If you experienced abuse as a child, you might retain a lingering sense of trauma that haunts you like a ghost, creeping up and attacking at your most vulnerable moments. Perhaps the ghost took the form of brute force that left painful, purplish-red bruises on your skin. Or maybe it possessed you through annihilating words, seizing control of your mind. No matter how you met your ghost, the effects of childhood trauma can be devastating.
In the mid-1990s, Dr. Vince Felitti at Kaiser Permanente and Dr. Robert Anda at the CDC conducted the Adverse Childhood Experiences Study which surveyed over 17,000 adults about their exposure to physical, emotional, or sexual abuse during their childhood years as well as parental substance abuse, mental illness, and domestic violence, among other factors. They found that childhood adversity is vastly more common than recognized: Two-thirds of the participants had endured one or more influential adverse childhood experiences. The researchers also discovered a correlation between a high number of survey points and harmful health outcomes. A score of four or more increased the risk of depression by four and a half and suicidality by a shocking 12 times when compared to those surveyed with a score of zero.
Adverse childhood experiences may increase an individual’s stress levels, which can, in turn, contribute to harmful health outcomes. The famed “fight-or-flight” stress response is vital in a life-threatening situation. Chronic stress, on the other hand, prompts the overproduction of cortisol, a potent stress hormone. Excess cortisol halts the creation of new hippocampal neurons and causes the existing nerve cells in the hippocampus, a brain region involved in memory and learning, to atrophy. These changes might explain why survivors often experience memory problems, their ghost obscuring painful reminders in shadows and fog. 
According to Dr. Nadine Burke Harris, the founder of the Center for Youth Wellness, MRI brain scans of individuals with childhood trauma have shown a measurable increase in the size of the amygdala, the brain’s fear center, which has a hand in shaping hypervigilant behavior. Childhood trauma “affects areas like the nucleus accumbens, the pleasure and reward center of the brain that is implicated in substance dependence,” she explains, and weakens impulse control by inhibiting the proper functioning of the prefrontal cortex. These changes in brain structure and function might be the reason survivors of childhood trauma are more likely to engage in high-risk behavior.
Yet despite those terrifying findings, all hope is not lost. With a more comprehensive understanding of how exposure to child abuse affects the brain, people can learn how to manage their stress response and thus reverse the effects of their childhood trauma. Parents may also learn how to avoid abusive behavior when raising their children, disrupting the cycle of intergenerational trauma. As Dr. Harris says, “This is treatable. This is beatable.” Through compassionate research, mental health care, and increased awareness of the haunts of childhood trauma, we may — at last — have the tools to put the ghosts to rest.