Right on the heels of a study showing that people with fibromyalgia have trouble focusing or paying attention comes another study linking cognitive problems to a balky stress response.
In “Salivary cortisol is associated with cognitive changes in patients with fibromyalgia“, Taiwanese researchers assessed whether a reduction in functioning of one of the two major stress response systems in the body – the HPA axis – was also associated with cognitive problems in FM. They did this by assessing salivary cortisol levels and cognitive functioning (with subjective questionnaires and objective cognitive tests.)
“Stress” was a strong focus throughout the paper. These researchers believe the HPA axis problems in FM (and presumably chronic fatigue syndrome (ME/CFS), as the issues are similar) are “secondary”; i.e. they derive from the enormous levels of stress the diseases produce. As we’ll see, though, the focus on stress can get tricky.
Dr. Klimas and her team at Nova Southeastern University in Florida, by the way, would disagree about the idea that HPA axis problems are “secondary” in diseases like ME/CFS. Their supercomputer work suggests that they’re so important to these diseases that their two-drug protocol uses drugs which first inhibit neuroinflammation (etanercept) and then reset the HPA axis (mifepristone).
This study found a moderate relationship between low salivary cortisol levels in the morning and late evening, and cognitive issues involving memory, language and executive functioning. The authors reported that a similar pattern of altered cortisol levels and cognition have been found in chronic fatigue syndrome (ME/CFS), post-traumatic stress disorder (PTSD), Cushing’s disease and Addison’s disease.
But why would an inadequate or balky stress response (low cortisol levels) affect cognition? Since cortisol is used to blunt immune activation, low cortisol levels could result in increased inflammation which could result in many symptoms, including cognitive problems, if the inflammation occurred in the brain.
The authors also suggested problems with the hippocampus – a part of the limbic system of the brain involved in both stress processing and memory – may be involved. Problems in the hippocampus have indeed cropped up in FM.
- Low morning and late evening cortisol levels in fibromyalgia were linked to problems with memory, language and executive functioning.
- The link between low cortisol levels and cognition may involve higher levels of inflammation.
- The authors suggested that problems with the hippocampus may play a role as well.
- While cognitive deficits were found, people with FM felt they were cognitively worse off than the tests suggested.
- One explanation for that derives from a model called Functional Cognition Disorder, which posits that people with diseases like FM and ME/CFS are paying so much attention to their symptoms that they’re having difficulty focusing on the tasks at hand.
- Several studies, though, suggest why people with ME/CFS/FM often report that thinking is so much more effortful.
- They suggest that people with FM have to recruit more brain regions than healthy people to do the same tasks – an inherently inefficient and effortful process.
- It appears that the “gates” which filter out sensory information from the body may be broken – subjecting the brain to a torrent of information it must process – on top of whatever other tasks are being engaged in.
- The brains of FM patients also appear to have trouble ignoring innocuous stimuli – such a background noises – placing a further drain on the brain.
- Several lines of evidence also suggest low brain energy reserves may make it more effortful and difficult to engage in cognitive tasks.
- Low cortisol presumably means a predisposition to higher levels of inflammation. Given that, a safe way of raising cortisol levels would be helpful. A blog on that possibility is coming up.
While the cognitive tests did pick up some problems, the FM patients, in a pattern that’s shown up before, reported more problems with cognitive functioning than the tests indicated; i.e. they reported worse cognitive problems than the tests indicated they had. This same pattern – patients consistently seemingly over-reporting the cognitive issues – has shown up in chronic fatigue syndrome (ME/CFS) and migraine as well.
That, plus the focus on “stress”, helped open the door to something called the functional cognition disorder model. The authors cited studies suggesting that heightened self-monitoring, perfectionism, overloading, etc. could also play a role in the cognitive problems found in FM.
The Functional Cognition Disorder Model
The “functional cognitive disorder (FCD)“, championed by Teodoro and others, proposes that something akin to poor stress management is producing or contributing to cognitive dysfunction which appears in the absence of identifiable brain damage, and in people who report more cognitive problems than the tests pick up.
A central tenet of this interpretation is that an “excessive attention towards the body, severe pain and fatigue” prevents the patients from focusing on external events; i.e. the cognitive task at hand. The other side of that coin is the possibility that people with ME/CFS/FM are simply getting bombarded by pain, fatigue and other symptoms, but Teodoro apparently rejects that idea.
It’s startling to see the kind of machinations researchers can engage in. For instance, Teodora takes affront at the marked increase in the “perception of effort” which takes place when people with ME/CFS are challenged with increasingly difficult cognitive tests. Teodoro believes that increased “perception of effort” is due to three things:
- an “interpretive bias for somatic information” showing up; i.e. the tougher a cognitive test is, the more people with ME/CFS/FM tend focus on their body sensations;
- “a greater operational demand to control and monitor cognitive processes”; i.e. the more difficult a test is, the more people with ME/CFS/FM focus on monitoring and controlling their thought processes;
- “a sense of insufficiency resulting from unrealistically high expectations about one’s performance”.
It turns out that easier explanations are available…
A Biological Explanation?
Other explanations suggest that cognitive processes might, in fact, be breaking down, or that one’s brain, when placed under load, might just be running out of juice.
One study, for instance, showed that people with FM must activate more brain regions; i.e. must use more energy to carry out the same cognitive tasks as healthy controls. This study suggests that it’s actually harder and more fatiguing for people with FM to do cognitive tasks.
Other studies suggest that the brainstem may not be filtering all the sensory stimuli that it should – causing the brain to be pummeled with stimuli – and use up resources to deal with that.
Other studies have shown that the brains of people with fibromyalgia have more trouble blocking out innocuous stimuli. Our brains should be able to assess stimuli and stop paying attention to them if they’re not relevant to the task at hand.
A 2016 study with the charming title, “Habituation deficit of auditory N100m in patients with fibromyalgia“, found that to be a problem. As the participants watched slides, the researchers stealthily introduced small sounds into the headphones the participants were wearing. Then they watched their brainwaves.
Instead of becoming habituated to these sounds, the FM patients’ brains remained stubbornly fixated on them. (The same pattern, interestingly, has also been found in migraine and irritable bowel syndrome.) This suggests all these diseases come with an extra added component – a distracted, inefficient and easily overwhelmed brain.
A recent study suggested that brains of people with ME/CFS have lower energy reserves and essentially poop out more quickly when stressed than the brains of healthy controls. That made sense given the reduced cerebral blood flows and lactate accumulations found – both of which suggested that ME/CFS/FM brains were stuck in a low energy state. So much could seemingly easily be explained by small blood vessel problems that inhibit blood flows to the brain, muscles, etc. The neuroinflammation findings loom large as well.
As was noted in an earlier blog, it’s also very possible that the pain processing centers of the brain are robbing Peter to pay Paul. In this scenario, the pain processing pathways have become so dominant that they’re taking resources away from parts of the brain we usually use to pay attention and carry out cognitive tasks.
The good news about the kind of seemingly whacky conceptions of Teodoro and colleagues is that they’re steadily being supplanted by the march of science.
There’s also the possible intersection between low cortisol and cognitive problems. Hypocortisolism in the form of low morning salivary cortisol levels, in particular, has been found. We don’t know how important it is or what role it plays, but given the supposition that inflammation is a major driver of illness in these diseases, it would be good to get that problem fixed.
One reason we don’t know about the role of low cortisol is the difficulty and controversy around safely raising cortisol levels. A new approach to that popped up in the scientific literature recently. Coming up next:
- A (Too?) Easy Way to Raise Cortisol and Reduce Inflammation?