A case report: Pavlovian conditioning as a risk factor of heroin 'overdose' death

'It was like coming back from the clouds': a qualitative analysis of the lived experience of overdose consequent to drug use among a cohort of people who use drugs in Scotland

BACKGROUND

Globally, non-fatal overdose (NFOD) rates consequent to drug use, typically opioids, continue increasing at a startling rate. Existing quantitative research has revealed myriad factors and characteristics linked to experiencing NFOD, but it is critically important to explore the lived context underlying these associations. In this qualitative study, we sought to understand the experiences of NFOD among people who use drugs in a Scottish region in order to: enhance public policy responses; inform potential intervention development to mitigate risk; and contribute to the literature documenting the lived experience of NFOD.

METHODS

From June to July 2021, two peer researchers conducted face-to-face semi-structured interviews with people who use drugs who had experienced recent NFOD attending harm reduction services in Tayside, Scotland. These were transcribed verbatim and evaluated using thematic analysis with an inductive approach which had an experiential and essentialist orientation.

RESULTS

Twenty people were interviewed across two sites. Of those, 15 (75%) were male and mean age was 38.2 (7.7) years. All had experienced at least one NFOD in the prior six months, and all reported polydrug use. Five themes were identified, within which 12 subthemes were situated. The themes were: social context; personal risk-taking triggers; planned and impulsive consumption; risk perception; and overdose reversal. The results spoke to the environmental, behavioural, cognitive, economic, and marketplace, factors which influence the context of NFOD in the region.

CONCLUSIONS

A complex interplay of behavioural, psychological, and situational factors were found to impact the likelihood of experiencing NFOD. Structural inequities which policy professionals and civic leaders should seek to remedy were identified, while service providers may seek to reconfigure healthcare provision for people who use drugs to account for the interpersonal, psychological, and social factors identified, which appear to precipitate NFOD.

TRIAL REGISTRATION

Not applicable.

All Hands on Deck: We Need Multiple Approaches To Uncover the Neuroscience behind the Opioid Overdose Crisis

Opioid use disorder (OUD) affects millions of people throughout the United States, yet there are only three Food and Drug Administration-approved pharmacological treatments. Though these treatments have been shown to be effective, the number of overdose deaths continues to rise. The increase of fentanyl, fentanyl analogs, and adulterants in the illicit drug supply has further complicated treatment strategies. Preclinical researchers strive to model OUD to better understand this complicated disorder, and this research is a critical enabler for the development of novel treatments. As a result, there are many different preclinical models of OUD. Often, researchers form strong opinions on what they believe to be the "best" model to mimic the human condition. Here, we argue that researchers should be supportive of multiple models to promote new perspectives and discoveries and always consider the trends in human opioid use when designing preclinical studies. We describe the benefits of contingent and noncontingent models as well as models of opioid withdrawal and how each of these can help illuminate different components of OUD.

Coordinated activity of a central pathway drives associative opioid analgesic tolerance

Opioid analgesic tolerance, a root cause of opioid overdose and misuse, can develop through an associative learning. Despite intensive research, the locus and central pathway subserving the associative opioid analgesic tolerance (AOAT) remains unclear. Using a combination of chemo/optogenetic manipulation with calcium imaging and slice physiology, here we identify neuronal ensembles in a hierarchically organized pathway essential for AOAT. The association of morphine-induced analgesia with an environmental condition drives glutamatergic signaling from ventral hippocampus (vHPC) to dorsomedial prefrontal cortex (dmPFC) cholecystokininergic (CCKergic) neurons. Excitation of CCKergic neurons, which project and release CCK to basolateral amygdala (BLA) glutamatergic neurons, relays AOAT signal through inhibition of BLA μ-opioid receptor function, thereby leading to further loss of morphine analgesic efficacy. This work provides evidence for a circuit across different brain regions distinct for opioid analgesic tolerance. The components of this pathway are potential targets to treat opioid overdose and abuse.

The association between buprenorphine treatment duration and mortality: a multi-site cohort study of people who discontinued treatment

BACKGROUND AND AIMS

Buprenorphine is an effective medication for opioid use disorder that reduces mortality; however, many patients are not retained in buprenorphine treatment, and an optimal length of treatment after which patients can safely discontinue treatment has not been identified. This study measured the association between buprenorphine treatment duration and all-cause mortality among patients who discontinued treatment. Secondary objectives were to measure the association between treatment duration and drug overdose and opioid-related overdoses.

DESIGN

Multi-site cohort study.

SETTING

Eight US health systems.

PARTICIPANTS

Patients who initiated and discontinued buprenorphine treatment between 1 January 2012 and 31 December 2018 (n = 6550). Outcomes occurring after patients discontinued buprenorphine treatment were compared between patients who initiated and discontinued treatment after 8-30, 31-90, 91-180, 181-365 and > 365 days.

MEASUREMENTS

Covariate data were obtained from electronic health records (EHRs). Mortality outcomes were derived from EHRs and state vital statistics. Non-fatal opioid and drug overdoses were obtained from diagnostic codes. Four sites provided cause-of-death data to identify fatal drug and opioid-related overdoses. Adjusted frailty regression was conducted on a propensity-weighted cohort to assess associations between duration of the final treatment episode and outcomes.

FINDINGS

The mortality rate after buprenorphine treatment was 1.82 per 100 person-years (n = 191 deaths). In regression analyses with > 365 days as the reference group, treatment duration was not associated with all-cause mortality and drug overdose (P > 0.05 for both). However, compared with > 365 days of treatment, 91-180 days of treatment was associated with increased opioid overdose risk (hazard ratio = 2.94, 95% confidence interval = 1.11-7.79).

CONCLUSIONS

Among patients who discontinue buprenorphine treatment, there appears to be no treatment duration period associated with a reduced risk for all-cause mortality. Patients who discontinue buprenorphine treatment after 91-180 days appear to be at heightened risk for opioid overdose compared with patients who discontinue after > 365 days of treatment.

Emergency department utilization and subsequent prescription drug overdose death

PURPOSE

Prescription drug overdose (PDO) deaths are a critical public health problem in the United States. This study aims to assess the association between emergency department (ED) utilization patterns in a cohort of ED patients and the risk of subsequent unintentional PDO mortality.

METHODS

Using data from the New York Statewide Planning and Research Cooperative System for 2006-2010, a nested case-control design was used to examine the relationship between ED utilization patterns in New York State residents of age 18-64 years and subsequent PDO death.

RESULTS

The study sample consisted of 2732 case patients who died of PDO and 2732 control ED patients who were selected through incidence density sampling. With adjustment for demographic characteristics, and diagnoses of pain, substance abuse, and psychiatric disorders, the estimated odds ratios of PDO death relative to one ED visit or less in the previous year were 4.90 (95% confidence interval [CI]: 4.50-5.34) for those with two ED visits, 16.61 (95% CI: 14.72-18.75) for those with three ED visits, and 48.24 (95% CI: 43.23-53.83) for those with four ED visits or more.

CONCLUSIONS

Frequency of ED visits is strongly associated with the risk of subsequent PDO death. Intervention programs targeting frequent ED users are warranted to reduce PDO mortality.

Learning and the wisdom of the body

According to Spence, the learning researcher's task is to explain the relationship between experimental variables and behavior changes occurring with practice. Spence eschewed biological speculation. In contrast, for a biologist, "explanation" consists of ascertaining how the observed behavior increases reproductive success. Fundamental to achieving reproductive success is survival to sexual maturity, and such survival depends on homeostatic mechanisms attenuating the effects of physiological disturbances that threaten existence. Drugs are one way of disrupting homeostatic functioning, and studies of drug effects indicate that homeostatic mechanisms are engaged not just by pharmacological perturbations, but also by stimuli that signal such perturbations. Similarly, we attenuate the effects of a variety of nonpharmacological stimuli by such anticipatory homeostatic adjustments. The learning researcher is a homeostasis researcher.