Researchers uncovered clues to the cause of "brain fog" hidden in spinal fluid.

A research team noticed a unique pattern of immune molecules in the cerebrospinal fluid of people suffering from myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is often described as "brain fog," Columbia University's Mailman School of Public Health reported.

The team used immunoassay testing methods to measure levels of 51 immune biomarkers, or cytokines, in the cerebrospinal fluid of 32 people with ME/CFS for a period of about seven years. The team also looked at 40 who patients suffered from multiple sclerosis and 19 were healthy controls.

The team observed the immune molecule interleukin 1 was depressed in those with ME/CFS when compared with the other two groups. The cytokine eotaxin was elevated in patients with both the ME/CFS and MS groups, but not in the control group.

"We now know that the same changes to the immune system that we recently reported in the blood of people with ME/CFS with long-standing disease are also present in the central nervous system," said Mady Hornig, professor of Epidemiology and director of translational research at the Center for Infection and Immunity at the Mailman School. "These immune findings may contribute to symptoms in both the peripheral parts of the body and the brain, from muscle weakness to brain fog."

The finding suggest human monoclonal antibodies, which regulate immune responses, could be used to treat these conditions if they prove to be safe.

"Diagnosis of ME/CFS is now based on clinical criteria. Our findings offer the hope of objective diagnostic tests for disease as well as the potential for therapies that correct the imbalance in cytokine levels seen in people with ME/CFS at different stages of their disease," said W. Ian Lipkin, MD, John Snow Professor of Epidemiology and director of the Center for Infection and Immunity.

The findings were published in a recent edition of the journal Molecular Psychiatry.