Lesson 5 - Collateral Information
1. Introduction
Why this topic matters
Obtaining high-quality collateral information is one of the defining features of a comprehensive ADHD assessment. While the patient's own account forms the foundation of the clinical interview, ADHD is a neurodevelopmental disorder that typically affects multiple areas of functioning across different settings throughout life. No single individual, regardless of how insightful they are, is able to provide a complete picture of every aspect of their developmental history and day-to-day functioning. Collateral information therefore allows clinicians to build a more accurate, balanced and reliable understanding of the individual's presentation.
Collateral information serves several important purposes. Firstly, it helps establish whether ADHD symptoms were present during childhood, supporting one of the key diagnostic requirements that symptoms began early in development. Secondly, it provides evidence regarding how symptoms have affected functioning across different environments, such as home, school, work and social settings. Finally, it allows clinicians to compare different perspectives, identifying areas of agreement as well as understanding why differences in observations may exist.
One of the common misconceptions among less experienced clinicians is that collateral information is sought simply to confirm or disprove what the patient has reported. In reality, this is not its purpose. Parents, teachers, partners, employers and the patient themselves each observe the individual under different circumstances and with different expectations. Rather than expecting complete agreement, clinicians should use collateral information to develop a richer understanding of how ADHD presents across different contexts. Apparent discrepancies often provide valuable clinical information rather than representing contradictions.
The importance of collateral information extends beyond diagnosis. It also contributes to differential diagnosis, helps identify co-occurring conditions, provides insight into protective factors and environmental supports, and informs treatment planning. For children, teacher reports may reveal difficulties that are less apparent at home or highlight strengths that can be built upon. For adults, partners or family members often provide valuable observations regarding organisation, emotional regulation, daily routines and executive functioning that the individual may have normalised over many years.
Obtaining collateral information also demonstrates good clinical practice. ADHD assessments frequently involve reconstructing developmental patterns that span decades. Memories naturally become less precise over time, and individuals may unintentionally underestimate or overestimate the severity of their difficulties. By integrating information from multiple sources, clinicians can develop a formulation that is more robust, balanced and evidence-based than one based solely on self-report.
How it fits into the overall course
Throughout the previous lessons, we have explored the core principles of ADHD assessment, including the diagnostic criteria, comprehensive history taking, developmental history and the assessment of functional impairment. These topics have demonstrated how clinicians identify ADHD symptoms, understand their developmental progression and evaluate their impact on everyday functioning.
This lesson builds upon those foundations by examining how collateral information strengthens clinical decision-making. We will discuss why collateral information is important, who should provide it, what information is most helpful and how to interpret situations in which different informants describe different experiences. We will also explore the strengths and limitations of common assessment tools, including rating scales and school reports, and discuss practical strategies for integrating multiple sources of information into a coherent clinical formulation.
The ability to gather, interpret and synthesise collateral information is a hallmark of high-quality ADHD assessment. Rather than viewing each source in isolation, experienced clinicians learn to combine information from patients, families, schools, workplaces and historical records into a single developmental narrative. This approach not only improves diagnostic accuracy but also enables clinicians to provide more meaningful psychoeducation, formulate more individualised treatment plans and work collaboratively with patients and their families throughout the assessment process.
2. Learning Outcomes
By the end of this lesson, learners should be able to:
Explain the role of collateral information in ADHD assessment and describe why it is essential for establishing developmental history, assessing functional impairment and improving diagnostic accuracy.
Identify appropriate sources of collateral information across different age groups, including parents, caregivers, teachers, partners, employers, school reports and historical records, recognising the strengths and limitations of each source.
Interpret collateral information critically, recognising that differences between informants are common and should be understood within the context of the environments in which observations are made rather than viewed as contradictions.
Evaluate the strengths and limitations of standardised rating scales and questionnaires, understanding how these tools should complement, rather than replace, comprehensive clinical assessment and diagnostic reasoning.
Integrate information from multiple sources into a coherent clinical formulation, balancing self-report, collateral accounts, developmental history and clinical observations to support accurate diagnosis and treatment planning.
Apply best practice when obtaining and using collateral information, recognising situations in which limited or conflicting information requires careful clinical judgement while maintaining a person-centred, evidence-based approach to assessment.
3. The Lecture
Why Collateral Information Matters
Imagine assessing a 32-year-old man who describes lifelong difficulties with concentration, organisation and procrastination. He is convinced he has ADHD and provides numerous examples from his current life. During the consultation, however, he struggles to remember much about his childhood. He vaguely recalls being "a bit dreamy" at school but cannot provide many specific examples. His parents are still alive, and school reports are available.
Now imagine a second patient of the same age who reports similar symptoms but whose parents describe him as exceptionally organised throughout childhood. His school reports consistently comment on excellent concentration, good organisation and careful attention to detail. His difficulties only began during university following a prolonged period of anxiety.
Both patients present with attentional difficulties, yet the collateral information leads us towards very different diagnostic formulations.
This illustrates one of the central principles of ADHD assessment.
Collateral information is not collected because we distrust the patient's account. It is collected because ADHD is a developmental disorder that unfolds over many years, across multiple environments and is observed by many different people. No single informant can provide a complete picture.
Experienced clinicians therefore think of collateral information as another piece of the diagnostic puzzle rather than a test of whether the patient is telling the truth.
What Is Collateral Information?
Collateral information refers to information obtained from sources other than the patient to help understand their developmental history, current functioning and the impact of their symptoms across different settings.
These sources may include:
Parents or caregivers
Partners or spouses
Siblings
Teachers
Employers or colleagues (less commonly)
School reports
Previous medical records
Educational psychology reports
Previous neurodevelopmental assessments
Social care records where relevant
Each source contributes a different perspective.
Rather than asking which source is "correct", clinicians should ask:
"What does each source tell me about how this individual functions in different environments?"
Why Self-Report Alone Is Not Enough
Patients are usually the most important source of information during an ADHD assessment.
However, relying exclusively on self-report has limitations.
Adults may have difficulty remembering childhood accurately.
Parents naturally forget aspects of childhood over time.
Children often lack the insight required to recognise executive functioning difficulties.
Some individuals minimise difficulties because they have become normalised.
Others overestimate symptoms because they are distressed or actively searching for an explanation.
None of these situations imply dishonesty.
They simply reflect the limitations of human memory and perception.
Collateral information allows clinicians to compensate for these limitations by bringing together multiple perspectives.
Importantly, the aim is not to replace self-report but to complement it.
ADHD Is Context Dependent
One of the reasons collateral information is so valuable is that ADHD rarely presents identically across every environment.
Consider a child who struggles to concentrate throughout the school day but appears relatively settled at home.
Does this mean they do not have ADHD?
Not necessarily.
School places sustained demands upon attention, organisation, emotional regulation and behavioural inhibition.
Home may be less structured, more predictable and involve activities that the child enjoys.
Conversely, another child may appear well behaved at school but become emotionally dysregulated at home.
After suppressing hyperactive or impulsive behaviours throughout the school day, they may simply have exhausted their capacity for self-regulation.
Neither presentation is unusual.
Different environments reveal different aspects of ADHD.
Understanding these differences is one of the major strengths of collateral information.
Choosing the Right Informants
Not every source of collateral information carries equal value in every assessment.
The most useful informants are those who know the individual well and have observed them over prolonged periods of time.
Parents
Parents remain one of the most valuable sources of developmental information.
They often provide detailed examples of:
early behaviour
emotional regulation
organisation
school routines
friendships
family interactions
developmental milestones
childhood coping strategies
Parents also help establish whether symptoms were present before the age at which increasing environmental demands exposed them.
Teachers
Teachers observe children within an environment that places considerable demands upon attention, organisation and behavioural regulation.
Importantly, teachers compare one child against many others of the same developmental age.
Their observations often provide valuable information regarding:
classroom attention
task completion
organisation
peer relationships
behavioural regulation
academic functioning
However, teachers only observe children within one particular setting.
Their observations should therefore complement rather than replace parental information.
Partners
For adult assessments, partners frequently provide valuable information about everyday executive functioning.
Patients often become accustomed to their own organisational difficulties and underestimate their impact.
Partners may describe:
forgotten appointments
unfinished tasks
financial disorganisation
household routines
emotional regulation
time management
social functioning
These observations often illustrate functional impairment more clearly than symptom descriptions alone.
School Reports
Historical school reports can be particularly valuable because they were written before ADHD assessment was being considered.
Comments such as:
"Frequently distracted."
"Fails to complete work."
"Needs constant reminders."
"Capable but inconsistent."
"Talks excessively."
may provide objective evidence that symptoms were present during childhood.
Equally informative are reports that consistently describe excellent concentration, organisation and sustained attention throughout childhood.
Historical documents should always be interpreted within the wider clinical context rather than in isolation.
When Informants Disagree
Perhaps the greatest source of anxiety for new clinicians is conflicting collateral information.
Fortunately, disagreement is common.
Imagine the following.
The parent describes severe ADHD symptoms.
The teacher reports very few concerns.
Should the assessment stop?
Absolutely not.
The next question should be:
"Why might these observations differ?"
Several explanations are possible.
The classroom may be highly structured.
The child may expend enormous effort maintaining concentration at school before becoming dysregulated at home.
Teachers may observe predominantly academic functioning while parents witness homework, routines and emotional regulation.
Alternatively, symptoms may genuinely be more prominent within one environment.
Each explanation provides clinically useful information.
Experienced clinicians become curious about disagreement rather than frustrated by it.
Rating Scales Are Helpful—but They Are Not Diagnostic
One of the most common misconceptions among clinicians is that ADHD rating scales determine whether someone has ADHD.
They do not.
Rating scales provide structured information about symptom frequency and functional impact.
Examples include:
SNAP-IV
Vanderbilt ADHD Rating Scales
Conners Rating Scales
Adult ADHD Self-Report Scale (ASRS)
Weiss Functional Impairment Rating Scale (WFIRS)
These instruments improve the consistency of assessment and help identify areas requiring further exploration.
However, they have important limitations.
They depend upon subjective reporting.
They may be influenced by mood, anxiety or expectations.
They cannot adequately assess differential diagnoses.
Most importantly, they cannot replace clinical judgement.
Think of rating scales as screening and assessment tools rather than diagnostic tests.
The diagnosis is always made through comprehensive clinical assessment.
The Importance of Historical Records
Historical records often provide valuable information that neither patients nor relatives remember.
Examples include:
school reports
educational psychology assessments
paediatric clinic letters
CAMHS records
occupational health reports
university support documentation
These documents help reconstruct developmental patterns and may provide evidence of symptoms long before ADHD was considered.
Nevertheless, absence of historical documentation should never prevent diagnosis.
Many adults simply no longer possess school reports or previous records.
Diagnosis should always be based upon the totality of available evidence.
Integrating Multiple Sources
Experienced clinicians rarely view individual sources of information separately.
Instead, they gradually build a coherent formulation.
Imagine the following evidence.
The patient describes lifelong disorganisation.
Parents describe excessive forgetfulness throughout childhood.
School reports repeatedly mention incomplete homework.
The partner reports frequent forgotten appointments.
The clinician observes distractibility during the consultation.
No single observation proves ADHD.
Together, however, they create a highly consistent developmental narrative.
This process of synthesising information from multiple sources lies at the heart of expert ADHD assessment.
When Collateral Information Is Limited
Not every patient can provide extensive collateral information.
Some adults have no living parents.
Others were adopted.
Some experienced childhood trauma or unstable care arrangements.
Historical records may no longer exist.
In these situations, clinicians should make every reasonable effort to obtain alternative information while recognising the limitations of the available evidence.
Diagnosis should not automatically be excluded because collateral information is incomplete.
Instead, clinicians should consider:
the quality of the developmental history
current symptom presentation
functional impairment
available historical evidence
consistency across the assessment
differential diagnoses
Good clinical judgement becomes particularly important in these situations.
Clinical Example
A 42-year-old accountant presents requesting assessment for ADHD after reading about executive functioning difficulties online.
He describes lifelong procrastination, poor organisation and chronic lateness.
His wife reports that he forgets appointments, loses important paperwork and leaves numerous household tasks unfinished despite good intentions.
His mother remembers that he constantly forgot school equipment, needed repeated reminders to complete homework and was frequently described as "capable but easily distracted."
School reports repeatedly mention careless mistakes and incomplete classwork.
Although no single piece of information confirms ADHD, the combination of self-report, partner history, parental recollections and historical school reports provides a consistent developmental picture that strongly supports the diagnosis.
This illustrates why collateral information should never be viewed as isolated evidence. Its greatest value lies in how multiple sources combine to produce a coherent clinical formulation.
Key Learning Points
Collateral information strengthens ADHD assessment by providing additional perspectives on developmental history, symptom presentation and functional impairment.
The purpose of collateral information is to complement self-report rather than confirm or refute it.
Parents, teachers, partners and historical records each contribute unique information and should be interpreted within the context of the environment in which observations were made.
Differences between informants are common and often provide valuable clinical insights rather than representing contradictions.
Rating scales and questionnaires are useful assessment tools but are not diagnostic tests and should never replace comprehensive clinical assessment.
Experienced clinicians synthesise information from multiple sources into a single developmental narrative rather than relying upon any individual piece of evidence.
When collateral information is limited, diagnosis should be based on the overall balance and quality of the available evidence rather than the absence of a particular document or informant.
4. Clinical Perspective
Obtaining collateral information is one of the defining characteristics of a high-quality ADHD assessment. While diagnostic criteria often focus attention on symptom counts, experienced clinicians recognise that understanding an individual's neurodevelopment requires listening to multiple perspectives and integrating them into a coherent clinical formulation. Collateral information rarely provides simple confirmation or contradiction. Instead, it adds depth, context and nuance to the assessment.
One of the greatest shifts that occurs as clinicians gain experience is learning to value differences between informants rather than viewing them as problems to be resolved. Parents, teachers, partners and patients all observe different aspects of the individual's functioning. Their accounts are therefore expected to differ. The clinician's role is not to decide who is correct but to understand why different people have experienced the individual differently.
Clinical Pearls
Think of collateral information as complementary, not confirmatory.
A common misconception is that collateral information exists to verify the patient's account.
This is not its purpose.
Every informant observes the individual within a different environment, under different expectations and at different stages of development.
A teacher may primarily observe sustained attention within a structured classroom, while a parent witnesses homework, bedtime routines, emotional regulation and family interactions. A partner may provide valuable insight into organisation, financial management and household responsibilities that would never be apparent during a consultation.
Rather than asking:
"Does this confirm what the patient told me?"
Ask:
"What additional perspective does this source provide?"
This subtle shift in thinking often transforms the quality of the assessment.
Disagreement is often clinically informative.
One of the most valuable lessons for clinicians is that differing accounts do not necessarily weaken the diagnosis.
In fact, they often strengthen the formulation.
For example, a child who appears settled at school but becomes highly dysregulated at home may be demonstrating the effects of prolonged effort to maintain self-control throughout the school day.
Similarly, an adult may minimise organisational difficulties because they have lived with them for decades, while their partner provides numerous examples of their everyday impact.
When collateral information differs, become curious rather than concerned.
Differences frequently provide important clues about environmental demands, coping strategies and compensatory mechanisms.
Look for recurring themes rather than identical examples.
Experienced clinicians rarely expect different informants to describe precisely the same behaviours.
Instead, they look for common underlying patterns.
For example, one teacher may describe a child as "constantly distracted", another as "slow to complete work" and a parent as "needing repeated reminders to finish simple tasks."
Although the wording differs, all three observations may reflect the same underlying executive functioning difficulties.
The consistency of the developmental pattern is often more important than consistency of language.
Historical records often become more valuable with time.
School reports, educational psychology assessments and previous clinic letters were usually written long before ADHD assessment was being considered.
For this reason, they are often less influenced by retrospective interpretation or diagnostic expectation.
Comments such as "capable but inconsistent," "needs constant encouragement" or "frequently forgets equipment" may seem relatively minor when read individually, but repeated observations over several years can provide compelling evidence of longstanding difficulties.
Always consider the pattern across multiple reports rather than placing undue emphasis on isolated comments.
Practical Tips for Everyday Practice
Whenever possible, obtain collateral information before the assessment rather than afterwards.
Reviewing school reports, questionnaires and developmental information in advance allows you to target areas requiring clarification during the clinical interview and makes the consultation considerably more efficient.
Explain to patients and families why collateral information is requested.
Some individuals worry that clinicians do not believe what they are saying or that someone else is being asked to "judge" them.
Reassure them that ADHD affects multiple settings and that hearing different perspectives helps build a more complete understanding of their experiences.
When reviewing rating scales or questionnaires, avoid simply calculating scores.
Instead, pay particular attention to the written comments and examples provided by parents, teachers or partners.
These qualitative observations often provide richer clinical information than numerical scores alone.
If collateral information appears inconsistent, explore the circumstances in which behaviours occur.
Ask questions such as:
"What is different about school compared with home?"
"What support does your partner provide that perhaps others don't see?"
"How much effort does it take to appear organised at work?"
These conversations often reveal why different informants have reached different conclusions.
Finally, remember that the quality of collateral information is usually more important than the quantity.
One thoughtful, detailed account from someone who knows the patient extremely well may be considerably more informative than several brief questionnaires containing minimal information.
Common Pitfalls and Misconceptions
Expecting complete agreement between informants.
Perfect agreement is uncommon.
Different people observe different behaviours in different situations.
The aim is to understand these differences rather than eliminate them.
Treating rating scales as diagnostic tests.
Standardised questionnaires are valuable assessment tools, but they cannot diagnose ADHD.
They should always be interpreted alongside the developmental history, functional impairment, clinical interview and mental state examination.
Clinical judgement remains paramount.
Ignoring collateral information that does not fit the initial impression.
Confirmation bias can affect every clinician.
It is tempting to focus on information that supports an emerging diagnosis while dismissing evidence that appears inconsistent.
Instead, actively consider information that challenges your hypothesis.
Doing so often leads to a more balanced and robust formulation.
Assuming absence of evidence is evidence of absence.
Older school reports may contain little information about attention or behaviour.
Some schools write only brief reports, while others focus exclusively on academic progress.
Similarly, parents may genuinely struggle to remember childhood details decades later.
Limited collateral information should not automatically be interpreted as evidence against ADHD.
Overlooking environmental influences.
Children and adults behave differently depending upon the demands placed upon them.
Highly structured environments may reduce observable symptoms, whereas unstructured settings often reveal executive functioning difficulties more clearly.
Always interpret collateral information within the context in which it was obtained.
Advice for Newly Qualified Doctors
Early in your ADHD assessments, you may feel uncertain when different informants describe apparently contradictory experiences.
This uncertainty is entirely normal.
Rather than trying to determine who is correct, focus on understanding the context behind each observation.
Ask yourself:
"What might explain these different perspectives?"
Develop the habit of summarising collateral information as you review it.
For example:
"His parents consistently describe lifelong forgetfulness and poor organisation. School reports repeatedly mention incomplete work and distractibility, while his partner describes ongoing difficulties managing finances and appointments."
This approach naturally encourages synthesis rather than viewing each source separately.
Avoid allowing any single questionnaire or school report to dominate your diagnostic reasoning.
Each source represents one part of the overall assessment and should always be interpreted alongside the clinical interview, developmental history and functional impairment.
Finally, remember that obtaining collateral information is not an administrative exercise.
It is an opportunity to understand the individual's life from multiple perspectives. The more curious you become about these different viewpoints, the richer your assessments will become.
Situations Requiring Particular Clinical Judgement
Adults with no available collateral information
Some adults have no living parents, were adopted, experienced childhood adversity or have no access to historical records.
In these situations, make every reasonable attempt to obtain alternative evidence, such as siblings, partners or previous educational documentation.
If this is not possible, base your diagnostic decision on the quality and consistency of the available developmental history while acknowledging any limitations.
Conflicting parent and teacher reports
This is one of the most common situations encountered in paediatric ADHD assessment.
Rather than viewing disagreement as evidence against ADHD, consider differences in environmental demands, classroom structure, behavioural expectations and the child's coping strategies.
Understanding why reports differ is often more informative than the reports themselves.
Adults who have developed exceptional compensatory strategies
Partners frequently describe considerably greater impairment than the patient recognises.
These individuals may have normalised years of coping strategies and underestimate the effort required to maintain everyday functioning.
Collateral information is particularly valuable in identifying hidden impairment within this group.
Children educated in highly supportive environments
Small class sizes, experienced teachers, one-to-one support or exceptionally organised parents may significantly reduce the visible impact of ADHD symptoms.
Explore the level of support required to achieve current functioning rather than judging functioning solely by observable outcomes.
Final Clinical Message
High-quality ADHD assessment is rarely based upon a single source of information. Instead, it involves carefully listening to multiple voices, understanding the context in which each perspective has developed and integrating them into a coherent developmental narrative. Experienced clinicians do not seek perfect agreement between informants; they seek consistency in the underlying developmental pattern while remaining curious about the reasons behind any differences. When interpreted thoughtfully, collateral information transforms an assessment from a simple collection of symptoms into a rich understanding of how ADHD has influenced an individual's life across different settings and stages of development.
5. Summary
Collateral information is a fundamental component of a comprehensive ADHD assessment and plays a vital role in improving diagnostic accuracy. While the patient's own account remains central to the assessment process, no single individual can provide a complete picture of how ADHD symptoms have presented across different stages of development and in different environments. By integrating information from multiple sources, clinicians can develop a richer and more balanced understanding of the individual's lifelong pattern of functioning.
Throughout this lesson, we have explored the purpose of collateral information and emphasised that it should complement, rather than confirm or refute, the patient's account. Parents, teachers, partners, school reports and historical records each provide unique perspectives based on the situations in which they have observed the individual. Experienced clinicians recognise that differences between informants are common and often reflect variations in environmental demands, expectations and coping strategies rather than inaccuracies in reporting.
We have also considered the strengths and limitations of different sources of collateral information. Parents and caregivers frequently provide valuable insight into early development and family functioning, teachers contribute observations from structured educational settings, partners often highlight everyday executive functioning difficulties in adulthood and historical documents offer contemporaneous evidence of childhood behaviours. Standardised questionnaires and rating scales can help structure information gathering but should never replace comprehensive clinical assessment or clinical judgement.
An important theme throughout this lesson has been the need to synthesise information rather than evaluate each source in isolation. Individual observations may appear relatively unremarkable when considered separately, but together they often reveal a clear and consistent developmental pattern that supports an evidence-based clinical formulation. Equally, when collateral information is incomplete or conflicting, clinicians should remain curious, explore the reasons for these differences and consider the overall balance of evidence rather than relying upon any single informant.
Finally, we have highlighted that collateral information contributes to far more than diagnosis alone. It strengthens the developmental history, provides evidence of functional impairment across multiple settings, assists with differential diagnosis, identifies protective factors and informs treatment planning. By integrating collateral information thoughtfully and systematically, clinicians are able to develop a more accurate understanding of the individual's strengths, challenges and support needs, leading to more person-centred assessment and more effective clinical care.
In the next lesson, we will begin exploring the first of the three core symptom domains of ADHD: Inattention. We will examine each inattentive symptom in detail, discuss how these symptoms present across childhood and adulthood and consider practical strategies for distinguishing clinically significant inattention from the attentional difficulties experienced as part of everyday life.
6. Further Reading
Collateral information is one of the cornerstones of high-quality ADHD assessment. Although no single source of information is sufficient to establish or exclude a diagnosis, integrating evidence from patients, families, schools, workplaces and historical records improves diagnostic accuracy and supports a comprehensive developmental formulation. The following resources provide evidence-based guidance on obtaining, interpreting and integrating collateral information throughout the assessment process.
National Clinical Guidelines
National Institute for Health and Care Excellence (NICE)
Attention Deficit Hyperactivity Disorder: Diagnosis and Management (NG87).
NICE NG87 recommends that ADHD assessments should be based on information gathered from multiple sources whenever possible. The guideline emphasises obtaining a comprehensive developmental history, assessing symptoms across more than one setting and collecting collateral information from parents, caregivers, teachers or other appropriate informants to improve diagnostic accuracy and inform treatment planning.
International Clinical Guidelines and Consensus Statements
American Academy of Child and Adolescent Psychiatry (AACAP)
Practice Parameter for the Assessment and Treatment of Children and Adolescents With Attention-Deficit/Hyperactivity Disorder.
The AACAP Practice Parameter recommends obtaining information from multiple informants, including parents, teachers and the child, recognising that ADHD symptoms often vary across settings. It also discusses the importance of integrating behavioural observations, developmental history and rating scales into the overall clinical assessment rather than relying on any single source.
Canadian ADHD Resource Alliance (CADDRA)
Canadian ADHD Practice Guidelines.
The CADDRA guidelines provide practical recommendations for gathering collateral information across the lifespan. They discuss the use of developmental history, school reports, rating scales, partner reports and historical documentation, while emphasising that clinical judgement remains central to diagnosis.
World Federation of ADHD
The World Federation of ADHD International Consensus Statement: 208 Evidence-based Conclusions About the Disorder.
This international consensus statement reinforces that ADHD diagnosis should be based upon a comprehensive clinical assessment incorporating developmental history, collateral information and evidence of functional impairment across multiple settings. It highlights the importance of integrating information from several sources rather than relying solely on self-report or questionnaire scores.
Landmark Research Papers
Achenbach TM, McConaughy SH and Howell CT.
Child/Adolescent Behavioral and Emotional Problems: Implications of Cross-Informant Correlations for Situational Specificity.
This landmark paper explored the degree of agreement between parents, teachers and young people when reporting behavioural and emotional difficulties. It demonstrated that differences between informants are common and often reflect genuine variations in behaviour across different environments rather than inaccuracies in reporting. These findings have had a major influence on modern ADHD assessment.
De Los Reyes A and Kazdin AE.
Informant Discrepancies in the Assessment of Childhood Psychopathology: A Critical Review, Theoretical Framework and Recommendations for Further Study.
This influential review explains why discrepancies between informants should not automatically be viewed as errors. Instead, differing perspectives may provide valuable information about contextual influences, environmental demands and symptom variability across settings.
Kooij JJS, Bijlenga D, Salerno L, et al.
Updated European Consensus Statement on Diagnosis and Treatment of Adult ADHD.
This consensus statement discusses the challenges of obtaining collateral information during adult ADHD assessments and provides practical recommendations for reconstructing developmental history using parents, siblings, partners, school reports and other historical sources when available.
High-Quality Review Articles
Thapar A and Cooper M.
Attention Deficit Hyperactivity Disorder. The Lancet. 2016.
This comprehensive review discusses ADHD assessment across the lifespan and highlights the importance of obtaining collateral information alongside developmental history and functional assessment to improve diagnostic confidence.
Posner J, Polanczyk GV and Sonuga-Barke E.
Attention-Deficit Hyperactivity Disorder. The Lancet. 2020.
An up-to-date review examining the diagnosis of ADHD across childhood and adulthood. The authors discuss the importance of multiple informants, contextual assessment and careful clinical formulation.
Faraone SV, Asherson P, Banaschewski T, et al.
Attention-Deficit/Hyperactivity Disorder.
This review summarises current evidence regarding ADHD diagnosis and reinforces that no single questionnaire, informant or assessment tool is sufficient in isolation. Accurate diagnosis requires the integration of multiple sources of evidence through comprehensive clinical assessment.
Recommended Books
Barkley RA.
Attention-Deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment.
Widely regarded as one of the definitive clinical references on ADHD, this handbook provides detailed guidance on obtaining collateral information, interpreting differing reports from informants and integrating developmental history into diagnostic decision-making.
Barkley RA and Murphy KR.
Attention-Deficit Hyperactivity Disorder: A Clinical Workbook.
This practical companion text contains examples of interviews, rating scales and assessment strategies, illustrating how collateral information contributes to high-quality clinical formulations.
Rutter M, Bishop DVM, Pine DS, Scott S, Stevenson J, Taylor E and Thapar A (Editors).
Rutter's Child and Adolescent Psychiatry.
This authoritative textbook discusses the principles of multi-informant assessment across child and adolescent psychiatry, providing valuable context for understanding why collateral information is essential in neurodevelopmental assessments.
Suggested Reading for This Lesson
If you would like to consolidate the key concepts covered in this lesson, the following resources are particularly recommended:
NICE Guideline NG87: Attention Deficit Hyperactivity Disorder: Diagnosis and Management.
*AACAP Practice Parameter for the Assessment and Treatment of Children and Adolescents With Attention-Deficit/Hyperactivity Disorder.
*Canadian ADHD Resource Alliance (CADDRA): Canadian ADHD Practice Guidelines.
De Los Reyes A and Kazdin AE. Informant Discrepancies in the Assessment of Childhood Psychopathology.
Thapar A and Cooper M. Attention Deficit Hyperactivity Disorder. The Lancet. 2016.
Barkley RA. Attention-Deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment.
Together, these resources reinforce one of the central principles of this lesson: no single informant provides the complete picture. High-quality ADHD assessment depends upon thoughtfully integrating information from multiple perspectives, understanding the context in which each observation was made and synthesising the evidence into a coherent developmental formulation that supports accurate diagnosis and person-centred care.
7. Knowledge Check
The following questions are designed to reinforce the key principles discussed in this lesson. As with previous lessons, read the explanation for every answer, including the incorrect options. Understanding why an answer is incorrect often strengthens clinical reasoning just as much as identifying the correct answer.
Question 1
Why is collateral information considered an important part of an ADHD assessment?
A. It replaces the patient's own account of their symptoms.
B. It provides additional perspectives on the individual's development and functioning across different settings.
C. It is only required when assessing children.
D. It is primarily used to determine which medication should be prescribed.
Correct answer: B
Explanation
A. Incorrect. The patient's own account remains central to the assessment. Collateral information complements rather than replaces self-report.
B. Correct. ADHD affects multiple areas of functioning across different environments. Information from parents, teachers, partners and historical records helps clinicians build a more complete and reliable picture of the individual's developmental history and current functioning.
C. Incorrect. Although collateral information is particularly valuable in childhood assessments, it also plays an important role when assessing adults.
D. Incorrect. While collateral information contributes to treatment planning, its primary role is to improve diagnostic accuracy and clinical formulation.
Question 2
Which of the following is the most appropriate way to think about collateral information?
A. It is used to confirm whether the patient is telling the truth.
B. It provides additional perspectives that contribute to the overall clinical formulation.
C. It is only useful when self-report appears unreliable.
D. The clinician should decide which informant is correct.
Correct answer: B
Explanation
A. Incorrect. Collateral information is not obtained because clinicians distrust the patient.
B. Correct. Different informants observe different aspects of the individual's life. Their perspectives complement one another and contribute to a richer understanding of the presentation.
C. Incorrect. Even when self-report is entirely reliable, collateral information remains valuable.
D. Incorrect. The aim is rarely to decide who is correct. Instead, clinicians seek to understand why different observations may exist.
Question 3
A child's parents report significant ADHD symptoms at home, while the teacher reports relatively few concerns in school. What is the most appropriate clinical response?
A. Exclude ADHD because symptoms are not reported by both informants.
B. Assume the parents are exaggerating.
C. Explore why the child's presentation differs across settings before reaching any conclusions.
D. Base the diagnosis solely on the teacher's report.
Correct answer: C
Explanation
A. Incorrect. Differences between settings are common and require further exploration.
B. Incorrect. There is no reason to assume exaggeration without evidence.
C. Correct. Variations in environmental demands, structure, expectations and coping strategies frequently explain differing observations.
D. Incorrect. No single informant should determine the outcome of the assessment.
Question 4
Which source of collateral information is often particularly valuable because it was written before ADHD assessment was being considered?
A. Internet forums.
B. School reports.
C. Social media posts.
D. Occupational health questionnaires completed after diagnosis.
Correct answer: B
Explanation
A. Incorrect. Internet discussions are not reliable sources of developmental information.
B. Correct. School reports provide contemporaneous observations of behaviour and functioning, reducing the influence of retrospective interpretation.
C. Incorrect. Social media content is unlikely to provide structured developmental evidence.
D. Incorrect. These documents are useful but may already be influenced by awareness of ADHD.
Question 5
Which statement best describes the role of ADHD rating scales?
A. They provide a definitive diagnosis of ADHD.
B. They replace the need for a clinical interview.
C. They provide structured information that should be interpreted alongside the wider clinical assessment.
D. They are only useful for research.
Correct answer: C
Explanation
A. Incorrect. Rating scales cannot diagnose ADHD.
B. Incorrect. A comprehensive clinical assessment remains essential.
C. Correct. Rating scales help structure information gathering and identify areas for further exploration but should always be interpreted within the context of the overall assessment.
D. Incorrect. Rating scales are valuable in routine clinical practice when used appropriately.
Question 6
An adult reports lifelong organisational difficulties but has no surviving parents and no school reports. What is the most appropriate approach?
A. Conclude that ADHD cannot be diagnosed.
B. Diagnose ADHD based solely on current symptoms.
C. Obtain alternative collateral information where possible and base the diagnosis on the overall balance of evidence.
D. Stop the assessment because childhood information is unavailable.
Correct answer: C
Explanation
A. Incorrect. Lack of historical records does not automatically exclude ADHD.
B. Incorrect. Current symptoms alone are insufficient for diagnosis.
C. Correct. Partners, siblings, previous medical records or a detailed developmental history may still provide valuable evidence. Diagnosis should reflect the quality and consistency of all available information.
D. Incorrect. Assessments should continue even when collateral information is incomplete.
Question 7
Why do experienced clinicians often find disagreements between informants clinically useful?
A. Because one informant is usually intentionally misleading.
B. Because disagreements often reveal how ADHD presents differently across environments.
C. Because teachers are generally more accurate than parents.
D. Because disagreements usually exclude ADHD.
Correct answer: B
Explanation
A. Incorrect. Most informants provide honest observations based on their own experiences.
B. Correct. Different environments place different demands on attention, organisation and self-regulation. Variations between reports often provide valuable insight into contextual influences.
C. Incorrect. Different informants contribute different perspectives rather than one being inherently more reliable.
D. Incorrect. Disagreement is common and should prompt further exploration rather than exclusion of ADHD.
Question 8
Which of the following is the best example of high-quality collateral information?
A. A brief statement that "everything is fine."
B. A teacher describing repeated difficulties sustaining attention, completing work and following classroom instructions over several years.
C. A social media comment from a friend.
D. A newspaper article about ADHD.
Correct answer: B
Explanation
A. Incorrect. General statements provide limited clinical information.
B. Correct. Specific behavioural examples observed over time are highly informative and contribute meaningfully to the clinical formulation.
C. Incorrect. Casual observations from friends rarely provide sufficient developmental context.
D. Incorrect. General information about ADHD is not collateral information about the individual being assessed.
Question 9
When reviewing multiple sources of collateral information, what should clinicians primarily look for?
A. Identical wording from every informant.
B. A consistent developmental pattern across different sources and settings.
C. The questionnaire with the highest score.
D. The opinion of whichever informant knows the patient longest.
Correct answer: B
Explanation
A. Incorrect. Different people naturally describe behaviours in different ways.
B. Correct. The clinician's role is to identify consistent themes that support a coherent developmental narrative rather than expecting identical descriptions.
C. Incorrect. Rating scale scores should never be interpreted in isolation.
D. Incorrect. The length of the relationship does not necessarily determine the quality or relevance of the information.
Question 10
Which statement best summarises the role of collateral information in ADHD assessment?
A. It is an optional administrative exercise that rarely changes the diagnosis.
B. It is only required for medico-legal purposes.
C. It strengthens diagnostic accuracy by helping clinicians understand symptoms, development and functional impairment across multiple settings.
D. It should always be prioritised over the patient's own account.
Correct answer: C
Explanation
A. Incorrect. High-quality collateral information frequently strengthens clinical formulation and diagnostic confidence.
B. Incorrect. Collateral information is a core component of good clinical practice, not simply a legal requirement.
C. Correct. By integrating self-report with observations from multiple informants and historical records, clinicians develop a more robust understanding of the individual's developmental history and current functioning.
D. Incorrect. The patient's own account remains central to the assessment. Collateral information should complement, not replace, their perspective.
Reflection
Before progressing to the next lesson, consider the following questions:
Why is collateral information intended to complement rather than validate the patient's own account?
How can differences between parents, teachers, partners and other informants improve rather than weaken your clinical formulation?
What are the strengths and limitations of rating scales, school reports and historical records?
How would you approach an assessment when high-quality collateral information is unavailable?
How can integrating information from multiple sources improve diagnostic accuracy and support more personalised treatment planning?
If you can confidently explain the purpose of collateral information, evaluate different sources critically and synthesise multiple perspectives into a coherent developmental formulation, you are ready to move on to the next lesson, where we will begin exploring the first core symptom domain of ADHD: Inattention.
