Physiological measures differentiate CFS from depression
September 21, 2004
Chronic fatigue syndrome (CFS) and depression have distinct biological properties, researchers have found, which not only suggest the existence of unique etiologies but may also be used to distinguish between the two disorders.
There is considerable overlap in the symptoms of CFS and depression, which has led researchers to question whether CFS is indeed a disorder in its own right, or just a manifestation of depression, note Hanna Pazderka-Robinson and colleagues, from the University of Alberta in Edmonton, Canada.
The team found, however, that, unlike patients with depression, those with CFS had lower skin conductance levels and higher skin temperatures in the arms and legs.
Recognizing that the autonomic nervous system has been implicated in CFS, Pazderka-Robinson et al used electrodermal analysis to look at skin conductance and temperature as a potential means of distinguishing the disorder from depression.
They obtained data for 36 non-depressed individuals with CFS, 19 with depression alone, and 33 mentally healthy controls. Bilateral electrodermal activity was recorded using electrodes placed on the third and fourth fingers of each hand, while skin temperature was measured with transducers on the fifth finger.
The researchers found that skin temperature levels differed significantly between the CFS patients and those with depression, at an average of 34.1 Â°C versus 31.1 Â°C, respectively, while the average level among the controls was 30.1 Â°C.
Similarly, average skin tonic conductance levels did not differ significantly between patients with depression and controls, but were significantly reduced in patients with CFS.
Reporting in the International Journal of Psychophysiology, the team concludes, "These findings indicate, that despite overtly similar cognitive and symptom profiles, depression and CFS patients can be differentiated with psychophysiological measures. This study adds to the growing body of evidence demonstrating that CFS and depression have distinct neurobiological profiles, consistent with unique etiologies."
Int J Psychophysiol 2004; 53: 171-182