Multiple Sclerosis is a very strong example of how a brain disturbance can underlie problems of mood and thinking.
In his original description of Multiple Sclerosis, French neurologist Charcot articulated how stress would seem to be important in causing relapses. Indeed, setbacks in balance, sensation and strength were believed to relate to the attacks of "hysteria".
We've advanced the lingo over a couple of hundred years, i.e. we've refined our terms and moved from the sexist to the neuropathological.
Let me give you a statement from MS researcher Dr. Gold and translate:
"Insensitivity to glucocorticoid and beta-adrenergic modulation might be involved in overshooting inflammation in MS, whereas hyperactivity of the HPA axis has been linked to neurodegeneration and increased disability."
- SM Gold, et al.- The role of stress-response systems for the pathogenesis and progression of MS. Trends Immunol. 2005 Dec;26(12):644-52.
The stress reaction, that is, the organism's response to danger, fear, and general difficulties encountered, involves increasing blood levels of steroids made by our own adrenal glands.
There is also a surge in beta adrenergic hormonal processing in this situation leading to increasing heart and breathing rates, sweating and tremulousness. This revved up activity also causes more immune system activity, for example increased movement of white blood cells into the blood stream and into organs which get inflamed when such cells arrive on the scene. So if an MS patient is insensitive to these chemical stress reactions, there will be "overshooting of inflammation". Put another way, there will be too much inflammation in the Central Nervous System, a key cause for the symptoms of MS!!! In turn, increasing stress will in turn lead to overproduction of steroids by the body through the "HPA" pathway starting in the hypothalamus, going to the pituitary, leading to the adrenals-the steroid production site. A brain exposed to long term increases in steroids can become badly damaged (neurodegeneration) and worsen disability.
More and more, we are realizing that MS disability includes "cognitive dysfunction", i.e. difficulties in thinking. What are the types of cognitive dysfunction?
- Thinking Speed
- Executive Functioning (planning and judgment)
- Visuospatial Perception
Stress and the effects of inflammation and brain injury caused by the MS process can worsen problems in these cognitive areas. Deciphering what thinking subdivisions are impaired in MS is made more difficult by the fact that mood troubles, particularly depression plus fatigue can interfere with a clear determination of what cognitive realms are not up to par.