Effects of Cognitive and Physical Fatigue on Subjective Cognitive Deficits in MS Versus Healthy Controls

Two common symptoms of multiple sclerosis (MS) are cognitive and physical fatigue, but much remains unknown about their co-occurrence. A study evaluated the correlation between cognitive and physical fatigue and subjective cognitive deficits in patients with MS and healthy controls.

Thirty patients with MS and 30 healthy controls self-reported fatigue, depression, cognitive deficits, and personality traits. Reports were analyzed per hierarchical regression models. The dependent variable was the frequency of cognitive mistakes, and the independent variable was the extent of cognitive and physical fatigue.

In both patients with MS and healthy controls, the only independent and significant factor associated with cognitive mistakes was cognitive fatigue, which, when adjusting for age, mood, and physical fatigue, was responsible for 13.3% of additional variance in the MS group. No significant correlation was observed between physical fatigue and cognitive mistakes. In the healthy control group, age was associated with cognitive mistakes, but the correlation was not significant in the MS group. In patients with MS, a significant association was observed between depression and cognitive mistakes and cognitive fatigue.

“The interplay of cognitive fatigue and subjective cognitive impairment can be generalized, with the exception of the variables of age and depression, which were shown to have differing impacts on cognitive mistakes in [patients with] MS and healthy controls, respectively,” the study authors concluded. “Future research should further investigate the link between cognitive fatigue and attention lapses in daily life by using various objective assessments.”