Genes, Childhood Trauma, and ADHD: A Complex Relationship

Monday, March 3, 2025.

A groundbreaking study from Brazil has added new layers to our understanding of attention-deficit hyperactivity disorder (ADHD), reinforcing what many therapists and families have long intuited: ADHD is shaped by both our biology and our earliest experiences.

Researchers found that a person’s genetic predisposition to ADHD and experiences of childhood maltreatment each independently increase the likelihood of experiencing ADHD symptoms in adulthood.

But here’s where it gets even more fascinating—the study suggests that genetic risk for ADHD may also subtly increase a child’s chances of experiencing maltreatment.

Published in Molecular Psychiatry, these findings reveal just how deeply intertwined nature and nurture are in shaping a person’s journey through life.

ADHD: More Than a Childhood Struggle

ADHD isn’t just about bouncing off the walls or forgetting homework—it’s a deeply ingrained neurodevelopmental difference that influences attention, impulse control, and emotional regulation.

While often diagnosed in childhood, its effects ripple well into adulthood, shaping relationships, careers, and daily life in ways both frustrating and profound.

For many, ADHD means struggling to keep track of responsibilities, managing time, or maintaining focus in conversations.

It’s an ongoing dance between the mind’s wiring and the world’s expectations, making it essential to understand how different forces—both genetic and environmental—contribute to this condition.

Nature, Nurture, and the Intricate Dance of Development

For decades, scientists have known that ADHD runs in families, strongly suggesting a genetic component.

But genes don’t operate in a vacuum. Life experiences—particularly negative ones like childhood maltreatment—can leave lasting marks on brain development, amplifying ADHD symptoms or making them more difficult to manage.

This study sought to unravel just how genes and environment interact. The researchers explored two key possibilities:

• Gene-environment interaction: Could genetic risk for ADHD be amplified or diminished depending on a person’s childhood experiences?

• Gene-environment correlation: Do genetic traits themselves increase the likelihood of experiencing certain environments—in this case, childhood maltreatment?

Unlike many studies conducted in high-income nations, this research took place in Brazil, a middle-income country where childhood adversity rates tend to be higher. This broader perspective helps shed light on how these patterns unfold in diverse social contexts.

Following the Lives of a Generation

The study drew from the 2004 Pelotas birth cohort, a long-term project tracking nearly all babies born in Pelotas, Brazil, that year.

By the time participants turned 18, they completed the Adult Self Report Scale for ADHD, which assessed their levels of inattention, impulsivity, and hyperactivity. Their mothers or caregivers also provided assessments, offering an external perspective on their child’s behaviors.

To measure genetic predisposition, researchers analyzed DNA samples collected when the participants were just six years old. From this, they calculated an ADHD polygenic risk score—a measure of inherited likelihood of developing ADHD symptoms.

Childhood maltreatment was assessed through reports from mothers when the children were ages 6 and 11, covering behaviors like yelling, shaking, or hitting. While this doesn’t capture every facet of childhood adversity, it provides crucial insight into early environmental stressors.

What the Study Revealed

The findings painted a nuanced picture of ADHD’s origins:

Genetics Matter—But They’re Not the Whole Story – People with higher ADHD genetic scores were more likely to exhibit ADHD symptoms at age 18, as reported by both themselves and their mothers.

Childhood Maltreatment Leaves Deep Imprints – Those who had experienced more childhood maltreatment were more likely to struggle with ADHD symptoms in adulthood. This was true for both physical and psychological maltreatment, underscoring the long-lasting effects of early adversity.

Genetic Risk May Shape a Child’s Experiences – In an unexpected twist, the study found that children with a higher genetic predisposition for ADHD were more likely to experience maltreatment.

Further analysis suggested that ADHD symptoms at age six played a mediating role—meaning children who showed ADHD symptoms early in life were more likely to elicit negative reactions from caregivers, creating a feedback loop of stress and misunderstanding.

Interestingly, the researchers did not find that maltreatment altered the genetic risk for ADHD. Instead, genes and environment exerted their influence independently.

What This Means for Families and Clinicians

From a therapist’s perspective, these findings reinforce what many of us see in our work: ADHD is not just about willpower or “bad parenting.”

It’s a complex interplay of inherited traits and lived experiences, and understanding this can lead to more compassionate approaches in both parenting and treatment.

• Compassion for Kids with ADHD – If a child struggles with impulse control or focus, it’s not because they’re defiant or lazy. Their brains may simply be wired differently. This study underscores the importance of patience, structure, and positive reinforcement.

• Trauma-Informed Parenting – For children predisposed to ADHD, harsh discipline or neglect can worsen symptoms rather than correct them. Parents and caregivers who adopt a gentler, more understanding approach can help break cycles of frustration and miscommunication.

• Early Intervention is Key – Since early ADHD symptoms can contribute to stressful parent-child dynamics, providing support as early as possible—whether through behavioral therapy, parent coaching, or school accommodations—can make a profound difference in a child’s trajectory.

Limitations and the Path Forward

As with any study, there are caveats. Some participants were lost to follow-up, which may have influenced results.

The maltreatment assessments relied on maternal reports, potentially underrepresenting some experiences.

Additionally, the genetic risk scores were based on research predominantly conducted in European populations, which may not perfectly translate to diverse groups like those in Brazil.

That said, the study’s longitudinal design and use of multiple assessment tools strengthen its findings.

Future research should expand to include additional environmental stressors, such as economic hardship and educational experiences, to deepen our understanding of how ADHD develops.

Final Thoughts: A Call for Understanding and Support

As a couples therapist, I’ve seen firsthand how undiagnosed or misunderstood ADHD can impact relationships—not just between partners, but between parents and children.

This study serves as a powerful reminder that ADHD is neither a simple genetic lottery nor a product of poor upbringing. It’s an intricate tapestry woven from both nature and nurture, and our response should be just as nuanced.

By fostering environments of support, patience, and early intervention, we can help folks with ADHD navigate their unique challenges—not just as children, but throughout their entire lives.

Be Well, Stay Kind, and Godspeed.

RESEARCH:

The study, Gene–maltreatment interplay in adult ADHD symptoms: main role of a gene–environment correlation effect in a Brazilian population longitudinal study, was authored by Luciana Tovo-Rodrigues, Laísa Camerini, Thais Martins-Silva, Marina Xavier Carpena, Carolina Bonilla, Isabel Oliveira Oliveira, Cristiane Silvestre de Paula, Joseph Murray, Aluísio J. D. Barros, Iná S. Santos, Luis Augusto Rohde, Mara Helena Hutz, Julia Pasqualini Genro, and Alicia Matijasevich.