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Researchers investigate the risk association between opioids and dementia among people who have a high intake of opioids.

The use of opioids is associated with an increased risk for dementia, but only from a certain intake quantity, results from a Danish observational study showed. The more opioids people use, the higher the risk for dementia. The investigators emphasized that these findings need to be validated through causative research.

Dr. Nelsan Pourhadi, MD, from Copenhagen University Hospital Rigshospitalet, in Denmark, and colleagues investigated data from 1,872,854 individuals between 60 to 75 years of age in the year 2000, or turning 60 between 2000 and 2020, to assess the link between opioid use and the risk for dementia¹. People with cancer, established dementia, or previous opioid use or addiction were not included in the study.

In total, 93,638 cases of all-cause dementia were identified. Incidence-density-matching per sex and age was conducted using 468,190 controls. The investigators applied a total standardized dose (TSD) to compare the quantity of opioids that was taken by an individual. One TSD was equivalent to 30 mg of oral morphine per day. Also, the authors used a default 5-year lag time window between the last opioid intake and the diagnosis of dementia to reduce reverse causation bias.

“There was an association between opioid use and dementia,” said Dr. Pourhadi. “But this association only appeared to exist if a patient had used 90 TSDs or more.” For people between 60 to 75 years of age who had used between 31–90 TSDs, the incidence rate ratio (IRR) was 1.06 (95% CI 0.99–1.13). In the same age category, the IRRs for those who had used between 91 to 200 TSDs, between 201–500 TSDs, and over 500 TSDs were 1.28 (95% CI 1.16–1.41), 1.44 (95% CI 1.28–1.62), and 1.58 (95% CI 1.43–1.75). This trend was consistent across age categories, except for the 90+ category, in which the authors did not find an association between opioid use and the risk for dementia. Furthermore, the effect was consistent irrespective of ‘weak’ or ‘strong’ opioid use but appeared to be less pronounced in the chronic-pain subgroup of patients.

“Following these findings, it would be interesting to investigate the link between opioid use and dementia in dementia subtypes and to examine the potential causality of the observed associations,” Dr. Pourhadi concluded.

Medical writing support was provided by Robert van den Heuvel.

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