Literature Review

Opioid use in the elderly a dementia risk factor?


 

FROM AMERICAN JOURNAL OF GERIATRIC PSYCHIATRY

Opioid use in the elderly is associated with an almost 40% increased risk of dementia in new findings that suggest exposure to these drugs may be another modifiable risk factor for dementia.

“Clinicians and others may want to consider that opioid exposure in those aged 75-80 increases dementia risk, and to balance the potential benefits of opioid use in old age with adverse side effects,” said Stephen Z. Levine, PhD, professor, department of community mental health, University of Haifa (Israel).

The study was published online in the American Journal of Geriatric Psychiatry.

Widespread use

Evidence points to a relatively high rate of opioid prescriptions among older adults. A Morbidity and Mortality Weekly Report noted 19.2% of the U.S. adult population filled an opioid prescription in 2018, with the rate in those over 65 double that of adults aged 20-24 years (25% vs. 11.2%).

Disorders and illnesses for which opioids might be prescribed, including cancer and some pain conditions, “are far more prevalent in old age than at a younger age,” said Dr. Levine.

This high rate of opioid use underscores the need to consider the risks of opioid use in old age, said Dr. Levine. “Unfortunately, studies of the association between opioid use and dementia risk in old age are few, and their results are inconsistent.”

The study included 91,307 Israeli citizens aged 60 and over without dementia who were enrolled in the Meuhedet Healthcare Services, a nonprofit health maintenance organization (HMO) serving 14% of the country’s population. Meuhedet has maintained an up-to-date dementia registry since 2002.

The average age of the study sample was 68.29 years at the start of the study (in 2012).

In Israel, opioids are prescribed for a 30-day period. In this study, opioid exposure was defined as opioid medication fills covering 60 days (or two prescriptions) within a 120-day interval.

The primary outcome was incident dementia during follow-up from Jan. 1, 2013 to Oct. 30, 2017. The analysis controlled for a number of factors, including age, sex, smoking status, health conditions such as arthritis, depression, diabetes, osteoporosis, cognitive decline, vitamin deficiencies, cancer, cardiovascular conditions, and hospitalizations for falls.

Researchers also accounted for the competing risk of mortality.

During the study, 3.1% of subjects were exposed to opioids at a mean age of 73.94 years, and 5.8% of subjects developed dementia at an average age of 78.07 years.

Increased dementia risk

The risk of incident dementia was significantly increased in those exposed to opioids versus unexposed individuals in the 75- to 80-year age group (adjusted hazard ratio, 1.39; 95% confidence interval, 1.01-1.92; z statistic = 2.02; P < .05).

The authors noted the effect size for opioid exposure in this elderly age group is like other potentially modifiable risk factors for dementia, including body mass index and smoking.

The current study could not determine the biological explanation for the increased dementia risk among older opioid users. “Causal notions are challenging in observational studies and should be viewed with caution,” Dr. Levine noted.

However, a plausible mechanism highlighted in the literature is that opioids promote apoptosis of microglia and neurons that contribute to neurodegenerative diseases, he said.

The study included 14 sensitivity analyses, including those that looked at females, subjects older than 70, smokers, and groups with and without comorbid health conditions. The only sensitivity analysis that didn’t have similar findings to the primary analysis looked at dementia risk restricted to subjects without a vitamin deficiency.

“It’s reassuring that 13 or 14 sensitivity analyses found a significant association between opioid exposure and dementia risk,” said Dr. Levine.

Some prior studies did not show an association between opioid exposure and dementia risk. One possible reason for the discrepancy with the current findings is that the previous research didn’t account for age-specific opioid use effects, or the competing risk of mortality, said Dr. Levine.

Clinicians have a number of potential alternatives to opioids to treat various conditions including acetaminophen, non-steroidal anti-inflammatory drugs, amine reuptake inhibitors (ARIs), membrane stabilizers, muscle relaxants, topical capsaicin, botulinum toxin, cannabinoids, and steroids.

A limitation of the study was that it didn’t adjust for all possible comorbid health conditions, including vascular conditions, or for use of benzodiazepines, and surgical procedures.

In addition, since up to 50% of dementia cases are undetected, it’s possible some in the unexposed opioid group may actually have undiagnosed dementia, thereby reducing the effect sizes in the results.

Reverse causality is also a possibility as the neuropathological process associated with dementia could have started prior to opioid exposure. In addition, the results are limited to prolonged opioid exposure.

Pages

Recommended Reading

Study casts doubt on safety, efficacy of L-serine supplementation for AD
MDedge Psychiatry
Neurology, psychiatry studies overlook sex as a variable
MDedge Psychiatry
Many Americans missing an opportunity to prevent dementia
MDedge Psychiatry
Long COVID neuropsychiatric deficits greater than expected
MDedge Psychiatry
Hearing, vision loss combo a colossal risk for cognitive decline
MDedge Psychiatry