Adults can develop symptoms associated with post-traumatic stress disorder even if they don’t have a clear memory of a childhood trauma that may have caused it, according to researchers at the University of California, Los Angeles.
Andrew M. Poulos, PhD, a postdoctoral fellow in psychology at UCLA when the research was done, and colleagues discovered that explicit memory, which involves voluntary recollection from prior experience, may not be necessary to suffer from PTSD.
The team exposed lab rats that were 17 days old (about age 2 in human years) to electric shocks, a form of unpredictable stress. At 80 days (young adult in human years), they tested the rats again for the memory of the event and fear response.
Rats tend to stand still when they experience fear. When they recall a traumatic memory, they freeze.
“We saw no freezing in the rats when they were placed in the traumatic context again,” said Michael Fanselow, PhD, a UCLA psychology professor and the study’s senior author. “If these memories are formed in adulthood, they never forget them.”
The findings, published in Biological Psychiatry, indicate that not remembering a traumatic event does not preclude a person or animal from experiencing some of the negative consequences of trauma, such as anxiety and heightened fear.
Because PTSD affects the brain in many ways, successful treatments for PTSD will need to target these changes, Fanselow added.
If you nearly drowned during your childhood, you may have a fear of water as an adult — the near death experience was so traumatic it still impacts your life. Traumatic memories from childhood could cause you to develop post-traumatic stress disorder in adulthood.