Cognitive changes in spinocerebellar ataxia type 2

Cognitive disorders and dementia occur in 19 to 42% of patients with spinocerebellar ataxia type 2 (SCA2). Neuropsychological tests can reveal executive dysfunction, impaired visual and verbal memory, tongue and speech impairment, attention disorders and impaired verbal fluency.

We performed psychiatric and neuropsychological examinations in 12 patients diagnosed with genetically confirmed SCA2 and 12 healthy volunteers matching the patients in age, gender, and length of education. The level of motor impairment was determined using the brief ataxia rating scale (BARS). The neuropsychological examination focused on testing executive functions, short-term visual and verbal memory, attention, psychomotor tempo, visual motor coordination, learning ability and comprehension ability. The tests were divided into two subgroups according to the difficulty of motor tasks. The cognitive abilities composite score (CACS) was determined by calculating the arithmetic mean of T scores of the respective tests.

Patients with SCA2 had significantly lower CACSs (p=0.00005) compared to the healthy volunteers. Patients exhibited impaired performance in both difficult and simple motor tests. The severity of cognitive impairment was related to the age at the onset of the disease (p=0.002) but not to the duration or to the overall BARS score.

Compared to healthy volunteers, patients with SCA2 exhibited significantly worse cognitive performance in all areas tested, including the tests of simple motor tasks. Moreover, the cognitive performance of patients worsened as the difficulty of the motor tasks increased.