A type of medication once thought to be potentially damaging to the brain due to its impact on gut health appears to not increase a person’s risk of dementia. According to a recent US study, the use of antibiotics in healthy older adults is not linked to cognitive impairment or dementia.
Cognitive impairment involves minor issues with memory and thinking, such as forgetting events or misplacing items, while dementia is a more severe condition that interferes with daily life. The study’s lead author, Professor Andrew Chan from Harvard Medical School in Massachusetts, explained: “Antibiotics have been found in previous research to disrupt the gut microbiome, which is the community of tiny organisms that live in our intestines and support digestion.
“Because the gut microbiome has been found to be important for maintaining overall health, and possibly cognitive function, there was concern that antibiotics may have a harmful long-term effect on the brain. Given that older adults are more frequently prescribed antibiotics and are also at higher risk for cognitive decline, these findings offer reassurance about using these medications.”
The research, published online in the journal Neurology, involved 13,571 healthy individuals aged over 70. The term “healthy” was defined as not having heart disease, dementia, serious physical disabilities or any health issues that could potentially shorten their lifespan to less than five years.
All participants were free from cognitive impairment and dementia during the initial two years of the study. During this period, the researchers determined the participants’ antibiotic use by examining prescription records.
Just under two-thirds (63%) of the participants used antibiotics at least once during this time. The participants were then split into two groups: those who had used antibiotics and those who had never used them.
They were also categorised based on the number of antibiotic prescriptions they had received in the first two years, ranging from zero to five or more, to determine if increased antibiotic usage heightened a person’s risk.
Participants were then monitored for an average of five additional years, during which 461 individuals developed dementia and 2,576 developed cognitive impairment. The researchers then investigated whether antibiotic use during the first two years was linked with changes in thinking and memory skills over time.
Participants underwent a series of cognitive tests at the beginning of the study, after one year, and then every two years thereafter. These tests assessed thinking and memory abilities such as attention, executive function, and language. The research team then analysed the scores, comparing individuals who took antibiotics to those who did not. They found no significant difference between the two groups.
After adjusting for factors such as family history of dementia, cognitive function at the start of the study and medications known to affect cognition, the team discovered that antibiotic use was not linked with increased risks for cognitive impairment or dementia when compared to non-use of the medications. The researchers also found no associations with cumulative antibiotic use, continued use and specific types of antibiotics.
Prof Chan suggests that longer studies are required as the participants were only monitored for a relatively short period.