Background: Event-related potentials (ERPs) and time-frequency analysis investigate cognition-related brain activity. The Symbol-Digit Modalities Test (SDMT) assesses cognitive processing in people with Multiple Sclerosis (pwMS). EEG may reveal neurophysiological dynamics during SDMT, aiding in identifying electrophysiological biomarkers of cognitive impairment. Methods: We developed an EEG-SDMT paradigm, presenting a symbol-number legend and 180 symbol-digit pairs. Reaction times (RTs) and 32-channel EEG data were recorded from 75 pwMS (50 F; 53.36 ± 10.03 years; EDSS 5.95 ± 1.01) and 22 healthy controls (HC) (15 F; 51.36 ± 13.88 years). Results: PwMS showed longer SDMT-ERP peak latency (612.87 ± 111.21 ms) vs HC (520.44 ± 79.99 ms) (p < 0.001). The cognitive processing component was delayed in pwMS (460.99 ± 117.23 ms) vs HC (376.39 ± 73.80 ms) (p < 0.001). Both latencies correlated with EEG-SDMT RTs (r = 0.278, p < 0.01; r = 0.214, p < 0.05). PwMS exhibited reduced alpha (200-300 ms) and theta (300−600 ms) activity (p < 0.01) in centro-parietal regions. EEG-SDMT RTs inversely correlated with SDMT scores (r = −0.718, p < 0.01). Conclusions: Our EEG-SDMT paradigm reveals neurophysiological correlates of SDMT performance, significantly impaired in pwMS, mainly due to cognitive rather than visual processing differences.
Tacchini, M, Gamberini, G, Rossi, C, Rodegher, M, Gradassi, A, Chiveri, L, Schependom, JV, Nagels, G, Dini, M, Comi, G & Leocani, L 2026, '30 Electrophysiological markers of cognition in MS: an EEG study during SDMT', Clinical Neurophysiology, vol. 187. https://doi.org/10.1016/j.clinph.2026.2111785
Tacchini, M., Gamberini, G., Rossi, C., Rodegher, M., Gradassi, A., Chiveri, L., Schependom, J. V., Nagels, G., Dini, M., Comi, G., & Leocani, L. (2026). 30 Electrophysiological markers of cognition in MS: an EEG study during SDMT. Clinical Neurophysiology, 187. https://doi.org/10.1016/j.clinph.2026.2111785
@article{fc13a1c88d43405bb1a3b2a5ab81fc21,
title = "30 Electrophysiological markers of cognition in MS: an EEG study during SDMT",
abstract = "Background: Event-related potentials (ERPs) and time-frequency analysis investigate cognition-related brain activity. The Symbol-Digit Modalities Test (SDMT) assesses cognitive processing in people with Multiple Sclerosis (pwMS). EEG may reveal neurophysiological dynamics during SDMT, aiding in identifying electrophysiological biomarkers of cognitive impairment. Methods: We developed an EEG-SDMT paradigm, presenting a symbol-number legend and 180 symbol-digit pairs. Reaction times (RTs) and 32-channel EEG data were recorded from 75 pwMS (50 F; 53.36 ± 10.03 years; EDSS 5.95 ± 1.01) and 22 healthy controls (HC) (15 F; 51.36 ± 13.88 years). Results: PwMS showed longer SDMT-ERP peak latency (612.87 ± 111.21 ms) vs HC (520.44 ± 79.99 ms) (p < 0.001). The cognitive processing component was delayed in pwMS (460.99 ± 117.23 ms) vs HC (376.39 ± 73.80 ms) (p < 0.001). Both latencies correlated with EEG-SDMT RTs (r = 0.278, p < 0.01; r = 0.214, p < 0.05). PwMS exhibited reduced alpha (200-300 ms) and theta (300−600 ms) activity (p < 0.01) in centro-parietal regions. EEG-SDMT RTs inversely correlated with SDMT scores (r = −0.718, p < 0.01). Conclusions: Our EEG-SDMT paradigm reveals neurophysiological correlates of SDMT performance, significantly impaired in pwMS, mainly due to cognitive rather than visual processing differences.",
keywords = "biological marker, adult, clinical article, cognition, cognitive defect, conference abstract, controlled study, electroencephalogram, electroencephalography, electrophysiology, event related potential, evoked response, female, frequency analysis, human, latent period, male, multiple sclerosis, normal human, reaction time, symbol digit modalities test",
author = "Marta Tacchini and Giulia Gamberini and Chiara Rossi and Mariaemma Rodegher and Alessandro Gradassi and Luca Chiveri and Schependom, \{Jeroen Van\} and Guy Nagels and Michelangelo Dini and Giancarlo Comi and Letizia Leocani",
year = "2026",
month = jul,
day = "1",
doi = "10.1016/j.clinph.2026.2111785",
language = "English",
volume = "187",
journal = "Clinical Neurophysiology",
issn = "1388-2457",
publisher = "Elsevier Ireland Ltd",
}