Early- and late-onset Alzheimer disease: Are they the same entity? / Enfermedad de Alzheimer de inicio precoz y de inicio tardío: ¿son la misma entidad?

Early-onset Alzheimer disease (EOAD), which presents in patients younger than 65 years, has frequently been described as having different features from those of late-onset Alzheimer disease (LOAD). This review analyses the most recent studies comparing the clinical presentation and neuropsychological, neuropathological, genetic, and neuroimaging findings of both types in order to determine whether EOAD and LOAD are different entities or distinct forms of the same entity. We observed consistent differences between clinical findings in EOAD and in LOAD. Fundamentally, the onset of EOAD is more likely to be marked by atypical symptoms, and cognitive assessments point to poorer executive and visuospatial functioning and praxis with less marked memory impairment. Alzheimer-type features will be more dense and widespread in neuropathology studies, with structural and functional neuroimaging showing greater and more diffuse atrophy extending to neocortical areas (especially the precuneus). In conclusion, available evidence suggests that EOAD and LOAD are 2 different forms of a single entity. LOAD is likely to be influenced by ageing-related processes.

[Neuropsychological profile of frontotemporal lobar degeneration]. / Perfil neuropsicológico de la degeneración lobar frontotemporal.

Frontotemporal lobar degeneration encompasses three different syndromes, with clinical and pathologic commonalities, making diagnosis difficult in early stages. Three subtypes are recognized: frontotemporal dementia and its three variants, corticobasal syndrome and supranuclear palsy syndrome. The objective of this study is to review the neuropsychological features of each syndrome in order to differentiate amongst subtypes as well as from other forms of dementia. We review multiple studies from the literature, highlighting the main clinical features, neuropathology and changes in brain imaging of each syndrome. Subsequently, we describe the neuropsychological profile compared to other dementias, and how it progresses over time. Although there is an overlap amongst the different subtypes of frontotemporal lobar degeneration, neuropsychological profiles can help identify subtypes and discriminate frontotemporal lobar degeneration from other forms of dementia.