Anesthesia and Memory: What Families Can Actually Do
Many older patients fear the anesthetic will take their memory. The clearer link to later decline is delirium, which families can help prevent.
Before surgery, older patients often ask me one question, and when they don’t, their children ask it for them. Will the anesthesia hurt my memory?
I tell them it is a fair worry, and then I tell them what the trials found. Most of it points to a different problem, one a family can help prevent.
Spinal or general, in a broken hip
The cleanest test of that question comes from older people who break a hip. In a trial called REGAIN, about 1,600 of them got one of two kinds of anesthetic, chosen by chance.1
A spinal numbs the lower body, and a general anesthetic puts the patient fully to sleep. About one in five developed delirium, a sudden confusion after surgery, and the rate was almost the same with either.
A second hip-fracture trial, called RAGA, also found no clear difference. We cannot carry these results over to other operations, such as heart or brain surgery, and neither trial measured dementia.2
Delirium, and what lowers the odds
When I see delirium on the ward, it is usually in the first days after an operation. A study called SAGES followed older surgical patients for up to six years, and about a quarter developed it.3
Their thinking declined about 40% faster in the years that followed, though the authors say nobody knows which causes which. An earlier SAGES paper found they already scored lower on thinking tests before surgery. A brain with less in reserve seems to tip over more easily.4
The good news is that delirium can often be prevented. A Cochrane review pooled hospital trials of programs that keep patients oriented, fed, moving, rested and able to see and hear, and they cut it by about 40%. In Taipei, a surgical trial more than halved it with orienting talk, help with eating and drinking, and early walking.5
| Year | Study | Finding |
|---|---|---|
| 2021 | Neuman et al., REGAIN N Engl J Med | 1,600 older adults with a broken hip. Delirium 20.5% with a spinal vs 19.7% with a general anesthetic. |
| 2022 | Li et al., RAGA JAMA | 950 hip-fracture patients. Delirium within 7 days, 6.2% regional with no sedation vs 5.1% general, a gap chance could explain. |
| 2013 | Chan et al., CODA J Neurosurg Anesthesiol | 921 patients. Lighter anesthesia guided by a brain monitor cut delirium from 24.1% to 15.6%, and thinking problems at 3 months from 14.7% to 10.2%. |
| 2019 | Wildes et al., ENGAGES JAMA | 1,232 older adults having major surgery. Brain-monitor guidance gave no benefit, delirium 26.0% vs 23.0%. |
| 2017 | Chen et al. JAMA Surg | 377 adults aged 65 and over having abdominal surgery. Delirium fell from 15.1% to 6.6% on the program. |
| 2021 | Burton et al., Cochrane Cochrane Database Syst Rev | 14 trials, 3,693 hospital patients. Multicomponent programs, delirium 10.5% vs 18.4%, RR 0.57, moderate certainty. |
Only the first two trials compared kinds of anesthetic. The brain-monitor trials disagree, so how deep the anesthetic should run is still an open question.
Here is how the pieces fit, from the operation to the confusion after it.
- Surgery sets off inflammation The reaction spreads through the whole body.
- The brain feels it In mice, blocking one inflammatory signal outside the brain prevented the brain inflammation and memory loss after surgery.9
- A brain with less reserve tips over People who got delirium already had lower thinking scores before surgery.4
- Delirium is the sign we can see In hip-fracture trials, the kind of anesthetic did not change how often it came.1
- Bedside care lowers the odds Orientation, food, walking, sleep and sensory aids, used together, cut delirium by about 40% in trials.5
Where this gets ahead of the evidence
“General anesthesia causes dementia.”
Unproven
Studies that follow people for years disagree, and none can separate the anesthetic from the surgery and the illness behind it. None of the trials here measured dementia.10,11,12
“So I should ask for a spinal.”
Not shown
The hip-fracture trials found no difference in delirium. The choice depends on your operation, so make it with your anesthesia team.1,2
“So I should delay my surgery.”
No
Nothing here is a reason to delay or refuse surgery, or to choose one anesthetic over another. Bring any worry about timing to your surgeon.
“Glasses and hearing aids prevent delirium.”
Untested alone
Nobody has tested them on their own. They are one part of the programs that cut delirium in trials.5
Will the anesthesia hurt my memory? Nobody can fully answer that yet, but the confusion that can follow surgery is something a family can help prevent.
References
- Neuman MD, et al. Spinal Anesthesia or General Anesthesia for Hip Surgery in Older Adults. N Engl J Med, 2021
- Li T, et al. Effect of Regional vs General Anesthesia on Incidence of Postoperative Delirium in Older Patients Undergoing Hip Fracture Surgery: The RAGA Randomized Trial. JAMA, 2022
- Kunicki ZJ, et al. Six-Year Cognitive Trajectory in Older Adults Following Major Surgery and Delirium. JAMA Intern Med, 2023
- Inouye SK, et al. The short-term and long-term relationship between delirium and cognitive trajectory in older surgical patients. Alzheimers Dement, 2016
- Burton JK, et al. Non-pharmacological interventions for preventing delirium in hospitalised non-ICU patients. Cochrane Database Syst Rev, 2021
- Chen CC, et al. Effect of a Modified Hospital Elder Life Program on Delirium and Length of Hospital Stay in Patients Undergoing Abdominal Surgery: A Cluster Randomized Clinical Trial. JAMA Surg, 2017
- Chan MT, et al. BIS-guided anesthesia decreases postoperative delirium and cognitive decline. J Neurosurg Anesthesiol, 2013
- Wildes TS, et al. Effect of Electroencephalography-Guided Anesthetic Administration on Postoperative Delirium Among Older Adults Undergoing Major Surgery: The ENGAGES Randomized Clinical Trial. JAMA, 2019
- Terrando N, et al. Tumor necrosis factor-alpha triggers a cytokine cascade yielding postoperative cognitive decline. Proc Natl Acad Sci U S A, 2010
- Dokkedal U, et al. Cognitive Functioning after Surgery in Middle-aged and Elderly Danish Twins. Anesthesiology, 2016
- Aiello Bowles EJ, et al. Anesthesia Exposure and Risk of Dementia and Alzheimer’s Disease: A Prospective Study. J Am Geriatr Soc, 2016
- Chen IW, et al. Comparison of regional vs. general anesthesia on the risk of dementia: a systematic review and meta-analysis. Front Public Health, 2024
Figure. Hippocampus image, Life Science Databases (LSDB), CC BY-SA 2.1 jp, via Wikimedia Commons.
