Hereditary spastic paraplegia type 4 is the most frequent mutation of hereditary spastic paraplegias. It is commonly described as pure, with progressive weakness of the lower limbs, pyramidal syndrome and vesico-sphincter disorders. However, cognitive disorders have been reported for over 20 years, but remain poorly characterized.

Our primary objective is to describe a pattern of cognitive impairment in Hereditary Spastic Paraplegia type 4 using 18-FDG-PET metabolic imaging.

As secondary objectives, we wish to study the presence of correlations between neuropsychological tests, clinical examination, 18-FDG-PET data and general and genetic data of the pathology. We also wish to investigate correlations between genotype and phenotype.

Inclusion Criteria:

• Patient over 18 years of age, living in the Grand Est region (France)
• Patient with a pathogenic or probably pathogenic variant (class 4 or 5) in the SPAST gene.

Exclusion Criteria:

• dementia comorbidities or cognitive disorders unrelated to the pathology that may affect neuropsychological tests.

Patients followed in the Grand Est region for type 4 spastic paraplegia with identification of a pathogenic or probably pathogenic variant in the SPAST gene.