Genetic factors may influence how well exercise buffers against childhood trauma

A new study published in the Journal of Psychiatric Research suggests that exercise can help reduce the psychological toll of childhood adversity—but only for some individuals. People who experienced adverse childhood environments were more likely to report psychological distress in young adulthood. However, those who exercised regularly showed lower levels of distress. Importantly, the benefit of exercise appeared to be influenced by a genetic variant in the brain-derived neurotrophic factor (BDNF) gene, suggesting that genetics may partly determine how well someone responds to physical activity as a buffer against childhood trauma.

Childhood adversity is a well-documented risk factor for psychological problems later in life. Events like neglect, abuse, loss of a parent, or growing up in an unstable or chaotic home environment can leave lasting emotional scars. Numerous studies have shown that such experiences increase the risk for anxiety, depression, substance abuse, and other psychiatric disorders. In Taiwan, where this study was conducted, about 6% of junior high school students have experienced two or more adverse events by the age of 12.

Given these risks, the researchers were interested in identifying protective factors that could reduce the likelihood of developing psychological symptoms in young adulthood. One such factor is exercise, which is widely known to improve mental health and reduce symptoms of anxiety and depression. Physical activity is thought to help regulate stress and improve mood by increasing blood flow and supporting brain chemistry. However, not everyone benefits equally from exercise, and some studies have pointed to genetic differences as one possible reason.

The researchers also focused on a genetic variation known as the BDNF Val66Met polymorphism. This variation affects the brain’s ability to produce and release brain-derived neurotrophic factor, a protein that plays an important role in brain development, learning, and emotional regulation. People with one version of this gene (carriers of the “Met” allele) tend to produce less of the protein in response to activity, which may limit the brain’s ability to adapt and heal in response to stress.

To explore the complex relationship between childhood adversity, exercise, genes, and mental health, the research team recruited 750 healthy young people aged 16 to 23 from southern Taiwan. The participants completed questionnaires that measured their history of childhood adversity, frequency of moderate to vigorous exercise, and levels of psychological distress. They also provided saliva samples for DNA testing to determine which version of the BDNF gene they carried.

The researchers used statistical models to examine whether exercise helped explain the link between adverse childhood experiences and psychological distress—and whether that pathway was affected by the BDNF gene. They also separated childhood adversity into two categories: adverse environments, such as growing up with a parent who had mental illness or substance use problems, and childhood maltreatment, such as physical abuse or neglect.

Overall, the study confirmed that higher levels of childhood adversity were linked to more psychological distress in young adulthood. It also found that individuals who had experienced adversity were less likely to report regular exercise. In turn, lower exercise levels were associated with higher psychological distress. This suggests that one reason childhood adversity may lead to poorer mental health is that it reduces engagement in healthy behaviors like physical activity.

However, the effect of exercise was not the same for everyone. When the researchers looked at participants’ genetic data, they found that the relationship between exercise and psychological distress depended on which version of the BDNF gene they carried. Specifically, individuals with the Met/Met genotype—those with two copies of the Met allele—experienced less benefit from exercise in terms of reducing psychological distress. For these individuals, even if they exercised regularly, the reduction in distress was smaller than for people with other genotypes.

The moderating effect of the BDNF gene was most evident for participants who had experienced adverse childhood environments, such as parental divorce, starvation, or household mental illness. In these cases, exercise helped buffer the psychological impact of early adversity—but only for those without the Met/Met genotype. In contrast, among those who had experienced direct maltreatment such as physical abuse, the benefit of exercise was not statistically significant, regardless of genetic differences.

These findings add to a growing body of research showing that genetics can shape how people respond to both adversity and interventions. While exercise is generally good for mental health, its ability to protect against the effects of childhood trauma may depend on the underlying biology of the individual.

The study has some important limitations. It was based on self-reported data, which can be influenced by memory biases or current mood. It also used a cross-sectional design, meaning the researchers could not determine the direction of cause and effect. For example, it is possible that psychological distress led to reduced exercise rather than the other way around. In addition, the study focused on a single genetic variation, and other genes may also play a role in how individuals respond to stress or benefit from physical activity.

Despite these limitations, the research offers a promising direction for personalized mental health strategies. It suggests that encouraging regular exercise might be especially helpful for young people who have experienced adverse environments in childhood. However, genetic differences such as the BDNF polymorphism may influence how much individuals benefit from these interventions. In the future, identifying such gene-environment interactions could help tailor mental health programs to better fit each individual’s biological and environmental background.

Further studies are needed to explore other possible mediators between childhood adversity and mental health, such as family relationships, social support, or emotional regulation. Researchers also suggest expanding the genetic analysis to include a wider range of variations that may affect resilience or vulnerability. As understanding of these complex interactions grows, it may become possible to develop more effective, personalized approaches to preventing and treating psychological distress in individuals with difficult early life experiences.

The study, “Exercise as a mediator between childhood adversity and psychological distress: Can BDNF moderate the mediating effect?,” was authored by Jia Chi Chan, Chih-Ting Lee, Yee-How Say, Yu-Fang Lin, and Meng-Che Tsai.