Both ADHD and child traumatic stress frequently co-occur with other conditions, such as anxiety, depression, or learning disabilities

Symptoms of child traumatic stress could be mistaken for ADHD and that the risk of misdiagnosis is high...  there is an overlap between ADHD symptoms and the effects of experiencing trauma... Unless symptoms are examined closely, the profiles of child traumatic stress and ADHD can appear to be similar... 

Eg...  Young children who experience trauma may have symptoms of hyperactivity and disruptive behavior that resemble ADHD... Trauma can make children feel agitated, troubled, nervous, and on alert... These behaviors can be mistaken for hyperactivity... What might seem like inattention in children who experience trauma might actually be symptoms of dissociation (feelings of unreality or being outside of one’s body) or the result of avoidance of trauma reminders... Among children who experience trauma, intrusive thoughts or memories of trauma (e.g., feeling like it is happening all over again) may lead to confused or agitated behavior which can resemble the impulsivity of ADHD...

Both ADHD and child traumatic stress frequently co-occur with other conditions, such as anxiety, depression, or learning disabilities... particularly Oppositional Defiant Disorder and Conduct Disorder— overlap with both child traumatic stress and ADHD...  a traumatic event can make an underlying psychological condition worse, resulting in greater symptoms... 

A comprehensive assessment for child traumatic stress includes the following... Assessing for a wide range of traumatic events and time of occurrence so that they can be linked to developmental stages , Assessing for a wide range of symptoms (including but not limited to symptoms of PTSD), such as high-risk behaviors, family environmental factors, functional impairments, and trauma reminders and triggers, as well as their time of onset, Assessing the child's strengths, talents, abilities, sources of emotional support, and capacity for resilience, Gathering information using a variety of techniques (clinical interviews, standardized measures, and behavioral observations), Gathering information from a variety of perspectives (child, caregivers, teachers, other providers, etc.), Conducting ongoing assessments because symptoms often change as children develop and have new experiences and exposures to new stressors...