Differential Effects of Various Anesthetic Agents on Cognitive Function in Patients With Alzheimer's Disease

Differential Effects of Various Anesthetic Agents on Cognitive Function in Patients With Alzheimer's Disease

The objective of the study is to determine the effects of different anesthetic agents on cognitive function in patients with Alzheimer's disease (AD). The investigators will test the hypothesis that anesthesia with desflurane or propofol, compared to isoflurane or sevoflurane, will have less of an effect on post-operative cognitive dysfunction in patients with AD.

Patients with mild-to-moderate Alzheimer's disease who are scheduled to have elective noncardiac, nonneurologic, nonvascular surgery will be recruited at the Massachusetts General Hospital (MGH). The study will first be introduced to patients at their preoperative surgical clinic appointment by his/her surgeon. If patients are interested in participating, they will notify their surgeons, and subsequent recruitment will take place at the MGH Pre-Admission Testing Area (PATA), a clinic for preoperative evaluation and medical optimization. Patient contact and recruitment, however, will only proceed with permission from (1) the patient him/herself and (2) the patient's surgeon. Per the Partners Human Research Committees-approved criteria, if patients do not have capacity for clinical-decision making but express a willingness to participate in the study, a surrogate (i.e. healthcare proxy and/or family member) co-signature will be required on the consent form. On the day of the subject's surgery, the anesthesia team will be allowed to choose one of four anesthetic options (i.e. propofol anesthesia, isoflurane anesthesia, sevoflurane anesthesia, or desflurane anesthesia) based on clinical preference and appropriateness. The research team will be blinded to the anesthetic to which subjects are assigned. Finally, patients will be followed for one year post-operatively with a battery of cognitive tests to determine differences in cognitive trajectory.

Inclusion Criteria:

• Patients diagnosed with Alzheimer's disease (AD) per Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.
• Patient recruitment permission granted by his/her surgeon
• Requires general anesthesia for elective noncardiac, nonneurologic, nonvascular surgery.

Exclusion Criteria:

• History of neurologic or psychiatric disease (i.e. stroke, psychosis, etc.)
• Non-native English speaker
• Severe visual or auditory disorder
• Sensitivity to sulfites (some propofol formulations at MGH may contain sodium metasulfite).
• Asthma (sulfite sensitivity is seen more frequently in asthmatic than in non-asthmatic people).