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Researchers at McLean’s Behavioral Genetics Lab are using animal models to study the effects of nicotine on vulnerability to post-traumatic stress disorder (PTSD) in a study funded by the Department of Defense (DoD). While the three-year, $600,000 study still has a year left to go, preliminary findings suggest that use of nicotine may be helpful in preventing some of the core signs of PTSD.
“Nicotine is a huge issue in the Armed Forces,” said William Carlezon, PhD, associate chief of McLean’s Division of Basic Neuroscience and lab director, who is heading the study. “According to
discussions I’ve had with people in the military, almost everybody smokes or chews tobacco,” he added. “Sometimes it is while preparing for action, and other times it is during downtime.”
The Behavioral Genetics Lab studies how the environment and experience affects the brain and how that, in turn, affects behavior. All of their studies are done on mice or rats.
Carlezon’s DoD research explores whether use of nicotine makes one more or less likely to develop the signs of PTSD or post-traumatic stress disorder, a condition that can develop after a person is exposed to one or more traumatic events such as may be seen on a battlefield. Symptoms may include recurring flashbacks, nightmares, avoidance or numbing of memories of the event and hyperarousal, among others.
It is known that nicotine, the primary drug in cigarettes and chewing tobacco, can have an anxiety-reducing effect on people. The study is not designed to answer questions about the drug’s anti-anxiety effects in people who already have PTSD as there have been numerous studies along those lines.
One of the reasons that this work is novel is that it examines whether nicotine use at the time of the stressful event can make it seem more or less anxiety-provoking, which plays an important role in the subsequent development of PTSD.
In addition to nicotine’s effects on anxiety, it can also enhance the attention span, learning and memory. For this reason, the researchers considered that nicotine use might actually make PTSD worse since the condition involves memories of traumatic events that can be difficult to forget or suppress. According to Carlezon, the study does not seem to show such a negative effect.
Carlezon emphasized that the results do not mean that smoking or chewing tobacco is a good thing for soldiers, since these are known to be associated with diminished fitness and serious diseases. However, it is possible the findings could lead to soldiers being issued a nicotine patch or some other nicotine delivery system as a way of protecting them from PTSD, as well as to reduce their need to smoke or chew.
“There is the possibility that they might have a better outcome,” he said.
Aside from the aforementioned study, another set of experiments currently underway is examining how the animals fare over time with longer periods of nicotine use after the trauma in order to determine if cycles of nicotine use and withdrawal can affect the signs of PTSD.