Alerting Network Dysfunction in Early Multiple Sclerosis

Abstract

The objective of this study is to assess attention in recently diagnosed relapsing-remitting multiple sclerosis patients. Twenty-seven patients with early multiple sclerosis and low clinical disability scores (EDSS<2) and 27 sex-, age-, and education-matched healthy controls underwent attention assessment using the Attentional Network Test, a computerized task designed to measure efficiency independently in 3 attentional networks (Alerting, Orienting and Executive Control). MS patients had significantly less efficiency in the Alerting network (p = .006). In contrast, in the Orienting and Executive Control networks, they did not differ from controls. A significant interaction between Alerting and Executive Control was also found in the MS patients (p = .007). Early relapsing-remitting multiple sclerosis particularly affects the Alerting domain of attention, whereas the Orienting and Executive Control domains are not affected.

Information processing speed and attention in multiple sclerosis: Reconsidering the Attention Network Test (ANT)

“…No significant differences in specific network effects have been found when small samples of patients and controls are compared (e.g., N = 11: Ishigami et al, 2013;N = 12: Omisade et al, 2012), probably due to these studies' insufficient statistical power. However, when larger samples were examined, both Urbanek et al (2010) and Crivelli et al (2012) reported deficits in patients' alerting network, whereas Wojtowicz et al (2013) found impaired performance on the executive control network.…”

“…Several studies have compared MS patients and controls on the attention networks comprising Posner's model (Crivelli et al, 2012;Ishigami, Fisk, Wojtowicz, & Klein, 2013;Omisade et al, 2012;Urbanek et al, 2010;Wojtowicz, Omisade, & Fisk, 2013). No significant differences in specific network effects have been found when small samples of patients and controls are compared (e.g., N = 11: Ishigami et al, 2013;N = 12: Omisade et al, 2012), probably due to these studies' insufficient statistical power.…”

“…The network effects reported by Wojtowicz et al (2013) were based on simple difference scores. Both Urbanek et al (2010) and Crivelli et al (2012) evaluated network effects with procedures designed to account for the differences in overall processing speed between the patients and controls. Urbanek et al used proportional scores, dividing the difference scores by the participant's overall average RT on all of the items of the ANT.…”

“…We intend to show that, when appropriate controls are imposed on differences in processing speed, the conflicting findings concerning MS patients' performance on the ANT are largely resolved. To do so, we examined network effects for MS patients and healthy controls first when these effects were assessed using difference scores and then when they were assessed using the proportional scores adopted by Urbanek et al (2010) and the residualized scores adopted by Crivelli et al (2012). We contend that a more accurate assessment of the impact of MS on attention networks emerges when the substantial between-group differences in processing speed are controlled using proportional or residualized scores.…”

“…For example, an individual's score for center cue was the mean of the median RTs for the center cue conditions that used no flankers, congruent flankers, and incongruent flankers. We also computed two additional scores replicating the measures of processing speed formulated by Urbanek et al (2010) and Crivelli et al (2012). The former consisted of the overall mean of the median scores for all 12 Warning Cue × Flanker conditions (RT all ).…”