• anesthetics;
  • dendritic spines;
  • learning disabilities;
  • neurodevelopment;
  • neurogenesis;
  • neuronal apoptosis;
  • neuronal preconditioning;
  • postoperative cognitive dysfunction;
  • postoperative delirium;
  • sedatives;
  • synaptogenesis.


The assumption that anesthesia has no serious, long-term, adverse central nervous system consequences may be true for most patients between 6 months and 60 years of age. However, for patients younger than 6 months or older than 60 years, that status quo assumption is under challenge from a growing body of evidence. Fetuses and newborns appear to be at risk because systems that would enable them to fully recover from the effects of more than 2 hours of anesthesia are still in development. In distinction, the elderly appear to be at risk because systems that once enabled them to fully recover have ever-diminishing capacity. Even for those between the age of 6 months and 60 years, full recovery may require replacing apoptosed neurons and pruning overabundant dendritic spines perhaps leaving patients not quite the same person that they were before they were anesthetized. Mt Sinai J Med 79:75–94, 2012.© 2012 Mount Sinai School of Medicine