. Long-term cognitive decline in older subjects was not attributable to noncardiac surgery or major illness. Anesthesiology. 2009 Nov;111(5):964-70. PubMed.

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  1. This is an important study. It sets new standards for the approach to peri-operative influences on cognition in the elderly by using established AD cohorts within the ADRC groups, and by examining and comparing both pre-surgery and post-surgery cognitive trajectories. Although this initial study could not detect a difference in these trajectories among control, illness, and surgery
    groups, the authors quite properly identified weaknesses that
    prevent it from being definitive at this point.

    These weaknesses include:

    1. Modest size: some groups had as few as 27 patients.

    2. Heterogeneity with respect to surgical procedures.

    3. A lack of detail with respect to surgery and anesthesia.

    4. Capture of procedures that occurred primarily at Wash U.
    hospitals; i.e., controls may have had surgery/illness elsewhere during
    the study period.

    5. No information on surgery or illness prior to ADRC entry.

    6. Elderly nature of all patients: vulnerable window not yet
    defined.

    7. Controls are not "wild-type" in that many are likely to be
    family members and therefore at higher risk of having AD neuropathology.

    To address these limitations, the authors have begun to recruit a
    much larger cohort involving multiple ADRCs, including those at UPenn, Harvard, WashU, Columbia, and others. This effort will take much longer but should be more definitive. It still has the problem of a narrow age window. Like head trauma is known to do, it could be that anesthesia and surgery change the trajectory of the neuropathology much earlier, long before any cognitive changes are
    evident, a possibility that this study design cannot capture. To at least capture more acute changes in neuropathology, I am advocating for well-designed peri-operative biomarker and/or imaging studies. We and other groups interested in this issue will be discussing both the basic and clinical science at a small meeting in Toronto in June 2010.

  2. Many studies have suggested that cognitive dysfunction may occur after anesthesia and surgery. However, opposite reports exist as well. In the recent retrospective cohort study, the authors have employed an approach of obtaining multiple assessments before the surgery or major illness and included participants with early Alzheimer disease. They have reported that there is no significant difference among surgery, major illness, or control groups in terms of the decline of cognitive function. However, they did find that the participants with dementia may decline more markedly than the participants without dementia.

    These findings are important. But like all other retrospective studies, this study has several limitations, including the difficulty to find appropriate controls, as described in the manuscript. Therefore, the findings from this study and other post-operative cognitive dysfunction studies strongly suggest that there is a need to perform an adequately powered, multicenter human study to further define post-operative cognitive dysfunction.

    View all comments by Zhongcong Xie
  3. Your report was quite informative. While there still may be few conclusive studies to link AD to anesthesia, my personal suspicions of a related link still hold. My Mom at the age of 80, active, clear-minded, and driving, had denture repair at University at Buffalo School of Medicine by a student who for some reason choose to put my mother and another patient to sleep to fit dentures! She was so confused afterwards she couldn't remember how to get home. She said she's never been the same since, with mild confusion, and now at age 85, on meds for early-stage AD. One may default the cause to being age related, but in view of my personal knowledge of the her behavior and history, I beg to differ with the theory that there is no connection.

    View all comments by Gerald Ramsey
  4. The age-old question of general anesthesia such as clindamycin causing shock to the autonomic nervous system by blunting it is documented. The adjustment to unconsciousness and then consciousness can produce cognitive decline.

    References:

    . Shock Produced by General Anesthesia With Relation to Disturbances of the Blood and Gastrointestinal Tract. JAMA, XL(18):1206-1212.

    View all comments by Kiumars Lalezarzadeh

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  1. Anesthesia and Cognitive Decline: No Link in Longitudinal Study