Scientists are uncovering links between psychiatric disorders and substances a person was exposed to, whether intentionally, such as through diet, smoking, or medication, or unintentionally, through air pollution, soil contaminants, or even stress. Experts in this cutting-edge field gathered at NIEHS March 21-22 to share insights on the biological pathways that may be involved.
“Environmental Risks for Psychiatric Disorders: Exploring Biological Mechanisms(https://tools.niehs.nih.gov/conference/erpd_2017/)” was a collaboration between Jonathan Hollander, Ph.D., from the NIEHS Division of Extramural Research and Training (DERT), and co-chairs Deborah Cory-Slechta, Ph.D., from University of Rochester Medical School; Tomas Guilarte, Ph.D., from Florida International University; and Mady Hornig, M.D., from Columbia University.
Cross-cutting topic with potential for prevention
“We are broadly defining the environment,” Hollander said, listing medications, chemicals, stressors, and nutritional factors among the exposures that would be addressed over the day-and-a-half event. Talks highlighted novel tools for research in this field, in which disorders typically have a variety of symptoms, certain symptoms appear in several disorders, and exposures may be difficult to measure.
“The subject is one of cross-cutting interest within the National Institutes of Health,” Hollander stated. Scientists with the National Institute of Mental Health (NIMH) and the National Institute of Drug Abuse were among the participants, including NIMH Director Joshua Gordon, M.D., Ph.D., who presented a keynote talk.
“It’s wonderful to get NIEHS and NIMH together to think about gene-environment interactions and the role of the environment in psychiatric illness,” Gordon said.
Keynote speaker John Gilmore, M.D., from the University of North Carolina at Chapel Hill (UNC), highlighted the benefits of better understanding such interactions. “Environmental risk factors may ultimately provide the best chance at prevention, as they are potentially preventable, while genetic risk factors are not,” Gilmore said.
Exposures, mechanisms, biomarkers, and more
Presentations and panel discussions addressed a broad range of topics.
- Evidence for the role of exposures in psychiatric and neurocognitive disorders, including epidemiologic studies, research on animal models, and a variety of approaches to uncovering the mechanisms involved.
- Types of exposures ranged from diet, infection, and trauma or stress, to marijuana, heavy metals, such as lead and mercury, and ultrafine particulate matter in air pollution.
- Mechanisms of action, including inflammation, effects on neuronal mechanisms and circuits, and epigenetic changes, which refer to changes in DNA that do not change the underlying sequence of amino acids.
- Gene-environment interactions — many psychiatric illnesses have a genetic component, but that rarely explains all cases. Anjene Addington, Ph.D., from NIMH, pointed out that schizophrenia affects an identical twin only about half the time.
- Potential biomarkers of exposure as a way to address some of the challenges in the field.
- Novel tools for study, such as zebrafish, mouse models, and the Comparative Toxicogenomics Database (CTD).
How to move forward?
“Environmental factors can act on genes, cellular processes, neural activity, and behavior,” Gordon pointed out. “And the same risk factors can predispose a person to multiple psychiatric symptoms. With such complexity, how do we move forward?” His talk summarized some of the environmental factors known to be involved in certain illnesses.
Suggestions encompassed laboratory techniques in rodent studies, epidemiological study design that clarifies gene-environment interactions, the role of sex differences in response to exposures, and the importance of microbes in the gut, especially with respect to messages sent to the brain via the vagus nerve, a key player in the gut-brain axis.
Ample discussion time provided for substantive exchange of ideas. “The talks have been great and thought provoking,” said Sheryl Moy, Ph.D., from UNC. “I appreciate the way speakers have highlighted the way animal models can inform or extend human studies.”
Hollander said the organizers will prepare a summary of the material presented at the workshop for publication.