People with Chronic Fatigue Syndrome have weakened muscles and, let’s face it, weakened brains as well. They can’t exercise worth a darn and their ability to focus, to process information quickly and to retain it, is shall we say, blunted. One would think those two problems are not related, but a recent Belgium study suggests they are intimately related.
We recently saw Dr. Bateman incorporate a bunch of different findings into a ‘big picture’ view of ME/CFS. This studies findings suggest that was a good thing to do.
Can recovery of peripheral muscle function predict cognitive task performance in chronic fatiguesyndrome with and without fibromyalgia? Ickmans K, Meeus M, De Kooning M, Lambrecht L, Pattyn N, Nijs J. Phys Ther. 2014 Apr;94(4):511-22. doi: 10.2522/ptj.20130367. Epub 2013 Dec 20.
Studies have shown that muscle recovery in Chronic Fatigue Syndrome takes longer than expected and the cognition problems (slowed information processing, reduced short term memory, difficulty concentrating) are evident.
These Belgium researchers wanted to know whether ME/CFS patients with longer muscle recovery times also did more poorly on the cognition tests. They gave cognition tests to ME/CFS and ME/CFS plus Fibromyalgia patients one day and then did a muscle challenge test using a handgrip tool the next.
They found that ME/CFS patients with or without Fibromyalgia who recovered their strength less quickly also did worse on the cognition tests; ie. poor muscle recovery is associated with reduced brain power. That’s probably not surprising to people with ME/CFS who get hit both physically and mentally after exerting themselves too much, but now it has to be explained.
The ME/CFS patients with Fibromyalgia (Wolfe criteria) also did worse on the cognition tests and took longer to recover from the muscle test than ME/CFS patients without FM. Since the more comobid conditions a person has the worse off they tend to be, this makes sense.
The Muscle Brain Connection
The Ickman’s group tied the muscle recovery/cognition results to a study by De Lange showing that reduced grey matter in the brains of ME/CFS patients was associated with reduced physical activity.
In that vein they suggested that reduced angiogenesis – blood vessel formation – and neurogenesis – nerve formation – associated with reduced physical activity might be responsible.
Indeed, it’s possible all things considered, that the more fit a person with ME/CFS is the better they do cognitively.
They also pointed to central sensitization as a probable factor; the more central sensitization present – the worsened muscle recovery and the poorer cognition you exhibit. Increased pain can dampen both muscle functioning and cognition, and the fact that the CFS patients with Fibromyalgia had substantially worse cognition than the ME/CFS patients without FM fit this ideda. .
They noted that other possibilities are present and we’re going to take a look at one.
Autonomic Nervous System
“Our findings add to the growing body of evidence linking autonomic dysfunction to the symptomatology in this poorly understood disease” Beaumont et. al.
Other factors, however, have been associated with poor cognition. Two consequences of autonomic dysregulation; low heart rate variability (HRV) and the presence of orthostatic symptoms, have been associated with reduced cognition in ME/CFS. Australian study authors argued that vagus nerve withdrawal was best associated with cognitive problems. (Interestingly, they also found reduced heart rate ‘recovery periods’ during cognitive testing. In a big picture attempt they proposed that pre-frontal cortex damage results in loss of autonomic nervous control, reduced vagal tone and poor cognition)
Newton’s finding that poor pH handling by the muscles in ME/CFS patients is associated with low heart rate variability effectively tied the autonomic nervous system problems in ME/CFS to muscle recovery issues. Her ability to further tie reduced pH handling in the muscles to reduced blood flows to the brain directly linked muscle, brain and ANS issues together.
Newton’s studies in other disorders back up her focus. Autonomic nervous system symptoms were highly correlated with cognitive issues in a immune thrombocytopenia study. Newton proposed that impaired ‘cerebrovascular autoregulation’ (impaired blood flows to the brain) were causing cognitive declines in primary biliary cirrhosis (PBC), another severely fatiguing disease, In 2008 Newton found that brain lesions and autonomic issues were associated with cognitive declines in PBC.
All this is to say that reduced grey volume and angiogenesis may very well be associated with both reduced cognition and muscle recovery in ME/CFS as the authors suggest, but an increasing body of work suggests autonomic dysregulation may play a key role.
With the low blood volume and autonomic nervous system issues present in ME/CFS it’s not hard to envision systemically reduced blood flows causing problems with both muscle recovery and the cognition. We do, after all, have two aerobically active areas of the body (muscles, brain) with problems. Perhaps it’s not so difficult to connect the two after all; simply follow the blood.
Time will tell. For now it’s great to see a connection made between these two critical problems in ME/CFS. At some point they and all the other seemingly disaparate findings in ME/CFS need to be explained.
Longer muscle recovery times are associated with cognitive declines in Chronic Fatigue Syndrome (ME/CFS). Explaining this strange muscle-brain connection works will likely require showing how similar issues affect both system. THe authors propose that reduced grey matter in the brain and central sensitization may play a role. The major controller of blood flows to both – the autonomic nervous system – is another possibility.
This study was intriguing because it connected too seemingly separate systems; the muscles and the brain. Explaining the results will require stitching together two systems that are not ordinarily stitched together – a good exercise in a disease that affects so many systems of the body.