Correlación entre el metabolismo de la glucosa cerebral (18F-FDG) y el flujo sanguíneo cerebral con marcadores de amiloide (18F-florbetapir) en práctica clínica: evidencias preliminares / Correlation between brain glucose metabolism (18F-FDG) and cerebral blood flow with amyloid tracers (18F-florbetapir) in clinical routine: Preliminary evidences

Este estudio comparó el rendimiento de las adquisiciones tempranas de 18F-florbetapir PET/TC con el de 18F-FDG PET/TC. Métodos: Se incluyó a 12 pacientes que se sometieron a PET/TC con 18F-FDG y una PET/TC con 18F-florbetapir en dos tiempos (exploración temprana de 1 a 6 min y exploración tardía de 50 min). La PET/TC fue analizada visualmente por 3médicos de medicina nuclear con diferente experiencia utilizando una escala de 4puntos (0=sin reducción, 1=leve, 2=moderada, 3=reducción severa) para 18F-florbetapir en fase temprana y 18F-FDG imágenes en 10 regiones corticales (frontal bilateral, temporal, parietal, occipital, cingulado/precúneo posterior) y fase tardía de 18F-florbetapir en las mismas regiones corticales utilizando una escala de 3puntos (0=normal, 1=anormal con placas menores, 2=anormal con placas importantes). Usamos SPM12 para el análisis semicuantitativo aplicando un análisis de correlación basado en ROI (considerando precúneo como región objetivo y normalizado para la unión global media), un análisis de covarianza tomando precúneo como objetivo y una comparación de DMN global (red de modo predeterminado). resultados: La concordancia entre lectores fue alta (kappa de Cohen 0,762 para 18F-FDG, 0,775 para 18F-florbetapir en la fase temprana y 0,794 para la fase tardía). Las puntuaciones visuales regionales de la fase temprana y la 18F-FDG se correlacionaron significativamente (ρ=0,867). También el análisis basado en el ROI, el análisis visual cerebral global y la comparación de DMN revelaron resultados concordantes, especialmente en parietal y precúneo (p <0,001). Conclusiones: Las exploraciones de fase temprana de 18F-florbetapir se correlacionan significativamente en imágenes cuantitativas y visuales con las exploraciones de 18F-FDG-PET/TC, lo que sugiere que se podría usar un marcadore de amiloide en lugar de 18F-FDG (AU)

This study compared the performance of 18F-florbetapir PET/CT early acquisitions to 18F-FDG PET/CT. Methods: We included 12 patients who underwent 18F-FDG PET/CT and a dual-time 18F-florbetapir PET/CT (1-6minutes early-scan and 50minutes late-scan). PET/CT were analyzed visually by 3nuclear medicine physicians with different experience using a four-point scale (0=no reduction, 1=slight, 2=moderate, 3=severe reduction) for 18F-florbetapir early-phase and 18F-FDG images in 10 cortical regions (bilateral frontal, temporal, parietal, occipital, posterior cingulate/precuneus), and 18F-florbetapir late-phase in the same cortical regions using a three-point scale (0=normal, 1=abnormal with minor plaques, 2=abnormal with major plaques). We used SPM12 for semiquantitative analysis applying a ROI-based correlation analysis (considering precuneus as target region and normalized for the mean global binding), a covariance-analysis taking precuneus as target and a comparison of global DMN (default mode network). esults: Inter-reader agreement was high (Cohen's kappa 0.762 for 18F-FDG, 0.775 for 18F-florbetapir early-phase and 0.794 for late-phase). Regional visual scores of early-phase and 18F-FDG were significantly correlated (ρ=0.867). Also ROI-based analysis, global brain visual analysis and DMN comparison revealed concordant results, especially at parietal and precuneus(p<0.001). Conclusions: 18F-florbetapir early-phase scans significantly correlate on quantitative and visual images with 18F-FDG-PET/CT scans, suggesting that amyloid tracer could be used instead of 18F-FDG (AU)

Clinical and radiological features of posterior cortical atrophy (PCA) in a GRN mutation carrier: a case report.

BACKGROUND AND PURPOSE: Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome, defined by a distinctive clinical-radiological profile, with Alzheimer's disease (AD) pathology accounting for the majority of cases. The aim of this report was to present the case of a patient with impairment of visual and constructional abilities as initial manifestations. METHOD: The patient underwent a multidimensional assessment, including neuropsychological evaluation, structural and functional imaging and genetic screening. RESULTS: Neurological and neuropsychological assessment showed an impairment of constructive and visuo-spatial skills, associated with dyscalculia, simultanagnosia, optic ataxia and oculomotor apraxia. In accordance with the latest consensus criteria, a diagnosis of PCA was made. Consistent with the clinical findings, structural and functional imaging showed a peculiar pattern of atrophy with primary involvement of right parieto-occipital cortices, whereas cerebrospinal fluid biochemical analysis did not reveal a profile compatible with AD pathology. Genetic screening identified a known pathogenic GRN mutation. CONCLUSION: We present a case of PCA in a GRN mutation carrier in whom a concomitant AD pathological process was excluded. Consequently, although lacking histological data, our case suggests GRN-related pathology causative of PCA. Through this report we provide further evidence for a new neurodegenerative pathway leading to PCA, extending the clinical spectrum of GRN-associated phenotypes.

Progression of behavioural disturbances in frontotemporal dementia: a longitudinal observational study.

BACKGROUND AND PURPOSE: Behavioural disturbances are the core features of frontotemporal dementia (FTD); however, symptom progression is still not well characterized during the entire course of the disease. The aim of the present study was to investigate behavioural symptoms at baseline and during the disease course in a large cohort of patients with behavioural variant FTD (bvFTD), non-fluent/agrammatic variant primary progressive aphasia (nfvPPA) and semantic variant primary progressive aphasia (PPA). METHODS: We evaluated 403 patients with FTD, 167 of whom had at least 1-year follow-up evaluation (for a total of 764 assessments). Behavioural symptoms were assessed and rated through the Neuropsychiatric Inventory (NPI) and Frontal Behavioural Inventory (FBI). Disease severity was evaluated through the Frontotemporal Lobar Degeneration -Clinical Dementia Rating scale (FTLD-CDR). Linear mixed models were used to model behavioural measures (NPI, FBI and the five FBI-behavioural core criteria scores) as a function of disease severity (FTLD-CDR score) and clinical phenotype. RESULTS: At baseline, patients with bvFTD showed more behavioural disturbances compared with those with nfvPPA (P = 0.004). Negative symptoms (apathy and loss of empathy) showed a trend to an increase throughout the course of the disease in both bvFTD and PPA (P < 0.001 until intermediate stages). Positive symptoms (disinhibition, perseverations and hyperorality) increased until intermediate phases (P < 0.001) followed by a progressive reduction in later phases, whereas they were less common in nfvPPA throughout the disease course. CONCLUSION: We demonstrated that behavioural disturbances differed in FTD and with disease severity. Positive symptoms appeared to improve in the advanced stages, highlighting the importance of taking into account the disease severity as outcome measure in clinical trials.

Review: Molecular pathology of frontotemporal lobar degenerations.

Frontotemporal lobar degeneration (FTLD) is a group of disorders that principally affect the frontal and temporal lobes of the brain. In many parts of the world, FTLD is rapidly becoming a serious health burden on society and, as a result, the molecular mechanisms that underlie its onset and development have been the target of intense research efforts in recent years. Nonetheless, despite crucial pathological and genetic discoveries in this area much is still uncertain about how the many genes associated with this disease cause the observed neurodegeneration. Moreover, it has not been easy to define the molecular mechanisms that account for the clinical and pathological heterogeneity of the various FTLD subtypes, characterized by aggregates of Tau, TAR-DNA-Binding Protein-43 (TDP-43), and less often Fused in Sarcoma (FUS) protein. In this review, we will examine some of the emerging discoveries in this field: from the recent importance of autoimmunity to the presence of substantial variations in the composition and localization of TDP-43 and FUS brain aggregates in patients, and how they might affect the course of the disease. All together, these new results demonstrate how the observed clinical heterogeneity underlies considerable complexity at both the molecular and the disease pathway level. A better characterization of all this complexity will be essential for a more accurate stratification of patient cohorts for further studies and, eventually, for trials of therapy.

Antinuclear antibodies in Frontotemporal Dementia: the tip's of autoimmunity iceberg?

Recent studies suggest a role of the autoimmune system dysregulation in Frontotemporal dementia (FTD). In the present study, we performed a broad immunological screening in a large sample of sporadic FTD patients. We reported a significant increase of antinuclear autoantibodies (ANA) positivity in 100 FTD patients as compared to 100 healthy controls (HC) (60% vs. 13%, p < .001). In FTD, ANA-positive and ANA-negative patients did not differ for any clinical feature. These data extend and further confirm autoimmune dysregulation in FTD. However, it still remains to be clarified whether these antibodies have a potential pathogenic role or represent simply an epiphenomenon.

Publisher Correction: Anti-AMPA GluA3 antibodies in Frontotemporal dementia: a new molecular target.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Anti-AMPA GluA3 antibodies in Frontotemporal dementia: a new molecular target.

Frontotemporal Dementia (FTD) is a neurodegenerative disorder mainly characterised by Tau or TDP43 inclusions. A co-autoimmune aetiology has been hypothesised. In this study, we aimed at defining the pathogenetic role of anti-AMPA GluA3 antibodies in FTD. Serum and cerebrospinal fluid (CSF) anti-GluA3 antibody dosage was carried out and the effect of CSF with and without anti-GluA3 antibodies was tested in rat hippocampal neuronal primary cultures and in differentiated neurons from human induced pluripotent stem cells (hiPSCs). TDP43 and Tau expression in hiPSCs exposed to CSF was assayed. Forty-one out of 175 screened FTD sera were positive for the presence of anti-GluA3 antibodies (23.4%). FTD patients with anti-GluA3 antibodies more often presented presenile onset, behavioural variant FTD with bitemporal atrophy. Incubation of rat hippocampal neuronal primary cultures with CSF with anti-GluA3 antibodies led to a decrease of GluA3 subunit synaptic localization of the AMPA receptor (AMPAR) and loss of dendritic spines. These results were confirmed in differentiated neurons from hiPSCs, with a significant reduction of the GluA3 subunit in the postsynaptic fraction along with increased levels of neuronal Tau. In conclusion, autoimmune mechanism might represent a new potentially treatable target in FTD and might open new lights in the disease underpinnings.

Clinical and biological phenotypes of frontotemporal dementia: Perspectives for disease modifying therapies.

Frontotemporal Dementia (FTD) is a progressive neurodegenerative condition which encompasses a group of clinically, neuropathologically and genetically heterogeneous disorders characterized by selective involvement of the frontal and temporal lobes. FTD is characterized by changes in behaviour and personality, frontal executive deficits and language dysfunction. Different phenotypes have been defined on the basis of presenting clinical symptoms, behavioural variants of FTD (bvFTD) and primary progressive aphasia (PPA), which includes nonfluent/agrammatic variant PPA (avPPA) and semantic variant PPA (svPPA). These presentations can overlap with atypical parkinsonian disorders (i.e., corticobasal syndrome, progressive supranuclear palsy) and amyotrophic lateral sclerosis. Each syndrome can be associated with one or more neuropathological hallmark, and in some cases it may be due to autosomal inherited disorder caused by mutations in a number of genes. Currently, there is no specific treatment available to prevent disease progression. FTD treatment is based on symptomatic management, and most therapies lack quality evidence from randomized, placebo-controlled clinical trials. Recent advances in the understanding of FTD pathophysiology and genetics have led to the development of potentially disease-modifying therapies. In this review, we discussed current knowledge and recommendations with regards to symptomatic and disease-modifying therapies.

Modulating risky decision-making in Parkinson's disease by transcranial direct current stimulation.

BACKGROUND AND PURPOSE: Performance on gambling tasks in Parkinson's disease (PD) is of particular interest, as pathological gambling is often associated with dopamine replacement therapy in these patients. We aimed to evaluate the effects of transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (DLPFC) in modulating gambling behaviour in PD. METHODS: We assessed the effects of cathodal tDCS over the right DLPFC during the Iowa Gambling Task in 20 patients with PD, compared with sham stimulation. We then conducted a second experimental design, assessing the effects of anodal tDCS over the right DLPFC. RESULTS: We observed that cathodal tDCS over the right DLPFC increased Iowa Gambling Task scores compared with sham stimulation. In the second experimental design, we did not find significant differences between anodal and sham tDCS. CONCLUSIONS: Cathodal tDCS over the right DLPFC possibly reduces the pathological overdrive in frontostriatal networks in patients with PD on dopaminergic medication, thus modulating impulsive and risky decision-making.

Source-Based Morphometry Multivariate Approach to Analyze [123I]FP-CIT SPECT Imaging.

PURPOSE: [123I]FP-CIT (DaTSCAN®) single-photon emission computed tomography (SPECT) imaging is widely used to study neurodegenerative parkinsonism, by measuring presynaptic dopamine transporter (DAT) in striatal regions. Beyond DAT, [123I]FP-CIT may be considered for other monoaminergic systems, in particular the serotonin transporter (SERT). Independent component analysis (ICA) implemented in source-based morphometry (SBM) could represent an alternative method to explore monoaminergic pathways, studying the relationship among voxels and grouping them into "neurotransmission" networks. PROCEDURES: One hundred forty-three subjects [84 with Parkinson's disease (PD) and 59 control individuals (CG)] underwent DATSCAN® imaging. The [123I]FP-CIT binding was evaluated by multivariate SBM approach, as well as by a whole-brain voxel-wise univariate (statistical parametric mapping, SPM) approach. RESULTS: As compared to the univariate whole-brain approach (SPM) (only demonstrating striatal [123I]FP-CIT binding reduction in PD group), SBM identified six sources of non-artefactual origin, including basal ganglia and cortical regions as well as brainstem. Among them, three sources (basal ganglia and cortical regions) presented loading scores (as index of [123I]FP-CIT binding) significantly different between PD and CG. Notably, even if not significantly different between PD and CG, the remaining three non-artefactual sources were characterized by a predominant frontal, brainstem, and occipito-temporal involvement. CONCLUSION: The concept of source blind separation by the application of ICA (as implemented in SBM) represents a feasible approach to be considered in [123I]FP-CIT (DaTSCAN®) SPECT imaging. Taking advantage of this multivariate analysis, specific patterns of variance can be identified (involving either striatal than extrastriatal regions) that could be useful in differentiating neurodegenerative parkinsonisms.

The Italian dementia with Lewy bodies study group (DLB-SINdem): toward a standardization of clinical procedures and multicenter cohort studies design.

Dementia with Lewy bodies (DLB) causes elevated outlays for the National Health Systems due to high institutionalization rate and patients' reduced quality of life and high mortality. Furthermore, DLB is often misdiagnosed as Alzheimer's disease. These data motivate harmonized multicenter longitudinal cohort studies to improve clinical management and therapy monitoring. The Italian DLB study group of the Italian Neurological Society for dementia (SINdem) developed and emailed a semi-structured questionnaire to 572 national dementia centers (from primary to tertiary) to prepare an Italian large longitudinal cohort. The questionnaire surveyed: (1) prevalence and incidence of DLB; (2) clinical assessment; (3) relevance and availability of diagnostic tools; (4) pharmacological management of cognitive, motor, and behavioural disturbances; (5) causes of hospitalization, with specific focus on delirium and its treatment. Overall, 135 centers (23.6 %) contributed to the survey. Overall, 5624 patients with DLB are currently followed by the 135 centers in a year (2042 of them are new patients). The percentage of DLB patients was lower (27 ± 8 %) than that of Alzheimer's disease and frontotemporal dementia (56 ± 27 %) patients. The majority of the centers (91 %) considered the clinical and neuropsychological assessments as the most relevant procedure for a DLB diagnosis. Nonetheless, most of the centers has availability of magnetic resonance imaging (MRI; 95 %), electroencephalography (EEG; 93 %), and FP-CIT single photon emission-computerized tomography (SPECT; 75 %) scan for clinical applications. It will be, therefore, possible to recruit a large harmonized Italian cohort of DLB patients for future cross-sectional and longitudinal multicenter studies.

Impulse control disorder in PD: A lateralized monoaminergic frontostriatal disconnection syndrome?

BACKGROUND: Impulse Control Disorder symptoms (ICD) in Parkinson's disease (PD) has been recently associated by magnetic Resonance imaging with impaired cortico-striatal connectivity, especially between left putamen and frontal associative areas. METHODS: 84 patients entered the study (21 PD-ICD+ and 64 PD-ICD-) and underwent DATSCAN imaging. The striatal tracer uptake was evaluated using BRASS software (Hermes, Sweden). The whole-brain analysis was performed with Statistical Parametric Mapping (SPM). RESULTS: PD-ICD+ showed a significant reduction of left putaminal and left inferior frontal gyrus tracer uptake compared to PD-ICD-. Functional covariance analysis using left putamen as the seed point showed that, in contrast to ICD-patients, ICD+ patients had no functional covariance with contralateral basal ganglia and ipsilateral cingulate cortex, as index of an impaired inter- and intra-hemispheric dopamine binding in PD-ICD+. DISCUSSION: the results support and expand the concept of a functional disconnection syndrome linked to ICD symptoms in PD patients through an asymmetric molecular frontostriatal network breakdown with left basal ganglia as central hub.

Subcortical matter in the α-synucleinopathies spectrum: an MRI pilot study.

α-Synucleinopathies, such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB), are characterized by α-synuclein accumulation from brainstem structures to the neocortex. PD and DLB are clinically distinguishable, while discrimination between Parkinson Disease Dementia (PDD) and DLB can be subtle and based on the temporal relationship between motor and cognitive symptoms. To explore patterns of subcortical atrophy in PD, PDD and DLB, and assess specific differences between PD and PDD, and between DLB and PDD. 16 PD, 11 PDD and 16 DLB patients were recruited and underwent 1.5 Tesla structural MRI scanning. Segmentation of subcortical structures was performed with a well-validated, fully-automated tool, and volume and shape for each structure were compared between groups. PDD and DLB patients showed global subcortical atrophy compared to PD patients. Greater hippocampal atrophy was the specific trait that distinguished PDD from PD, while greater atrophy of the pallidi discriminated DLB from PDD. Vertex analysis revealed specific shape differences in both structures. Our results suggest that automated, time-sparing, subcortical volumetry may provide diagnostically useful information in α-synucleinopathies. Future studies on larger samples and with iron-sensitive MRI contrasts are needed.

Left parietal cortex transcranial direct current stimulation enhances gesture processing in corticobasal syndrome.

BACKGROUND AND PURPOSE: Corticobasal syndrome (CBS) is a clinical entity characterized by higher cortical dysfunctions associated with asymmetric onset of levodopa-resistant parkinsonism, dystonia and myoclonus. One of the most typical and distressful features of CBS is limb apraxia, which affects patients in their everyday life. Transcranial direct current stimulation (tDCS) is a non-invasive procedure of cortical stimulation, which represents a promising tool for cognitive enhancement and neurorehabilitation. The present study investigated whether anodal tDCS over the parietal cortex (PARC), would improve ideomotor upper limb apraxia in CBS patients. METHODS: Fourteen patients with possible CBS and upper limb apraxia were enrolled. Each patient underwent two sessions of anodal tDCS (left and right PARC) and one session of placebo tDCS. Ideomotor upper limb apraxia was assessed using the De Renzi ideomotor apraxia test that is performed only on imitation. RESULTS: A significant improvement of the De Renzi ideomotor apraxia test scores (post-stimulation versus pre-stimulation) after active anodal stimulation over the left PARC was observed (χ(2) = 17.6, P = 0.0005), whilst no significant effect was noticed after active anodal stimulation over the right PARC (χ(2) = 7.2, P = 0.07). A post hoc analysis revealed a selective improvement in the De Renzi ideomotor apraxia score after active anodal stimulation over the left PARC compared with placebo stimulation considering both right (P = 0.03) and left upper limbs (P = 0.01). CONCLUSIONS: These findings indicate that tDCS to the PARC improves the performance of an ideomotor apraxia test in CBS patients and might represent a promising tool for future rehabilitation approaches.

Italian Frontotemporal Dementia Network (FTD Group-SINDEM): sharing clinical and diagnostic procedures in Frontotemporal Dementia in Italy.

In the prospect of improved disease management and future clinical trials in Frontotemporal Dementia, it is desirable to share common diagnostic procedures. To this aim, the Italian FTD Network, under the aegis of the Italian Neurological Society for Dementia, has been established. Currently, 85 Italian Centers involved in dementia care are part of the network. Each Center completed a questionnaire on the local clinical procedures, focused on (1) clinical assessment, (2) use of neuroimaging and genetics; (3) support for patients and caregivers; (4) an opinion about the prevalence of FTD. The analyses of the results documented a comprehensive clinical and instrumental approach to FTD patients and their caregivers in Italy, with about 1,000 newly diagnosed cases per year and 2,500 patients currently followed by the participating Centers. In analogy to other European FTD consortia, future aims will be devoted to collect data on epidemiology of FTD and its subtypes and to provide harmonization of procedures among Centers.

SAP97-mediated ADAM10 trafficking from Golgi outposts depends on PKC phosphorylation.

A disintegrin and metalloproteinase 10 (ADAM10) is the major α-secretase that catalyzes the amyloid precursor protein (APP) ectodomain shedding in the brain and prevents amyloid formation. Its activity depends on correct intracellular trafficking and on synaptic membrane insertion. Here, we describe that in hippocampal neurons the synapse-associated protein-97 (SAP97), an excitatory synapse scaffolding element, governs ADAM10 trafficking from dendritic Golgi outposts to synaptic membranes. This process is mediated by a previously uncharacterized protein kinase C phosphosite in SAP97 SRC homology 3 domain that modulates SAP97 association with ADAM10. Such mechanism is essential for ADAM10 trafficking from the Golgi outposts to the synapse, but does not affect ADAM10 transport from the endoplasmic reticulum. Notably, this process is altered in Alzheimer's disease brains. These results help in understanding the mechanism responsible for the modulation of ADAM10 intracellular path, and can constitute an innovative therapeutic strategy to finely tune ADAM10 shedding activity towards APP.

Results from a pilot study on amiodarone administration in monogenic frontotemporal dementia with granulin mutation.

Frontotemporal dementia (FTD) is one of the most important neurodegenerative conditions and Granulin (GRN) is one of the major genes associated to the disease. FTD-GRN patients are still orphan for any evidence-based target-therapy approach. Interestingly, it has been recently found that alkalizing agents rescued haploinsufficiency in cellular models expressing FTD-GRN mutations. We set up a pilot phase II clinical trial in five FTD patients with GRN Thr272s(g.1977_1980delCACT) mutation, to determine if amiodarone (200 mg/day) may (1) reverse progranulin deficiency and (2) delay disease progression. Each patient was scheduled for 7 study visits over 12 months period. We assessed GRN levels at baseline and after amiodarone administration during the treatment course. Somatic and neurologic examinations, along with cognitive and behavioral assessment were recorded as well. No significant effect on peripheral GRN levels was observed. In treated FTD, disease course did not differ when compared with a group of untreated FTD-GRN patients. This is the first trial targeting progranulin rescue in FTD-GRN patients using amiodarone. Despite the negative findings, it may be interesting to extend this attempt to a larger sample of subjects and to other alkalizing agents to restore granulin haploinsufficiency.

Reserve mechanisms in neurodegenerative diseases: from bench to bedside and back again.

In the course of neurodegenerative disorders there are several mechanisms that may counteract the pathological process, mitigating the clinical manifestations of the disease. Usually referred as cognitive reserve hypothesis, this theoretical framework posits that individuals with enriched cognitive status (i.e. with higher educational and occupational levels and higher individual social achievement) may cope better with the occurrence of cognitive decline by a more efficient recruitment of neural networks sustaining higher-level functions. Cognitive reserve was initially studied in Alzheimer's disease, but this concept has been soon after extended also to other neurodegenerative disorders, such as Frontotemporal Dementia, Parkinson's disease, and Huntington's disease, suggesting a general applicability of cortical plasticity phenomena in contrasting neurodegeneration. The neural underpinnings of these dynamic compensatory mechanisms open the possibility for strategic interventions based on environmental approaches. In this continuously growing field, the aim of the present review is to explore new acquisitions, derived from basic research and clinical grounds, on cognitive reserve mechanisms and the potential application as novel therapeutic targets in neurodegenerative diseases.

Neuroanatomical correlates of behavioural phenotypes in behavioural variant of frontotemporal dementia.

BACKGROUND: Behavioural variant of frontotemporal dementia (bvFTD) frequently presents complex behavioural changes, that rarely occur in isolation. Targeting behavioural phenotypes instead of single behavioural symptoms may potentially provide a disease model in which to investigate brain substrates of behavioural abnormalities. OBJECTIVE: To identify behavioural phenotypes and to assess the associated brain correlates in a cohort of patients with bvFTD. METHODS: Two hundred and seven consecutive individuals fulfilling clinical criteria for bvFTD were enrolled. Each participant's caregiver completed frontal behavioural inventory on 24 key behavioural disturbances. Confirmatory factor analysis (CFA) models were applied, and behavioural phenotypes identified. For each phenotype, a score was derived based on the "best" CFA model (Bifactor CFA). One hundred two participants underwent SPECT scan. A regression analysis between scores for each factor and regional cerebral blood flow was carried out (P<0.001). RESULTS: One "general" behavioural phenotype and four factors were identified, that were termed "disinhibited", "apathetic", "aggressive", and "language" phenotypes. The most robust brain correlate was identified for "disinhibited" phenotype, in the region of the anterior cingulated and anterior temporal cortex, bilaterally, and for apathetic phenotype in the left dorsolateral frontal cortex. As expected, language phenotype correlated with greater hypoperfusion in the left frontotemporal lobes. No significant correlation between aggressive phenotype and regional cerebral blood flow was found. Moreover, the "general" behavioural severity was associated with greater damage in the right frontal lobe. CONCLUSIONS: Behavioural phenotypes are associated with specific brain damage in bvFTD, involving distinct cerebral networks.