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- Last Updated: 05 December 2015 05 December 2015
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Brain function
The current status of researching brain function in CFS/ME was reviewed by Gudrun Lange (University of Medicine and Dentistry of New Jersey—UMDNJ). She described some of the neurocognitive tests used to demonstrate cognitive dysfunction in CFS/ME, and pointed out that testing is much more positive in bedridden subjects (presumably sicker) and after maximal exertion (say on a bicycle or treadmill).
Radiological tools that demonstrate positive findings are MRI, CT scanning, SPECT and PET scanning (which measure cerebral blood flow), Proton Magnetic SPECT or Magnetic Resonance Spectroscopy (they measure brain metabolites such as glucose), and blood oxygen level dependent Functional MRI (or fMRI, which measures activation in areas of the brain, say to pain).
Studies so far have demonstrated that:
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PWCs perform as accurately as healthy controls, but require more regions of the brain (that is, PWCs have to work harder to get the same results);
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The key cognitive deficit in PWC's is their speed of information processing; and,
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Metabolic findings have been variable, depending on the metabolite and the group studying it.
Doctors from Barcelona, Spain, and Santiago, Chile, presented their results of SPECT scanning in PWCs compared to patients with depression. Dr. Garcia-Quintana showed that cerebral blood flow is decreased in the frontal lobes (only) of depressed patients, but reduced in frontal lobes and brainstem in PWCs. PWCs also have an increase of blood flow in the thalamus (a pain control center). Following exercise (or mental strain such as puzzles, short stories, or cubing numbers) the cerebral blood flow was markedly decreased in frontal, pre-frontal, anterior temporal, and cingulated regions in more than 87% of subjects studied. Increased blood levels of the enzymes elastace and RNaseL correlated with more severe loss of cerebral blood flow.
Comment: This is old news, but confirms previous studies in the US. We have known for over a decade that frontal, temporal lobe, and brainstem blood flow is reduced in PWCs, which is thought to cause problems with creativity/motivation/memory (frontal lobes), mood and memory (temporal lobes), and the sleep/fatigue/autonomic centers of the brainstem. We also knew that both exercise and mental exertion exacerbate this reduced blood flow for up to 72 hours! The new twist is that elevated elastase and RNaseL levels correlate with reduced blood flow.
Fumihara Togo (UMDNJ) presented a short but elegant paper that studied motor tasks and performance time in PWCs. Subjects would focus on a target—in this case an arrow pointing left or right—and touch one key for left, another for right. Togo demonstrated that motor performance was normal in CFS/ME, but that PWCs were slower to perform. In contrast, depressed patients had difficulty with both motor skills and speed.
A similar kind of finger-tapping study was described by Mark Van Ness, Christopher Snell, and Staci Stevens (University of the Pacific). They measured simple reaction time (the response to a simple target) and complex reaction time (response to a target hidden within other information) at rest, and then 30 minutes and 24 hours after an exercise test. They found that PWCs were a bit slower to respond than matched controls even at rest, worst 30 minutes after exercise, and still delayed 24 hours later. This held for simple or complex reaction time.
Hiro Kuratsune (Kansai University, Japan) concluded this session with a summary of what is known about brain function in CFS. We know:
- The MRI is abnormal in the majority of PWCs due to numerous T2 weighted hyperintense spots or foci, and evidence of demyelination.
- PWCs with more brain abnormalities tend to be more physically impaired.
- The volume of gray matter is reduced in proportion to reduced physical activity (that is, the brain shrinks in PWCs who are inactive!)
- Cerebral blood flow is diminished, especially in the cingulate area (controls attention, autonomic nervous system), temporal lobes (control mood, motivation), and frontal lobes (motivation, creativity, and short term memory).
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The concentration of acetyl-carnitine is reduced, particularly in the cingulate, and supplementing acetyl-carnitine may increase neurotransmitters such as GABA. glutamine, and aspartate. Acetyl-carnitine supplementation may also improve attention..
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5-HT (serotonin) transporter binding was reduced in the rostral cingulate area in PWCs, which may help explain fatigue and pain.