[Late-onset frontotemporal degenerations].

Frontotemporal lobar degeneration (FTLD) encompasses a heterogeneous group of neurodegenerative disorders, including a wide range of clinical, neuropathological, and genetic entities, whose late-onset forms remain underdiagnosed in clinical practice. Although FTLD is less frequent than Alzheimer's disease (AD) in older adults, recent epidemiological studies indicate that its incidence increases with age, peaking around the seventh decade, thereby challenging the traditional view of FTLD as a disorder predominantly affecting younger individuals. In older patients, diagnostic accuracy is reduced by the frequent absence of typical early-onset features. Late-onset FTLD often presents with less characteristic clinical phenotypes, including attenuated behavioural symptoms, misleading memory impairment suggestive of AD, and subtle motor or language manifestations, all of which contribute to delayed recognition. From a neuropathological perspective, late-onset FTLD displays distinct features compared with earlier-onset forms, including less pronounced frontotemporal atrophy, a higher frequency of mixed pathologies, and the presence of age-related lesions, which may influence clinical expression. In clinical practice, the identification of FTLD in older adults relies on a multimodal approach integrating detailed clinical and neuropsychological evaluation with structural or functional neuroimaging. In the absence of FTLD-specific biomarkers, cerebrospinal fluid biomarkers of AD are frequently used to support the diagnostic process, primarily to identify or exclude concomitant AD pathology, although their interpretation requires caution in this age group. Genetic analyses may also contribute to the diagnostic assessment, particularly in presentations compatible with the behavioural variant of FTLD, including late-onset cases. Overall, integrating clinical, neuropsychological, imaging, biomarker, and genetic data is essential to improve the recognition of late-onset FTLD and optimize patient management in this population.