Conference Coverage

Anxiety and fatigue impair processing speed in MS



Anxiety and fatigue interact significantly and affect the rate of processing speed in patients with multiple sclerosis (MS), according to data described at the annual meeting of the Consortium of Multiple Sclerosis Centers. Increased anxiety is associated with slower processing speed in the context of increasing cognitive fatigue. “This [finding] has implications on development of cognitive remediation strategies, which may aim to target patient fatigue or anxiety to improve processing speed,” said Caroline Altaras, a doctoral candidate at Yeshiva University in New York, and colleagues.

Approximately 90% of patients with MS have fatigue, which can be a highly debilitating symptom. Fatigue often is understood to include motor fatigue (difficulty maintaining physical stamina) and cognitive fatigue (difficulty maintaining mental stamina). MS-related fatigue decreases patients’ quality of life, including cognitive functioning.

Anxiety is a psychiatric comorbidity that is highly prevalent in MS and that has a bidirectional association with fatigue. Anxiety and fatigue independently impair cognitive function.

Impaired processing speed is the most common cognitive impairment among patients with MS. Ms. Altaras and colleagues conducted a study to analyze how anxiety and fatigue interact to affect processing speed in MS. They evaluated total fatigue, cognitive fatigue, and motor fatigue separately. The investigators collected data from 183 patients with MS who had been referred by physicians for neuropsychological testing at the MS Center at Holy Name Medical Center in Teaneck, New Jersey. Researchers measured patients’ anxiety and fatigue using the Hospital Anxiety and Depression Scale (HADS, a self-reported measure) and the Fatigue Scale for Motor and Cognitive Functions (FSMC), which measures cognitive fatigue and motor fatigue. Patients also took the Symbol Digit Modalities Test (SDMT), a neuropsychological measure of processing speed. Ms. Altaras and colleagues created three multivariate general linear models using SPSS 25.0 to test the hypothesized relationships, using fatigue types (cognitive, motor, and total) as separate outcomes. The investigators controlled their analyses for gender, age, and education.

The researchers found a significant interaction effect of cognitive fatigue and anxiety on SDMT score. Specifically, patients with MS and minimal anxiety and cognitive fatigue had similar SDMT performance; as anxiety increased, patients who had increased cognitive fatigue demonstrated worse performance on the SDMT. Ms. Altaras and colleagues observed that SDMT performance improved slightly with worsening anxiety when cognitive fatigue was minimal. Although total fatigue interacted significantly with anxiety to affect SDMT performance, motor fatigue did not, which suggests that the effects of total fatigue largely resulted from cognitive fatigue.

The study had no outside financial support, and the authors reported no disclosures.

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