More than one in five adults in the US experience mental illness each year, according to data from the National Alliance on Mental Illness . And more than one in seven young people ages 6–17 experience a mental health disorder, with 50 percent of all mental illness occurring throughout one's lifetime beginning by age 14 and 75 percent by age 24.
Psychologists have long espoused that how parents raise their children during their early years of life has a huge impact on their mental health and happiness as they grow up. Something as simple as praising or scolding a child can be deeply internalized and could determine whether or not that child struggles with depression, anxiety, or substance use as a teenager or young adult.
But how and where the connection is made between parenting behaviors and future susceptibility to a mental health disorder is harder to discern. Notre Dame psychologist Kaylin Hill has devoted the past 15 years of her career to better understanding emotions and depression—and how to break the cycle of intergenerational mental health issues.
Hill, an assistant professor in Notre Dame's Department of Psychology , has found that parents' child-rearing methods during the preschool years coincide with how that child experiences joy and satisfaction across adolescence—a period during which the risk for mental health issues is at its highest. Her research was recently published in Communications Psychology, part of the Nature journal suite of publications.
"In this project, we demonstrate that early parenting is associated with one of the largest neural indicators of risk for mental health concerns we know of to date," said Hill, a clinical psychologist and faculty affiliate with Notre Dame's Shaw Center for Children and Families and Eck Institute for Global Health .
Hill focuses her work on how to reduce the burden and strain of depression on individuals and families; and through her directorship of Notre Dame's Psychophysiology of Affect across the Lifespan (PAL) Lab , she seeks to understand what makes those individuals vulnerable in the first place and how best to intervene.
Finding the common thread between behaviors and future susceptibility
Hill and her research team began their work by observing the one-on-one interactions and parenting behavior between 3-year-old children and their parents. They then compared that data to the development of neural reward responsiveness—how the brain responds to rewards or positive stimuli—of those same children at ages 9, 12, 15, and 18. This longitudinal study spanned 15 years and included 465 young people and their parents at Stony Brook University in New York, and was supported by a grant from the National Institute of Mental Health.
Previous research has shown that adequate reward processing in the brain is necessary for adolescents and adults to experience joy, excitement, and pleasure—a phenomenon that can even be seen in early childhood.
"This study is really the first of its kind that measures what early life experiences are associated with reward processing from childhood through late adolescence or early adulthood," Hill said. "And reward processing seems to be one of those pieces to the puzzle of what may put us at risk for developing mental disorders. Being able to observe reward processing, and how it develops from ages 9 to 18, is really helpful to understanding depression risk."
When watching the 3-year-old children and their parents interact in the laboratory at the start of the study, Hill and her team coded how often they saw positive parenting behaviors (displaying warmth, support, and encouragement) versus negative parenting behaviors (being harsh, heavy-handed, or overly intrusive).
Those coded interactions were compared to the data recorded from the brain's responses to rewarding stimuli. With an electroencephalogram (EEG), which uses small electrodes attached to the scalp through a cap to record the brain's electrical activity, the scientists were able to track reward processing at the brain level.
In this study, the researchers used money as the reward for winning a guessing game, which allowed them to look at the brain's electrical signals in response to a win versus a loss. Because the EEG system is adaptable to a range of individuals across abilities and cognitive stages, the scientists were able to assess reward processing at the brain level beginning at age 9 and followed up at ages 12, 15, and 18.
Their findings indicated that the children who experienced higher levels of positive parenting got more excited about winning the money, while the children raised with a more negative parenting style were less enthusiastic.
"What we saw is that the more positive, and less negative, parenting behaviors we observed at age 3, the larger the brain's reward response seemed to be for individuals across adolescence," Hill said.
In other words, the more praise and affirmation children receive from their parents at a young age, the better they are at recognizing the joyful things in life. The work of Hill and her team demonstrated that positive parenting experienced in the early years may teach children's brains how to respond to good things—fun activities, friendships, success, and well-being.
On the flip side, if a parent is particularly harsh or intrusive, that child's brain may develop a low reward response—a difficulty experiencing pleasure and happiness that subsequently opens the door to sadness and despondency.
"Experiencing positive parenting seems to help facilitate reward processing, which is important for promoting physical and mental health," added Hill, who is also a faculty affiliate with Notre Dame's Neuroscience and Behavior program and its Human Neuroimaging Center .
Discoveries point toward possibility of early intervention
The study's findings point to an opportunity for intervention, which Hill believes may need to include parents and children. She says it is critical to support parents—perhaps even before their child is born—as well as children and adolescents, in order to address the series of events from parent behaviors observed at age 3 to child development from ages 3 to 18. She notes that while this study was observational, it gives important clues for how experiences and development may unfold over time.
Current research indicates that the most reliable and prominent predictor of depression is family history, paired with the experience of a stressful life event. According to Hill, this study opens up a world of possibilities in terms of what intervention could look like. "There's something very important about early parent-child interactions and parenting behaviors," she said. "And I love that because behaviors are so much more open to intervention than a genetic explanation to what is driving risk within families."
Hill and her team hope their work can inform a broader conversation about how to prevent depression, one of the most prevalent and debilitating mental disorders. "We are trying to pull together a single strand—one explanation of likely many that exists—of what puts someone at risk and how we can intervene," she said.
