Thursday, April 10, 2025

UC tracks 'evolving' opioid epidemic across U.S.

Epicenter shifted from Northwest to East, driven by move from prescription painkillers to fentanyl

University of Cincinnati

OPIOIDS — image:
Researchers identified hot spots in fatal drug overdoses that allowed them to track the epicenter of the opioid epidemic across the United States between 2005 and 2020.
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Credit: UC DIGITAL EPIDEMIOLOGY LAB

The heart of the opioid epidemic that killed 665,341 people in the United States between 2005 and 2020 shifted geographically from the Northwest to the East, according to a new geographical analysis.

In a study published in the journal The Lancet Regional Health — Americas, epidemiologists at the University of Cincinnati tracked the epicenter of this life-shattering epidemic over space and time across the country, driven largely by a move from prescription opiates to heroin to synthetic substances like fentanyl.

Researchers say this geographic shift can be narrowed between 2013 and 2016 as lawmakers implemented stricter regulations limiting access to opioids and law enforcement began prosecuting doctors for allegedly prescribing them irresponsibly.

In the absence of a legal remedy, many people with substance use disorder began turning to illicit drugs such as heroin and fentanyl, UC College of Arts and Sciences Professor Diego Cuadros said.

“The key message is this is an evolving epidemic,” Cuadros said.

Researchers in UC’s Digital Epidemiology Lab discovered that the populations affected by substance use disorder also changed over the course of the deadly epidemic from homogeneously White populations to populations that now include many Black victims. Meanwhile, the substance of choice has shifted from prescription opioids to heroin and now synthetic opioids, the study found.

“Between 2013 and 2016, Black communities started having access to these synthetic opiates. And those communities have been more affected, particularly by fentanyl,” Cuadros said.

Drug overdoses are the leading cause of death for Americans ages 18 to 44, according to the Centers for Disease Control and Prevention, which provided mortality stats for the study.

“As the supply and demand dynamic of the substance evolved, so, too, did the vulnerable populations,” lead author and UC graduate Santiago Escobar said. “The type of substances being abused, as well as the means used to access them, were key determinants of which populations suffered a higher mortality.”

Study co-author Neil McKinnon, president of Central Michigan University, noted the benefits of tracking an epidemic over time.

“The epidemic is really a series of mini-epidemics, which we identify as hotspots, across rural and urban America,” he said. “We hope our results will assist those in addressing the opioid crisis.”

The research team has been studying the opioid epidemic for much of the past decade. In 2018 they identified hot spots where the opioid epidemic was having a disproportionate effect in Ohio. Subsequently, they identified similar trends nationwide in 2021 using county data to find 25 clusters where the rates of fatal drug overdoses were highest.

And then Cuadros and his students turned their attention to the COVID-19 pandemic.

“Epidemics like HIV are stable. We don’t see changes in hotspots. But for COVID, we saw different variants like delta and omicron crop up,” he said.

Those variants had a disproportionate effect both in cases of infections and deaths across the United States, he said.

“We have a similar situation here with substance use disorder,” Cuadros said. “We’re facing an epidemic that is very complex and dynamic and evolves over time.”

Journal

The Lancet Regional Health - Americas

DOI

10.1016/j.lana.2025.101075

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Spatiotemporal analysis of substance use disorder mortality in the United States: an observational study of emerging hotspots and vulnerable populations

Article Publication Date

9-Apr-2025

Guinea pigs: a promising animal model to study the human embryo

University of Montreal Hospital Research Centre (CRCHUM)

image:
Sophie Petropoulos, a CRCHUM researcher and professor at Université de Montréal, and Jesica Romina Canizo, a research associate in Petropoulos’ lab at the CRCHUM and study's co- first author
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Credit: CHUM

CRCHUM researcher Sophie Petropoulos and her team reveal for the first time that the guinea pig pre-implantation embryo is very similar to the human embryo, spurring a better understanding of infertility and early human development.

The first few days of a human embryo’s development, known as pre-implantation, are important. It’s when the first cells are formed, and these decide if the embryo can survive, how it will implant in the womb and how the tissues of the fetus will develop.

Today there are still logistical, ethical and legal limitations to using human embryos for research purposes, so scientists use alternative models including stem cell-based and animal models.

In a new study published in Nature Cell Biology, Sophie Petropoulos, a researcher at both Université de Montréal’s affiliated hospital research centre, the CRCHUM, and the Karolinska Institutet, in Sweden, shows that guinea pigs can serve as a reliable and robust small animal model to enhance our understanding of two key areas of research: comparative biology and human embryogenesis.

The guinea pig has long been used for studies in developmental biology and is very similar to humans in terms of general physiology. It is also the only small animal that, in females, goes through a full estrous cycle as women do, undergoes a similar implantation process and develops similar placentas.

“Despite these noted similarities, preimplantation development had not been studied,” said Petropoulos, an associate professor at UdeM and holder of a Canada Research Chair in Functional Genomics of Reproduction and Development. “Our lab is focused on understanding infertility and early human development, so we wanted to identify a model that we could use to answer our questions.”

A complete atlas of genes

“In our study, we used a technique known as single-cell RNA sequencing to produce a complete atlas of the genes involved in the guinea pig pre-implantation development, and examined their timing and expression. We also inhibited and activated signalling pathways to see how these genes could affect embryo development” she said. “When we compared the development of the guinea pig embryo to our previous work, we were very surprised by its striking resemblance to early human embryogenesis.”

That discovery opens new possibilities for understanding women’s infertility and for developing therapeutics to help ensure a healthy pregnancy, said Petropoulos, who was aided in her study by its two first authors: Jesica Romina Canizo, a research associate in Petropoulos’ lab at the CRCHUM, and Cheng Zhao, a research specialist in her lab at the Karolinska Institutet.

“The guinea pig model can help scientists understand how early exposure to drugs or environmental disruptions affect the health outcomes for babies in the long term, or why some women have recurring implantation failure,” Petropoulos said.

She and her team have now started to study post-implantation embryo development and gastrulation, during which all the organs and tissues of the human body are formed. With 80 per cent of pregnancy failures occurring in the first trimester, scientists are keen to understand this period of human development, known as the “black box”.

In the long term, the guinea pig preimplantation embryo model might provide extremely useful information about the best conditions for the development of healthy embryos and fetuses, Petropoulos and her team believe. This could help to improve fertility treatments and assist reproductive technologies.

Science writing: Bruno Geoffroy

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About this study

“The guinea pig serves as an alternative model to study human preimplantation development,” by Jesica Romina Canizo and Cheng Zhao under the supervision of Sophie Petropoulos, was published online April 4, 2025, in Nature Cell Biology. Funding was provided by the CRCHUM, the Research Center in Reproduction and Fertility, the Swedish Research Council and the Swedish Society for Medical Research. The research utilized the CRCHUM’s cellular imaging core facility and the animal facility.

About the CHUM Research Centre (CRCHUM)

Université de Montréal's affiliated hospital research centre, the CRCHUM, is one of North America’s leading hospital research centres. It strives to improve the health of adults through a continuum of research spanning disciplines such as basic science, clinical research and population health. About 2,130 people work at CRCHUM. These include more than 550 researchers and nearly 530 graduate students and postdoctoral fellows. crchum.com

About Université de Montréal

Deeply rooted in Montréal and dedicated to its international mission, Université de Montréal is one of the top universities in the French-speaking world. Founded in 1878, Université de Montréal today has 13 faculties and schools, and together with its two affiliated schools, HEC Montréal and Polytechnique Montréal, constitutes the largest centre of higher education and research in Québec and one of the major centres in North America. It brings together 2,300 professors and researchers and has close to 67,000 students. umontreal.ca