Consensus Statement – First international workshop on anesthetics and Alzheimer’s disease

The workshop was held in May, 2008 at the University of Pennsylvania and the consensus document was recently published in Anesthesia and Analgesia.  The statement provides 8 conclusions: 1) The benefits of general anesthetics in allowing surgery and other painful procedures likely outweighs the potentially toxic effects that are currently known.  2) Evidence from animal models suggests that inhaled anesthetic exposure increases the pathologic changes normally associated with Alzheimer’s disease.  For example, in adult wild type rats and mice, isoflurane exposure alone produces decrements in learning and memory that persist for weeks or months.  There are also a number of other well described changes in various animals.  3) In vitro studies provide evidence that inhaled anesthetics interact with recognized pathways of neurodegeneration and produce effects consistent with increased cellular stress.  4) A number of potential mechanisms for the accelerated neuropathyology seen after general anesthetics have been identified.  However the group felt that there is a higher priority to determining the magnitude and presence of anesthetic-induced long term behavioral effects, preferably in humans.  5) The data on the probability of a particular anesthetic drug to cause changes is sparse.  More work is needed; particularly work that directly compares the various anesthetic drugs.  6) Hypothermia during or after anesthesia may be an independent risk factor.  7) The potential effects of anesthesia and surgery at young ages on long term learning and memory have not been examined in clinical studies.  In adults, post operative cognitive decline is well described.  However, the relationship of anesthetic drug to post operative cognitive decline is speculative at best when based on the currently available studies.  8) The long time- course of neurodegenerative diseases coupled with the relatively short period of normal post operative follow-up means that acceleration of Alzheimer’s disease after anesthesia may not have been recognized.  Given the available evidence, the potential for anesthetics to have long term cognitive effects needs serious attention and further study.  In their closing statement the group cautioned against premature, extrapolated conclusions with respect to anesthesia safety.  They felt that “physicians working and publishing in the area have a responsibility to be objective and candid about the limitations surrounding the clinical implications of their work, particularly with in vitro and animal models, as well as with small or retrospective clinical studies.”  The entire statement is only 2.5 pages.  It is clearly written.  I have abstracted only part, it is worth reading in its entirety of you have an interest or concern about these issues.  Baranov D et al: Consensus statement: First international workshop on anesthetics and Alzheimer’s disease.  Anesth Analg 2009;108:1627-30

David S. Smith, M.D., Ph.D.

 

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