Cerebral Perfusion Patterns Abnormal in CFS Patients

WESTPORT, Jun 23 (Reuters Health) - High-resolution single-photon emission tomography shows significant similarities — and differences — between patients with chronic fatigue syndrome (CFS) and those with major depression.

Dr. Klaus P. Ebmeier of Edinburgh University in the UK and associates evaluated scans from 30 subjects with CFS in whom current psychiatric illness was excluded, 12 subjects with a diagnosis of major depressive episode, and 15 healthy control subjects. Subjects were matched for age, gender, premorbid IQ and handedness.

As reported in the June issue of the British Journal of Psychiatry, uptake of technetium-99m was greater in the right thalamus, the pallidum, and putamen in subjects with CFS and those with depression compared with healthy controls. However, the chronic fatigue syndrome patients exhibited increased perfusion in the left thalamus. Decreased perfusion in the left prefrontal cortex was found in patients with depression.

The researchers attribute the increased perfusion observed in chronic fatigue syndrome and depression to "disturbances of motor function...and effort perception," rather than to "low mood and inactivity," that are characteristic of both disorders.

"Importantly for chronic fatigue syndrome, the lateral ventral nucleus of the thalamus receives input from muscle afferents and the cerebellum that provide critical information about motor state," the investigators write. They explain that thalamic overactivity may be associated with higher levels of vigilance required for previously automatic tasks.

The decreased prefrontal perfusion in the depressed patients compared with those with CFS fits in with the fact that patients with depression have similar motor but more profound cognitive deficits than patients with chronic fatigue syndrome.

From these data the researchers conclude that biological disturbance in chronic fatigue syndrome is not limited to those with comorbid depressive symptoms. However, these changes are quantitative and currently are not useful in the clinical diagnosis of chronic fatigue syndrome.

Br J Psychiatry 2000;176:550-556.