Anatomical and functional differences between the Paced Auditory Serial Addition Test and the Symbol Digit Modalities Test

Abstract

The Paced Auditory Serial Addition Test (PASAT) and the Symbol Digit Modalities Test (SDMT) are generally used to detect cognitive impairments in multiple sclerosis patients. Although both seem to be sensitive to the slow information-processing speed, some results suggest that they do not involve the same cognitive functions. The aim of the present study is to observe possible differences between these tasks to help understand their utility to cognitive assessment. A total of 17 participants were recruited for the study and completed a block-design version of each task. Comparisons between tasks were calculated using an analysis of variance (ANOVA; p < .05, familywise error, FWE, corrected). We observed activations in the left frontal and parietal areas during both tasks; however, the PASAT activated more frontal areas than did the SDMT. These tasks require an efficient transfer of information among large areas. Moreover, the PASAT requires more executive functions to be executed.

Keywords:

• Information-processing speed
• Working memory
• Paced Auditory Serial Addition Test
• Symbol Digit Modalities Test
• Functional magnetic resonance imaging

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This research was supported by grants provided by the Fundación Dávalos-Fletcher and the Consolider-Ingenio 2010 program (Spanish Ministry of Science and Education) to C. Avila.