To pick a random study of many: https://pubmed.ncbi.nlm.nih.gov/29086104/
"Children with ADHD were more likely than controls to have ever experienced a traumatic event (27 vs 16%; OR: 1.99; 95% CI 1.21, 3.27). This difference remained significant in the adjusted model (OR: 1.76, 95% CI 1.03, 3.01) accounting for child factors (age and gender) and family socio-demographic factors (parent age, parent high school completion and single parent status). Among those with ADHD, trauma-exposed children had higher parent-reported ADHD severity and more externalizing problems than non-exposed children, however, this effect attenuated in adjusted model. Children with ADHD were more likely to have experienced a traumatic event than controls. The high prevalence of trauma exposure in our sample suggests that clinicians should evaluate for trauma histories in children presenting with ADHD. "
Or another: https://pubmed.ncbi.nlm.nih.gov/27816036/
"Childhood Trauma Exposure is common in Substance Use Disorder patients and associated with adult ADHD but not with the persistence of childhood ADHD into adulthood. These findings suggest that the increased rate of adult ADHD in SUD patients with CTE is not the consequence of a negative effect of CTE on the persistence of childhood ADHD into adulthood, but a direct expression of the high rate of childhood ADHD in SUD patients with CTE."
Or this one: https://pubmed.ncbi.nlm.nih.gov/19337826/
"Controlling for demographic variables, comorbid disorders, and ADHD severity, we noted significant associations between lifetime depression and environmental adversities, including victimization trauma, parent-child conflict, and behaviorally-independent negative life events. "