Talking about immune cells in the brain (microglia), Jarod younger says this-
These immune cells are sensitive to so many factors and can be triggered in so many ways that virtually any stressor,
from an infection to toxins to psychological stress, can potentially trigger a state of microglial sensitization in the right individual.
With their ability to produce dozens of different inflammatory mediators, Younger believes that the difference between ME/CFS and FM could simply come down to small differences in how the microglia are tweaked.
Both diseases could be triggered by high rates of immune activation which, over time, sensitizes the microglia to such an extent that they start pumping out inflammatory factors at the first sign of a stressor.
I wonder if the microglial "sensitization" Jarod Younger is talking about here could be the "switch" that gets turned on, causing PEM and CFS?
In some it gets turned on very fast with a viral infection or some other stressor/trigger. In others, the microglia become slowly sensitized over time. Taking months or years to develop CFS.
I think the key word here is sensitization. He says the microglia could become "sensitized". As I understand that, it means they basically over-react to what would normally be un-noticed or very mild stimulus.
Like low grade immune system activation, toxins or psychological stressors. Sending out much higher levels of cytokines in the brain, causing brain inflammation, PEM, pain, fatigue and other symptoms.
I have read about microglial sensitization before, it seems to be a real dysfunction from what I understand.