Half of bvFTD patients indeed received a prior primary-psychiatric diagnosis ( 9, 12).Īs FTLD is a heterogenous pathophysiological entity, bvFTD can be caused by different underlying pathologies ( 13– 15). Due to relatively large symptomatic overlap and the lack of established biomarkers, the prevalence of bvFTD may well be underestimated because of frequent misdiagnoses with either a different neurodegenerative cognitive disorder or a primary psychiatric disorder ( 9– 11). Converging evidence then suggests that bvFTD is the second most frequent young-onset (<65 years old) cognitive neurodegenerative disorder following Alzheimer's disease (AD) ( 4, 7, 8). Within the most relevant age range of 45 to 65 years, 10–30 in 100,000 people are estimated to be affected by FTLD ( 4, 7). The average disease onset of bvFTD is estimated within the early sixth decade of life although patients can also be substantially younger or older as some cases with a disease onset in the 20s and after 85 years of age have been described ( 4– 6). Prevalence rates are further clouded because bvFTD, FTD, or FTLD patients are not systematically considered separately across studies. Estimated prevalence rates highly vary depending on the employed diagnostic criteria which have been considerably refined during the last two decades ( 1– 3). Fronto-Temporal Lobar Degeneration (FTLD) is the broader pathological disease spectrum also encompassing FTD, motoneuron disease (MND), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). Accounting for this symptomatology is a pronounced and relatively focused neural loss in bilateral frontal, insular, and/or anterior temporal cortices that can typically be found in patients early in the disease.īvFTD is the most frequent clinical syndrome of FTD (which also includes two other clinical dementia syndromes with predominant language dysfunctions). We finally outline both, future opportunities and major challenges with regard to the role of clinical neuropsychology in detecting bvFTD and related neurocognitive disorders.īehavioral variant frontotemporal dementia (bvFTD) is a neurodegenerative disease characterized by early progressive changes in behavior, social conduct, emotional processing as well as specific cognitive impairments ( 1, 2). In particular, evidence on specific impairments in social and emotional processing, praxis abilities as well as interoceptive processing in bvFTD is summarized and potential links with behavior and classic cognitive domains are discussed. We then review more recent developments and evidence on cognitive, behavioral and psychological symptoms of bvFTD beyond the diagnostic criteria which may prospectively enhance the early detection and differential diagnosis in clinical routine. We highlight both, practical difficulties as well as current controversies regarding an overlap of symptoms and particularly cognitive impairments with other neurodegenerative and primary psychiatric diseases.
With this review, we aim for a critical appraisal of common methods to access the behavioral and psychological symptoms as well as the cognitive alterations presented in the diagnostic criteria for bvFTD. Their evaluation however, requires expertise and in-depth assessments of cognitive functions, history taking, clinical observations as well as caregiver reports on behavioral and psychological symptoms and their respective changes. Early detection of bvFTD thus relies on correct application of clinical diagnostic criteria. Since the histopathology of the disease is heterogeneous and identified genetic mutations only account for ~30% of cases, there are no reliable biomarkers for the diagnosis of bvFTD available in clinical routine as yet. Characterized by frontal, insular, and/or temporal brain atrophy, patients present with heterogeneous constellations of behavioral and psychological symptoms among which progressive changes in social conduct, lack of empathy, apathy, disinhibited behaviors, and cognitive impairments are frequently observed.
1Section for Neuropsychology, Department of Neurology, University Hospital Münster, Münster, Germany.Andreas Johnen 1 * and Maxime Bertoux 2 *