting under pressure and stress. The conceptual model suggests resilience may be achieved through the collective and collaborative role of psychological strengths, practical approaches to adapting to life with dementia, continuing with hobbies, interests and activities, strong relationships with family and friends, peer support and education, participating in community activities and support from healthcare professionals. Most of these themes are not reflected in resilience outcome measures.

CONCLUSIONS

Practitioners adopting a strengths-based approach utilising the conceptual model at the point of diagnosis and post-diagnosis support may help individuals achieve resilience through appropriately tailored services and support. This 'resilience practice' could also extend to other degenerative or debilitating chronic conditions a person faces in their life course.

"Better Living with Non-memory-led Dementia": protocol for a feasibility randomised controlled trial of a web-based caregiver educational programme

BACKGROUND

Non-memory-led dementias such as posterior cortical atrophy (PCA), primary progressive aphasia (PPA) and behavioural variant frontotemporal dementia (bvFTD) are low prevalent and often affect individuals under the age of 65. Tailored educational and support resources for caregivers of people living with these dementia phenotypes are scarce and unevenly distributed geographically. Web-based educational programmes are emerging as promising alternatives to improve caregiver self-efficacy and well-being. Here, we present the protocol of a study aiming to assess the feasibility of a co-produced online educational programme for caregivers of people living PCA, PPA and bvFTD: the Better Living with Non-memory-led Dementia programme.

METHODS

A randomised controlled feasibility trial will be conducted on a sample of 30 caregivers of people living with PCA, PPA and bvFTD. Participants will be recruited among members of the support organisation Rare Dementia Support (based at UCL in the UK). The intervention group will be given access to an 8-week co-produced web-based educational programme consisting of 6 modules addressing education about PCA, PPA and bvFTD and support strategies for the person with dementia and for the caregiver. The control group will receive treatment as usual (TAU). Feasibility will be measured through feasibility of recruitment, clinical measurement tools and acceptability. Clinical measures will be used to assess preliminary efficacy and data on completion rates, missing data and variability used to decide on measures to be included in a full-scale trial. Allocation ratio will be 2:1 (intervention:control) stratified by diagnosis. Feasibility of recruitment and acceptability will be assessed. Clinical measures will be administered at baseline and 8-week and 3-month post-randomisation. The control group will be offered access to the intervention at the completion of data collection. Participants will be unblinded, and all measures will be self-reported online.

DISCUSSION

Online-delivered educational programmes show potential for improving care competency of caregivers and may contribute to overcoming geographical inequalities in local provision of support services. This pilot study will inform a fully powered international trial to determine the effectiveness of Better Living with Non-memory-led Dementia.

TRIAL REGISTRATION

This trial has been registered prospectively on the Clinical Trials Registry on 1st September 2022, registration number NCT05525377.

Development of an item pool for a patient reported outcome measure of resilience for people living with dementia

BACKGROUND AND OBJECTIVES

Policies to support people living with dementia increasingly focus on strengths-based approaches, highlighting the importance of building resilience. This research responds to the lack of a suitable resilience measure for people with dementia. It develops a pool of items to inform a new measure of resilience for this population.

METHODS

A conceptual model and associated data informed the item generation of the draft resilience measure. Regular meetings with professionals (n = 7) discussed response-scale formatting, content and face validity, leading to refinement and item reduction. Cognitive interviews with people living with dementia (n = 11) then examined the face and content validity of items and the suitability of response-scale formatting. These two phases informed subsequent revision and further item reduction of the resilience measure.

RESULTS

The first item generation exercise led to 140 items. These were independently assessed by the professionals and this refinement reduced the measure to 63 items across 7 domains of the conceptual model (psychological strengths; practical approaches for adapting to life with dementia; continuing with hobbies, interests and activities; strong relationships with family and friends; peer support and education; participating in community activities; the role of professional support services). Cognitive interviews explored the 63 items with people living with dementia. Detailed feedback led to items removed due to difficulty with (a) understanding (N = 7); (b) answering (n = 11); (c) low preference for that item (n = 6); and (d) presence of a preferred item within a cluster of similar questions (n = 4). Items were amended to enhance clarity/conciseness (n = 19) leading to a final 37-item pool.

CONCLUSION

Established methods for measurement development included the expertise of people with dementia and led to the generation of a set of items for a new resilience measure that were understandable and acceptable to this target population. This 37-item pool reflects the conceptual understanding of resilience in dementia as being derived across individual, community and societal level resources.

Video Conferencing Peer Support and Rarer Forms of Dementia: An Exploration of Family Carers' Positive Experiences

Little is known regarding the nuanced experiences of family carers for people living with rare dementias (PLWRD), with no known literature exploring their positive experiences of caring discussed within peer support group settings. This article explores family carers of PLWRD's positive experiences reported in video conferencing peer support groups. Six peer support group sessions involving a total of nine participants were qualitatively analysed using thematic analysis, guided by the conceptual framework of positive aspects of caring (CFPAC) (Carbonneau et al., 2010). Six themes were identified: (1) Protecting, maintaining, enjoying and finding strength in their relationship with the PLWRD; (2) Using tools and resources in response to challenges; (3) Positive impact of interactions and others' responses to the dementia; (4) Overcoming barriers to taking a break while maintaining their wellbeing, (5) Maintaining positive outlooks and showing psychological resilience in adversity; and (6) Attributing meaning to the caring role. This article highlights family carers of PLWRD's positive psychological, physical and social resources, balanced against the challenges of caring and maintaining their wellbeing, and identifies ways of promoting family carers' positive caring experiences and resources within healthcare and supportive settings.

"I felt like I had been put on the shelf and forgotten about" - lasting lessons about the impact of COVID-19 on people affected by rarer dementias

BACKGROUND

The public health measures imposed in many countries to contain the spread of COVID-19 resulted in significant suspensions in the provision of support and care for people with dementia. The negative effects of these measures have been extensively reported. However, little is known about the specific impact on people with young onset, non-memory-led and inherited dementias. This group may have experienced different challenges compared to those with late onset dementia given their non-memory phenotypes and younger age. We explored the impact of the first COVID-19 lockdown on people living with familial Alzheimer's disease, behavioural variant frontotemporal dementia, familial frontotemporal dementia, dementia with Lewy bodies, posterior cortical atrophy and primary progressive aphasia and their carers in the UK and their self-reported strategies for coping.

METHODS

This was a mixed methods study. An online survey was administered to people with dementia and family carers recruited via Rare Dementia Support. Free-text responses were analysed using framework analysis to identify key issues and themes.

RESULTS

184 carers and 24 people with dementia completed the survey. Overall, people with dementia experienced worsening of cognitive symptoms (70%), ability to do things (62%), well-being (57%) and changes to medication (26%) during lockdown. Carers reported a reduction in the support they received (55%) which impacted their own mental health negatively. Qualitative analysis of free-text responses shed light on how the disruption to routines, changes to roles and responsibilities, and widespread disconnection from friends, family and health and social care support varied according to phenotype. These impacts were exacerbated by a more general sense that precious time was being lost, given the progressive nature of dementia. Despite significant challenges, respondents demonstrated resilience and resourcefulness in reporting unexpected positives and strategies for adapting to confinement.

CONCLUSIONS

This study has highlighted the specific impacts of the COVID-19 restrictions on people with young onset, non-memory-led and inherited dementias, including behavioural variant frontotemporal dementia, primary progressive aphasia and posterior cortical atrophy, and their carers. The specific challenges faced according to diagnosis and the self-reported strategies speak to the importance of - and may inform the development of - tailored support for these underrepresented groups more generally.

'Like going into a chocolate shop, blindfolded': What do people with primary progressive aphasia want from speech and language therapy?

BACKGROUND

Primary progressive aphasia (PPA) describes a group of language-led dementias. PPAs are complex, diverse and difficult to diagnose, and therefore conventional models of aphasia and dementia treatment do not meet their needs. The research evidence on intervention for PPA is developing, but to date there are only a few case studies exploring the experiences of people with PPA (PwPPA) themselves.

AIMS

To explore the experiences and opinions of PwPPA and their communication partners (CPs) to understand how speech and language therapy (SLT) services can better meet their needs.

METHODS & PROCEDURES

A qualitative research approach was used whereby PwPPA and their friends or family members were recruited to participate in focus groups, via advertisements in the Rare Dementia Support PPA group newsletters. Consenting participants were allocated to attend one of four focus groups hosted on an online video conferencing platform. Participants were asked about their communication difficulties, and how SLT could address these needs. All meetings were transcribed, and data were examined using reflexive thematic analysis.

OUTCOMES & RESULTS

Six PwPPA and 14 CPs representing all three PPA variants and mixed PPA participated in the focus groups. Four main themes were identified during the analysis of the focus group discussions: (1) CPs' burden, (2) adjusting to the diagnosis, (3) communication abilities and difficulties and (4) beyond language. A further 10 subthemes were identified.

CONCLUSIONS & IMPLICATIONS

This study provides a greater understanding of the experiences and needs of PwPPA and their families in relation to SLT. This work underlines the importance of a person-centred approach that considers the broader needs of both the PwPPA and the people around them. This will enable service providers to deliver SLT that meets the needs of PwPPA and their families and will also inform future research in this field.

WHAT THIS PAPER ADDS

What is already known on this subject We know that PwPPA can maintain or even make improvements in word retrieval and speech fluency with SLT exercises. There is also developing evidence of the benefits of interventions such as CP training, communication aid support and other functional interventions. What this paper adds to existing knowledge This study provides an understanding of the experiences and opinions of people living with PPA and their families in relation to SLT. Results demonstrate that PwPPA and their families have to navigate a complex journey, identifying strategies to support communication but also the influence of personality and other cognitive symptoms. SLT was useful, but not always available. What are the potential or actual clinical implications of this work? This study will enable service providers to better plan, justify funding for and delivery of SLT that will meet the needs of PwPPA and their families. Most importantly this work underlines the importance of a person-centred approach, incorporating the broader needs of the person with PPA and those around them.

Symptom-led staging for primary progressive aphasia

The primary progressive aphasias (PPA) present complex and diverse challenges of diagnosis, management and prognosis. A clinically-informed, syndromic staging system for PPA would take a substantial step toward meeting these challenges. This study addressed this need using detailed, multi-domain mixed-methods symptom surveys of people with lived experience in a large international PPA cohort. We administered structured online surveys to caregivers of patients with a canonical PPA syndromic variant (nonfluent/agrammatic (nvPPA), semantic (svPPA) or logopenic (lvPPA)). In an 'exploratory' survey, a putative list and ordering of verbal communication and nonverbal functioning (nonverbal thinking, conduct and wellbeing, physical) symptoms was administered to 118 caregiver members of the UK national PPA Support Group. Based on feedback, we expanded the symptom list and created six provisional clinical stages for each PPA subtype. In a 'consolidation' survey, these stages were presented to 110 caregiver members of UK and Australian PPA Support Groups, and refined based on quantitative and qualitative feedback. Symptoms were retained if rated as 'present' by a majority (at least 50%) of respondents representing that PPA syndrome, and assigned to a consolidated stage based on majority consensus; the confidence of assignment was estimated for each symptom as the proportion of respondents in agreement with the final staging for that symptom. Qualitative responses were analysed using framework analysis. For each PPA syndrome, six stages ranging from 1 ('Very mild') to 6 ('Profound') were identified; earliest stages were distinguished by syndromic hallmark symptoms of communication dysfunction, with increasing trans-syndromic convergence and dependency for basic activities of daily living at later stages. Spelling errors, hearing changes and nonverbal behavioural features were reported at early stages in all syndromes. As the illness evolved, swallowing and mobility problems were reported earlier in nfvPPA than other syndromes, while difficulty recognising familiar people and household items characterised svPPA and visuospatial symptoms were more prominent in lvPPA. Overall confidence of symptom staging was higher for svPPA than other syndromes. Across syndromes, functional milestones were identified as key deficits that predict the sequence of major daily life impacts and associated management needs. Qualitatively, we identified five major themes encompassing 15 subthemes capturing respondents' experiences of PPA and suggestions for staging implementation. This work introduces a prototypical, symptom-led staging scheme for canonical PPA syndromes: the PPA Progression Planning Aid (PPA 2 ). Our findings have implications for diagnostic and care pathway guidelines, trial design and personalised prognosis and treatment for people living with these diseases.

Using Music to Develop a Multisensory Communicative Environment for People with Late-Stage Dementia

Background and Objectives

Research has indicated the benefit of music interventions on biological, psychological, and cognitive aspects of dementias, yet there is limited research focusing on music’s role in communication. This study developed a conceptual understanding of how people with late-stage dementia may express themselves nonverbally and interact with others during a live music group over time.

Research Design and Methods

Eight people with advanced dementias in residential care (aged 82–97 years), four care staff, and three musicians participated in 8-hr-long weekly live Music for Life sessions and listened to 1-hr-long recorded music session. Visual grounded theory was used to analyze video data collected nonintrusively via the Fly 360-degree camera.

Results

The live music group facilitated a multisensory communicative environment allowing for verbal and nonverbal communicative actions, social interactional components and agency to develop over time. These aspects were influenced by three factors: time, one-to-one interaction within a group setting and the characteristics of the music.

Discussion and Implications

Nonverbal communication in later-stage dementia may be overlooked or underestimated by busy care staff and families. Using music as an interactive way to communicate can help develop mirroring and turn-taking which has been shown to improve quality of life for people with communication impairment, increase their nonverbal communication and allow for a connection to be built between people. Although further research is recommended, individuals responsible for residential care should feel confident that the development of ongoing music groups for this population is warranted as part of ongoing care.

Augmenting Dementia Cognitive Assessment With Instruction-Less Eye-Tracking Tests

Eye-tracking technology is an innovative tool that holds promise for enhancing dementia screening. In this work, we introduce a novel way of extracting salient features directly from the raw eye-tracking data of a mixed sample of dementia patients during a novel instruction-less cognitive test. Our approach is based on self-supervised representation learning where, by training initially a deep neural network to solve a pretext task using well-defined available labels (e.g. recognising distinct cognitive activities in healthy individuals), the network encodes high-level semantic information which is useful for solving other problems of interest (e.g. dementia classification). Inspired by previous work in explainable AI, we use the Layer-wise Relevance Propagation (LRP) technique to describe our network's decisions in differentiating between the distinct cognitive activities. The extent to which eye-tracking features of dementia patients deviate from healthy behaviour is then explored, followed by a comparison between self-supervised and handcrafted representations on discriminating between participants with and without dementia. Our findings not only reveal novel self-supervised learning features that are more sensitive than handcrafted features in detecting performance differences between participants with and without dementia across a variety of tasks, but also validate that instruction-less eye-tracking tests can detect oculomotor biomarkers of dementia-related cognitive dysfunction. This work highlights the contribution of self-supervised representation learning techniques in biomedical applications where the small number of patients, the non-homogenous presentations of the disease and the complexity of the setting can be a challenge using state-of-the-art feature extraction methods.

Sequences of cognitive decline in typical Alzheimer's disease and posterior cortical atrophy estimated using a novel event-based model of disease progression

Introduction

This work aims to characterize the sequence in which cognitive deficits appear in two dementia syndromes.

Methods

Event‐based modeling estimated fine‐grained sequences of cognitive decline in clinically‐diagnosed posterior cortical atrophy (PCA) (n=94) and typical Alzheimer's disease (tAD) (n=61) at the UCL Dementia Research Centre. Our neuropsychological battery assessed memory, vision, arithmetic, and general cognition. We adapted the event‐based model to handle highly non‐Gaussian data such as cognitive test scores where ceiling/floor effects are common.

Results

Experiments revealed differences and similarities in the fine‐grained ordering of cognitive decline in PCA (vision first) and tAD (memory first). Simulation experiments reveal that our new model equals or exceeds performance of the classic event‐based model, especially for highly non‐Gaussian data.

Discussion

Our model recovered realistic, phenotypical progression signatures that may be applied in dementia clinical trials for enrichment, and as a data‐driven composite cognitive end‐point.

Preparatory planning framework for Created Out of Mind: Shaping perceptions of dementia through art and science

Created Out of Mind is an interdisciplinary project, comprised of individuals from arts, social sciences, music, biomedical sciences, humanities and operational disciplines. Collaboratively we are working to shape perceptions of dementias through the arts and sciences, from a position within the Wellcome Collection. The Collection is a public building, above objects and archives, with a porous relationship between research, museum artefacts, and the public.  This pre-planning framework will act as an introduction to Created Out of Mind. The framework explains the rationale and aims of the project, outlines our focus for the project, and explores a number of challenges we have encountered by virtue of working in this way.

The clinical, neuroanatomical, and neuropathologic phenotype of TBK1-associated frontotemporal dementia: A longitudinal case report

INTRODUCTION

Mutations in the TANK-binding kinase 1 (TBK1) gene have recently been shown to cause frontotemporal dementia (FTD). However, the phenotype of TBK1-associated FTD is currently unclear.

METHODS

We performed a single case longitudinal study of a patient who was subsequently found to have a novel A705fs mutation in the TBK1 gene. He was assessed annually over a 7-year period with a series of clinical, cognitive, and magnetic resonance imaging assessments. His brain underwent pathological examination at postmortem.

RESULTS

The patient presented at the age of 64 years with an 18-month history of personality change including increased rigidity and obsessiveness, apathy, loss of empathy, and development of a sweet tooth. His mother had developed progressive behavioral and cognitive impairment from the age of 57 years. Neuropsychometry revealed intact cognition at first assessment. Magnetic resonance imaging showed focal right temporal lobe atrophy. Over the next few years his behavioral problems progressed and he developed cognitive impairment, initially with anomia and prosopagnosia. Neurological examination remained normal throughout without any features of motor neurone disease. He died at the age of 72 years and postmortem showed TDP-43 type A pathology but with an unusual novel feature of numerous TAR DNA-binding protein 43 (TDP-43)-positive neuritic structures at the cerebral cortex/subcortical white matter junction. There was also associated argyrophilic grain disease not previously reported in other TBK1 mutation cases.

DISCUSSION

TBK1-associated FTD can be associated with right temporal variant FTD with progressive behavioral change and relatively intact cognition initially. The case further highlights the benefits of next-generation sequencing technologies in the diagnosis of neurodegenerative disorders and the importance of detailed neuropathologic analysis.

Serum neurofilament light chain protein is a measure of disease intensity in frontotemporal dementia

OBJECTIVE

To investigate serum neurofilament light chain (NfL) concentrations in frontotemporal dementia (FTD) and to see whether they are associated with the severity of disease.

METHODS

Serum samples were collected from 74 participants (34 with behavioral variant FTD [bvFTD], 3 with FTD and motor neuron disease and 37 with primary progressive aphasia [PPA]) and 28 healthy controls. Twenty-four of the FTD participants carried a pathogenic mutation in C9orf72 (9), microtubule-associated protein tau (MAPT; 11), or progranulin (GRN; 4). Serum NfL concentrations were determined with the NF-Light kit transferred onto the single-molecule array platform and compared between FTD and healthy controls and between the FTD clinical and genetic subtypes. We also assessed the relationship between NfL concentrations and measures of cognition and brain volume.

RESULTS

Serum NfL concentrations were higher in patients with FTD overall (mean 77.9 pg/mL [SD 51.3 pg/mL]) than controls (19.6 pg/mL [SD 8.2 pg/mL]; p < 0.001). Concentrations were also significantly higher in bvFTD (57.8 pg/mL [SD 33.1 pg/mL]) and both the semantic and nonfluent variants of PPA (95.9 and 82.5 pg/mL [SD 33.0 and 33.8 pg/mL], respectively) compared with controls and in semantic variant PPA compared with logopenic variant PPA. Concentrations were significantly higher than controls in both the C9orf72 and MAPT subgroups (79.2 and 40.5 pg/mL [SD 48.2 and 20.9 pg/mL], respectively) with a trend to a higher level in the GRN subgroup (138.5 pg/mL [SD 103.3 pg/mL). However, there was variability within all groups. Serum concentrations correlated particularly with frontal lobe atrophy rate (r = 0.53, p = 0.003).

CONCLUSIONS

Increased serum NfL concentrations are seen in FTD but show wide variability within each clinical and genetic group. Higher concentrations may reflect the intensity of the disease in FTD and are associated with more rapid atrophy of the frontal lobes.