Adult ADHD is being recognised more frequently than ever.

For many people, this is positive. Adults who spent years being described as lazy, inconsistent, disorganised or “not living up to their potential” are finally receiving an explanation for lifelong difficulties.

But increasing awareness has created another question:

How accurate is the first ADHD diagnosis?

And when is it sensible to seek a second opinion?

The scientifically responsible answer is that there is no reliable global percentage telling us that a first ADHD diagnosis is correct 80%, 90% or 95% of the time.

ADHD has no single laboratory gold standard against which every clinician’s diagnosis can be tested.

Instead, diagnostic accuracy depends greatly on how the assessment was performed.

A diagnosis reached after a detailed developmental history, assessment of impairment across settings, collateral information and careful exclusion of competing psychiatric conditions is very different from a diagnosis made after a ten-minute consultation and a positive screening questionnaire.

That distinction matters.

ADHD Is a Clinical Diagnosis

There is currently no blood test, MRI, EEG, QEEG or computerized test that independently proves that somebody has ADHD.

International guidelines continue to place the clinical and developmental assessment at the centre of diagnosis.

NICE recommends that ADHD should be diagnosed by an appropriately trained specialist based on:

• a full clinical and psychosocial assessment,
• a complete developmental and psychiatric history,
• assessment of symptoms across different areas of life,
• observer information where available,
• and evaluation of functional impairment.

Importantly, NICE explicitly states that ADHD should not be diagnosed solely from a rating scale or observational measure.

That immediately explains why the quality of first diagnoses can vary.

The ASRS Is a Screening Tool—not an ADHD Diagnosis

One of the most commonly used tools in adult ADHD is the Adult ADHD Self-Report Scale, or ASRS.

It is extremely useful.

It is quick.

It can identify people who deserve a more detailed ADHD assessment.

But a positive ASRS should not be translated into:

“You definitely have ADHD.”

Research illustrates why.

In one primary-care study, the short ASRS had excellent sensitivity but a positive predictive value of only 52%. In other words, it was good at identifying people who might need assessment, but a positive screen did not automatically establish ADHD.

A 2023 systematic review of adult ADHD self-report measures came to an even stronger conclusion. Across the available studies, negative screens were generally useful for ruling out ADHD, but false-positive rates among positive screens were substantial. Even in clinical samples, the best positive predictive values reached about 61%, while many studies reported considerably lower values.

Another study of psychiatric outpatients found that 54.8% screened positive on the ASRS, while only 11.9% had ADHD documented through diagnostic or treatment indicators in their medical record. The discrepancy illustrates how symptoms captured by ADHD questionnaires can also occur in other psychiatric conditions.

Therefore:

Positive ASRS = investigate ADHD

not

Positive ASRS = ADHD confirmed.

Why Can Screening Produce So Many False Positives?

Because many ADHD symptoms are nonspecific.

Consider the following complaints:

• “I cannot concentrate.”
• “I procrastinate.”
• “I forget things.”
• “I cannot finish tasks.”
• “My mind keeps jumping around.”
• “I feel restless.”
• “I am always overwhelmed.”

These can occur in ADHD.

But they can also occur in:

• anxiety disorders,
• depression,
• bipolar disorder,
• OCD,
• PTSD,
• autism,
• sleep deprivation,
• substance use,
• chronic stress,
• medication effects,
• learning disorders.

NICE specifically highlights substantial overlap between ADHD and other psychiatric and neurodevelopmental conditions and emphasizes the need for careful differential diagnosis.

This is why diagnosing ADHD from present-day concentration problems alone is risky.

Childhood History Is One of the Most Important Diagnostic Anchors

ADHD is a neurodevelopmental disorder.

For an adult diagnosis, the clinician should therefore ask:

Was there evidence of the same pattern during childhood?

Not necessarily a formal diagnosis.

Many adults—particularly intelligent or highly supported children—were never identified.

But there should usually be some developmental evidence.

For example:

• unfinished homework,
• chronic careless mistakes,
• losing books or belongings,
• daydreaming,
• difficulty sitting through lessons,
• repeatedly forgetting instructions,
• inconsistent academic performance,
• excessive talking,
• impulsive behaviour,
• dependence on parents for organisation,
• chronic last-minute studying.

NICE recommends specialist assessment in adults when typical ADHD manifestations began during childhood, persisted through life, cannot be better explained by another psychiatric diagnosis, and cause meaningful impairment.

If an adult says:

“My concentration was excellent until I developed severe anxiety at age 28”

that requires a different formulation from:

“I have been like this since Class III.”

A Detailed Interview Performs Better Than a Questionnaire Alone

Structured diagnostic interviewing can substantially improve diagnostic accuracy.

In one clinical study of adults undergoing ADHD assessment, the structured DIVA interview achieved approximately 90% sensitivity and 73% specificity. Adding selected Continuous Performance Test measures increased specificity to around 83% while maintaining 90% sensitivity.

A later validation of DIVA-5 across nine psychiatric outpatient clinics reported approximately 92% overall diagnostic accuracy, with sensitivity of about 91% and specificity of about 94% relative to specialist diagnostic assessment.

The lesson is not that everybody must undergo one particular branded interview.

It is that:

a systematic diagnostic interview performs very differently from a symptom checklist used in isolation.

What About CPT?

Continuous Performance Tests can objectively measure aspects of:

• sustained attention,
• reaction time,
• response variability,
• omission errors,
• commission errors,
• impulsive responding.

They can provide useful additional information in selected cases.

But CPT does not independently diagnose ADHD.

The previously mentioned adult ADHD study found that neuropsychological tests by themselves generally had limited ability to distinguish ADHD from other psychiatric patients. Selected CPT variables became more useful when combined with a structured diagnostic interview.

This is an important principle:

Objective testing may increase confidence around a good clinical assessment. It should not substitute for one.

What About QEEG?

Quantitative EEG is being studied extensively in ADHD and can identify electrophysiological patterns relevant to attention and arousal.

Historically, measures such as theta-beta ratio received considerable attention.

But ADHD is heterogeneous.

There is no single QEEG pattern present in every person with ADHD, and no brain map currently replaces the developmental psychiatric assessment.

QEEG is therefore better considered an adjunctive or exploratory source of objective information in selected cases, rather than a yes/no ADHD test.

The same principle applies:

clinical diagnosis first; technology used selectively to answer additional questions.

So How Accurate Is a Proper ADHD Assessment?

We cannot give one universal percentage.

But research suggests something important.

When specialist assessments use:

• structured interviewing,
• developmental history,
• functional impairment,
• differential diagnosis,
• informant information,

diagnostic performance can be quite strong.

For example, DIVA-based studies have reported sensitivity and specificity around or above the 90% range in some specialist samples.

But when diagnosis is effectively reduced to:

“ASRS positive + concentration problems = ADHD”

false positives become much more likely.

The question is therefore not simply:

“How accurate is ADHD diagnosis?”

It is:

“How rigorous was the diagnostic process?”

ADHD Can Also Be Missed

The opposite problem is equally important.

Concerns about overdiagnosis should not obscure the fact that adult ADHD can also remain undiagnosed for years.

Reviews of the literature have documented substantial under-recognition of adult ADHD, particularly when patients first present with comorbid depression, anxiety or substance-related difficulties.

NICE similarly notes that adults being treated for other psychiatric conditions may have previously unrecognised ADHD.

So there are two diagnostic errors to avoid:

calling every concentration problem ADHD

and

missing lifelong ADHD because the person currently presents with anxiety or depression.

Good assessment has to protect against both.

Why Does the First Diagnosis Sometimes Change?

There are several legitimate reasons.

1. Childhood information was unavailable initially

An adult may initially struggle to remember childhood symptoms.

Later, parents, siblings or school reports provide important evidence.

2. Another psychiatric condition becomes clearer

A person initially appearing inattentive may later develop obvious bipolar symptoms, severe anxiety or another condition that changes the formulation.

3. Comorbidity becomes apparent

The correct answer may not be:

ADHD or autism

but:

ADHD and autism.

Likewise:

ADHD and anxiety

or:

ADHD and OCD.

4. Symptoms change over time

A seven-year follow-up of 227 adults diagnosed with ADHD found that approximately 30% no longer met full ADHD diagnostic criteria at follow-up, with a smaller proportion reaching full remission. That represents changes in illness expression over time rather than necessarily showing that the initial diagnosis was wrong.

A changing diagnosis therefore does not automatically mean the first clinician made an error.

ADHD or Anxiety?

This is one of the most frequent differential diagnoses.

Both can produce:

• poor concentration,
• restlessness,
• procrastination,
• sleep difficulty,
• inconsistent performance.

The distinction often becomes clearer through chronology.

In ADHD:

“I have struggled with organisation and attention for as long as I can remember.”

In primary anxiety:

“I concentrate reasonably well when I am calm, but when I worry my mind becomes completely occupied.”

Of course, both can coexist.

That is why diagnosis requires more than counting symptoms.

ADHD or Depression?

Depression can cause:

• reduced motivation,
• impaired concentration,
• slowed cognition,
• procrastination,
• forgetfulness,
• executive dysfunction.

The key question again becomes:

Were these problems present before the depressive episode?

Someone who was exceptionally organised until developing depression at age 35 has a different history from someone who has missed deadlines since school and subsequently developed depression after years of underperformance.

ADHD or Bipolar Disorder?

This distinction is particularly important because both can involve:

• distractibility,
• impulsivity,
• increased activity,
• rapid speech,
• emotional dysregulation.

But ADHD symptoms tend to be trait-like and longstanding.

Bipolar symptoms are more characteristically episodic, associated with distinct changes from the person’s usual functioning.

For example:

“I have always been distractible.”

differs from:

“For ten days I slept three hours a night, felt unusually powerful, started multiple businesses and spent ₹3 lakh impulsively.”

The timeline often provides the answer.

ADHD or Sleep Deprivation?

A person sleeping four or five hours every night can develop:

• attention problems,
• poor working memory,
• irritability,
• slowed reactions,
• executive dysfunction.

Shift work, insomnia and obstructive sleep apnoea can therefore create an ADHD-like cognitive presentation.

If sleep is never assessed, diagnostic confidence falls.

ADHD or Autism?

ADHD and autism can occur together.

Both can involve:

• executive-function problems,
• social difficulties,
• sensory issues,
• emotional dysregulation,
• intense engagement with preferred interests.

But social-communication differences, restricted interests, sensory patterns and developmental history may suggest autism in addition to—or instead of—ADHD.

A second opinion becomes particularly useful when one diagnosis does not fully explain the person’s functioning.

When Should You Consider a Second Opinion for ADHD?

Not everyone diagnosed with ADHD needs one.

If the assessment was detailed, the developmental history is convincing, impairment is clear, alternative explanations were considered and treatment is working well, another assessment may add very little.

A second opinion becomes more worthwhile when several warning signs are present.

The diagnosis was based almost entirely on ASRS

Screening questionnaires alone are insufficient for diagnosis.

There was almost no childhood history

Adult ADHD should be anchored in a developmental pattern.

Nobody asked about other psychiatric disorders

Anxiety, depression, bipolar disorder, autism, OCD and substance use can substantially complicate diagnosis.

The consultation was extremely brief

Complex adult ADHD assessment often requires substantially more than symptom counting.

The diagnosis does not explain the whole picture

For example, ADHD treatment improves concentration but severe social or sensory difficulties remain unexplained.

Several ADHD medications have failed

Treatment failure should trigger reconsideration of diagnosis, adherence, dose, comorbidity and treatment strategy.

NICE specifically recommends obtaining a second opinion or tertiary-service review when ADHD symptoms remain unresponsive after one or more stimulants and one non-stimulant.

Medication causes significant adverse effects

The diagnosis may still be correct, but the treatment strategy deserves reconsideration.

Different psychiatrists have given substantially different diagnoses

For example:

ADHD versus bipolar disorder.

ADHD versus anxiety.

ADHD versus autism.

A structured reassessment can help reconstruct the developmental timeline.

A Second Opinion Should Not Simply Repeat the ASRS

There is little value in:

ASRS → positive → ADHD

followed by:

another ASRS → positive → ADHD confirmed.

A useful second opinion should increase the amount and quality of information.

That may include:

• detailed developmental history,
• structured diagnostic interview,
• parent or partner collateral history,
• school records where available,
• assessment of impairment,
• psychiatric differential diagnosis,
• review of previous treatment response,
• standardized rating scales,
• objective attention testing in selected cases.

The purpose is not simply to produce another score.

It is to increase diagnostic confidence.

What Should You Bring for an ADHD Second Opinion?

If available:

• previous prescriptions,
• previous ADHD assessment,
• ASRS/WURS results,
• childhood school reports,
• college records,
• previous psychological assessments,
• information from parents or siblings,
• list of medications tried,
• doses,
• duration,
• benefits,
• side effects.

A treatment timeline can be particularly helpful.

For example:

Methylphenidate 10 mg — inadequate duration

Methylphenidate 20 mg — improved focus but appetite suppression

Atomoxetine — partial benefit after adequate trial

That information helps distinguish:

incorrect diagnosis

from

correct diagnosis but suboptimal treatment.

Does Response to Stimulants Confirm ADHD?

No.

This is another common misconception.

Improved alertness or productivity after a stimulant does not independently prove ADHD.

People without ADHD can also experience changes in alertness, motivation or concentration after stimulant exposure.

A review specifically addressing adult ADHD overdiagnosis emphasised that response to stimulant medication is not diagnostically informative and recommended using multiple information sources instead.

Treatment response can support an overall formulation.

It should not create the diagnosis retrospectively.

What Does the Evidence Ultimately Tell Us?

There is no scientifically defensible statement such as:

“The first ADHD diagnosis is correct 85% of the time.”

The available evidence does not give us such a universal figure.

What research does show is much more useful:

Screening questionnaires can generate many false positives when used alone.

Structured specialist interviews perform considerably better.

Collateral and developmental information improve assessment.

Psychiatric comorbidity makes diagnosis more difficult.

ADHD can be both overdiagnosed and underdiagnosed.

And therefore:

The reliability of an ADHD diagnosis depends less on how many tests were performed and more on whether the developmental history, impairment and differential diagnosis were assessed properly.

ADHD Assessment and Second Opinions in Chennai

At ATTN Clinic, I approach ADHD diagnosis as a clinical formulation first, rather than beginning with a brain scan or assuming that a positive questionnaire establishes ADHD.

For a straightforward case, a detailed psychiatric interview together with appropriate tools such as ASRS, WURS or Vanderbilt may provide sufficient diagnostic clarity.

Where uncertainty remains, assessment can be expanded selectively to include:

• structured developmental assessment,
• collateral history,
• Continuous Performance Testing,
• objective cognitive and attention profiling,
• and QEEG-based assessment where clinically appropriate as an adjunct rather than a standalone diagnostic test.

A second opinion may be particularly useful when:

• the diagnosis was made primarily from a questionnaire,
• childhood symptoms remain unclear,
• ADHD overlaps with anxiety, depression, autism, OCD or bipolar symptoms,
• multiple treatments have failed,
• or the patient simply does not feel that the existing diagnosis adequately explains their difficulties.

The goal should not be:

“Find evidence that proves ADHD.”

It should be:

“Determine which diagnosis best explains this person’s lifelong cognitive, behavioural and functional pattern—and choose treatment accordingly.”

Dr. Srinivas Rajkumar T

Senior Consultant Psychiatrist
MD Psychiatry — AIIMS New Delhi

Clinical interests include Adult ADHD, Autism, Cognitive Profiling, QEEG, Continuous Performance Testing and Technology-Assisted Psychiatry

ATTN Clinic — Attention. Understood.

Apollo Clinic, opposite Phoenix Market City, Velachery, Chennai

Appointments: +91 85951 55808
Email: srinivasaiims@gmail.com

A second opinion is not necessary simply because ADHD was diagnosed. It becomes valuable when the evidence behind that diagnosis is weak, the clinical picture is complex, or treatment response raises new questions.