- •Scores on the SDMT represent deficits in sensorial, cognitive or motor processing.
- •There is a need to isolate and characterise cognitive IPS deficits in MS.
- •We demonstrated significant cognitive IPS deficits in early MS patients.
- •Cognitive IPS deficits were not associated with SDMT performance.
The assessment of cognitive information processing speed (IPS) is complicated in MS, with altered performance on tests such as the Symbol Digit Modalities Test (SDMT) potentially representing changes not only within cognitive networks but in the initial sensorial transmission of information to cognitive networks, and/or efferent transmission of the motor response.
We aimed to isolate and characterise cognitive IPS deficits in MS using ocular motor tasks; a prosaccade task (used to assess and control for sensorial and motor IPS) which was then used to adjust performance on the Simon task (cognitive IPS).
All participants (22 MS patients with early disease, 22 healthy controls) completed the ocular motor tasks and the SDMT. The Simon task assessed cognitive IPS by manipulating the relationship between a stimulus location and its associated response direction. Two trial types were interleaved: (1) congruent, where stimulus location = response direction; or (2) incongruent, where stimulus location ≠ response direction. RESULTS MS patients did not perform differently to controls on the SDMT. For OM tasks, when sensorial and motor IPS was controlled, MS patients had significantly slower cognitive IPS (incongruent trials only) and poorer conflict resolution. SDMT performance did not correlate with slower cognitive IPS in MS patients, highlighting the limitation of using SDMT performance to interpret cognitive IPS changes in patients with MS.
Cognitive IPS deficits in MS patients are dissociable from changes in other processing stages, manifesting as impaired conflict resolution between automatic and non-automatic processes. Importantly, these results raise concerns about the SDMT as an accurate measure of cognitive IPS in MS.
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Multiple Sclerosis and Related Disorders
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Cognitive impairment in multiple sclerosis.Lancet Neurol. 2008; 7: 1139-1151
- Cognitive impairment in different MS subtypes and clinically isolated syndromes.J. Neurol. Sci. 2008; 267: 100-106
- Is speed of processing or working memory the primary information processing deficit in multiple sclerosis?.J. Clin. Exp. Neuropsyc. 2004; 26: 550-562
- Information-processing speed is the primary deficit underlying the poor performance of multiple sclerosis patients in the paced auditory serial addition test (PASAT).J. Clin. Exp. Neuropsychol. 2008; 30: 789-796
- Is speed of processing or working memory the primary information processing deficit in multiple sclerosis?.J. Clin. Exp. Neuropsychol. 2004; 26: 550-562
- The temporal dynamics of visual processing in multiple sclerosis.Appl. Neuropsychol. Adult. 2016; 23: 133-140
- Information processing speed in multiple sclerosis: past, present, and future.Mult. Scler. J. 2017; 23: 772-789
- Information Processing Speed in Clinical Populations.in: DeLuca J Kalmar JH Taylor & Francis, Philadelphia, PA, US2008 (xv, 312-xv)
- Differentiating simple versus complex processing speed: influence on new learning and memory performance.J. Clin. Exp. Neuropsyc. 2003; 25: 489-501
- Cognitive control of eye movements.Brain Cogn. 2008; 68: 327-340
- The Simon effect as tool and heuristic.Acta Psychol. 2011; 136: 189-202
- The Simon effect”: a potent behavioral mechanism.Acta Psychol. 2011; 136: 181
- Visualizing the temporal dynamics of spatial information processing responsible for the Simon effect and its amplification by inhibition of return.Acta Psychol. 2011; 136: 235-244
- Micro- and macro-adjustments of task set: activation and suppression in conflict tasks.Psychol. Res. 2002; 66: 312-323
- Dynamics of saccade parameters in multiple sclerosis patients with fatigue.J. Neurol. 2012; 259: 2656-2663
- Symbol Digit Modalities Test.Western Psychological Services, Los Angeles1973
- Conditional and unconditional automaticity: a dual-process model of effects of spatial stimulus-response correspondence.J. Exp. Psychol. 1994; 20: 731-750
- Dimensional overlap: cognitive basis for stimulus-response compatibility–a model and taxonomy.Psychol. Rev. 1990; 97: 253-270
- Prefrontal cortex and neural mechanisms of executive function.J Physiol. Paris. 2013; 107: 471-482
- Ocular motor measures of cognitive dysfunction in multiple sclerosis I: inhibitory control.J. Neurol. 2015; 262: 1130-1137
- Antisaccade performance in patients with multiple sclerosis.Cortex. 2009; 45: 900-903
- Longitudinal assessment of antisaccades in patients with multiple sclerosis.PLoS ONE. 2012; 7
- Executive functioning in relapsing-remitting multiple sclerosis patients without cognitive impairment: a task-switching protocol.Mult. Scler. 2018; 24: 1328-1336
- Multiple sclerosis: executive dysfunction, task switching and the role of attention.Mult. Scler. J. Exp. Transl. Clin. 2018; 42055217318771781
- Procedural variations in the stroop and the symbol digit modalities test: impact on patients with multiple sclerosis.Arch. Clin. Neuropsychol. 2013; 28: 452-462
- Stroop performance in multiple sclerosis: information processing, selective attention, or executive functioning?.J. Int. Neuropsychol. Soc. 2008; 14: 805-814
- Information processing speed and attention in multiple sclerosis: reconsidering the attention network test (ANT).J. Clin. Exp. Neuropsychol. 2015; 37: 518-529
- Alerting network dysfunction in early multiple sclerosis.J. Int. Neuropsychol. Soc. 2012; 18: 757-763
- Repeated measurement of the attention components of patients with multiple sclerosis using the attention network test-interaction (ANT-I): stability, isolability, robustness, and reliability.J. Neurosci. Methods. 2013; 216: 1-9
- Attention network test reveals alerting network dysfunction in multiple sclerosis.Mult. Scler. 2010; 16: 93-99
- Control of visually guided saccades in multiple sclerosis: disruption to higher-order processes.Neuropsychologia. 2009; 47: 1647-1653
- Cognitive deficits in multiple sclerosis correlate with changes in fronto-subcortical tracts.Mult. Scler. 2008; 14: 364-369
- Altered functional connectivity and performance variability in relapsing-remitting multiple sclerosis.Mult. Scler. 2014; 20: 1453-1463
- Hyperconnectivity of the dorsolateral prefrontal cortex following mental effort in multiple sclerosis patients with cognitive fatigue.Mult. Scler. 2016; 22: 1665-1675
Published online: November 21, 2019
Accepted: November 11, 2019
Received in revised form: November 7, 2019
Received: March 22, 2019
© 2019 Published by Elsevier B.V.