Association between spinocerebellar ataxias caused by glutamine expansion and psychiatric and neuropsychological signals - a literature review.

The autosomal dominant cerebellar ataxias, also known as spinocerebellar ataxias (SCA), are characterized by cerebellar degeneration and by their afferent and efferent connections. Currently, at least 31 types of SCA are described, among which a subset, comprising types 1, 2, 3, 6, 7, 17 of the disease, is distinguished due to sharing the same form of mutation involving the repetition of the series of CAG triplets, known as polyglutamine diseases (SCApolyQ). Through a systematic literature review using the Pubmed, PsycoINFO, LILACS and SciELO databases and the keywords Spinocerebellar Ataxia in association with the words neuropsychiatric, psychological, cognitive impairment(s) and psychiatric comorbidities this study aimed to identify the possible associations between SCApolyQ and neuropsychological and psychiatric symptoms/disorders. A greater presence of symptoms of depression and anxiety was evidenced, as well as the existence of cognitive impairments in the patients with SCApolyQ when compared with the general population, with important differences in the profile of these impairments among the types of SCA. It was observed that the findings, in general, indicated greater impairment in the executive functions, verbal fluency and verbal memory and that there was a higher concentration of studies for SCA2 and SCA3. However, there is a need for a greater number of studies using a more homogeneous methodology, which perform direct comparisons between the types of ataxias and that explore some of the still little evaluated neuropsychological functions and the different psychiatric disorders in their amplitude.