Persons with CFIDS who also have orthostatic intolerance (OI) are a clinically identifiable subgroup from those who have CFIDS without OI. This subgroup would likely benefit from treatments specifically aimed at improving OI, according to a study by Dr. Ronald Schondorf and colleagues at McGill University in Montreal, Canada.
In the study published in the Feb. 15, 1999, issue of The Journal of the Autonomic Nervous System, the researchers noted that patients with OI (40% of a group of unselected CFIDS patients) typically were younger and their onset less sudden than those without OI. Interestingly, the researchers also argued against deconditioning as a cause of the OI, noting that the degree of OI in these patients correlated conversely with the duration of illness (in other words, the longer a person had been ill with CFIDS, the less OI they experienced).
Study funded in part by grants from The CIFDS Association of America