Why Collateral History is Crucial When Diagnosing ADHD in Adults
Diagnosing Attention-Deficit/Hyperactivity Disorder (ADHD) in adults is a nuanced and often complex task. Unlike childhood ADHD, where behaviours are typically observed in structured school environments and reported by teachers or parents, assessing for adult ADHD often relies on retrospective self-report. This introduces a significant margin for error—making collateral history an essential part of a robust diagnostic process.
What Is Collateral History?
Collateral history involves gathering information from someone who knows the individual well—often a parent, sibling, partner, or long-term friend. This additional perspective can shed light on symptoms the person may not fully remember, recognise, or report in their entirety themselves.
Why It Matters in Adult ADHD Assessments
There are several reasons why relying on self-report alone can be insufficient when diagnosing ADHD in adults:
Retrospective bias: Adults may struggle to accurately recall symptoms from childhood, which are required for a diagnosis under DSM-5 criteria (onset before age 12).
Low self-awareness: ADHD can impair self-perception and executive functioning, meaning individuals might genuinely overlook or misinterpret the extent of their difficulties (Barkley et al., 2008).
Symptom masking: Adults often develop compensatory strategies or internalise their difficulties, especially if they’ve been undiagnosed for decades.
Overlap with other conditions: Symptoms of ADHD can mimic or co-occur with mood disorders, anxiety/stress, trauma, to name a few.
Collateral history helps to better distinguish ADHD from other psychiatric presentations and ensures that the clinician is working with a complete picture.
Evidence From the Literature
The value of collateral history is supported by a strong evidence base:
Sibley et al. (2012) found that adult self-reports of childhood ADHD symptoms had limited reliability and that parental recall significantly improved diagnostic validity.
Kooij et al. (2010), in the European Consensus Statement, emphasised the importance of retrospective childhood data and collateral sources in diagnosing adult ADHD.
Barkley et al. (2008) highlighted that impaired self-awareness in adults with ADHD necessitates validation of self-reported symptoms through collateral sources.
Adler et al. (2006) demonstrated that the inclusion of collateral information could help differentiate ADHD from other psychiatric conditions with overlapping symptoms.
AQAS Standards and Collateral History
The AQAS standards, published in Frontiers in Psychiatry (Asherson et al., 2023), provide a comprehensive framework for the quality assurance of adult ADHD diagnostic services in the UK. One of their key principles is the use of collateral history:
“Wherever feasible, clinicians should seek to obtain corroborative information from a parent, caregiver, or other informant who knew the patient in childhood, in order to support the retrospective diagnosis” (Asherson et al., 2023).
These standards, developed by experts across the NHS and academic settings, stress that failure to include collateral input can undermine the reliability of the diagnostic process—potentially leading to misdiagnosis or missed diagnosis. The AQAS framework encourages the use of validated tools and structured interviews for both self-report and informant-based history, such as the Wender Utah Rating Scale (WURS) or the Barkley Adult ADHD Rating Scale.
Practical Tips for Clinicians
Always ask for a collateral source of information if available—ideally a parent or caregiver who can comment on childhood behaviours.
Use structured tools for informant input to improve reliability and comparability.
Document clearly when collateral history is not available, and seek alternative corroborating evidence (e.g., school records).
Be sensitive: Some patients may not have contact with family members due to trauma, estrangement, or adoption. In these cases, historic documentation or consistent longitudinal symptom patterns may provide a partial substitute.
Final Thoughts
Adult ADHD is a chronic neurodevelopmental condition that is often underdiagnosed or misdiagnosed. A collateral history is not a mere add-on—it is a critical element that adds depth, reliability, and accuracy to the assessment process. Incorporating it systematically, as recommended by NICE (2018) and the AQAS standards, is a mark of high-quality care.
References
Adler, L. A., Spencer, T. J., Faraone, S. V., et al. (2006). Validity of pilot Adult ADHD Self-Report Scale (ASRS) to rate adult ADHD symptoms. Annals of Clinical Psychiatry, 18(3), 145–148.
Asherson, P., Adamou, M., Ahmed, L., et al. (2023). AQUA-8: Standards for the diagnosis and treatment of adult ADHD in the UK. Frontiers in Psychiatry, 14, 1167602. https://doi.org/10.3389/fpsyt.2023.1167602
Barkley, R. A., Murphy, K. R., & Fischer, M. (2008). ADHD in Adults: What the Science Says. Guilford Press.
Kooij, J. J. S., Bejerot, S., Blackwell, A., et al. (2010). European consensus statement on diagnosis and treatment of adult ADHD: The European Network Adult ADHD. BMC Psychiatry, 10, 67.
National Institute for Health and Care Excellence (NICE). (2018). Attention deficit hyperactivity disorder: diagnosis and management (NICE Guideline NG87).
Sibley, M. H., Pelham, W. E., Molina, B. S. G., et al. (2012). When diagnosing ADHD in young adults: Which information source is best? Journal of Consulting and Clinical Psychology, 80(4), 682–693.