RESUMEN
Frontotemporal dementia (FTD) affects behavior, language, and personality. This study aims to explore functional connectivity changes in three FTD variants: behavioral (bvFTD), semantic (svPPA), and nonfluent variant (nfvPPA). Seventy-six patients diagnosed with FTD by international criteria and thirty-two controls were investigated. Functional connectivity from resting functional magnetic resonance imaging (fMRI) was estimated for the whole brain. Two types of analysis were done: network basic statistic and topological measures by graph theory. Several hubs in the limbic system and basal ganglia were compromised in the behavioral variant apart from frontal networks. Nonfluent variants showed a major disconnection with respect to the behavioral variant in operculum and parietal inferior. The global efficiency had lower coefficients in nonfluent variants than behavioral variants and controls. Our results support an extensive disconnection among frontal, limbic, basal ganglia, and parietal hubs.
Asunto(s)
Afasia Progresiva Primaria/fisiopatología , Conectoma/métodos , Demencia Frontotemporal/fisiopatología , Red Nerviosa/fisiopatología , Anciano , Afasia Progresiva Primaria/diagnóstico por imagen , Femenino , Demencia Frontotemporal/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Red Nerviosa/diagnóstico por imagen , Afasia Progresiva Primaria no Fluente/diagnóstico por imagen , Afasia Progresiva Primaria no Fluente/fisiopatologíaRESUMEN
BACKGROUND: Early progressive nonfluent aphasia (PNFA) may be difficult to differentiate from semantic dementia (SD) in a nonspecialist setting. There are descriptions of the clinical and neuropsychological profiles of patients with PNFA and SD but few systematic comparisons. METHOD: We compared the performance of groups with SD (n=27) and PNFA (n=16) with comparable ages, education, disease duration, and severity of dementia as measured by the Clinical Dementia Rating Scale on a comprehensive neuropsychological battery. Principal components analysis and intergroup comparisons were used. RESULTS: A 5-factor solution accounted for 78.4% of the total variance with good separation of neuropsychological variables. As expected, both groups were anomic with preserved visuospatial function and mental speed. Patients with SD had lower scores on comprehension-based semantic tests and better performance on verbal working memory and phonological processing tasks. The opposite pattern was found in the PNFA group. CONCLUSIONS: Neuropsychological tests that examine verbal and nonverbal semantic associations, verbal working memory, and phonological processing are the most helpful for distinguishing between PNFA and SD.