A common form of medication that was previously found to "disrupt the gut microbiome", therefore raising concerns that they may have a harmful long-term effect on the brain, has now been found not to trigger dementia after all - according to a new study.
A new US study suggests that, for healthy older adults, using antibiotics is not associated with an increased risk of cognitive impairment or dementia. Cognitive impairment is when someone has subtle changes in thinking and memory, such as forgetting events and losing items more often.
Dementia is when thinking and memory problems become more advanced and affect a person’s ability to complete daily tasks. Study author Professor Andrew Chan, of Harvard Medical School, Massachusetts, said: “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.
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“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 study, published online by the journal Neurology, involved 13,571 healthy people over the age of 70. Researchers defined healthy as not having heart disease, dementia, serious physical disabilities or any health problems that might shorten their life to less than five years.
All the participants were free of cognitive impairment and dementia during the first two years of the study. During that time, the research team determined participants’ antibiotic use by reviewing prescription records.
Just under two-thirds of the participants (63%) used antibiotics at least once during that time. The participants were divided into two groups, those who used antibiotics and those who had never used antibiotics.
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Researchers also divided them into groups based on how many antibiotic prescriptions they had in the first two years, from zero to five or more prescriptions, so they could review if more antibiotics increased a person’s risk.
Participants were then followed for an average of five more years, during which 461 people developed dementia and 2,576 people developed cognitive impairment. Researchers then examined if antibiotic use during the first two years was associated with changes over time in thinking and memory skills.
Participants took a series of cognitive tests at the start of the study, after one year, and then every two years thereafter. The tests measured thinking and memory skills like attention, executive function and language.
The research team then looked at the scores and compared people who took antibiotics to those who did not. They did not find a 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 found that antibiotic use was not associated with increased risks for cognitive impairment or dementia when compared to not using the medications.
The researchers also found no associations with cumulative antibiotic use, continued use and specific types of antibiotics. Prof Chan says longer studies are needed as the participants were only followed for a relatively short period.