Electrophysiological and neuropsychological assessment of cognition in spinocerebellar ataxia type 1 patients: a pilot study

Background Event-related potentials (ERPs) reflect cognitive processing: negative early components (N100, N200) are involved in the sensory and perceptual processing of a stimulus, whereas late positive component P300 requires conscious attention. Both neuropsychological and affective disorders are present in patients with spinocerebellar ataxia type 1 (SCA1), but the underlying mechanisms need further clarification. Materials and methods In this pilot study, we assessed cognitive processing by recording auditory ERPs in 16 consecutive SCA1 patients and 16 healthy controls (HC) matched for age and sex. Motor and nonmotor symptoms were evaluated using the Scale for the Assessment and Rating of Ataxia (SARA) and an extensive neuropsychological battery. ERPs were recorded using an oddball paradigm, and peak latency and amplitude of N100, N200, and P300 were measured in the averaged responses to target tones. Results We found in SCA1 significantly increased latencies of N200 and P300 (p=0.033, p=0.007) and decreased amplitudes of N100 and P300 (p=0.024, p=0.038) compared with HC. Furthermore, P300 latency had the highest AUC in the discrimination of SCA1 in ROC analysis. The expansion of trinucleotide repeats correlated with P300 latency (r=−0.607, p=0.048), whereas both P300 and N100 amplitudes correlated with the severity of motor symptoms (r=−0.692, p=0.003; r=−0.621; p=0.010). Significant correlations between P300 latency and the scores of Emotion Attribution Task (r=−0.633, p=0.027), as well as between N200 latency and the scores of Frontal Assessment Battery and Stroop test (r=−0.520, p=0.047; r=0.538, p=0.039), were observed. Conclusions This research provides for the first time an extensive characterization of ERPs as useful electrophysiological markers to identify early cognitive dysfunction in SCA1.