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She is 34, referred with a four-year history of losing track mid-conversation, missed appointments and a work capability that has fallen away since a restructure. She also has a documented history of childhood abuse by a stepfather, disclosed at 19 and never treated. Her mother is alive, willing to act as an informant, and was married to him throughout.
Two clinicians will read that referral and reach opposite conclusions. One sees trauma sequelae mislabelled as ADHD. The other sees lifelong ADHD that trauma has been allowed to explain away for two decades. Both are pattern-matching. The case is hard not because ADHD and PTSD share symptoms, but because trauma damages the evidence you would normally use to separate them.
This guide covers how to assess ADHD and PTSD in an adult with a trauma history: where the two diverge, which shortcuts do not hold, how to build a developmental history that trauma has degraded, and what to do when the only available informant is implicated. It sits alongside our differentials on ADHD and EUPD and ADHD and bipolar disorder.
Symptom content is where ADHD and trauma-related disorders look most alike: poor concentration, restlessness, irritability, disrupted sleep. Onset and course are where they diverge most reliably, and the developmental history is worth the work for that reason alone.
The first three carry the weight. The fourth is supporting detail, as is the quality of inattention: distractibility toward competing stimuli, against attention pulled inward by trauma material. Patients rarely separate these unprompted, so they have to be probed. The cross-setting question is the same one you ask for Criterion C, asked with the trauma timeline in mind.
The years before the index trauma are the highest-value evidence available.
Complex PTSD is an ICD-11 diagnosis, coded 6B41. All the diagnostic requirements for PTSD must be met: re-experiencing the event in the present, avoidance of reminders, and a persistent sense of heightened current threat. Complex PTSD adds severe and persistent problems in three further areas: affect regulation, a diminished or worthless view of oneself with shame, guilt or failure linked to the trauma, and difficulty sustaining relationships and feeling close to others.
DSM-5-TR does not include complex PTSD. It has PTSD, with a cluster for negative alterations in cognitions and mood, and a “with dissociative symptoms” specifier, which is limited to persistent or recurrent depersonalisation or derealisation. A clinician working from DSM-5-TR who writes “complex PTSD” is borrowing from a different classification and should say so.
Diagnosing ADHD under DSM-5-TR and complex PTSD under ICD-11 in the same report is defensible, but only if the report states it. Mixing the two silently is a common technical weakness in reports of this kind. The overlap with emotional instability is real too: affect dysregulation is a complex PTSD criterion, and emotional dysregulation is common in ADHD, so it cannot decide the question on its own.
The framing that does most harm is the assumption that one diagnosis subtracts from the other. A 2025 systematic review by Magdi and colleagues, which included 21 studies, reported adult ADHD and PTSD comorbidity ranging from 28% to 36% across the studies it reviewed. ADHD in people with PTSD was associated with greater psychosocial impairment and more severe PTSD symptoms. That range comes from a narrative synthesis of varied studies rather than a pooled estimate, but the direction is consistent.
The relationship between childhood maltreatment and ADHD is less causal than it first appears. In the E-Risk cohort of 2,232 British twins, Stern and colleagues (2018) found that childhood ADHD predicted later abuse and neglect, and that once childhood ADHD was accounted for, childhood abuse and neglect did not predict ADHD in young adulthood. A Swedish co-twin study of 9-year-olds by Dinkler and colleagues (2017) found that most of the association between maltreatment and neurodevelopmental problems was explained by shared genetic factors.
The practical conclusion is simple. Trauma in the history is not evidence against ADHD, and ADHD is not a reason to leave trauma unassessed.
The received wisdom is that dissociative absence points to trauma and distractible absence points to ADHD. The data do not support that as a rule. Esposito and colleagues (2025) surveyed 400 adults from the general population online and grouped them by symptom measures for PTSD, adverse childhood experiences and ADHD. Dissociation scores were associated mainly with ADHD symptom severity rather than with the trauma measures, and the ADHD group scored higher on the amnesia dimension than the PTSD group.
That was a cross-sectional, self-report, non-clinical sample, and it cannot show that ADHD causes dissociation. But it undermines the shortcut. If dissociation contributes to the formulation at all, it is through its phenomenology, such as depersonalisation that follows reminders, not through a total score. The mental state examination is where that detail is captured.
Retrospective recall is imperfect before trauma is added. In the Milwaukee follow-up, Barkley and colleagues (2002) found that young adults self-reported far lower ADHD persistence than their parents reported for them, although their recall of their own childhood ADHD correlated moderately with parent ratings made at the time. Our guide to retrospective recall of childhood symptoms covers the general problem.
Trauma compounds it in predictable ways. Periods around events may be poorly encoded or actively avoided, whole years may be organised around the trauma rather than around school, and families often hold a sanctioned account that every member repeats.
Where the patient’s account and the informant’s differ, the gap is itself information. Our article on informant and self-report discrepancy sets out how to weigh it.
This is the situation the standard assessment model does not plan for, and it arises often enough to need a position. Where a parent perpetrated the trauma, or was present and did not act, that informant is usually unusable. The main reason is not that their account would be inaccurate, but that obtaining it can cause harm.
Hold the opposite error in view as well. Declining to diagnose because the developmental evidence is thin, when it is thin precisely because of the trauma, penalises the patient twice.
DSM-5-TR Criterion E requires that the symptoms are not better explained by another mental disorder. “Better explained” is not the same as “also present”. A trauma history satisfies the exclusion only if the ADHD-type symptoms are accounted for by the trauma-related condition, which generally means they post-date the exposure and track it.
Where there is credible evidence of symptoms before the exposure, the trauma diagnosis does not explain them, and a co-occurring formulation is the accurate one. Write the reasoning out: the exposure timeline, what is known about function before it, which symptoms the trauma condition accounts for and which it does not, and what evidence would change your view. Our guide to documenting Criterion E and our article on writing the ADHD diagnostic report cover the wording in more detail.
No. ADHD and PTSD frequently co-occur in adults, and childhood ADHD itself raises the risk of later maltreatment. What matters is whether symptoms were present before the exposure and across settings.
No. Dissociative experiences are reported more often in people with ADHD symptoms than many clinicians expect, and a high total score does not discriminate between ADHD and trauma. The pattern, such as depersonalisation triggered by reminders, is more informative than the total.
Do not use them. Substitute other informants and documents covering different settings, record the substitution, and state what the absence of a parental account means for the confidence of your conclusion.
No. Complex PTSD is an ICD-11 diagnosis (6B41). DSM-5-TR has PTSD with a dissociative symptoms specifier. If a report uses both manuals, it should say which diagnosis comes from which.
There is no consensus standard behind this differential that we could find. The Delphi study by Sarr and colleagues covers complex PTSD alongside autism, attachment disorders and EUPD, but does not include ADHD among the conditions it compares, and we found no published consensus statement on separating ADHD from PTSD or complex PTSD in adults. A report stating that a presentation is “more consistent with complex PTSD than ADHD” therefore rests on the clinician’s reasoning, and the report should show that reasoning.
Developmental history taking, informant interviewing and differential diagnosis are core parts of Global ADHD Network’s ADHD Specialist Certification. For complex presentations using a structured interview, see our guide to the DIVA-5 in complex presentations.
