Anesthetics and Brain Function

The Effect of Anesthetics on Cell Proliferation in the Dentate Gyrus of the Adult Rat
2005 Seed Grant
Avery Tung, Ph.D.
The University of Chicago

In most patients, anesthesia today is safer than ever before. However, recent studies have found that more than 1/3 of older patients recovering from anesthesia and surgery experience lingering difficulties in concentrating, remembering, and learning. Although subtle, these changes can last for months, prolonging recovery and worsening quality of life for elderly patients undergoing surgery. The mechanism underlying this effect of anesthesia on cognitive function in the elderly is unknown. One previously unexplored possibility is that anesthetics suppress the production of new neurons (neurogenesis) in the adult brain. These neurons are produced primarily in areas of the brain involved in memory and learning, and play an important role in adaptive learning in animals. Moreover, fewer new neurons are produced with increasing age, making neurogenesis a plausible mechanism for anesthetic-induced cognitive dysfunction in the elderly. By selectively staining newly produced neurons in the brain, we plan to study how anesthetics and age affect neurogenesis. Information gained from this project will contribute not only to the study of anesthetic effects in elderly patients, but also enrich our basic understanding of how experiences, awareness, and behavior influence the brain.
Because of the increased safety of anesthesia and the aging US population, more elderly patients than before are receiving anesthesia. A consequence of this demographic change, however, is the somewhat surprising observation that more than 1/3 of older patients recovering from anesthesia and surgery experience lingering difficulties in concentrating, remembering, and learning. Although subtle, these cognitive changes can last for months, prolong hospitalization, and worsen quality of life. When combined with recent evidence that excessively deep anesthesia may be harmful, the presence of these cognitive difficulties in older patients suggests that anesthesia may not be as safe for elderly patients as for younger ones. Our work will begin to explore the mechanisms linking anesthesia and reduced cognitive function by looking at how anesthetics affect the brain’s ability to grow new neurons. An improved understanding of how anesthetics change brain function in the elderly will not only allow anesthesiologists to identify which patients are most at risk, but also suggest potential treatments to reduce or eliminate this problem.

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