Traumatic events can overwhelm your body and mind, leaving a lasting mark on your mood, relationship, and sense of self long after the trauma has ended. When trauma impairs your ability to develop full emotional maturity, this is known as arrested psychological development. Trauma can “freeze” your emotional response at the age you experienced it. When you feel or act emotionally younger than your actual age, this is known as age regression. Age regression means that, later in life, child-like behavior patterns can appear again when we feel unsafe or when we encounter triggers related to previous trauma — even if we’re unaware that we’ve been triggered.  “When an individual is traumatized, especially early on in life, the memory of the trauma is stored both in the brain and the body,” explains Carla Marie Manly, PhD, a clinical psychologist, trauma specialist, and author based in Sonoma, California. “As a result, if healing does not occur, the traumatic incident can impede healthy development.  “In essence, depending on the severity of the trauma, [your] entire way of being may be formed around the traumatic incident,” Manly adds.  This is because, on a neurobiological level, the trauma is not properly processed. It can rewire your brain in such a way that ultimately influences your thought patterns and behavioral responses as you get older, she says.  According to 2015 research, age regression can happen in children and adults. A small-scale 2007 study notes that regression may be more common in younger adults than older adults.  Though many therapists and counselors believe that trauma can cause age regression and leave people stuck at a certain age, few research studies are looking into its validity and usefulness in trauma therapy. source