The pursuit for markers of disease progression in behavioral variant frontotemporal dementia: a scoping review to optimize outcome measures for clinical trials

Behavioral variant frontotemporal dementia (bvFTD) is a neurodegenerative disorder characterized by diverse and prominent changes in behavior and personality. One of the greatest challenges in bvFTD is to capture, measure and predict its disease progression, due to clinical, pathological and genetic heterogeneity. Availability of reliable outcome measures is pivotal for future clinical trials and disease monitoring. Detection of change should be objective, clinically meaningful and easily assessed, preferably associated with a biological process. The purpose of this scoping review is to examine the status of longitudinal studies in bvFTD, evaluate current assessment tools and propose potential progression markers. A systematic literature search (in PubMed and Embase.com) was performed. Literature on disease trajectories and longitudinal validity of frequently-used measures was organized in five domains: global functioning, behavior, (social) cognition, neuroimaging and fluid biomarkers. Evaluating current longitudinal data, we propose an adaptive battery, combining a set of sensitive clinical, neuroimaging and fluid markers, adjusted for genetic and sporadic variants, for adequate detection of disease progression in bvFTD.

Social cognition differentiates phenocopy syndrome of behavioural variant frontotemporal dementia from behavioural variant frontotemporal dementia

BACKGROUND

Patients displaying clinical features of behavioural variant of frontotemporal dementia (bvFTD) but lacking both neuroimaging abnormalities and clinical progression are considered to represent the phenocopy syndrome of bvFTD (phFTD). Extensive clinical overlap between early phase bvFTD and phFTD hampers diagnostic distinction. We aimed to assess the diagnostic value of clinician-rated, self-reported and caregiver-reported symptoms for clinical distinction between phFTD and bvFTD.

METHODS

There were 33 phFTD and 95 probable bvFTD patients included in the study (total N = 128). Clinician-rated, self-reported tests and caregiver-reported symptoms were compared between phFTD and bvFTD on social cognition, behaviour, mood and activities of daily living (ADL). Scores were compared between groups, followed by multiple logistic regression analysis, adjusted for age and sex. Receiver operating characteristic curves were plotted to assess diagnostic value.

RESULTS

Using clinician-rated and self-reported tests, phFTD patients performed better on facial emotion recognition and reported more depressive symptoms. Caregiver-reported behavioural symptoms indicated higher behavioural and ADL impairment in phFTD compared to bvFTD. Facial emotion recognition provided highest diagnostic accuracy for distinction of phFTD from bvFTD (area under the curve (AUC) 0.813 95% CI 0.735-0.892, P < 0.001, sensitivity 81%, specificity 74%) followed by depressive symptoms (AUC 0.769 95% 0.674-0.864, P < 0.001 sensitivity 81%, specificity of 63%).

CONCLUSION

Social cognition tests are most suitable for distinction of phFTD from bvFTD. Caregiver-reported questionnaires and phFTD diagnosis seemed inversely correlated, showing more symptoms in phFTD. Further research is needed on phFTD aetiology and in caregivers taking into account disease burden to assess what explains this discrepancy between clinician-rated and caregiver-based tools.

[Automated speech analysis can distinguish frontotemporal dementia from depression: a pilot study]

BACKGROUND

Differentiating the behavioural variant of frontotemporal dementia from a depression is challenging. Recent development of automated speech analyses might add to diagnostic.

AIM

To investigate the value of automated speech analyses in differentiating bvFTD from a depressive disorder.

METHOD

A semistructured interview was recorded in 15 patients with bvFTD, 15 patients with a depressive disorder and 15 healthy controls, which was transcribed and analysed. Acoustic and semantic values were extracted and classified using machine learning.

RESULTS

Acoustic values showed an 80% accuracy for differentiating bvFTD from depressive disorder and semantic values showed an 70.8% accuracy.

CONCLUSION

Acoustic as well as semantic values show significant differences between bvFTD and depressive disorder. In automated speech analyses researches should consider privacy matters as well as possible confounders like age, sex and ethnicity. This study should be repeated in a larger population.

[A 51-year-old man with primary progressive aphasia]

Primary progressive aphasia (PPA) is a form of dementia in which brain circuits responsible for language and speech show progressive impairments. Based on consensus criteria PPA is divided into 3 main variants: a nonfluent/agrammatic, a semantic and a logopenic variant. Each variant has specific clinical characteristics, including neuropsychiatric symptoms, and is associated with different neuropathological findings. We describe a 51-year-old man with neuropsychiatric symptoms and progressive language disturbances. The diagnosis PPA was established after an extensive work-up in a psychiatric clinic. We describe which factors contributed to this complex diagnostic process and discuss why knowledge of this disorder is relevant for psychiatrists.

The bvFTD phenocopy syndrome: a case study supported by repeated MRI, [18F]FDG-PET and pathological assessment

A clinical syndrome with neuropsychiatric features of bvFTD without neuroimaging abnormalities and a lack of decline is a phenocopy of bvFTD (phFTD). Growing evidence suggests that psychological, psychiatric and environmental factors underlie phFTD. We describe a patient diagnosed with bvFTD prior to the revision of the diagnostic guidelines of FTD. Repeated neuroimaging was normal and there was no FTD pathology at autopsy, rejecting the diagnosis. We hypothesize on etiological factors that on hindsight might have played a role. This case report contributes to the understanding of phFTD and adds to the sparse literature of the postmortem assessment of phFTD.

[Frontotemporal dementia diagnoses within the psychiatric practice: pitfalls and practical tools]

BACKGROUND

The behavioural variant of frontotemporal dementia (bvFTD) strongly resembles primary psychiatric disorders. Furthermore, a bvFTD mimic may occur, without neurodegenerative aetiology.

AIM

To offer psychiatrist clinical tools for making or ruling out a bvFTD diagnosis.

METHOD

To present the results of the first prospective cohort study on bvFTD patients and primary psychiatric patients. Results are discussed within the context of the international literature.

RESULTS

Frontotemporal atrophy on imaging confirms a suspected bvFTD diagnosis. Merely fulfilling the bvFTD clinical criteria, with or without frontotemporal hypometabolism on functional imaging, may also result from primary psychiatric disorders or the bvFTD-phenocopy syndrome. A high level of stereotypy, hyperorality, a low level of depressive symptoms, impaired social cognition or absent insight increases the probability of bvFTD. Biomarker or genetic tests and follow-up are recommended. CONCLUSIONS A bvFTD diagnosis should be made multidisciplinary. Without the confirmation of atrophy or genetics, great reserve in making the diagnosis is in place and careful analyses for psychiatric aetiologies is advised.

Disease trajectories in behavioural variant frontotemporal dementia, primary psychiatric and other neurodegenerative disorders presenting with behavioural change

Behavioural variant frontotemporal dementia (bvFTD) is characterized by behavioural and social cognitive disturbances, while various psychiatric and neurodegenerative disorders may have similar clinical symptoms. Since neurodegenerative disorders are eventually progressive, whereas primary psychiatric disorders are not, this study aimed to investigate whether the change in clinical symptoms over time differed between groups and which biomarkers predicted rate of decline. Disease trajectories (median follow-up = 3 years) of frontal and stereotyped behaviour, general and frontal cognitive functioning, and social cognition were examined in bvFTD (n = 34), other neurodegenerative (n = 28) and primary psychiatric disorders (n = 43), all presenting with late-onset frontal lobe syndrome (45-75 years), using linear mixed models. To gain more insight in underlying pathological processes driving disease progression, we studied the association of baseline cerebrospinal fluid (CSF) (neurofilament light (NfL) and YKL-40 levels, phosphotau₁₈₁ to total tau ratio) and neuroimaging markers with disease trajectories. Frontal behavioural symptoms (e.g., disinhibition, apathy) worsened over time in bvFTD, whereas they improved in psychiatric disorders and remained stable in other neurodegenerative disorders. General and frontal cognitive decline was observed in bvFTD and other neurodegenerative disorders, but not in psychiatric disorders. None of the groups showed change in stereotypy and social cognition. For all diagnostic groups, higher CSF NfL levels were associated with faster frontal cognitive decline. A modest association was observed between caudate volume and stereotyped behaviour. Tracking frontal behavioural symptoms and cognition has potential to distinguish bvFTD from other disorders. CSF NfL levels seem to be associated with decline in frontal cognitive functioning.

Hypometabolism of the posterior cingulate cortex is not restricted to Alzheimer's disease

When differential diagnosis of dementia includes both Alzheimer's disease (AD) and the behavioural variant of frontotemporal dementia (bvFTD), distribution of cerebral glucose metabolism as measured using [¹⁸F]‑2‑fluoro‑2‑deoxy‑d‑glucose positron emission tomography ([¹⁸F]FDG-PET) may be helpful. One important clue for differentiation is the presence of hypometabolism in the posterior cingulate cortex (PCC), usually associated with AD. PCC hypometabolism however, could also be present in bvFTD. Therefore, the specificity of PCC hypometabolism was examined. Based on visual reading PCC hypometabolism was present in 69–73/81 probable AD patients, in 10–16/33 probable bvFTD patients, and in 0–1/22 cognitive normal (CN) subjects. Findings were validated using a PCC to reference tissue [¹⁸F]FDG standard uptake value ratio (SUVr) cut-off, which was derived from the receiver operating characteristic (ROC) separating probable AD from CN, resulting in 9–14/33 bvFTD patients having PCC hypometabolism, depending on the reference tissue used. In conclusion, PCC hypometabolism is not restricted to AD.

Diagnostic Accuracy of the Frontotemporal Dementia Consensus Criteria in the Late-Onset Frontal Lobe Syndrome

BACKGROUND/AIMS

We aimed to prospectively assess the diagnostic accuracy of the revised criteria for behavioural variant frontotemporal dementia (bvFTD) among subjects presenting with a frontal lobe syndrome in middle-late adulthood.

METHODS

Patients were included based on a predominant behavioural clinical presentation, a Frontal Behavioural Inventory (FBI) score of ≥11 and/or a Stereotypy Rating Inventory (SRI) score of ≥10. At baseline, the fulfilment of the international consensus criteria for behavioural variant FTD (FTDC) was systematically recorded. The 2-year follow-up consensus diagnosis was used as the gold standard to calculate sensitivity and specificity of the FTDC criteria for possible and probable bvFTD.

RESULTS

Two-year follow-up data were available for 116 patients (85%). Two-year follow-up consensus diagnoses consisted of probable/definite bvFTD (n = 27), other dementia (n = 30), psychiatric disorders (n = 46) and other neurological disorders (n = 13). Sensitivity for possible bvFTD was 85% (95% CI 70-95%) at a specificity of 27% (95% CI 19-37%). Sensitivity for probable bvFTD was 85% (95% CI 69-95%), whereas their specificity was 82% (95% CI 73-89%).

CONCLUSIONS

We found a good diagnostic accuracy for FTDC probable bvFTD. However, the specificity for FTDC possible bvFTD was low. Our results reflect the symptomatic overlap between bvFTD, other neurological conditions and psychiatric disorders, and the relevance of adding neuroimaging to the diagnostic process.

Cerebrospinal fluid biomarker examination as a tool to discriminate behavioral variant frontotemporal dementia from primary psychiatric disorders

INTRODUCTION

To prospectively determine the diagnostic value of cerebrospinal fluid (CSF) levels total-tau (tau) to amyloid-β_1-42 ratio (Aβ_1-42) ratio (tau/Aβ_1-42 ratio), phosphorylated-tau (p-tau) to tau ratio (p-tau/tau ratio), neurofilament light chain (NfL) and YKL40 in the late-onset frontal lobe syndrome, in particular for the differential diagnosis of behavioral variant frontotemporal dementia (bvFTD) versus primary psychiatric disorders (PSY).

METHOD

We included patients with a multidisciplinary 2-year-follow-up diagnosis of probable/definite bvFTD (n = 22) or PSY (n = 25), who underwent a detailed neuropsychiatric clinical examination, neuropsychological test battery, and magnetic resonance imaging at baseline. In all cases, CSF was collected through lumbar puncture at baseline. We compared CSF biomarker levels between the two groups and measured the diagnostic accuracy for probable/definite bvFTD, using the follow-up diagnosis as the reference standard.

RESULTS

The best discriminators between probable/definite bvFTD and PSY were the levels of CSF NfL (area under the curve [AUC] 0.93, P < .001, 95% confidence interval [CI] 0.85-1.00), p-tau/tau ratio (AUC 0.87, P < .001, 95% CI 0.77-0.97), and YKL40 (AUC 0.82, P = .001, 95% CI 0.68-0.97). The combination of these three biomarkers had a sensitivity of 91% (95% CI 66%-100%) at a specificity of 83% (95% CI 65%-95%) with an AUC of 0.94 (P < .001, 95% CI 0.87-1.00) for bvFTD. CSF tau/Aβ_1-42 ratio was less accurate in differentiating between bvFTD and PSY.

DISCUSSION

We found a good diagnostic accuracy for higher levels of CSF NfL and YKL40 and reduced p-tau/tau ratio in distinguishing bvFTD from PSY. We advocate the use of these CSF biomarkers as potential additional tools to neuroimaging in the diagnosis of bvFTD versus PSY.

Formal Psychiatric Disorders are not Overrepresented in Behavioral Variant Frontotemporal Dementia

While psychiatric misdiagnosis is well-known in behavioral variant frontotemporal dementia (bvFTD), a systematic evaluation of standardized criteria for psychiatric disorders in bvFTD is still missing. Our aim was to define frequency and character of DSM-IV psychiatric disorders among patients with probable and definite bvFTD compared to possible bvFTD, other neurodegenerative diseases, and psychiatric diagnoses, using MINI-International Neuropsychiatric Interview. We additionally compared psychiatric prodromes between these groups. Subjects were participants of the late-onset frontal lobe (LOF) study, a longitudinal multicenter study. In each patient, after baseline diagnostic procedure, a neurologist and geriatric psychiatrist made a joint clinical diagnosis. Independently, a structured diagnostic interview according to DSM-IV and ICD-10 criteria (MINI-Plus) was performed by a trained professional blinded to clinical diagnosis. Out of 91 patients, 23 with probable and definite bvFTD, 3 with possible bvFTD, 25 with a non bvFTD neurodegenerative disease, and 40 with a clinical psychiatric diagnosis were included. Overall frequency of formal current and past psychiatric disorders in probable and definite bvFTD (21.7% current, 8.7% past) did not differ from other neurodegenerative diseases (12.0% current, 16.0% past) or possible bvFTD (66.7% current, 66.7% past), but was less than in patients with a clinical psychiatric diagnosis (57.5% current, 62.5% past; p <  0.01). In probable and definite bvFTD unipolar mood disorders were most common. Formally diagnosed psychiatric disorders are not overrepresented in probable bvFTD, suggesting that psychiatric misdiagnosis in bvFTD can be reduced by strictly applying diagnostic criteria. In suspected bvFTD close collaboration between neurologists and psychiatrists will advance diagnostics and subsequent treatment.

Identifying Specific Clinical Symptoms of Behavioral Variant Frontotemporal Dementia Versus Differential Psychiatric Disorders in Patients Presenting With a Late-Onset Frontal Lobe Syndrome

OBJECTIVE

Early differentiation between psychiatric disorders and behavioral variant frontotemporal dementia (bvFTD) is of paramount importance in patients with the late-onset frontal lobe syndrome. As bvFTD in patients will deteriorate, psychiatric disorders are treatable. To date, misdiagnosis often occurs due to an overlap of symptoms and lack of specific biomarkers. The aim of our study was to investigate whether specific symptoms could separate bvFTD from psychiatric disorders.

METHODS

In a naturalistic, prospective, multicenter study, 137 patients (aged 45-75 years, 72% male) with a late-onset frontal lobe syndrome were included based on their scores on the Frontal Behavioral Inventory (FBI) and the Stereotypy Rating Inventory (SRI) from April 2011 to June 2013. In a multidisciplinary consensus meeting, diagnoses were established based on elaborate neuropsychological testing, magnetic resonance imaging, fludeoxyglucose F 18 positron emission tomography, cerebrospinal fluid biomarkers, and clinical examination by a neurologist and a psychiatrist based on the International bvFTD Criteria Consortium for bvFTD and DSM-IV-TR criteria for psychiatric disorders.

RESULTS

Forty-four subjects (32.8%) were diagnosed with a psychiatric disorder, 10 (7.3%) with possible bvFTD, and 45 (32.8%) with probable bvFTD. A logistic regression analysis was performed with "psychiatry or bvFTD" as dependent variable and clinical variables (Montgomery-Asberg Depression Rating Scale [MADRS], SRI, FBI) and demographics as independent variables. A positive history of psychiatric illness, male gender, lower SRI scores and higher MADRS scores were predictive of psychiatric disorders, explaining 65.2% of the variance in diagnosis of psychiatry versus bvFTD (χ²₅ = 60.04, P < .001). On the FBI, symptom level verbal apraxia/aphasia and impulsivity were predictive of bvFTD, whereas irritability was predictive of psychiatric disorders.

CONCLUSIONS

In daily clinical practice, specific subtyping of clinical symptoms in patients with late-onset frontal lobe syndrome may aid in differentiating bvFTD patients from psychiatric patients and may provide guidance in patient management.

Impact of Imaging and Cerebrospinal Fluid Biomarkers on Behavioral Variant Frontotemporal Dementia Diagnosis within a Late-Onset Frontal Lobe Syndrome Cohort

BACKGROUND

The criteria for behavioral variant frontotemporal dementia (bvFTD) incorporate MRI and [18F]-FDG-PET. Cerebrospinal fluid (CSF) analysis is merely advised for excluding Alzheimer's disease.

AIMS

We aimed to assess the impact of biomarkers on diagnostic certainty and contingent changes of bvFTD diagnosis within the clinically relevant neuropsychiatric differential diagnosis of subjects with a late-onset frontal lobe syndrome (LOF).

METHODS

We included 137 patients with LOF, aged 45-75 years, 72% males. Biomarker disclosure was considered contributing after any substantial difference in diagnostic certainty or a diagnostic change. Percentages of contributing biomarkers were compared between three major diagnostic groups (bvFTD, psychiatry, other neurological disorders). Certainty levels in stable diagnostic groups were compared to those with a diagnostic change.

RESULTS

Biomarkers contributed in 53, 60 and 41% of the LOF patients for MRI, [18F]-FDG-PET and CSF, respectively. Biomarkers changed the diagnosis in 14% of cases towards bvFTD and in 13% from bvFTD into an alternative. Those that changed had a lower level of a priori diagnostic certainty compared to stable diagnoses.

CONCLUSION

Our study not only supports the widely accepted use of MRI and [18F]-FDG-PET in diagnosing or excluding bvFTD, but also shows that CSF biomarkers aid clinicians in the diagnostic process.

Schizophrenia as a mimic of behavioral variant frontotemporal dementia

Recently, the diagnostic criteria for the behavioral variant of frontotemporal dementia were revised. Although these criteria offer a relatively high sensitivity, their specificity is yet unknown. We describe a 54-year-old woman fulfilling criteria for both late-onset schizophrenia and probable behavioral variant frontotemporal dementia. Following an initial presentation with psychosis, she developed progressive apathy, compulsiveness, and executive dysfunction. Moreover, bilateral frontotemporal hypometabolism was seen on [(18)F]fludeoxyglucose-positron emission tomography. A post-mortem diagnosis of schizophrenia was established, given the clinical picture combined with the pathological exclusion of a neurodegenerative cause. Our case suggests that patients with other brain disorders may meet the current diagnostic criteria for probable frontotemporal dementia. Further clinicopathological validation of these criteria is needed to determine their exact specificity.

Clinico-Pathological Correlations of the Frontal Lobe Syndrome: Results of a Large Brain Bank Study

AIMS

A clinical frontal lobe syndrome (FLS) is generally attributed to functional or structural disturbances within frontal-subcortical circuits. We studied the distribution of pathological brain changes in FLS. Additionally, the prevalence of FLS among various disorders was studied.

METHODS

We systematically screened clinical files of donors to the Netherlands Brain Bank (n = 2,814) for FLS. A total of 262 FLS cases were identified, and the distribution of postmortem pathological changes within the frontal-subcortical circuits was extracted from their neuropathological reports.

RESULTS

In 244 out of 262 patients (93%), pathological changes within the frontal-subcortical circuits were found: 90 subjects (34%) with frontal cortical pathology and 18 (7%) with pathology restricted to subcortical grey matter nuclei, whereas 136 subjects (52%) showed both cortical and subcortical pathology. In 18 subjects (7%), no pathology was found in the examined areas. The prevalence of FLS was highest in frontal-temporal lobar degeneration, followed by progressive supranuclear palsy and vascular dementia [χ(2)(6, n = 1,561) = 222.64, p < 0.01].

CONCLUSION

In this large brain bank study, the distribution of pathological changes in subjects with FLS was shown to be frontal-subcortical for the first time. A minority of FLS cases had pathology in the subcortical regions only or no frontal pathology at all.

Psychiatric diagnoses underlying the phenocopy syndrome of behavioural variant frontotemporal dementia

INTRODUCTION

The frontotemporal dementia (FTD) consortium criteria (2011) emphasise the importance of distinguishing possible and probable behavioural variant FTD (bvFTD). A significant number of possible patients with bvFTD do not show functional decline and remain with normal neuroimaging over time, thus exhibiting the bvFTD phenocopy syndrome. A neurodegenerative nature is unlikely but an alternative explanation is missing. Our aim was to detect psychiatric conditions underlying the bvFTD phenocopy syndrome after extensive evaluation.

METHODS

We included patients with the bvFTD phenocopy syndrome whereby patients with probable bvFTD served as a control group. Patients had to have undergone both neurological and psychiatric evaluation. Their charts were reviewed retrospectively. Using both qualitative and quantitative methods, psychiatric and psychological conditions associated with the clinical syndrome were determined in both groups and their relative frequencies were compared.

RESULTS

Of 181 suspected bvFTD cases, 33 patients with bvFTD phenocopy syndrome and 19 with probable bvFTD were included. Recent life events, relationship problems and cluster C personality traits were the most prevalent psychiatric/psychological conditions. The frequency of these conditions was higher in the group of patients with the bvFTD phenocopy syndrome (n=28) compared to the probable bvFTD group (n=9) (χ(2) p<0.05).

CONCLUSIONS

This is the first study thoroughly exploring psychiatric causes of the bvFTD phenocopy syndrome, revealing that in most cases multiple factors played a contributory role. Our study gives arguments for neurological and psychiatric collaboration when diagnosing bvFTD. Prompt diagnosis of treatable psychiatric conditions is to be gained.

Identifying bvFTD Within the Wide Spectrum of Late Onset Frontal Lobe Syndrome: A Clinical Approach

OBJECTIVE

The behavioral variant of frontotemporal dementia (bvFTD) can be difficult to diagnose because of the extensive differential diagnosis, including many other diseases presenting with a frontal lobe syndrome. We aimed to identify the diagnostic spectrum causing a late onset frontal lobe syndrome and examine the quality of commonly used instruments to distinguish between bvFTD and non-bvFTD patients, within this syndrome.

METHODS

A total of 137 patients fulfilling the criteria of late onset frontal lobe syndrome, aged 45 to 75 years, were included in a prospective observational study. Diagnoses were made after clinical and neuropsychological examination, and neuroimaging and cerebral spinal fluid results were taken into account. Baseline characteristics and the scores on the Mini-Mental State Exam (MMSE), frontal assessment battery (FAB), Frontal Behavioral Inventory (FBI), and Stereotypy Rating Inventory (SRI) were compared between the bvFTD and the non-bvFTD group.

RESULTS

Fifty-five (40%) of the patients received a bvFTD diagnosis (33% probable and 7% possible bvFTD). Fifty-one patients (37%) had a psychiatric disorder, including 20 with major depressive disorder. Thirty-one patients received an alternative neurological, including neurodegenerative, diagnosis. MMSE and FAB scores were unspecific for a particular diagnosis. A score above 12 on the positive FBI subscale or a score above 5 on the SRI were indicative of a bvFTD diagnosis.

CONCLUSION

A broad spectrum of both neurological and psychiatric disorders underlies late onset frontal lobe syndrome, of which bvFTD was the most prevalent diagnosis in our cohort. The commonly used MMSE and the FAB could not successfully distinguish between bvFTD and non-bvFTD, but this could be achieved with the more specific FBI and SRI.

Historical evolution of the frontal lobe syndrome

The function of the frontal lobes and the related frontal lobe syndrome have not been described in detail until relatively late in history. Slowly, the combination of knowledge from animal models, the detailed examination of symptoms after traumatic frontal lobe injuries, and the rise and fall of psychosurgery has led to increasing insight into frontal lobe function. The frontosubcortical circuits have been described and increasingly related to clinical syndromes, confirmed by the latest developments in functional connectivity networks.

Building a new paradigm for the early recognition of behavioral variant frontotemporal dementia: Late Onset Frontal Lobe Syndrome study

OBJECTIVE

To describe the aims and design of the ongoing Late Onset Frontal Lobe Syndrome study (LOF study), a study on the spectrum of neurodegenerative and psychiatric etiologies causing behavioral changes in later life, and on the role of magnetic resonance imaging (MRI), [(18)F]-fluorodeoxyglucose-positron emission tomography (FDG-PET), and cerebrospinal fluid (CSF) biomarkers in predicting and identifying the different underlying pathologies with a special focus on the behavioral variant of frontotemporal dementia.

METHODS

The LOF study is an observational cross-sectional and prospective follow-up study. Patients aged 45-75 years with a frontal behavioral change consisting of apathy, disinhibition, or compulsive/stereotypical behavior were included (April 2011-2013). Patients underwent a multidisciplinary assessment by a neurologist and psychiatrist and MRI, CSF, and PET measurements at inclusion and after 2 years of follow-up.

RESULTS

The diagnostic added value of MRI, PET, and CSF results and their predictive value will be measured after 2 years of follow-up.

CONCLUSION

This is the first large-scale prospective follow-up study of patients with late-onset behavioral disorders.