Convergence of connected language and SPECT in variants of frontotemporal lobar degeneration

The characterization of frontotemporal lobar degeneration (FTLD) is complicated and not widely recognized. Connected language measures (ie, discourse) and functional neuroimaging may advance knowledge specifying early distinctions among frontal dementias. The present study examined the correspondence of discourse measures with (1) clinical diagnosis and (2) single photon emission computed tomography (SPECT) imaging. Nineteen subjects were selected from Alzheimer's Disease Center (ADC) participants if they were diagnosed with early-stage frontotemporal lobar degeneration and also underwent single photon emission computed tomography and discourse evaluation. First, clinical diagnoses given by specialists at an Alzheimer's Disease Center were compared with the discourse-based diagnostic profiles. Secondly, compromised brain regions that were predicted from discourse profiles were compared with SPECT findings. Results revealed a significant correspondence between the ADC diagnosis and the discourse-based diagnoses. Also, the discourse profiles across frontotemporal lobar degeneration subtypes were consistently associated with distinctive patterns of SPECT hypometabolism in the right frontal, left frontal, or left temporal lobes. These findings suggest that discourse methods may be systematized to provide an efficient adjunct measure beyond the traditional word and sentential level measures. Objectifying complex language performance may contribute to early detection and differentiation among frontotemporal lobar degeneration variants because consensus in the literature states that language is a core disturbance of frontotemporal lobar degeneration.     

Episodic memory and regional atrophy in frontotemporal lobar degeneration

It has been unclear to what extent memory is affected in frontotemporal lobar degeneration (FTLD). Since patients usually have atrophy in regions implicated in memory function, the frontal and/or temporal lobes, one would expect some memory impairment, and that the degree of atrophy in these regions would be inversely related to memory function. The purposes of this study were (1) to assess episodic memory function in FTLD, and more specifically patients' ability to episodically re-experience an event, and determine its source; (2) to examine whether memory performance is related to quantified regional brain atrophy. FTLD patients (n=18) and healthy comparison subjects (n=14) were assessed with cued recall, recognition, "remember/know" (self-reported re-experiencing) and source recall, at 30 min and 24h after encoding. Regional gray matter volumes were assessed with high resolution structural MRI concurrently to testing. Patients performed worse than comparison subjects on all memory measures. Gray matter volume in the left medial temporal lobe was positively correlated with recognition, re-experiencing, and source recall. Gray matter volume in the left posterior temporal lobe correlated significantly with recognition, at 30 min and 24h, and with source recall at 30 min. Estimated familiarity at 30 min was positively correlated with gray matter volume in the left inferior parietal lobe. In summary, episodic memory deficits in FTLD may be more common than previously thought, particularly in patients with left medial and posterior temporal atrophy.     

Patterns of white matter atrophy in frontotemporal lobar degeneration

BACKGROUND: Structural magnetic resonance imaging (MRI) has been used to investigate the in vivo pathology of frontotemporal lobar degeneration. However, few neuroimaging studies have focused on white matter (WM) alterations in this disease. OBJECTIVES: To use volumetric MRI techniques to identify the patterns of WM atrophy in vivo in 2 clinical variants of frontotemporal lobar degeneration-frontotemporal dementia (FTD) and semantic dementia-and to compare the patterns of WM atrophy with those of gray matter (GM) atrophy in these diseases. DESIGN: Structural MRIs were obtained from patients with FTD (n = 12) and semantic dementia (n = 13) and in cognitively healthy age-matched controls (n = 24). Regional GM and WM were classified automatically from high-resolution T1-, T2-, and proton density-weighted MRIs with Expectation-Maximization Segmentation and compared between the groups using a multivariate analysis of covariance model that included age and WM lesion volumes as covariates. RESULTS: Patients with FTD had frontal WM atrophy and frontal, parietal, and temporal GM atrophy compared with controls, who had none. Patients with semantic dementia had temporal WM and GM atrophy and patients with FTD had frontal GM atrophy. Adding temporal WM volume to temporal GM volume significantly improved the discrimination between semantic dementia and FTD. CONCLUSIONS: These results show that patients with frontotemporal lobar degeneration who are in relatively early stages of the disease (Clinical Dementia Rating score, 1.0-1.2) have WM atrophy that largely parallels the pattern of GM atrophy typically associated with these disorders.     

Autobiographical memory and patterns of brain atrophy in frontotemporal lobar degeneration

Autobiographical memory paradigms have been increasingly used to study the behavioral and neuroanatomical correlates of human remote memory. Although there are numerous functional neuroimaging studies on this topic, relatively few studies of patient samples exist, with heterogeneity of results owing to methodological variability. In this study, fronto-temporal lobar degeneration (FTLD), a form of dementia affecting regions crucial to autobiographical memory, was used as a model of autobiographical memory loss. We emphasized the separation of episodic (recollection of specific event, perceptual, and mental state information) from semantic (factual information unspecific in time and place) autobiographical memory, derived from a reliable method for scoring transcribed autobiographical protocols, the Autobiographical Interview [Levine, B., Svoboda, E., Hay, J., Winocur, G., & Moscovitch, M. Aging and autobiographical memory: Dissociating episodic from semantic retrieval. Psychology and Aging, 17, 677-689, 2002]. Patients with the fronto-temporal dementia (FTD) and mixed fronto-temporal and semantic dementia (FTD/SD) variants of FTLD were impaired at reconstructing episodically rich autobiographical memories across the lifespan, with FTD/SD patients generating an excess of generic semantic autobiographical information. Patients with progressive nonfluent aphasia were mildly impaired for episodic autobiographical memory, but this impairment was eliminated with the provision of structured cueing, likely reflecting relatively intact medial-temporal lobe function, whereas the same cueing failed to bolster the FTD and FTD/SD patients' performance relative to that of matched comparison subjects. The pattern of episodic, but not semantic, autobiographical impairment was enhanced with disease progression on 1- to 2-year follow-up testing in a subset of patients, supplementing the cross-sectional evidence for specificity of episodic autobiographical impairment with longitudinal data. This behavioral pattern covaried with volume loss in a distributed left-lateralized posterior network centered on the temporal lobe, consistent with evidence from other patient and functional neuroimaging studies of autobiographical memory. Frontal lobe volumes, however, did not significantly contribute to this network, suggesting that frontal contributions to autobiographical episodic memory may be more complex than previously appreciated.     

Mapping the onset and progression of atrophy in familial frontotemporal lobar degeneration

BACKGROUND: Frontotemporal lobar degeneration (FTLD) may be inherited as an autosomal dominant disease. Studying patients "at risk" for developing FTLD can provide insights into the earliest onset and evolution of the disease. METHOD: We carried out approximately annual clinical, MRI, and neuropsychological assessments on an asymptomatic 51 year old "at risk" family member from a family with FTLD associated with ubiquitin-positive and tau-negative inclusion bodies. We used non-linear (fluid) registration of serial MRI to determine areas undergoing significant regional atrophy at different stages of the disease. RESULTS: Over the first 26 months of the study, the patient remained asymptomatic, but subsequently developed progressive speech production difficulties, and latterly severe orofacial dyspraxia, dyscalculia, frontal executive impairment, and limb dyspraxia. Regional atrophy was present prior to the onset of symptoms, and was initially centred on the left dorsolateral prefrontal cortex and the left middle frontal gyrus. Latterly, there was increasing asymmetric left frontal and parietal atrophy. Imaging revealed excess and increasing global atrophy throughout the study. Neuropsychological evaluation revealed mild intellectual impairment prior to the onset of these clinical symptoms; frontal executive and left parietal impairment subsequently emerged, culminating in widespread cognitive impairment. Fluid registered MRI allowed the emerging atrophy patterns to be delineated. CONCLUSION: We have demonstrated the onset and progressive pattern of in vivo atrophy in familial FTLD using fluid registered MRI and correlated this with the clinical features. Fluid registered MRI may be a useful technique in assessing patterns of focal atrophy in vivo and demonstrating the progression of degenerative diseases.     

Hippocampal atrophy on MRI in frontotemporal lobar degeneration and Alzheimer's disease

BACKGROUND: Hippocampal atrophy on magnetic resonance imaging (MRI) is an early characteristic of Alzheimer's disease. However, hippocampal atrophy may also occur in other dementias, such as frontotemporal lobar degeneration (FTLD). OBJECTIVE: To investigate hippocampal atrophy on MRI in FTLD and its three clinical subtypes, in comparison with Alzheimer's disease, using volumetry and a visual rating scale. METHODS: 42 patients with FTLD (17 frontotemporal dementia, 13 semantic dementia, and 12 progressive non-fluent aphasia), 103 patients with Alzheimer's disease, and 73 controls were included. Hippocampal volumetry and the easily applicable medial temporal lobe atrophy (MTA) rating scale were applied to assess hippocampal atrophy. RESULTS: Multivariate analysis of variance for repeated measures showed an effect of diagnostic group on hippocampal volume. There was a significant diagnosis by side (left v right) interaction. Both FTLD and Alzheimer's disease showed hippocampal atrophy compared with controls. Results of the visual MTA rating scale confirmed these findings. Within the FTLD subtypes there were marked differences in hippocampal atrophy. Frontotemporal dementia and semantic dementia showed bilateral hippocampal atrophy, and in semantic dementia the left hippocampus was smaller than in Alzheimer's disease. No significant hippocampal atrophy was detected in non-fluent progressive aphasia. CONCLUSIONS: Hippocampal atrophy is not only a characteristic of Alzheimer's disease but also occurs in FTLD. The three clinical subtypes of FTLD show different patterns of hippocampal atrophy.     

Occupation attributes relate to location of atrophy in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) often presents with asymmetric atrophy. We assessed whether premorbid occupations in FTLD patients were associated with these hemispheric asymmetries. In a multi-center chart review of 588 patients, occupation information was related to location of tissue loss or dysfunction. Patients with atrophy lateralized to the right had professions more dependent on verbal abilities than patients with left-lateralized or symmetrical atrophy. In a subgroup of 96 well-characterized patients with quantified neuroimaging data, the lateralization effect was localized to the temporal lobes and included verbal and mathematical ability. Patients whose professions placed high demands on language and mathematics had relatively preserved left temporal relative to right temporal volumes. Thus, occupation selection occurring in early adulthood is related to lateralized brain asymmetry in patients who develop FTLD decades later in the relatively deficient hemisphere. The finding suggests that verbal and mathematical occupations may have been pursued due to developmental right-lateralized functional impairment that precedes the neurodegenerative process. Alternatively, long-term engagement of activities associated with these occupations contributed to left-lateralized reserve, right-lateralized dysfunction, or both.     

Distinct MRI atrophy patterns in autopsy-proven Alzheimer's disease and frontotemporal lobar degeneration

To better define the anatomic distinctions between Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD), we retrospectively applied voxel-based morphometry to the earliest magnetic resonance imaging scans of autopsy-proven AD (N = 11), FTLD (N = 18), and controls (N = 40). Compared with controls, AD patients showed gray matter reductions in posterior temporoparietal and occipital cortex; FTLD patients showed atrophy in medial prefrontal and medial temporal cortex, insula, hippocampus, and amygdala; and patients with both disorders showed atrophy in dorsolateral and orbital prefrontal cortex and lateral temporal cortex (P(FWE-corr) < .05). Compared with FTLD, AD patients had decreased gray matter in posterior parietal and occipital cortex, whereas FTLD patients had selective atrophy in anterior cingulate, frontal insula, subcallosal gyrus, and striatum (P < .001, uncorrected). These findings suggest that AD and FTLD are anatomically distinct, with degeneration of a posterior parietal network in AD and degeneration of a paralimbic fronto-insular-striatal network in FTLD.     

Delusions in frontotemporal lobar degeneration

We assessed the significance and nature of delusions in frontotemporal lobar degeneration (FTLD), an important cause of young-onset dementia with prominent neuropsychiatric features that remain incompletely characterised. The case notes of all patients meeting diagnostic criteria for FTLD attending a tertiary level cognitive disorders clinic over a three year period were retrospectively reviewed and eight patients with a history of delusions were identified. All patients underwent detailed clinical and neuropsychological evaluation and brain MRI. The diagnosis was confirmed pathologically in two cases. The estimated prevalence of delusions was 14 %. Delusions were an early, prominent and persistent feature. They were phenomenologically diverse; however paranoid and somatic delusions were prominent. Behavioural variant FTLD was the most frequently associated clinical subtype and cerebral atrophy was bilateral or predominantly right-sided in most cases. We conclude that delusions may be a clinical issue in FTLD, and this should be explored further in future work.     

Progranulin and frontotemporal lobar degeneration

Frontotemporal lobar degeneration is the term used to describe the non-Alzheimer clinical syndromes of frontotemporal dementia, semantic dementia and progressive non-fluent aphasia, regardless of the underlying neuropathological features. Considerable progress has been made in recent years in our understanding of the aetiology of this disorder, notably the identification of mutations in tau and progranulin genes, both on chromosome 17q21. Mutations in tau appear to affect the ability of tau to bind microtubules and/or increase this protein’s ability to form fibrils. In contrast, progranulin mutations cause haploinsufficiency leading to TDP-43 accumulation. These genes collectively account for 10–20% of FTLD. However, it is clear that much remains to be discovered before our knowledge of this heterogeneous condition is complete.     

Patterns of MRI atrophy in tau positive and ubiquitin positive frontotemporal lobar degeneration

We applied optimised voxel based morphometry (VBM) to brain MRIs from autopsy proven cases of tau positive frontotemporal lobar degeneration (FTLD-T, n = 6), ubiquitin and TDP-43 positive/tau negative FTLD (FTLD-U, n = 8) and cognitively normal controls (n = 61). The analysis revealed that FTLD-T and FTLD-U both show atrophy in the frontal cortex and striatum, but striatal atrophy is more severe in FTLD-T. Manual region of interest tracing of caudate and putamen volumes confirmed the VBM findings. These anatomical differences may help distinguish between FTLD spectrum pathological subtypes in vivo.     

Epidemiology of frontotemporal lobar degeneration

A few epidemiologic studies have dealt with the prevalence of frontotemporal lobar degeneration (FTLD), including Pick's disease. The aim of this study was to review the epidemiologic studies of FTLD in western countries and to compare them with those in Japan. A community-based study of early-onset dementia in London revealed that 12% of cases with frontotemporal dementia (FTD) fulfilled the Lund-Manchester criteria in contrast to 34% of cases with Alzheimer's disease (AD) in a sample of 185 cases. The Cambridge Group has recently examined the prevalence of early-onset dementia in a community-based study. Of 108 cases, 15.7% had FTLD and 25% had AD. FTLD included 13 FTD cases, and 2 each with semantic dementia (SD) and nonfluent progressive aphasia (PA). Almost one third of cases with FTLD (29%) had a positive family history. Of our consecutive 330 outpatients with dementia (hospital setting without age limitation), 42 (12.7%) had FTLD and 215 (65.1%) had AD. In our series of patients, 22 FTD, 15 SD and 5 PA cases were identified. There was no family history in all subtypes of FTLD. Epidemiologic studies, both community-based and hospital-based, demonstrate that FTLD is a more common cause of early-onset dementia than previously recognized. Regarding the subtypes of FTLD, in Japan, compared with the data from the UK, FTD is less common, SD may be more common and PA is equally common. The reason for this discrepancy is supposed to be mainly based on the role of heredity.     

Different patterns of magnetic resonance imaging atrophy for frontotemporal lobar degeneration syndromes

BACKGROUND: Frontotemporal lobar degeneration (FTLD) is an uncommon degenerative dementia that presents with focal cognitive and behavioral deficits. OBJECTIVE: To determine the correlation of the different presentations of FTLD with structural neuroimaging findings. DESIGN AND PATIENTS: In a blinded study, we retrospectively evaluated the clinical presentations and magnetic resonance imaging (MRI) patterns of atrophy in 59 patients with FTLD and 26 patients with probable Alzheimer disease at a memory disorders clinic. RESULTS: Analysis of variance revealed a significant difference in the patterns of atrophy in the FTLD and Alzheimer disease groups. Patients with FTLD presenting with altered personal conduct had significant bifrontal atrophy, whereas patients presenting with semantic dementia had significant left temporal and bifrontal atrophy compared with other groups. Disinhibited behavior and hyperphagia correlated with right frontal atrophy, and fluent, anomic aphasia correlated with left temporal atrophy. CONCLUSIONS: We found that the type of clinical presentation of FTLD correlates with specific areas of atrophy. Our method of analysis may be useful to elicit further anatomic-behavioral relationships in degenerative brain disorders.     

Odour identification in frontotemporal lobar degeneration

Abstract Little information is available concerning olfactory processing in frontotemporal lobar degeneration (FTLD). We undertook a case-control study of olfactory processing in three male patients fulfilling clinical criteria for FTLD. Odour identification (semantic analysis) and odour discrimination (perceptual analysis) were investigated using tests adapted from the University of Pennsylvania Smell Identification Test. General neuropsychometry and structural volumetric brain magnetic resonance imaging (MRI) were also performed. The three patients with FTLD exhibited a disorder of olfactory processing with the characteristics of a predominantly semantic (odour identification) deficit. This olfactory deficit was more prominent in patients with greater involvement of the temporal lobes on MRI. Central deficits of odour identification may be more common in FTLD than previously recognised, and these deficits may assist in clinical characterisation.     

EEG abnormalities in frontotemporal lobar degeneration

The EEG appearances in patients with frontotemporal lobar degeneration (FTLD) were compared with those in patients with Alzheimer disease (AD). EEG abnormalities were found in 61% of FTLD patients, with the degree of EEG abnormality increasing with dementia severity. There was no significant difference in the severity of EEG abnormality between the FTLD and AD patient groups. These data suggest a need for reappraisal of the role of the EEG in the diagnostic differentiation of FTLD from AD.     

Initial complaints in frontotemporal lobar degeneration

AIMS: Frontotemporal lobar degeneration (FTLD) is probably underrecognized. The goal of this study was to investigate initial complaints of both patients and their caregivers at first specialist referral. Also, we tried to assess whether misrecognition of symptoms contributed to diagnostic delay. METHODS: The case notes of all patients diagnosed with FTLD at the VU University Medical Center, Alzheimer Center of Amsterdam, The Netherlands, since 1998 were retrospectively reviewed. Only patients of whom detailed information of first specialist referral was available were included. The diagnosis of FTLD was based on the clinical diagnostic criteria of Neary and Snowden, supported by ancillary investigations. RESULTS: Forty-six patients with FTLD were included. Twenty-one patients had frontotemporal dementia (FTD), 17 semantic dementia (SD) and 8 progressive nonfluent aphasia (PA). The majority of the FTD patients presented without complaints or with somatic complaints and nearly a quarter of them expressed memory complaints. The presenting complaints of most of their caregivers differed from the patients' complaints and often consisted of cognitive complaints. In SD and PA, language problems but also forgetfulness were presented. Misrecognition of the initial symptoms in some cases seemed to have contributed to diagnostic delay. CONCLUSION: Presenting complaints in FTLD can be misleading. In our cohort, memory complaints occurred relatively often. A multidisciplinary approach, including a structured behavioral interview, is important to recognize symptoms of FTLD.     

Frontotemporal lobar degeneration without lobar atrophy

BACKGROUND: Frontotemporal lobar degeneration with ubiquitin-only-immunoreactive neuronal inclusions (FTLD-U) is the most common form of frontotemporal dementia. Neuronal loss and gliosis in cornu ammonis 1 and the subiculum of the hippocampus are features of hippocampal sclerosis (HpScl), which occurs in many cases of FTLD-U. OBJECTIVE: To determine if there were any clinical or magnetic resonance imaging correlates of HpScl in FTLD-U. DESIGN: We reviewed demographics and clinical features of 24 cases of FTLD-U and subjectively assessed the severity of neuronal loss and frequency of ubiquitin-positive neuronal lesions in the frontal and temporal cortices and the dentate gyrus of the hippocampus. SETTING: Mayo Clinic, Rochester, Minn. Patients Twenty-six cases were identified from the medical records linkage system query that met clinical criteria and had autopsy material available for additional studies. Two cases were excluded from further analysis after pathologic studies revealed coexisting Alzheimer disease, leaving 24 cases included in the study. Cases were subdivided based on the presence or absence of HpScl. MAIN OUTCOME MEASURES: Patterns of gray matter atrophy were assessed in cases of FTLD-U with and without HpScl using voxel-based morphometry. RESULTS: Six of the 24 cases of FTLD-U did not have HpScl. No differences were found in demographic or clinical features, including disease duration, between cases with and without HpScl; however, voxel-based morphometry analysis revealed minimal cortical atrophy in cases without HpScl, which was significantly different from the pattern of moderate to severe frontal and temporal lobe atrophy in FTLD-U with HpScl. This finding was in keeping with histopathologic observations. CONCLUSIONS: Despite similar clinical features, cases of FTLD-U with HpScl differ from those without HpScl with respect to pathologic findings and structural imaging. Specifically, FTLD-U without HpScl showed on average minimal or no cortical atrophy, even at end-stage disease. Consequently, FTLD-U without HpScl does not conform to the proposed FTLD staging scheme, is underrecognized, and may have different genetic and environmental underpinnings.     

Survival in two variants of tau-negative frontotemporal lobar degeneration: FTLD-U vs FTLD-MND

Pathologic diagnoses in frontotemporal lobar degeneration (FTLD) include tau-positive FTLD and tau-negative FTLD. Two variants of tau-negative FTLD are FTLD with motor neuron disease (FTLD-MND) and FTLD with motor neuron disease type inclusions but without motor neuron disease (FTLD-U). An analysis of patient outcomes in these cases reveals that FTLD-MND has significantly shorter survival than FTLD-U, suggesting that FTLD-MND is a more aggressive disease process.     

Antemortem diagnosis of frontotemporal lobar degeneration

The objective of this article is to study the accuracy of antemortem clinical diagnoses of frontotemporal lobar degenerations (FTLDs). From brain autopsies performed on subjects enrolled in the Mayo Alzheimer Center between 1991 and 2003, cases with neuropathological diagnoses of FTLD were identified. Neuropathological diagnoses of FTLDs were based on consensus criteria for FTLD. The initial clinical histories, neuropsychological test results, brain imaging studies, and initial clinical diagnoses were reviewed. There were 34 pathological FTLD cases among 433 subjects who underwent autopsy; 29 of these 34 cases were diagnosed as FTLD antemortem based on the sum of clinical, neuropsychological, and imaging features (sensitivity, 85%). The specificity was 99%. Among the 34 cases with pathological FTLD, 27 (79%) had clinical histories diagnostic of an FTLD syndrome, 20 (62%) had neuropsychological profiles consistent with FTLD, 17 (50%) had magnetic resonance scans consistent with FTLD, and 7 of 8 who had functional imaging studies had ones consistent with FTLD. In those with incorrect antemortem diagnoses, three were thought to have Alzheimer's disease, one was considered hard to classify, and one was diagnosed with vascular dementia. The antemortem consensus diagnosis of FTLD was moderately sensitive and very specific. With experienced clinicians and awareness of the unique manifestations of FTLD, accurate antemortem diagnosis was feasible.