Sensitivity of current criteria for the diagnosis of behavioral variant frontotemporal dementia

Common and unique gray matter correlates of episodic memory dysfunction in frontotemporal dementia and Alzheimer's disease

Conflicting evidence exists regarding the integrity of episodic memory in the behavioral variant of frontotemporal dementia (bvFTD). Recent converging evidence suggests that episodic memory in progressive cases of bvFTD is compromised to the same extent as in Alzheimer's disease (AD). The underlying neural substrates of these episodic memory deficits, however, likely differ contingent on dementia type. In this study we sought to elucidate the neural substrates of episodic memory performance, across recall and recognition tasks, in both patient groups using voxel-based morphometry (VBM) analyses. We predicted that episodic memory dysfunction would be apparent in both patient groups but would relate to divergent patterns of neural atrophy specific to each dementia type. We assessed episodic memory, across verbal and visual domains, in 19 bvFTD, 18 AD patients, and 19 age- and education-matched controls. Behaviorally, patient groups were indistinguishable for immediate and delayed recall, across verbal and visual domains. Whole-brain VBM analyses revealed regions commonly implicated in episodic retrieval across groups, namely the right temporal pole, right frontal lobe, left paracingulate gyrus, and right anterior hippocampus. Divergent neural networks specific to each group were also identified. Whereas a widespread network including posterior regions such as the posterior cingulate cortex, parietal and occipital cortices was exclusively implicated in AD, the frontal and anterior temporal lobes underpinned the episodic memory deficits in bvFTD. Our results point to distinct neural changes underlying episodic memory decline specific to each dementia syndrome.

Using the revised diagnostic criteria for frontotemporal dementia in India: evidence of an advanced and florid disease

BACKGROUND

The International Consortium (FTDC) that revised the diagnostic criteria for behavioural variant frontotemporal dementia (bvFTD) did not have an Asian representation. Whether the revised criteria are equally useful in the early detection of Asian bvFTD patients therefore remains largely unexplored. Earlier studies have indicated differences in clinical manifestations in Indian and other Asian bvFTD patients when compared to western groups. There is an urgent need for clarification, given the projected exponential rise in dementia in these countries and the imminent clinical trials on bvFTD.

OBJECTIVE

To assess how Indian bvFTD patients fulfil the FTDC criteria, hypothesizing that our patients might present differently early in the illness.

METHOD

In a hospital-based retrospective observational study, we assessed 48 probable bvFTD patients, diagnosed according to the FTDC criteria, for the speed with which these criteria were fulfilled, the frequency of individual symptoms and their order of appearance during the illness.

RESULTS

Most of our patients presented with moderate to severe dementia, in spite of having relatively short onset to diagnosis times. Patients on average took 1.4 years from onset to meet the FTDC criteria, with 90% of them presenting with four or more symptoms at diagnosis. Disinhibition was the commonest symptom and the first symptom in most patients.

CONCLUSION

With most patients presenting with advanced and florid disease, the FTDC criteria have little additional impact in early identification of bvFTD in India. Modifying the criteria further could allow detection of Indian patients early enough for their inclusion in future clinical trials.

Clinical diagnostic criteria and classification controversies in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) can manifest as a spectrum of clinical syndromes, ranging from behavioural impairment to language or motor dysfunction. Recently, revised diagnostic criteria have been proposed for the behavioural and progressive aphasia syndromes associated with frontotemporal degeneration. The present review will summarize these diagnostic guidelines and highlight some lingering controversies in the classification of FTLD clinical syndromes. We will discuss common tools and methods used to identify the insidious changes of behavioural variant frontotemporal dementia (bvFTD), the value of new, patient-based tasks of orbitofrontal function, and the issue of a benign or 'phenocopy' variant of bvFTD. With regard to primary progressive aphasia (PPA), we will discuss the scope of the semantic disorder in semantic-variant PPA, the nature of the speech disorder in non-fluent, agrammatic PPA, and the preliminary utility of a logopenic PPA classification.

Phenotypic variety in the presentation of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is a heterogeneous syndrome characterized by a progressive decline in behaviour or language associated with degeneration of the frontal and anterior temporal lobes. FTLD can be classified into three clinical syndromes based on the early and predominant symptoms: behavioural variant frontotemporal dementia (bvFTD); semantic dementia (SD); and progressive non-fluent aphasia (PNFA). Patients with bvFTD present with marked changes in personality and behaviour such as disinhibition, apathy, loss of sympathy, compulsive behaviours, hyperorality. Neuroimaging studies have highlighted frontal atrophy, hypometabolism and hypoperfusion. SD is characterized by a fluent anomic aphasia and behavioural changes with degeneration of the anterior temporal lobes. Patients with left-sided SD present with progressive loss of word knowledge and meaning about words, objects and concepts. Patients with PNFA present slow, effortful speech, impaired production and comprehension of grammar. PNFA is associated with atrophy, hypometabolism and hypoperfusion of the left perisylvian area. However, overlap between the syndromes can occur, particularly later in the course. In the absence of definitive biomarkers, the diagnosis is dependent on clinical symptoms. A new diagnostic criterion of bvFTD was published in 2011. Identification of the syndrome's core symptoms is important in clinical diagnosis.

Functional profile of patients with behavioral variant frontotemporal dementia (bvFTD) compared to patients with Alzheimer's disease and normal controls

There are few studies describing the functional changes in behavioral variant frontotemporal dementia (bvFTD) and it is not clear which aspects of functionality are affected by the disease.

Behavioural-variant frontotemporal dementia: an update

Behavioural-variant frontotemporal dementia (bvFTD) is characterised by insidious changes in personality and interpersonal conduct that reflect progressive disintegration of the neural circuits involved in social cognition, emotion regulation, motivation and decision making. The underlying pathology is heterogeneous and classified according to the presence of intraneuronal inclusions of tau, TDP-43 or occasionally FUS. Biomarkers to detect these histopathological changes in life are increasingly important with the development of disease-modifying drugs. Gene mutations have been found which collectively account for around 10-20% of cases including a novel hexanucleotide repeat on chromosome 9 (C9orf72). The recently reviewed International Consensus Criteria for bvFTD propose three levels of diagnostic certainly: possible, probable and definite. Detailed history taking from family members to elicit behavioural features underpins the diagnostic process with support from neuropsychological testing designed to detect impairment in decision-making, emotion processing and social cognition. Brain imaging is important for increasing the level of diagnosis certainty. Carer education and support remain of paramount importance.

MRI signatures of brain macrostructural atrophy and microstructural degradation in frontotemporal lobar degeneration subtypes

Brain magnetic resonance imaging (MRI) studies have demonstrated regional patterns of brain macrostructural atrophy and white matter microstructural alterations separately in the three major subtypes of frontotemporal lobar degeneration (FTLD), which includes behavioral variant frontotemporal dementia (bvFTD), semantic dementia (SD), and progressive nonfluent aphasia (PNFA). This study was to investigate to what extent the pattern of white matter microstructural alterations in FTLD subtypes mirrors the pattern of brain atrophy, and to compare the ability of various diffusion tensor imaging (DTI) indices in characterizing FTLD patients, as well as to determine whether DTI measures provide greater classification power for FTLD than measuring brain atrophy. Twenty-five patients with FTLD (13 with bvFTD, 6 with SD, and 6 with PNFA) and 19 healthy age-matched control subjects underwent both structural MRI and DTI scans. Measurements of regional brain atrophy were based on T1-weighted MRI data and voxel-based morphometry. Measurements of regional white matter degradation were based on voxelwise as well as regions-of-interest tests of DTI variations, expressed as fractional anisotropy, axial diffusivity, and radial diffusivity. Compared to controls, bvFTD, SD, and PNFA patients each exhibited characteristic regional patterns of brain atrophy and white matter damage. DTI overall provided significantly greater accuracy for FTLD classification than brain atrophy. Moreover, radial diffusivity was more sensitive in assessing white matter damage in FTLD than other DTI indices. The findings suggest that DTI in general and radial diffusivity in particular are more powerful measures for the classification of FTLD patients from controls than brain atrophy.

Ventromedial-frontopolar prefrontal cortex atrophy correlates with insight loss in frontotemporal dementia and Alzheimer's disease

Loss in insight is a major feature of frontotemporal dementia (FTD) but has been investigated relatively little. More importantly, the neural basis of insight loss is still poorly understood. The current study investigated insight deficit profiles across a large cohort of neurodegenerative patients (n = 81), including FTD and Alzheimer's disease (AD) patients. We employed a novel insight questionnaire, which tapped into changes across different domains: social interaction, emotion, diagnosis/treatment, language, and motivation. FTD subtypes varied considerably for insight loss, with the behavioral variant worst and the progressive non-fluent variant least affected. All other subtypes and AD showed milder but consistent insight loss. Voxel-based morphometry analysis revealed that overall insight loss correlated with ventromedial and frontopolar prefrontal atrophy, with exception of social interaction and emotion insight loss, which additionally correlated with lateral temporal and amygdala atrophy, respectively. Our results show that patients with neurodegenerative conditions show variable loss of insight, with ventromedial and frontopolar cortex regions appearing to be particularly important for insight.

Environmental dependency behaviours in frontotemporal dementia: have we been underrating them?

Environmental dependency (ED) behaviours, such as imitation behaviour (IB) and incidental utilization behaviour (UB), are considered pathognomonic of a frontal lesion and can play a unique role in diagnosing behavioural variant frontotemporal dementia (bvFTD). However, with only few focused observations of ED behaviour reported in earlier studies, their roles in the diagnosis of bvFTD have so far remained supportive. In this observational study, conducted in the cognitive clinic of a tertiary-care hospital, we explored the hypotheses that a focused and systematic search could uncover more ED behaviours in patients with bvFTD, and that the presence of ED behaviours such as incidental UB and IB should allow us to cleanly differentiate bvFTD from AD. Forty-one bvFTD patients and 75 probable AD patients, all diagnosed using accepted criteria, were seen by a neurologist and a neuropsychologist. Information regarding ED behaviour was obtained from the caregiver's history, observations for spontaneous behaviour and induction of the behaviour in the clinic. All ED behaviours were significantly more frequent in bvFTD compared with AD. UB (78 %; 66 % incidental) and IB (59 %) occurred exclusively in bvFTD. Multi-pronged and focused clinical assessment contributed to the high frequency of ED behaviours. Nearly two-thirds of bvFTD patients, but none with AD, showed three or more ED behaviours. We concluded that ED behaviours are more common in bvFTD than is currently recognized. UB, IB or three ED behaviours, if present, could clearly differentiate bvFTD from AD. A focused search should consistently uncover ED behaviours in bvFTD patients.

Disturbance of emotion processing in frontotemporal dementia: a synthesis of cognitive and neuroimaging findings

Accurate processing of emotional information is a critical component of appropriate social interactions and interpersonal relationships. Disturbance of emotion processing is present in frontotemporal dementia (FTD) and is a clinical feature in two of the three subtypes: behavioural-variant FTD and semantic dementia. Emotion processing in progressive nonfluent aphasia, the third FTD subtype, is thought to be mostly preserved, although current evidence is scant. This paper reviews the literature on emotion recognition, reactivity and expression in FTD subtypes, although most studies focus on emotion recognition. The relationship between patterns of emotion processing deficits and patterns of neural atrophy are considered, by integrating evidence from recent neuroimaging studies. The review findings are discussed in the context of three contemporary theories of emotion processing: the limbic system model, the right hemisphere model and a multimodal system of emotion. Results across subtypes of FTD are most consistent with the multimodal system model, and support the presence of somewhat dissociable neural correlates for basic emotions, with strongest evidence for the emotions anger and sadness. Poor emotion processing is evident in all three subtypes, although deficits are more widespread than what would be predicted based on studies in healthy cohorts. Studies that include behavioural and imaging data are limited. Future investigations combining these approaches will help improve the understanding of the neural network underlying emotion processing. Presently, longitudinal investigations of emotion processing in FTD are lacking, and studies investigating emotion processing over time are critical to understand the clinical manifestations of disease progression in FTD.

Differential impairment of source memory in progressive versus non-progressive behavioral variant frontotemporal dementia

Episodic memory has recently been shown to be impaired in the behavioral variant of frontotemporal dementia (bvFTD) when so-called non-progressive cases are excluded. Such non-progressive cases present with the behavioral features of bvFTD, but show no evidence of cognitive decline over time. To date, evidence regarding episodic memory performance in bvFTD subgroups on more stringent tasks is lacking. We investigated temporal and spatial source memory in progressive (n = 7) versus non-progressive (n = 12) bvFTD. BvFTD cases were retrospectively classified based on general cognitive decline on the Addenbrooke's Cognitive Examination Revised, and the presence of atrophy on structural neuroimaging, over 3 years following diagnosis. Progressors showed impaired temporal and spatial source retrieval. Non-progressors displayed temporal source deficits only. These differential source memory profiles point to the variability of episodic memory performance in bvFTD, and underscore the importance of differential diagnosis of bvFTD subgroups using longitudinal and neuroimaging data.

Neural correlates of behavioural symptoms in behavioural variant frontotemporal dementia and Alzheimer's disease: Employment of a visual MRI rating scale

Frontotemporal dementia (FTD) patients often present with severe behavioural disturbances and concomitant lack of insight. The underlying neural correlates of these disturbances are mostly attributed to prefrontal cortex dysfunction, but are still poorly understood.

Social cognition, executive functioning, and neuroimaging correlates of empathic deficits in frontotemporal dementia

The authors investigated aspects of interpersonal sensitivity and perspective-taking in relation to empathy, social cognitions, and executive functioning in 26 frontotemporal dementia (FTD) patients. Behavioral-variant FTD (bvFTD) patients were significantly impaired on caregiver assessments of empathy, although self-ratings were normal. Progressive nonfluent aphasia and semantic-dementia samples were rarely abnormal. In bvFTD, empathy ratings were found to be correlated with social cognition and executive functioning measures, but not depression. Voxel-based morphometry revealed that reduced empathic perspective-taking was related to bifrontal and left anterior temporal atrophy, whereas empathic emotions were related to right medial frontal atrophy. Findings suggest that bvFTD causes multiple types of breakdown in empathy, social cognition, and executive resources, mediated by frontal and temporal disease.

Loss of emotional insight in behavioral variant frontotemporal dementia or "frontal anosodiaphoria"

Loss of insight is a prominent clinical manifestation of behavioral variant frontotemporal dementia (bvFTD), but its characteristics are poorly understood. Twelve bvFTD patients were compared with 12 Alzheimer's disease (AD) patients on a structured insight interview of cognitive insight (awareness of having a disorder) and emotional insight (concern over having a disorder). Compared to the AD patients, the bvFTD patients were less aware and less concerned about their disorder, and they had less appreciation of its effects on themselves and on others. After corrective feedback ("updating"), the bvFTD patients were just as aware of their disorder as the AD patients but remained unconcerned and unappreciative of its effects. These findings suggest that lack of insight in bvFTD is not due to "anosognosia," or impaired cognitive and executive awareness of disease, but to "frontal anosodiaphoria," or lack of emotional concern over having bvFTD and its impact on themselves and others.

Nonprogressive behavioural frontotemporal dementia: recent developments and clinical implications of the 'bvFTD phenocopy syndrome'

PURPOSE OF REVIEW

The clinical features of behavioural variant frontotemporal dementia (bvFTD) are well established; however, recent work has identified patients fulfilling diagnostic criteria for the disease who do not appear to progress clinically. This review describes means of distinguishing this group at an early stage from patients who are likely to deteriorate.

RECENT FINDINGS

Despite indistinguishable clinical profiles, studies in a cohort of bvFTD patients showed a particularly good prognosis in a subgroup of predominantly male patients in whom initial structural imaging was normal. This could not be explained by differences in disease duration, and was confirmed by subsequent PET studies. Retrospective review of clinical data in these groups verified that the current clinical diagnostic criteria are both insensitive to true progressive bvFTD, particularly in the early stages, and also poorly specific. In contrast, measures of activity of daily living performance, executive function and tests of social cognition appear to have better discriminatory value for patients who show clear clinical progression, with many individual diagnoses verified by post mortem examination in this group.

SUMMARY

It remains doubtful that the nonprogressive group have a neurodegenerative disease. The implication for the current clinical diagnostic criteria and their proposed revision is discussed.

Sensitivity of revised diagnostic criteria for the behavioural variant of frontotemporal dementia

Based on the recent literature and collective experience, an international consortium developed revised guidelines for the diagnosis of behavioural variant frontotemporal dementia. The validation process retrospectively reviewed clinical records and compared the sensitivity of proposed and earlier criteria in a multi-site sample of patients with pathologically verified frontotemporal lobar degeneration. According to the revised criteria, 'possible' behavioural variant frontotemporal dementia requires three of six clinically discriminating features (disinhibition, apathy/inertia, loss of sympathy/empathy, perseverative/compulsive behaviours, hyperorality and dysexecutive neuropsychological profile). 'Probable' behavioural variant frontotemporal dementia adds functional disability and characteristic neuroimaging, while behavioural variant frontotemporal dementia 'with definite frontotemporal lobar degeneration' requires histopathological confirmation or a pathogenic mutation. Sixteen brain banks contributed cases meeting histopathological criteria for frontotemporal lobar degeneration and a clinical diagnosis of behavioural variant frontotemporal dementia, Alzheimer's disease, dementia with Lewy bodies or vascular dementia at presentation. Cases with predominant primary progressive aphasia or extra-pyramidal syndromes were excluded. In these autopsy-confirmed cases, an experienced neurologist or psychiatrist ascertained clinical features necessary for making a diagnosis according to previous and proposed criteria at presentation. Of 137 cases where features were available for both proposed and previously established criteria, 118 (86%) met 'possible' criteria, and 104 (76%) met criteria for 'probable' behavioural variant frontotemporal dementia. In contrast, 72 cases (53%) met previously established criteria for the syndrome (P < 0.001 for comparison with 'possible' and 'probable' criteria). Patients who failed to meet revised criteria were significantly older and most had atypical presentations with marked memory impairment. In conclusion, the revised criteria for behavioural variant frontotemporal dementia improve diagnostic accuracy compared with previously established criteria in a sample with known frontotemporal lobar degeneration. Greater sensitivity of the proposed criteria may reflect the optimized diagnostic features, less restrictive exclusion features and a flexible structure that accommodates different initial clinical presentations. Future studies will be needed to establish the reliability and specificity of these revised diagnostic guidelines.

Sensitivity of revised diagnostic criteria for the behavioural variant of frontotemporal dementia

Based on the recent literature and collective experience, an international consortium developed revised guidelines for the diagnosis of behavioural variant frontotemporal dementia. The validation process retrospectively reviewed clinical records and compared the sensitivity of proposed and earlier criteria in a multi-site sample of patients with pathologically verified frontotemporal lobar degeneration. According to the revised criteria, 'possible' behavioural variant frontotemporal dementia requires three of six clinically discriminating features (disinhibition, apathy/inertia, loss of sympathy/empathy, perseverative/compulsive behaviours, hyperorality and dysexecutive neuropsychological profile). 'Probable' behavioural variant frontotemporal dementia adds functional disability and characteristic neuroimaging, while behavioural variant frontotemporal dementia 'with definite frontotemporal lobar degeneration' requires histopathological confirmation or a pathogenic mutation. Sixteen brain banks contributed cases meeting histopathological criteria for frontotemporal lobar degeneration and a clinical diagnosis of behavioural variant frontotemporal dementia, Alzheimer's disease, dementia with Lewy bodies or vascular dementia at presentation. Cases with predominant primary progressive aphasia or extra-pyramidal syndromes were excluded. In these autopsy-confirmed cases, an experienced neurologist or psychiatrist ascertained clinical features necessary for making a diagnosis according to previous and proposed criteria at presentation. Of 137 cases where features were available for both proposed and previously established criteria, 118 (86%) met 'possible' criteria, and 104 (76%) met criteria for 'probable' behavioural variant frontotemporal dementia. In contrast, 72 cases (53%) met previously established criteria for the syndrome (P < 0.001 for comparison with 'possible' and 'probable' criteria). Patients who failed to meet revised criteria were significantly older and most had atypical presentations with marked memory impairment. In conclusion, the revised criteria for behavioural variant frontotemporal dementia improve diagnostic accuracy compared with previously established criteria in a sample with known frontotemporal lobar degeneration. Greater sensitivity of the proposed criteria may reflect the optimized diagnostic features, less restrictive exclusion features and a flexible structure that accommodates different initial clinical presentations. Future studies will be needed to establish the reliability and specificity of these revised diagnostic guidelines.

Convergent grey and white matter evidence of orbitofrontal cortex changes related to disinhibition in behavioural variant frontotemporal dementia

Disinhibition is a common behavioural symptom in frontotemporal dementia but its neural correlates are still debated. In the current study, we investigated the grey and white matter neural correlates of disinhibition in a sample of behavioural variant frontotemporal dementia (n = 14) and patients with Alzheimer's disease (n = 15). We employed an objective (Hayling Test of inhibitory functioning) and subjective/carer-based (Neuropsychiatric Inventory) measure of disinhibition to reveal convergent evidence of disinhibitory behaviour. Mean and overlap-based statistical analyses were conducted to investigate profiles of performance in patients with behavioural variant frontotemporal dementia, Alzheimer's disease and controls. Hayling Test and Neuropsychiatric Inventory scores were entered as covariates in a grey matter voxel-based morphometry, as well as in a white matter diffusion tensor imaging analysis to determine the underlying grey and white matter correlates. Patients with behavioural variant frontotemporal dementia showed more disinhibition on both behavioural measures in comparison to patients with Alzheimer's disease and controls. Voxel-based morphometry results revealed that atrophy in orbitofrontal/subgenual, medial prefrontal cortex and anterior temporal lobe areas covaried with total errors score of the Hayling Test. Similarly, the Neuropsychiatric Inventory disinhibition frequency score correlated with atrophy in orbitofrontal cortex and temporal pole brain regions. The orbitofrontal atrophy related to the objective (Hayling Test) and subjective (Neuropsychiatric Inventory) measures of disinhibition was partially overlapping. Diffusion tensor imaging analysis revealed that white matter integrity fractional anisotropy values of the white matter tracts connecting the identified grey matter regions, namely uncinate fasciculus, forceps minor and genu of the corpus callosum, correlated well with the total error score of the Hayling Test. Our results show that a network of orbitofrontal, anterior temporal and mesial frontal brain regions and their connecting white matter tracts are involved in inhibitory functioning. Further, we find convergent evidence for objective and subjective disinhibition measures that the orbitofrontal/subgenual brain region is critical for adapting and maintaining normal behaviour.

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

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

Eating disturbance in behavioural-variant frontotemporal dementia

Behavioural-variant frontotemporal dementia (bvFTD) is a progressive neurodegenerative brain disorder, clinically characterised by changes in cognition, personality and behaviour. Marked disturbances in eating behaviour, such as overeating and preference for sweet foods, are also commonly reported. This paper reviews the current literature on eating abnormalities in bvFTD, their clinical characteristics and biological correlates, and the contribution of hypothalamus to eating regulation. Existing literature shows that disturbance in an orbitofrontal-insular-striatal brain network underlies the emergence of eating disturbance in bvFTD. In addition, recent evidence indicates that degeneration and consequent dysregulation within the hypothalamus relates to significant feeding disturbance in this disease. These findings could provide a basis for the development of therapeutic models in bvFTD.

Assessment of mild dementia with amyloid and dopamine terminal positron emission tomography

We assessed the relationship between consensus clinical diagnostic classification and neurochemical positron emission tomography imaging of striatal vesicular monoamine transporters and cerebrocortical deposition of aβ-amyloid in mild dementia. Seventy-five subjects with mild dementia (Mini-Mental State Examination score≥18) underwent a conventional clinical evaluation followed by 11C-dihydrotetrabenazine positron emission tomography imaging of striatal vesicular monoamine transporters and 11C-Pittsburgh compound-B positron emission tomography imaging of cerebrocortical aβ-amyloid deposition. Clinical classifications were assigned by consensus of an experienced clinician panel. Neuroimaging classifications were assigned as Alzheimer's disease, frontotemporal dementia or dementia with Lewy bodies on the basis of the combined 11C-dihydrotetrabenazine and 11C-Pittsburgh compound-B results. Thirty-six subjects were classified clinically as having Alzheimer's disease, 25 as having frontotemporal dementia and 14 as having dementia with Lewy bodies. Forty-seven subjects were classified by positron emission tomography neuroimaging as having Alzheimer's disease, 15 as having dementia with Lewy bodies and 13 as having frontotemporal dementia. There was only moderate agreement between clinical consensus and neuroimaging classifications across all dementia subtypes, with discordant classifications in ∼35% of subjects (Cohen's κ=0.39). Discordant classifications were least frequent in clinical consensus Alzheimer's disease (17%), followed by dementia with Lewy bodies (29%) and were most common in frontotemporal dementia (64%). Accurate clinical classification of mild neurodegenerative dementia is challenging. Though additional post-mortem correlations are required, positron emission tomography imaging likely distinguishes subgroups corresponding to neurochemically defined pathologies. Use of these positron emission tomography imaging methods may augment clinical classifications and allow selection of more uniform subject groups in disease-modifying therapeutic trials and other prospective research involving subjects in the early stages of dementia.

Social cognition, executive functioning, and neuroimaging correlates of empathic deficits in frontotemporal dementia

The authors investigated aspects of interpersonal sensitivity and perspective-taking in relation to empathy, social cognitions, and executive functioning in 26 frontotemporal dementia (FTD) patients. Behavioral-variant FTD (bvFTD) patients were significantly impaired on caregiver assessments of empathy, although self-ratings were normal. Progressive nonfluent aphasia and semantic-dementia samples were rarely abnormal. In bvFTD, empathy ratings were found to be correlated with social cognition and executive functioning measures, but not depression. Voxel-based morphometry revealed that reduced empathic perspective-taking was related to bifrontal and left anterior temporal atrophy, whereas empathic emotions were related to right medial frontal atrophy. Findings suggest that bvFTD causes multiple types of breakdown in empathy, social cognition, and executive resources, mediated by frontal and temporal disease.

Behavioural-variant frontotemporal dementia: diagnosis, clinical staging, and management

Patients with behavioural-variant frontotemporal dementia (bvFTD) present with insidious changes in personality and interpersonal conduct that indicate progressive disintegration of the neural circuits involved in social cognition, emotion regulation, motivation, and decision making. The underlying pathological changes are heterogeneous and are characterised by various intraneuronal inclusions. Biomarkers to detect these histopathological changes in life are becoming increasingly important with the development of disease-modifying drugs. Gene mutations have been found that collectively account for around 10-20% of cases. Recently, criteria proposed for bvFTD define three levels of diagnostic certainty: possible, probable, and definite. Detailed history taking from family members to elicit behavioural features underpins the diagnostic process, with support from neuropsychological testing designed to detect impairment in decision making, emotion processing, and social cognition. Brain imaging is important for increasing the level of diagnostic certainty. A recently developed staging instrument shows much promise for monitoring patients and evaluating therapies, which at present are aimed at symptom amelioration. Carer education and support remain of paramount importance.

Eating and hypothalamus changes in behavioral-variant frontotemporal dementia

OBJECTIVE

Behavioral-variant frontotemporal dementia (bvFTD) is a progressive neurodegenerative brain disorder, clinically characterized by changes in cognition, personality, and behavior. Marked disturbances in eating behavior, such as overeating and preference for sweet foods, are also commonly reported. The hypothalamus plays a critical role in feeding regulation, yet the relation between pathology in this region and eating behavior in FTD is unknown. This study aimed to address this issue using 2 complementary approaches.

METHODS

First, 18 early stage bvFTD patients and 16 healthy controls underwent high-resolution structural magnetic resonance imaging and assessment of eating behavior. Hypothalamic volumes were traced manually on coronal images. Second, postmortem analyses of 12 bvFTD cases and 6 matched controls were performed. Fixed hypothalamic tissue sections were stained for a cell marker and for peptides regulating feeding behaviors using immunohistochemistry. Stereological estimates of the hypothalamic volume and the number of neurons and glia were performed.

RESULTS

Significant atrophy of the hypothalamus in bvFTD was present in both analyses. Patients with high feeding disturbance exhibited significant atrophy of the posterior hypothalamus. Neuronal loss, which was observed only in bvFTD cases with Tar DNA protein-43 deposition, was also predominant posteriorly. In contrast, orexin (hypocretin), neuropeptide Y, cocaine- and amphetamine-regulating transcript, and vasopressin-containing neurons that regulate appetite were spared in posterior nuclei known to participate in feeding regulation.

INTERPRETATION

Degeneration and consequent dysregulation within the hypothalamus relates to significant feeding disturbance in bvFTD. These findings provide a basis for the development of therapeutic models.

How preserved is episodic memory in behavioral variant frontotemporal dementia?

OBJECTIVE

Studies have shown variable memory performance in patients with behavioral variant frontotemporal dementia (bvFTD). Our study investigated whether this variability is due to the admixture of patients with true bvFTD and phenocopy patients. We also sought to compare performance of patients with bvFTD and patients with Alzheimer disease (AD).

METHODS

We analyzed neuropsychological memory performance in patients with a clinical diagnosis of bvFTD divided into those who progressed (n = 50) and those who remained stable (n = 39), patients with AD (n = 64), and healthy controls (n = 64).

RESULTS

Patients with progressive bvFTD were impaired on most memory tests to a similar level to that of patients with early AD. Findings from a subset of patients with progressive bvFTD with confirmed FTLD pathology (n = 10) corroborated these findings. By contrast, patients with phenocopy bvFTD performed significantly better than progressors and patients with AD. Logistic regression revealed that patients with bvFTD can be distinguished to a high degree (85%) on the immediate recall score of a word list learning test (Rey Auditory Verbal Learning Test).

CONCLUSIONS

Our results provide evidence for an underlying memory deficit in "real" or progressive behavioral variant frontotemporal dementia (bvFTD) similar to Alzheimer disease, though the groups differ in orientation scores, with patients with bvFTD being intact. Exclusion solely based on impaired neuropsychological memory performance can potentially lead to an underdiagnosis of FTD.

Determinants of survival in behavioral variant frontotemporal dementia

BACKGROUND

Behavioral variant frontotemporal dementia (bvFTD) is a common cause of younger onset dementia. Little is known about its rate of progression but a recently identified subgroup seems to have an excellent prognosis. Other determinants of survival are unclear.

METHODS

We analyzed survival in a large group of clinically diagnosed bvFTD patients (n = 91) with particular attention to demographic and clinical features at presentation. Of the 91 cases, 50 have died, with pathologic confirmation in 28.

RESULTS

Median survival in the whole group was 9.0 years from symptom onset, and 5.4 years from diagnosis. After the exclusion of 24 "phenocopy" cases, the analysis was repeated in a subgroup of 67 patients. The mean age at symptom onset of the pathologic group was 58.5 years and 16% had a positive family history. Their median survival was 7.6 years (95% confidence interval [CI] 6.6-8.6) from symptom onset and 4.2 years (95% CI 3.4-5.0) from diagnosis. The only factor associated with shorter survival was the presence of language impairment at diagnosis.

CONCLUSIONS

Patients with definite frontotemporal dementia have a poor prognosis which is worse if language deficits are also present. This contrasts with the extremely good outcome in those with the phenocopy syndrome: of our 24 patients only 1 has died (of coincident pathology) despite, in some cases, many years of follow-up.

Frontotemporal dementia and dementia with Lewy bodies in a case-control study of Alzheimer's disease

BACKGROUND

The clinical presentations in dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD) overlap considerably with that of Alzheimer's disease (AD) despite different pathological processes. Autopsy studies have also shown that multiple brain pathology occurs frequently, even in cases with a single clinical diagnosis. We aimed to determine the frequency of clinical diagnosis of FTD and DLB and the underlying pathology in a well-characterized cohort of patients with a clinical diagnosis of probable or possible AD.

METHODS

We conducted a retrospective analysis of 170 AD patients (probable AD = 83; possible AD = 87) originally enrolled in a case-control study, 27 with postmortem examination, to establish the number of cases meeting probable diagnosis for FTD and DLB, using a checklist of features compiled from their consensus criteria.

RESULTS

23/83 probable AD cases and 32/87 possible AD cases met probable criteria for another dementia, more commonly DLB than FTD. AD pathology was present in 8/15 probable AD and 8/12 possible AD cases coming to autopsy. DLB pathology was seen in four cases and FTD pathology in eight cases. In the AD cases reaching clinical diagnosis for a second dementia syndrome and coming to autopsy, a minority showed non-AD pathology only.

CONCLUSIONS

Presence of core clinical features of non-AD dementia syndromes is common in AD. Concordance between clinical and pathological diagnoses of dementia remains variable. We propose that repeat clinical examinations and structural neuroimaging will improve diagnostic accuracy. In addition, clinical diagnostic criteria for the main dementia syndromes require refinement.