Opioids And Memory: A mere coincidence?
Written by Kiran Dogra
Picture this: You’ve just graduated from UCLA and you’re about to start a new job at a prestigious company. You’re a regular opioid user, but one recent incident left you hospitalized after blacking out. When you wake up, you ask where you are. The doctor tells you that you overdosed on fentanyl and that your memory has been affected. You pause and repeatedly ask where you are for the next little while. Your nightmare scenario was the actual experience of Owen, who was one of a few individuals who developed anterograde amnesia (the inability to form new memories) as a result of a fentanyl overdose [1]. Though these cases are quite rare and unusual, opioids have been found to affect the hippocampus – the memory centre of the brain.
Let’s review the basics of how opioids work, and why people use them. Fentanyl is a strong opioid that is used to relieve pain. It creates a sense of euphoria and relaxation when dopamine (the “feel good” hormone) levels increase [8]. But how is it so dangerous? The drug binds to the body’s opioid receptors, which are located in parts of the brain that control pain, emotion and breathing rate [8]. If the dose is strong enough, it can obstruct breathing completely, resulting in death. In fact, fentanyl is 20 to 40 times more potent than heroin and 100 times more potent than morphine, so an accidental overdose could end up being fatal [4]. This clearly explains what happens to our bodies, but not our memories.
Dr. Jed Barash is a neurologist from Massachusetts who has been studying the relationship between addiction and brain damage. Further investigation into his first four patients between 2012 and 2015 prompted a statewide search for similar cases [1]. In a letter to the editors of The New England Journal of Medicine, Barash and colleagues (2018) noted that 14 American individuals with a history of opioid use suffered from severe anterograde amnesia and other cognitive deficits, including disorientation and inattention.
Barash’s work has been partially supported by past research. One study observed both anterograde and retrograde amnesia (memory loss from past events) among palliative care patients who regularly use morphine [6]. Across two days of testing, participants either received another dose of morphine on the first day or a placebo (a dummy pill) on the next test day. Researchers administered multiple tasks to assess attention and everyday memory. Before receiving a dose, participants heard a story (Wilson et al., 1985) and were asked to immediately recall what they heard. Following the dose, participants heard another story and were asked to immediately recall what they heard. After completing attention-related tasks, participants were asked to remember both the first and second stories that they previously heard. Additionally, participants completed a forward digit span (reciting numbers in the order they appear) and backwards digit span (reciting numbers in reverse order) task to examine attention and memory. Findings reveal retrograde memory impairment for participants who received morphine on day one, and anterograde memory impairment for participants who received a dose of morphine on day two [6]. Contrary to these findings, further work with a similar research design and measures (digit span, stories) showed that opioids did not substantially affect memory [3].
Given that this research is limited and mixed, more studies are needed to examine the relationship between opioids and memory. However, Barash may be revealing some important patterns. Those 14 individuals were not tested for traces of fentanyl, but four additional patients tested positive for the deadly drug [2]. Patients from past studies received fentanyl patches [6] while other studies did not mention fentanyl [3]. This means that patients could be using other drugs other than opioids (e.g., stimulants and/or hallucinogens). Understanding a person’s past substance use history is important, because individual differences for the type of drug and its frequency of use may vary from person to person. This warrants further investigation into the relationship between opioids and memory impairment.
Much of the aforementioned research on opioids and memory has been conducted in the United States and United Kingdom, but what does all of this mean for the people of our province? Fatal overdoses are rising in Canada compared to other countries (see Figure 1) [9], with British Columbia (BC) having the highest overdose rates in the entire country [5]. The crisis has gotten so bad that death due to overdoses in BC is higher than the rates of death by suicide, homicide and motor vehicle collisions combined [7].
Figure 1
More work is needed to explore the effects of fentanyl on memory, and ways we can support positive outcomes for individuals with daily tasks in their lives. While day-to-day activities can be as mundane as asking for directions to a new area or following the steps correctly for a new recipe, they are often overlooked. For overdose survivors like Owen, his inability to form new memories could threaten his performance on demanding tasks that require him to remember important conversations and learn new skills for his new job. The road to recovery is a long way ahead, but these recent discoveries are promising for the field of opioids and memory.
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References
[1] Aguirre, L. (2021). The memory thief and the secrets behind how we remember A medical mystery. Pegasus Books.
[2] Barash, J. A., Ganetsky, M., Boyle, K. L., Raman, V., Toce, M. S., Kaplan, S., Lev, M. H., Worth, J. L., & DeMaria, A.
(2018). Acute amnestic syndrome associated with fentanyl overdose. New England Journal of Medicine, 378(12),
1157–1158. https://doi.org/10.1056/nejmc1716355
[3] Friswell, J., Phillips, C., Holding, J., Morgan, C. J. A., Brandner, B., & Valerie Curran, H. V. (2008). Acute effects of
opioids on memory functions of healthy men and women. Psychopharmacology, 198(2), 243–250.
doi:10.1007/s00213-008-1123-x
[4] Government of Canada. (2021). Fentanyl. https://www.canada.ca/en/health-canada/services/substance
use/controlled-illegal-drugs/fentanyl.html#a1
[5] Government of Canada, S. C. (2021, February 17). Analytical studies: Methods and References Statistics Canada
British Columbia opioid Overdose Analytical FILE: Technical report. Statistics Canada British Columbia Opioid
Overdose Analytical File: Technical Report. https://www150.statcan.gc.ca/n1/pub/11-633-x/11-633-x2021003-
eng.htm.
[6] Kamboj, S. K., Tookman, A., Jones, L., & Curran, H. V. (2005). The effects of immediate-release morphine on
cognitive functioning in patients receiving chronic opioid therapy in palliative care. Pain, 117(3), 0–
395. doi:10.1016/j.pain.2005.06.022
[7] Ministry of Mental Health and Additions. (n. d.) Escalating BC's response to the overdose emergency. Government
of British Columbia. https://www2.gov.bc.ca/assets/gov/overdoseawareness/mmha_escalating_bcs_response_
report_final_26feb.pdf
[8] National Institute on Drug Abuse. (2021, June 1). Fentanyl DrugFacts. Retrieved from
https://www.drugabuse.gov/publications/drugfacts/fentanyl on August 30 2021
[9] Ritchie, H., & Roser, M. (2018, March 16). Opioids, cocaine, cannabis and illicit drugs. Our World in Data. Retrieved
November 2, 2021, from https://ourworldindata.org/illicit-drug-use.
Disclaimer
The blog posts are for informational and educational purposes only. The posts should not be considered as any type of advice (medical, mental health, legal, and/or religious advice). All blog posts have been researched, written, and edited by the undergraduate students and alumni of the Lifespan Cognition Lab. As a teaching and research-based lab, we encourage all lab members to help make knowledge more accessible to all communities through these posts.
