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Sometimes blog entries come to me from suggestions or news articles, but this one comes out of some research that I have studies as a result of work. It is not my own, but I have some peripheral involvement as a consultant. The topic is the so-called "mental fog" reported by patients who have undergone radiation therapy or chemotherapy (directed at the brain) or general anesthesia - the latter particularly after the age of 60.
Please note, I'm not saying it happens all the time, nor am I saying to avoid therapies that require either procedure. It's just that there are reports and validated results, and those have some known (and unknown) mechanisms involved.
The results are similar - some thinning of the gray matter (cell layers) of the cortex visible in MRI, some shadowing of different brain areas associated with memory, and a tendency toward greater forgetfulness, aphasia, and loss of attention than before the procedure. Comparison with like-aged subjects who have gone through similar procedures without the specific brain effects (radiation directed toward other body areas, local anesthesia or brief duration) reveal a slight, but not necessarily significant reduction in memory capabilities.
Neuroscientists think that the major culprit is inflammation. Radiation therapy induces heating of the brain tissue, chemotherapy drugs often irritate normal cells (they are designed to be toxic to cancer cells) and anesthetics cause changes in blood flow cell membranes. Inflammation causes pressure, and pressure alters the flow of nutrients into brain cells, as well as the flow of metabolic by-products out of the same cells. Prolonged or repeated inflammation causes cells to die... and hence the patient suffers from loss of function.
The curious feature of the "Fog" reported by these patients is that it is seldom an immediate effect, but rather takes about 6 months to a year to reveal the full extent of loss. This is where the unknown mechanisms come in, and there are certainly labs that are researching the reasons for the loss in mental function. It may be related to aging, and some theories speculate that normal age-related decline is simply accelerated.
What is also speculated is that some of the inflammation processes are self-perpetuating, but only at low levels, and with slow progression. New research is now aimed at replicating these results in animal models and testing a number of treatments - including anti-inflammatory drugs (not NSAIDs!) and even Alzheimer's treatment drugs. With better understanding will (hopefully) come better treatment. Still the best advice of all is to keep using and challenging your brain function with reading, puzzles, social activities and new experiences. Research has shown that using our memory and cognitive abilities are the best way to retain them to an advanced age.
Sort of puts a new spin on "Use it or Lose it", doesn't it?
[Apologies for the short post and schedule interruptions. I have finally met the impossible work deadlines for August and am at Dragon*Con this weekend. I should be able to get back to a better schedule in September.]