Years ago, I read a paper in which the authors proposed a model, in
which the immune system was conceptualized as a sensory organ for the
central nervous system. They did not think of it as the
primary purpose of the immune system, but they wanted to highlight the
fact that immune system activity does provide information to the brain,
and that information is, to some extent, perceptible of a conscious
I have to get ready for work, so I am not going to try to find the
reference. At least right now. I might get curious
enough to go looking for it later.
Now, we hear of another finding that strengthens that model (from
Medscape; free registration required):
August 24, 2006 –- Studying patients with colorectal cancer,
researchers confirm the link between cytokine levels and some of the
bothersome cognitive effects of disease. “Cytokine levels were elevated
in most patients,” lead author Janette Vardy, MD, from the Princess
Margaret Hospital in Toronto, Ontario, said. Her work appeared in a
poster session at the recent 42nd annual meeting of the American
Society of Clinical Oncology…
After reading the synopsis, I found myself wondering if the point had
really been proved, about the association between cytokine levels and
fatigue. The synopsis is, frankly, kind of muddled.
It was based upon a poster presentation, so we can’t yet see
the actual research and draw our own conclusions from the data.
This much was presented clearly:
Dr. Vardy and her team report that elevated cytokines
were associated with a greater deficit on computerized
neuropsychological testing at 6 months (P < .06).
Clearly, there is much more work that needs to be done in this area.
I think that it would be interesting to characterize fully
the association between particular cytokines, cognitive performance,
and “psychological” symptoms such as depression and fatigue.
Depression is a common complication from somatic illness.
This is a huge problem, and it would be good to have a better
understanding of the mechanism. One thing is clear: it is not
“all in your head.”