Effects of exercise on cognitive and motor function in chronic fatigue syndrome and depression

Abstract

Objectives-Patients with chronic fatigue syndrome complain of physical and mental fatigue that is worsened by exertion. It was predicted that the cognitive and motor responses to vigorous exercise in patients with chronic fatigue syndrome would diVer from those in depressed and healthy controls. Methods-Ten patients with chronic fatigue syndrome, 10 with depressive illness, and 10 healthy controls completed cognitive and muscle strength testing before and after a treadmill exercise test. Measures of cardiovascular functioning and perceived eVort, fatigue, and mood were taken during each stage of testing. Results-Depressed patients performed worst on cognitive tests at baseline. During the treadmill test, patients with chronic fatigue syndrome had higher ratings of perceived eVort and fatigue than both control groups, whereas patients with depression reported lower mood. After exertion, patients with chronic fatigue syndrome showed a greater decrease than healthy controls on everyday tests of focused (p=0.02) and sustained (p=0.001) attention, as well as greater deterioration than depressed patients on the focused attention task (p=0.03). No between group diVerences were found in cardiovascular or symptom measures taken during the cognitive testing. Conclusions-Patients with chronic fatigue syndrome show a specific sensitivity to the eVects of exertion on eVortful cognitive functioning. This occurs despite subjective and objective evidence of eVort allocation in chronic fatigue syndrome, suggesting that patients have reduced working memory capacity, or a greater demand to monitor cognitive processes, or both. Further insight into the pathophysiology of the core complaints in chronic fatigue syndrome is likely to be realised by studying the eVects of exercise on other aspects of everyday functioning. (J Neurol Neurosurg Psychiatry 1998;65:541-546)

The difference in patterns of motor and cognitive function in chronic fatigue syndrome and severe depressive illness

“…The MDD group had a significantly greater burden of depressive symptoms and more obviously impaired cognitive performance. Patients with CFS do have neuropsychological deficits, but these are subtle and most apparent when information processing demands are highest or after fatiguing exercise (Blackwood et al 1998). We found only limited evidence of differential diurnal effects on cognitive and motor function in CFS and MDD.…”

A real-time assessment of the effect of exercise in chronic fatigue syndrome

“…Because an earlier study showed that exercise resulted in a reduction of physical activity after a delay of five days (8), we hypothesized that subjective symptoms would not worsen immediately after exercise but instead would worsen a few days later. We also assessed cognitive function using a continuous performance test (9-11) because cognitive functioning is often impaired in CFS and may be negatively affected by exercise (12,13).…”

Chronic fatigue syndrome – mapping the interior

“…It is worth asking why CFS patients avoid, and a number of dynamic studies that observe changes in symptoms or psychomotor function in the context of exertion begin to explain better why this may happen. CFS patients do not show any evidence of peripheral muscular problems (Wessely et al 1998), but they do report more symptoms and show more marked changes in cognitive function following exercise than healthy controls (Blackwood et al 1998 ;LaManca et al 1988). The study by demonstrates a similar picture with CFS patients developing fatigue more rapidly than healthy controls when asked to perform tasks that involved prolonged attention.…”