Metabolic brain changes across different levels of cognitive impairment in ALS: a<sup>18</sup>F-FDG-PET study
Antonio Canosa, Cristina Moglia, Umberto Manera, Rosario Vasta, Maria Claudia Torrieri, Vincenzo Arena, Fabrizio D’Ovidio, Francesca Palumbo, Jean Pierre Zucchetti, Barbara Iazzolino, Laura Peotta, Andrea Calvo, Marco Pagani, Adriano Chiò
Abstract
Objective To identify the metabolic changes related to the various levels of cognitive deficits in amyotrophic lateral sclerosis (ALS) using 18 F-2-fluoro-2-deoxy-D-glucose positron emission tomography ( 18 F-FDG-PET) imaging. Methods 274 ALS patients underwent neuropsychological assessment and brain 18 F-FDG-PET at diagnosis. According to the criteria published in 2017, cognitive status was classified as ALS with normal cognition (ALS-Cn, n=132), ALS with behavioural impairment (ALS-Bi, n=66), ALS with cognitive impairment (ALS-Ci, n=30), ALS with cognitive and behavioural impairment (ALS-Cbi, n=26), ALS with frontotemporal dementia (ALS–FTD, n=20). We compared each group displaying some degree of cognitive and/or behavioural impairment to ALS-Cn patients, including age at PET, sex and ALS Functional Rating Scale-Revised as covariates. Results We identified frontal lobe relative hypometabolism in cognitively impaired patients that resulted more extensive and significant across the continuum from ALS-Ci, through ALS-Cbi, to ALS–FTD. ALS–FTD patients also showed cerebellar relative hypermetabolism. ALS-Bi patients did not show any difference compared with ALS-Cn. Conclusions These data support the concept that patients with cognitive impairment have a more widespread neurodegenerative process compared with patients with a pure motor disease: the more severe the cognitive impairment, the more diffuse the metabolic changes. Otherwise, metabolic changes related to pure behavioural impairment need further characterisation.