Cognitive impairment in spinocerebellar ataxia type 6

Objective: The aim of this study was to evaluate cognitive impairment in patients with spinocerebellar ataxia type 6 (SCA6) and to verify the role of cerebellar involvement in intellectual abilities. Methods: Cognitive function was examined in 18 patients with genetically confirmed SCA6 and in 21 age and education matched controls using a test battery for attention, verbal and visuospatial memory, as well as executive function. Results: Verbal fluency and immediate visual memory task were markedly impaired in SCA6 compared with the control group (p = 0.007, 0.004 and 0.014, respectively). The results of the Rule Shift Cards Test was reduced in patients with SCA6, but the reduction was not significant. These cognitive dysfunctions did not correlated with CAG repeat length, age at onset, ataxic motor dysfunctional scale or depression. Conclusions: Our results demonstrate that specific cognitive deficits occur in patients with SCA6, independent of ataxic motor dysfunction. These deficits may reflect disruption of cortico-cerebellar circuits.