Cognitive impairment in spinocerebellar ataxia type 6

¹ Department of Neurology, Nagoya University Graduate School of Medicine, Japan
² Department of Radiology, Nagoya University Graduate School of Medicine, Japan

^* To whom correspondence should be addressed. E-mail: sobueg{at}med.nagoya-u.ac.jp.

Accepted 23 July 2007

	Abstract

Objective: The aim of this study was to evaluate cognitive impairment in spinocerebellar ataxia type 6 (SCA6) patients and to verify the role of cerebellar involvement in intellectual abilities.

Methods: Cognitive function was examined in 18 patients with genetically confirmed SCA 6 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 that of the control group (p=0.007, 0.004, and 0.014 respectively). The results of the rule shift cards test was reduced in SCA6 patients, 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: These results demonstrate that specific cognitive deficits occur in patients with SCA6, independent of ataxic motor dysfunction. These deficits may reflect the disruption of cortico-cerebellar circuits.

Keywords: CAG repeat length, cognitive impairment, disruption of cortico-cerebellar circuits, international cooperative ataxia rating scale, spinocerebellar ataxia type 6