Memorial researcher studies generational impacts of stress
If you’re prone to getting a good fright from goblins, ghouls and other spooky characters at Halloween, Dr. Jacqueline Blundell can explain the science behind your fear.
It’s a topic she’s been studying since 1998, first as a student in the Department of Psychology, Faculty of Science, and now as an associate professor in the department.
As a student, her PhD centred on using predator stress as a way to induce fear in an animal model of post-traumatic stress disorder, while her current research looks at the long-term effects of fear.
“The most important thing I’ve learned is that animals, similar to people, respond differently to traumatic or fearful events,” she said. “Some animals just don’t care. As a PhD student, I studied cat-rat interactions and some rats would go over to the cat and pull or bat at its tail or even climb on it. Others had dramatically different responses. They froze or were so scared they empty their bowels.”
Dr. Blundell says diverse reactions are seen in the human world as well, including in her own home.
“My husband loves watching The Exorcist, but for me it’s a nightmare,” she said. “So, it’s not surprising that while many people are exposed to traumatic events, only a small portion of them go on to develop a stress-related disorder.”
The goal of her research, she says, is to understand why some people are resilient to traumatic stress while others develop psychopathologies.
One potential explanation she is currently exploring is parental experience.
“While the deleterious effects of traumatic stress on mental health are well known, we are increasingly aware that the harmful effects of traumatic stress during an individual’s lifetime can affect future generations,” said Dr. Blundell. “Holocaust survivors, for example, have children and grandchildren with a higher incidence of mental illness.”
Experiments in rodents confirm the effects of stress can be transmitted to future generations. She’s been working to produce an animal model which demonstrates these brain and behavioural changes by exposing prey animals to predators in a protected environment.
While the mice never actually come into contact with the rats, they show a stress response from being near them. Two weeks after the stressful encounter, male and female mice are bred and impact on the offspring is assessed.
“I really didn’t think that a five-minute exposure to a predator was sufficient to produce a change in offspring, but what we found really flabbergasted us,” said Dr. Blundell. “Despite the fact that the offspring have never been exposed to a stressor (i.e. the predator), they avoid open spaces, and don’t like bright light. Basically, they show a typical anxiety-like response.”
Surprisingly, the anxiety-like behaviour is also seen in the grandchildren of stressed mice, suggesting that the effects cross multiple generations.
“Genes get turned on or off at different times in a ‘normal’ environment.”
Dr. Blundell has found there are also changes in the stress system, including increased cortisol – the stress hormone – and changes in the glucocorticoid receptor, which is what cortisol binds to in the brain.
“Genes get turned on or off at different times in a ‘normal’ environment,” she said. “These experiences can change the expression of genes involved in our stress response and, in our studies, we have seen that these changes can be passed on to their offspring. Now that we have a model, our next step is to identify the mechanism by which this transference occurs.”
Improving mental health
What does it all mean for humans that have faced significant fear and stress?
Dr. Blundell says that, while their findings show those experiences can affect offspring, she believes it doesn’t have to.
“Given how plastic the brain is, I suspect there are lots of ways for us to remove that influence,” she said. “These animals also don’t have the sophisticated brains or the compensatory responses we have.”
While the researchers have yet to explore ways to mitigate the stress-induced changes, she also believes if the mice were given access to a more enriching environment, they could reduce those long-term impacts. Dr. Blundell says she would “hate” for people to think that just because something happened to their parents, it seals their fate.
“That’s not the case. By helping illuminate the mechanistic underpinnings of these generational effects of stress, our research may help identify at-risk individuals and potential novel targets for treatments, with the overall goal of improving mental health outcomes.”