Uncovering the association between fatigue and fatigability in multiple sclerosis using cognitive control

Abstract

Background: Fatigue and cognitive dysfunction are two common symptoms experienced by patients with multiple sclerosis (MS). The relationship between subjective and objective fatigue (fatigability) in MS is poorly understood. Cognitive control tasks might be more conducive to fatigability and more likely to show associations between subjective and objective cognitive fatigue in MS. Objective: To study the association between objective fatigability, as induced by a cognitive control task called the Blocked Cyclic Naming Task (BCNT), subjective fatigue and baseline cognitive functioning in patients with MS. Methods: Twenty-one patients with MS completed baseline questions about their disease, the Montreal Cognitive Assessment (MoCA) battery and self-reported questionnaires on trait fatigue, sleep and depression. Disability was captured using the expanded disability status scale (EDSS). Participants then performed the BCNT and were asked about their level of state momentary fatigue before and after the BCNT. The BCNT consists of several blocks of either related or unrelated pictures that participants name as quickly as possible. The pictures cycled 4 times in each block and the difference in the response times (RTs) between related and unrelated blocks was captured. Data were analyzed using repeated measures analysis of variance and Pearson correlations. Results: MS participants’ performance declined for the related, but not unrelated blocks. The difference in RTs between related and unrelated conditions increased with repetition across cycles (p < 0.001). Participants also showed objective fatigability with less repetition priming (p = 0.02) in the 4th quarter and with greater differences between related and unrelated conditions in the later part of the task. Objective fatigability was strongly associated with participants’ assessment of their level of momentary state fatigue (r =0.612, p =0.007). Conclusion: Using the appropriate tools, this study showed an association between subjective and objective cognitive fatigue in people with MS. The BCNT and cognitive control are useful tools in assessing patients with MS and should be explored in future, larger studies in this population.

Perceived fatigue and cognitive performance change in multiple sclerosis: Uncovering predictors beyond baseline fatigue

“…Therefore, whilst perceived fatigue change and reliable performance change may co-occur, it is not clear to what degree change in these is driven by fatigue per se. Contrary to other studies demonstrating relationships between perceived fatigue and cognitive performance fatigability (Cehelyk, Harvey, 2018, Wolkorte, Heersema, 2015 or motor fatigability (Loy, Taylor, 2017, Skurvydas, Brazaitis, 2011, Zijdewind, Prak, 2016, our results provide little general support for the role of fatigue variables in performance change. Whilst there was a link between cognitive impairment status and EDSS, neither had influence on perceived fatigue, fatigue change, or performance change, which are results that diverge from some other studies (Biberacher, Schmidt, 2018, Ghajarzadeh, Jalilian, 2013.…”

“…An increasing drive to examine cognitive performance fatigability in MS has demonstrated that people with MS are vulnerable to cognitive performance change (Berard et al , 2018, Cehelyk et al , 2018, Claros-Salinas et al , 2013, Wolkorte et al , 2015. However, similarly to our understanding of perceived fatigue, the factors influencing cognitive performance change remain unclear.…”

“…However, similarly to our understanding of perceived fatigue, the factors influencing cognitive performance change remain unclear. Although some recent studies (Aldughmi, Bruce, 2017, Cehelyk, Harvey, 2018, Wolkorte, Heersema, 2015 have demonstrated a relationship between perceived fatigue and cognitive performance fatigability, these have been analysed alongside concurrent motor tasks, and measurement of the multiple direct and indirect influences on fatigue has been inconsistent.…”

Cognitive Fatigue in Multiple Sclerosis: An Objective Approach to Diagnosis and Treatment by Transcranial Electrical Stimulation

“…Behaviorally, fatigability can be assessed through changes in reaction time, accuracy, and processing speed in simple alertness or vigilance tests over time. There are numerous studies showing increasing reaction times [25,33,38,39,45,47,59,60] and decreasing accuracy [32,41,42,43] with time-on-task, mostly assessed by administering simple reaction time tests such as the alertness subtest of the Test Battery for Attentional Performance (TAP) [61]. Claros-Salinas et al [33] measured fatigue in the TAP alertness task at three different time points during the course of one day.…”

“…Five studies especially examined subjective state-fatigue and their relationship to objective performance decline with time-on-task. Four studies found a positive relationship [25,43,47,60], while only one study did not [32]. Hence, longer reaction times with time-on-task as well as more omissions in the second half were shown to be associated with a greater feeling of momentary exhaustion [43,47,60].…”