- Antibiotic use is common in older people, with those over age 65 consuming 50% more antibiotics than younger adults.
- Using antibiotics is linked to disturbance of the gut microbiome, which may have effects on cognitive function.
- However, a new study may help reassure older adults who are concerned about taking antibiotics, particularly for recurrent or long-term infections.
- The study found that in healthy older adults, antibiotic use was not linked to increased dementia risk.
As people age, they are more susceptible to infections and, therefore, more likely to be prescribed antibiotics. In fact, a report from the World Health Organization (WHO) noted that people ages over 65 have the highest rate of antibiotic prescription, being 50% more likely to consume antibiotics than younger adults.
Although antibiotics are vital for destroying the bacteria that cause infections, they also kill beneficial bacteria, such as those that make up the gut microbiome, leading to gut dysbiosis.
However, findings from a new study should help reassure those who need to take antibiotics. The study, which followed healthy older adults for 5 years, found that antibiotic use was not associated with an increased risk of cognitive impairment and dementia.
The study is published in Neurology, the medical journal of the American Academy of Neurology.
“While the study is promising, its limitation lies in the relatively short follow-up period. Future studies that examine the long-term effects of antibiotic use are essential to provide a more comprehensive understanding. Additionally, expanding research to include participants with pre-existing health conditions may offer further insights into antibiotic use and cognitive health across diverse populations.”
— Steve Allder, MD, consultant neurologist at Re:Cognition Health, who was not involved in the study, speaking to Medical News Today
The researchers used Australian data from ASPREE (ASPirin in Reducing Events in the Elderly), a randomized trial of community-based older adults.
They identified 13,571 participants who did not develop dementia during the two years of follow-up and for whom they had prescription records. They divided the participants into two groups: those who had taken antibiotics at least once during the two years (63%) and those who had not.
To determine whether more antibiotics increased a person’s dementia risk, the researchers further divided the groups based on how many times individuals had been prescribed antibiotics during that period, from zero to more than 5.
They then followed them up for five years. Allder explained that a longer follow-up time would have given more weight to the findings:
“As the author acknowledges, a longer follow-up period would provide more robust data to verify the findings. A follow-up period of at least 10-15 years would be ideal to better evaluate long-term associations between antibiotic use and cognitive decline, as dementia and cognitive impairments often develop gradually over decades.”
Participants took cognitive tests at the start of the study, after one year, and then every two years until the end of the study. The tests measured cognition, memory, thinking and language skills, and executive function.
The researchers recorded any diagnosis of dementia or cognitive impairment without dementia during the follow-up period.
During the 5-year follow-up, 461 people developed dementia, and 2,576 people developed cognitive impairment.
After adjusting for sociodemographic and lifestyle factors, family history of dementia, baseline cognitive function and medications that affect cognition, the researchers analyzed whether there was any association between antibiotic use during the first 2 years and subsequent cognitive decline or dementia.
People who had taken antibiotics, even frequently or long term, showed no increased risk of developing dementia or cognitive decline.
There was also no association between specific antibiotic classes and dementia risk.
Allder told Medical News Today that the findings should reassure older adults, adding:
“The study clearly shows that antibiotic use does not increase the risk of cognitive impairment or dementia for healthy older adults. The results are encouraging, particularly given the prior concerns surrounding antibiotics and gut health. However, as always, antibiotics should be used responsibly and as prescribed by healthcare professionals.”
Allder’s reassurance was echoed by Clifford Segil, DO, neurologist at Providence Saint John’s Health Center in Santa Monica, CA, who was also not involved in the study.
“Recurrent infections requiring antibiotics indicate underlying illnesses, and infrequent antibiotic use should not be a scary thing to do in old age or when young,” he said.
“Elderly patients with infections often become confused and this transient confusion from an infection is called delirium. Older people being treated with antibiotics should be reassured that using antibiotics will treat delirium and have no effect on getting dementia,” Segil told us.
Both Allder and Segil gave additional advice for reducing dementia risk.
“Maintaining a healthy diet is crucial, with a focus on a Mediterranean diet rich in fruits, vegetables, whole grains, fish, and healthy fats. Regular physical activity, such as walking, swimming, or yoga, helps support brain health. […] Additionally, prioritizing sleep and stress management by practicing good sleep hygiene and using relaxation techniques can benefit brain health.”
— Steve Allder, MD
“Engaging in mental stimulation, like puzzles, reading, learning new skills, or participating in hobbies, keeps the brain active. Staying socially connected is also important, as social engagement through community activities promotes emotional and cognitive well-being,” he added.
Segil also emphasized the importance of mental stimulation, telling MNT:
“It is my opinion structure is important and I advise my retired patients to take classes at local universities. […] I think keeping your brain active, interacting with people, and staying up to date [is] very important. I also emphasize leaving your home is very healthy as it is important to get out, especially with all the modern technology and comforts of home.”