By testing proteins in spinal fluid, physicians may be able to distinguish between patients with chronic fatigue syndrome and those with a form of Lyme disease, a new study finds.

The conditions have similar symptoms, including fatigue and cognitive problems, and doctors have trouble distinguishing between the two.

The study identified two sets of proteins, one unique to chronic fatigue syndrome and other specific to neurologic post-treatment Lyme disease , as the condition is called when patients do not get better after they are treated.

Further research is needed on more patients to validate the findings and determine which of the proteins are true markers of each condition, the researchers said.

But the results suggest that neurologic post-treatment Lyme disease is a unique syndrome not a type of chronic fatigue syndrome, as many had previously believed, the researchers said.

"It seems to be its own entity," said study researcher Dr. Steven Schutzer, of the University of Medicine and Dentistry of New Jersey.

The study is published today (Feb. 23) in the journal PLoS ONE.

Examining spinal fluid

Because both conditions appear to involve abnormalities in the brain , Schutzer and his colleagues studied patients' spinal fluid.

Spinal fluid bathes the brain, and studying its components can give researchers an idea of what's going on inside, Schutzer said.

Their analysis involved spinal fluid from 43 patients with chronic fatigue syndrome, 25 patients with neurologic post-treatment Lyme disease and 11 healthy people.

The researchers detected 738 proteins unique to patients with chronic fatigue syndrome, and 692 proteins that were only found in patients with neurologic post-treatment Lyme disease.

The next steps will be to narrow down this large group of proteins by looking for a handful of them at a time in patient spinal fluid, Schutzer said.

Dismissed diseases

The findings suggest that the central nervous system is in some way involved in both conditions, but the researchers don't know whether the protein abnormalities are a cause or effect of the illnesses.

The findings provide biological evidence that patients with chronic fatigue syndrome have a physical disease, said Leonard Jason, a professor of psychology at DePaul University in Chicago, who was not involved in the study.

"This is, I believe, a very important paper, because many people continue to believe that chronic fatigue syndrome is a psychological illness, and tend to dismiss this illness as not having any biological markers," Jason said.

"Many people have dismissed both illnesses. This is really something that suggests that there really are differences between post-treatment Lyme disease and chronic fatigue syndrome," Jason said.

The next step will be to replicate the findings, and then try to further understand each disease based on the proteins, Jason said.

Pass it on: Patients with chronic fatigue syndrome and patients with Lyme disease have unique sets of proteins in their spinal fluid. Some of these proteins may help physicians diagnose these illnesses in the future.

Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @RachaelRettner.