The prevalence of cognitive dysfunction in the estonian population of the hereditary spastic paraplegia

The hereditary spastic paraplegias (HSPs) are neurodegenerative disorders of the motor system. The information about the prevalence of the cognitive dysfunction in HSP is inconsistent. The aim of the study was to describe the prevalence of cognitive dysfunction and the cognitive profiles of persons with HSP (pwHSP) compared to healthy controls. Subjects: Participating in the cognition study were 48 persons with HSP from the epidemiological study and 48 healthy controls. Of those with HSP, 81% (39/48) had pure and 19% (9/48) had complex forms. Among pwHSP, 20.8% (10/48) had pathogenic and 14.6% (7/48) had non-pathogenic mutations in the SPAST gene. There were no mutations detected in 31 persons with the SPAST gene. Methods: Neuropsychological test battery, MMSE Results. The results of the neuropsychological tests were significantly lower in persons with HSP than in the controls (Bonferroni correction, p < 0.00625). There were statistically significant differences in subtests measuring consistent long term retrieval (p < 0.001), later recall (p = 0.004) in verbal memory and symbol digit modalities (p = 0.0015). Five persons with HSP had an MMSE score of 24 or less. Conclusions: Our results demonstrate that cognitive dysfunction is present in 16.7% to 33.3% of persons with HSP, depending on the criteria applied. There was cognitive dysfunction in 30% of persons with a known pathogenic mutation in the SPAST gene. The most frequently damaged functions in HSP are consistent long term retrieval and later recall in verbal memory and symbol digit modalities tests that discriminate between controls and pwHSP with dysfunction (1.5 SD) in three or more domains. Dementia in HSP is rare.