As a post-​​doctoral researcher exam­ining ado­les­cent drug addic­tion at Harvard’s McLean Hos­pital between 2006 and 2008, Heather Bren­house took what her mentor called a “Friday after­noon flyer,” or a leap of faith. The move set the foun­da­tion for the research pro­gram she is now building as a newly appointed assis­tant pro­fessor of psy­chology in the Col­lege of Sci­ence at North­eastern University.

A decade ear­lier, Bren­house was working at a biotech firm exploring the inflam­ma­tory nature of Huntington’s dis­ease, with a par­tic­ular interest in a type of anti-​​inflammatory drug akin to Ibuprofen, called a COX-​​2 inhibitor. She began won­dering how many other dis­eases this drug type might help treat. “It had always been a bee in my bonnet.”

By the time she reached McLean, Bren­house had switched gears and began looking at the impact of early-​​life stress on ado­les­cent behav­ioral dis­or­ders. “I’m inter­ested in learning how early expe­ri­ences can derail normal devel­op­ment of the brain,” she said. “And how that makes the brain around ado­les­cence vul­ner­able to dis­or­ders like addic­tion, depres­sion and schizophrenia.”

Researchers had already demon­strated that these dis­eases cause both inflam­ma­tory and behav­ioral symp­toms. Bren­house wanted to figure out how, why and when the con­nec­tion between the ner­vous and immune sys­tems is made. “The more I looked into it, the more I real­ized, well, let’s try a COX-​​2 inhibitor.”

In 2011, Bren­house admin­is­tered COX-​​2 inhibitors to rat pups that had been iso­lated from their mother for hours a day. She then let them grow up under normal con­di­tions and looked at their brains once they reached ado­les­cence. The subset of pups that received the anti-​​inflammatory seemed to have devel­oped normal brains. On the other hand, those that did not receive the drug were defi­cient in a type of nerve cell called an interneuron.

Now at North­eastern, Bren­house plans to examine this phe­nom­enon fur­ther. The research is still in the early stages, but she has an idea of what might be going on. “What’s really fas­ci­nating about the brain is that dif­ferent parts of it develop at dif­ferent times,” she says. She notes that parts of the brain that are impor­tant for basic life func­tions develop ear­lier than others like the cortex, which plays a role in deci­sion making and begins to develop in adolescence.

According to Bren­house, ado­les­cent expo­sure to stress directly affects the devel­oping parts of the brain. “As the brain matures, those areas start to con­nect to the cortex,” she explained. “If the devel­op­ment of these early struc­tures is derailed, those con­nec­tions are also dysfunctional.”

Making mat­ters worse is the fact that the immune system is also affected by early life stress and begins to send con­fused mes­sages to the ado­les­cent brain. Bren­house impli­cates neural recep­tors and immune sig­nals: “We believe they interact, the inter­esting part is going to be to figure out how.”

Bren­house, PhD’05, expressed her excite­ment in returning to North­eastern, a uni­ver­sity that she says encour­ages risk taking. “Some­times you have to do the safe thing,” she said. “But the big leaps are impor­tant, too, and the most fun.”