New findings may help explain the phenomenon of "brain fog" suffered by some people with chronic fatigue syndrome, scientists said last night.
This condition, also called myalgic encephalomyelitis (ME), can bring a sense of cognitive dysfunction that is often described by patients as "brain fog".
Dr Mady Hornig and colleagues at Columbia University, USA, investigated further by testing the levels of 51 immune biomarkers called cytokines in cerebrospinal fluid.
Samples were taken from 32 patients with ME over a period of about seven years. Samples were also taken from 40 patients with multiple sclerosis and 19 healthy volunteers.
This showed that most cytokines, including the inflammatory immune molecule, interleukin 1, were present at lower levels in people with ME than in the other two groups. In contrast, one cytokine called eotaxin was higher among the ME and MS groups than in the control group.
Full details were published in the journal Molecular Psychiatry yesterday (31 March). The team state that their analysis "suggests a disturbance in interleukin 1 signalling". They add: "Our results indicate a markedly disturbed immune signature in the cerebrospinal fluid of cases that is consistent with immune activation in the central nervous system."
Dr Hornig said: "We now know that the same changes to the immune system that we recently reported in the blood of people with ME with long-standing disease are also present in the central nervous system. These immune findings may contribute to symptoms in both the peripheral parts of the body and the brain, from muscle weakness to brain fog.
"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."
Hornig, M. et al. Cytokine network analysis of cerebrospinal fluid in myalgic encephalomyelitis/chronic fatigue syndrome. Molecular Psychiatry 31 March 2015 doi: 10.1038/mp.2015.29
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