Dr Faisel Khan, Vascular Diseases Research Unit,
University Department of Medicine, Ninewells
Hospital and Medical School, Dundee DD1 9SY, UK
accepted 30 April 2003
Although the aetiology of chronic fatigue syndrome (CFS) is unknown, there have
been a number of reports of blood flow abnormalities within the cerebral circulation
and systemic blood pressure defects manifesting as orthostatic intolerance. Neither
of these phenomena has been explained adequately, but recent reports have linked
cerebral hypoperfusion to abnormalities in cholinergic metabolism. Our group has
previously reported enhanced skin vasodilatation in response to cumulative doses of
transdermally applied acetylcholine (ACh), implying an alteration of peripheral
cholinergic function. To investigate this further, we studied the time course of ACh-
induced vasodilatation following a single dose of ACh in 30 patients with CFS and
30 age- and gender-matched healthy control subjects. No differences in peak blood
flow was seen between patients and controls, but the time taken for the ACh
response to recover to baseline was significantly longer in the CFS patients than in
control subjects. The time taken to decay to 75% of the peak response in patients and
controls was 13Æ7 ± 11Æ3 versus 8Æ9 ± 3Æ7 min (P
1⁄4 0Æ03), respectively, and time
taken to decay to 50% of the peak response was 24Æ5 ± 18Æ8 versus 15Æ1 ± 8Æ9 min
(P
1⁄4 0Æ03), respectively. Prolongation of ACh-induced vasodilatation is suggestive
of a disturbance to cholinergic pathways, perhaps within the vascular endothelium
of patients with CFS, and might be related to some of the unusual vascular
symptoms, such as hypotension and orthostatic intolerance, which are characteristic
of the condition.
