Award-winning Purdue HHS researcher utilizes expertise in human behavior genetics and epigenetics in her work

Valerie Knopik

Written by: Tim Brouk, tbrouk@purdue.edu

Epigenetics refers to how your behaviors and environment can cause changes that affect the way your genes work, according to the Centers for Disease Control and Prevention. Unlike genetic changes or mutations, epigenetic changes are reversible and do not change the sequence of DNA bases, but they can change how your body reads a DNA sequence.

Choices such as smoking or regular exercise have been suggested to lead to epigenetic changes that may be passed on from one cell to its daughter cells.

Valerie Knopik, the Ben and Maxine Miller Professor and head of the Purdue University Department of Human Development and Family Science, is the lead author of a textbook, “Behavioral Genetics,” that explores epigenetics, among other topics. The book is now in its seventh edition.

“You can think about the epigenome as the cellular material that sits on top, or outside, of the genome,” Knopik wrote in 2017. “It is these epigenetic marks that tell your genes to switch on or off, to scream or whisper. It may be through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can change gene expression … .”

Knopik’s behavior genetics and epigenetics expertise recently featured her on podcasts and a speaking engagement at the MacDill Air Force Base in Tampa, Florida. Her research also contributed, in part, to earning the 2024 Leadership in Action Award from the Susan Bulkeley Butler Center for Leadership Excellence. The $1,000 award recognizes “Purdue faculty, staff and students who have shown exemplary leadership within their respective areas of expertise.” Knopik and the other awardees will be honored at the Dec. 6 Butler Center Leadership and Mentoring Community Banquet.

What roles do environmental factors, such as diet or stress, play in epigenetic changes, and how might these changes impact long-term health?

Epigenetic alterations come in many forms; the most frequently examined and best understood is DNA methylation (DNAm). DNAm occurs by the addition of a methyl group onto a cytosine-phosphate-guanine base pairing, which can decrease or inhibit expression (hypermethylation) or increase expression (hypomethylation) of a gene. The prenatal period is a time of particularly high DNAm activity; subsequent methylation of specific sites in specific tissues is critical to embryonic development. DNAm occurring in-utero can also influence gene expression throughout the lifespan. The implications of unfavorable fetal conditions associated with maternal smoking during pregnancy (MSDP) therefore may follow offspring into childhood development, measurable through DNAm.

DNAm is a necessary genomic process critical for normal development, but it is also influenced by environmental stressors, exposures and other genetic processes. Studies have found that in adolescence, many years after the initial prenatal exposure, children exposed to MSDP have differential DNAm compared to unexposed children. Prenatal secondhand smoke exposure — someone other than the mother smoking — has also been found to be associated with DNAm in genes that play important roles in detoxifying chemical products of cigarette smoking. How and whether these effects on DNAm have long-lasting effects on outcomes that we can actually see — behavioral outcomes such as ADHD — remains to be seen. Results are mixed in humans. 

That said, in animal models, which are more controlled, there is a robust literature on epigenetic mechanisms that play a role in how prenatal nicotine exposure influences offspring’s neurobehavioral development.

How has our understanding of epigenetics shifted over the past decade, and what do you see as the most exciting developments in the field?

In many ways, relative to what we know about genomic DNA, epigenetics is still a young field. I think we are learning more and more, not only about the impact of epigenetics but also how to best model, analyze and interpret these data. Epigenetic mechanisms are a natural part of development and play an important role in many developmental processes. However, there are other epigenetic alterations that are thought to be a function of exposures to things like stress, pollution, toxins and diet but also to things like social support and exercise. So, you can see there is a range of alterations from more “negative” to more “positive.” There is some suggestion — key word: suggestion — that there are some modalities and interventions that might help to offset negative impacts. These modalities can include meditation and other yoga-related practices but also can include social support, feeling connected and regular exercise. There might also be a connection to drug targets in the future.

How do you think epigenetics can contribute to personalized medicine, especially in areas like cancer treatment or neurological disorders?

Epigenetics can point us to possible biological mechanisms that may be involved in these relationships. But perhaps equally — if not more — important is the possibility that epigenetics can point us to environmental or other contextual variables that might be easier to intervene on.

You’ve recently been featured on podcasts for your work in epigenetics and mental health/wellness. You discussed evidence-based yoga and mindfulness as well as adjacent modalities and practices, such as community connection and how feeling supported can have an impact in this domain. How does this occur?

The current understanding is that much of this — the positive impact of yoga/mindfulness practices — may be mediated by the impact of these yoga/mindfulness modalities on our stress response, both nervous system response and endocrine (hypothalamic-pituitary-adrenal axis) response. Our stress response can be intricately involved in our overall health. Chronic stress is tied to mental health challenges, cardiovascular challenges, gastrointestinal challenges and cognitive challenges. Chronic stress affects virtually every system in our body. 

What was the MacDill Air Force Base experience like, and how does epigenetics affect military personnel, if at all?

Military personnel and their families can be under extreme stress via deployment or serving stateside. Some military personnel are, depending on their assignment, at higher risk of being exposed to chemicals and toxins. I was asked to go MacDill Airforce Base, which is actually a joint command base, so I spoke to members of all branches of the military because they started a wellness initiative and are working to educate and equip their teams with a “toolkit” of accessible tools that can be implemented to help increase mental health and well-being. 

It was an absolutely amazing experience. The audience was so engaged.  We could have gone well over the allotted time to continue the conversation.