New insights into how brain responds to extreme stress

Oct 15 2012

Researchers report new insights into how the brain responds to extreme stress, whether from combat, natural disasters, or repeated violent competition. The insights offer hope for detecting and treating several widespread and debilitating neuropsychiatric disorders, and were presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience and the world's largest source of emerging news about brain science and health.

Post-traumatic stress disorder (PTSD) is a severe anxiety disorder that can develop after experience of a traumatic or terrifying event, such as those experienced in combat or from sexual aggression. Such events can overwhelm the individual's ability to cope and lead to a long-lasting disorder. Symptoms include re-experiencing the original trauma through flashbacks or nightmares, often triggered by seemingly innocuous events. PTSD can harm an individual's relationships, ability to work, to sleep, and other aspects of life.

The lifetime prevalence of PTSD among adult Americans is 8 percent. Neither drug nor behavioral treatments currently available are consistently effective in treating PTSD. Therefore, scientists are studying brain changes associated with PTSD and related cognitive disorders, looking for clues to help in the development of new treatments.

Today's findings show that:

• A fast-acting antidepressant, ketamine, appears to aid the formation of new nerve connections in the brain, helping to extinguish fearful memories. The mouse study could possibly lead to new PTSD treatments (Neil Fournier, PhD, abstract 399.09).
• In a mouse model, when dopamine neurons in the brain's reward system are turned on and off with a genetically engineered "light switch," depressive symptoms also come and go. The research highlights the importance of this neural circuit as a potential target for new depression treatments (Dipesh Chaudhury, PhD, abstract 522.01).
• Brain images of adolescents taken before and after the 2011 Japanese earthquake reveal that pre-existing weakness in certain brain connections could be a risk factor for intensified anxiety and PTSD after a traumatic life experience (Atsushi Sekiguchi, MD, PhD, abstract 168.12).
• Rodent studies show that repeated violent, competitive encounters drive changes in brain activity that shapes the ongoing behavior of losers and winners in distinct ways, and can contribute to depression and/or anxiety (Tamara Franklin, PhD, abstract 399.10).

Other recent findings discussed show:

• How exposure to stress causes molecular changes that weaken the ability of the prefrontal cortex to regulate behavior, thought, and emotion, while strengthening more primitive brain circuits (Amy Arnsten, PhD, abstract 310).    

"New methods for looking deep into the brain are revealing a dynamic landscape that changes as it must to cope with trauma," said press conference moderator Sheena Josselyn, PhD, from the Hospital for Sick Children in Toronto, Ontario, an expert on the neural basis of brain function. "The more we learn about those changes, and how experiences remodel the brain, the more tools we will acquire for treating disorders that affect millions of people."