[Note: Cerebrospinal fluid (CSF) analysis examines a sample of the fluid surrounding the brain and spinal cord. CSF protects the central nervous system from injury, provides it with nutrients, and removes waste products by returning them to the blood. Theories about the reasons for elevated CSF lactate include the reduced cortical blood flow and mitochondrial dysfunction and/or increased oxidative stress that have been reported in ME/CFS patients (and associated with joint pain/post-exertion malaise).]
Chronic fatigue syndrome (CFS), a complex illness characterized by fatigue, impaired concentration, and musculoskeletal pain, is often misdiagnosed as a psychiatric illness due to the overlap of its symptoms with mood and anxiety disorders.
Using proton magnetic resonance spectroscopic imaging ((1)H MRSI), we previously measured levels of the major brain metabolites in CFS, in generalized anxiety disorder (GAD), and in healthy control subjects, and found significantly higher levels of ventricular cerebrospinal fluid (CSF) lactate in CFS compared to the other two groups.
In the present study, we sought to assess the specificity of this observation for CFS by comparing ventricular lactate levels in a new cohort of 17 CFS subjects with those in 19 healthy volunteers and in 21 subjects with major depressive disorder (MDD), which, like generalized anxiety disorder, is a neuropsychiatric disorder that has significant symptom overlap with CFS.
• Ventricular CSF lactate was significantly elevated in CFS compared to healthy volunteers, replicating the major result of our previous study.
• Ventricular lactate measures in MDD did not differ from those in either CFS or healthy volunteers.
• We found a significant correlation between ventricular CSF lactate and severity of mental fatigue that was specific to the CFS group.
• In an exploratory analysis, we did not find evidence for altered levels of the amino acid neurotransmitters, gamma-aminobutyric acid (GABA) and glutamate + glutamine ('Glx'), in CFS compared to MDD or healthy controls.
Future (1)H MRS studies with larger sample sizes and well-characterized populations will be necessary to further clarify the sensitivity and specificity of neurometabolic abnormalities in CFS and MDD.
Source: NMR in Biomedicine, Jul 2010;23(6):643-50. PMID: 20661876, by Murrough JW, Mao X, Collins KA, Kelly C, Andrade G, Nestadt P, Levine SM, Mathew SJ, Shungu DC. Department of Psychiatry, Mount Sinai School of Medicine, New York; Department of Radiology, Weill Medical College of Cornell University, New York; New York Medical College, Valhalla, New York, USA. [Email: firstname.lastname@example.org]