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How I Distinguish F90.2 From Trauma, Anxiety, and Life Stress in Adult Patients

Stanley Efrem

Feb 9, 2026

A 34-year-old professional sits across from me. "Doctor, I can't focus. I'm forgetful, impulsive, and my mind races constantly. I think I have ADHD." Her symptoms align perfectly with F90.2. Yet chronic anxiety presents identically. So does unresolved trauma, sleep deprivation from her newborn, and thyroid dysfunction. The diagnostic code appears straightforward; the clinical reality tells a different story.

This article outlines my clinical approach for separating ADHD Combined Type from its most persistent imitators. The stakes extend beyond coding accuracy—misdiagnosis leads directly to ineffective treatment.

Adult ADHD rarely stands alone. 80% of adults with ADHD have at least one comorbid psychiatric disorder [17], while approximately 70% experience another mental health condition including bipolar disorder, anxiety disorder, substance use disorder, or personality disorder [2]. Substance use disorders top the comorbidity list, followed by mood disorders, anxiety disorders, and personality disorders [2]. Add the reality that 40% to 50% of adult patients with ADHD have comorbid anxiety and mood disorders [2], and the diagnostic picture becomes remarkably complex.

These statistics reveal something essential: when adults present with inattention, impulsivity, and hyperactivity, pure ADHD occurs rarely. The clinical question shifts from "Does this patient have ADHD?" to "Which combination of conditions produces these symptoms, and what drives them primarily?"

Symptom overlap creates diagnostic confusion. 50% of ADHD patients develop anxiety disorders [2], and depression prevalence among ADHD patients spans 18.6% to 53.3% [2]. Multiple disorders share core ADHD symptoms [17]—inattention, restlessness, and impulsivity can stem from anxiety, depression, trauma, sleep disorders, bipolar disorder, or auditory processing difficulties [17]. Identical symptom patterns emerge from completely different biological and psychological roots.

Comorbid conditions amplify functional impairment and create substantial societal burden [3]. They alter clinical presentation, prognosis, and treatment response patterns [17]. Patients managing both anxiety and depression face greater disease burden, extended illness duration, and diminished quality of life compared to single-disorder presentations [2]. Comorbid anxiety correlates with more severe symptoms, increased psychiatric complexity, and earlier onset age [2].

The diagnostic challenge intensifies when considering that fewer than 20% of adults with ADHD receive diagnosis or treatment [17]. Many patients fall through diagnostic cracks—either misdiagnosed or overlooked entirely. Behavioral assessments depend on subjective reporting and retrospective memory from various sources, each carrying distinct behavioral expectations [17]. Incomplete patient history and symptom development understanding reduces diagnostic accuracy [17].

ICD-10 criteria for F90.2 define which symptoms to identify. They don't explain symptom origins. That distinction defines where clinical judgment begins—and where this article concentrates.

The Core Criteria: What F90.2 Actually Requires (and What It Doesn't)

Accurate differential diagnosis starts with understanding what F90.2 actually demands. The DSM-5 establishes the diagnostic framework for ADHD Combined Type, and each criterion holds clinical significance that shapes treatment decisions [11].

DSM-5 Symptom Thresholds for Combined Type

Age determines symptom requirements. Children through age 16 need six or more symptoms of inattention plus six or more symptoms of hyperactivity-impulsivity [11]. Adults and adolescents 17 and older require five or more symptoms from each category [11].

Combined type demands both dimensions simultaneously. A patient showing six inattentive symptoms but only three hyperactive-impulsive symptoms doesn't qualify for F90.2—that's predominantly inattentive type. Combined type ADHD requires documented evidence of at least five symptoms from both the inattention and hyperactive-impulsive categories in adults [15].

This threshold isn't arbitrary. Combined type creates a distinct clinical profile compared to predominantly inattentive or predominantly hyperactive-impulsive presentations. Symptom counts reflect both severity and pervasiveness across functional domains.

The 6-Month Duration Rule

Symptoms must persist for at least six months at a level inconsistent with developmental expectations [11]. This duration requirement screens out temporary stress reactions, situational difficulties, and acute psychiatric episodes.

Three months of concentration problems after a job loss doesn't constitute ADHD. Years of consistent, stable symptoms warrant closer examination. The six-month rule prevents pathologizing normal responses to life challenges.

The Childhood Onset Requirement (Before Age 12)

Several inattentive or hyperactive-impulsive symptoms must have appeared before age 12 [11]. This marks a shift from DSM-IV's age 7 requirement [16]. The change recognizes that ADHD symptoms may not be identified as such until later, despite retrospective presence [15].

Adults seeking initial diagnosis require collateral history establishing pre-age-12 manifestations [16]. Clinical interviews with parents, school record reviews, and childhood performance data become indispensable. Adult-onset inattention typically signals depression, anxiety, cognitive decline, or medical conditions—not ADHD.

Functional Impairment Across Multiple Settings

Symptoms must appear in two or more environments and demonstrate clear interference with social, educational, or occupational functioning [11]. This impairment criterion acts as a diagnostic safeguard against overdiagnosis [16].

Research reveals diagnostic gaps in practice. 77% of individuals screening positive for ADHD symptoms on checklists failed to meet impairment standards [16]. Additional studies found 41% of symptom-positive individuals didn't reach impairment thresholds [16]. ADHD symptoms without functional impairment don't qualify as mental disorder criteria [16].

Clinical assessment quality varies significantly. Three-quarters of clinicians miss at least one diagnostic criterion during evaluations, with more than half overlooking the impairment criterion completely [16]. This oversight threatens diagnostic validity and generates false-positive diagnoses [16].

Adult impairments typically include educational struggles, job instability, relationship difficulties, financial problems, substance misuse, and dangerous driving patterns [16]. I examine work performance specifically, financial management abilities, relationship maintenance, and daily responsibility completion [16].

DSM-5 criteria identify target symptoms. They don't explain symptom causation. Clinical judgment fills that critical gap.

The Differential Diagnosis Matrix: Distinguishing the Mimics

Differential diagnosis begins once symptom thresholds are confirmed. Clinical judgment now separates thorough assessment from accepting a patient's self-diagnosis at face value.

ADHD vs. Anxiety Disorders (F41.x): The Overlap and The Discriminator

Clinical anxiety presents significant symptom overlap with ADHD. Comorbidity rates span 27.9% to 50% of patients [17] [17] [16]. Both conditions share concentration difficulties, restlessness, sleep disruption, and irritability [16].

The inattention quality differs between conditions. ADHD concentration problems stem from boredom or external distractibility, while anxiety-related focus issues arise from intrusive worrying thoughts [16]. My diagnostic question: "When you're calm and not worried, can you focus?" A "yes" answer points toward anxiety. ADHD restlessness appears as fidgeting or movement needs, whereas anxiety restlessness feels tense and on-edge [16]. Certain hyperactivity markers (difficulty relaxing, feeling driven by a motor) align more closely with anxiety factors than ADHD [17]. Clinicians should identify ADHD evidence beyond shared symptoms, particularly within hyperactivity presentations [17].

ADHD vs. Post-Traumatic Stress Disorder (F43.1x): The Overlap and The Discriminator

ADHD and PTSD comorbidity estimates range 12% to 37% across lifespans [17]. Both present with concentration difficulties, restlessness, hyperactivity, distractibility, and impulsivity [17] [14]. Early adverse experiences create brain structure and chemistry changes that produce ADHD-like behaviors in trauma-exposed children [17].

Trauma history and trigger-based symptoms provide the key distinction. PTSD patients may struggle following instructions due to intrusive memory preoccupation, resembling ADHD distractibility [17]. PTSD hypervigilance can appear as ADHD inattention [17]. ADHD creates general distractibility; PTSD distractibility serves threat-scanning purposes. PTSD features avoidant and hypervigilant behaviors plus trauma re-experiencing, while ADHD involves attention deficits, behavioral inhibition problems, and regulation difficulties [17].

ADHD vs. Bipolar Disorder (F31.x): The Overlap and The Discriminator

20% of people with ADHD also experience bipolar disorder [15]. Both conditions present impulsivity, distractibility, increased talkativeness, restlessness, irritability, and mood regulation problems [16] [15]. Psychiatric and behavioral symptoms overlap significantly, especially with hypomanic episodes featuring hyperactivity, inhibition loss, racing thoughts, and rapid speech [16].

The critical distinction: mania occurs episodically, ADHD remains chronic [16]. Bipolar episodes last weeks to months, while ADHD symptoms persist consistently over time [17]. ADHD low frustration tolerance doesn't disappear, but bipolar children might show severe irritability for six months, then remain episode-free for years [16]. Mood stabilizers address bipolar symptoms; they don't resolve ADHD [16].

ADHD vs. Life Stress (Chronic Stress, Sleep Deprivation, Burnout): The Overlap and The Discriminator

This differential presents the greatest challenge. Chronic stress worsens symptoms and creates brain chemistry and structure changes that affect functioning [17]. Stress impacts the prefrontal cortex—the same brain region affected by ADHD [17]. Sleep deprivation triggers hyperactivity, impulsivity, and concentration problems [14]. More than half of diagnosed ADHD patients may have undiagnosed sleep disorders [15].

My key questions: "Were you like this as a child? Did teachers comment? Did you struggle before the stress began?" Cognitive symptoms emerging after stressful events aren't ADHD. Sleep deprivation mimics ADHD symptoms closely enough to cause frequent misdiagnosis [16].

ADHD vs. Substance Use Disorders (F10-F19): The Overlap and The Discriminator

ADHD occurs five to 10 times more frequently among adult alcoholics than the general population [17]. Adults receiving alcohol and substance abuse treatment show approximately 25% ADHD rates [17]. Meta-analysis data indicates nearly one in four substance use disorder patients also has ADHD [18].

Temporal relationship provides the discriminator. Did cognitive symptoms precede substance use? Otherwise, treat substance use first and reassess. Substance use can mimic ADHD symptoms, leading to ADHD overdiagnosis in addiction populations [19]. However, ADHD diagnoses made during treatment intake for actively using substance disorder patients remain valid indicators, showing 95.3% diagnostic stability over time [20].

The Role of Collateral Information and Testing

Collateral information transforms hunches into solid diagnoses. Without external validation, I'm essentially documenting what patients believe about themselves—filtered through decades of selective memory and present-day concerns.

Why Third-Party Reports Matter

Informant reports are more accurate than self-reports in adult ADHD assessment [6]. Young adults with genuine ADHD underreport their symptoms due to poor self-awareness, while those without ADHD tend to overreport [6]. This flips the standard clinical assumption that patients understand themselves best.

Third-party sources offer crucial insights into symptom consistency and persistence across time [8]. Parents, siblings, friends, and coworkers should contribute to every adult ADHD evaluation [6]. Someone who knew the patient during childhood can describe behavioral patterns that span developmental stages [8].

These reports reveal discrepancies that change everything. A patient might describe lifelong attention problems, but their spouse recalls excellent focus until recent job stress began.

Childhood Records and School Performance Data

School records contain objective details about academic performance and social behavior, especially inattention patterns [21]. Teacher narratives and discipline records validate or contradict retrospective symptom reports [6]. Objective records show good and excellent grades despite patients recalling academic struggles—completely altering the diagnostic picture [6].

School documentation reflects teacher observations from that specific time period, unaltered by decades of reinterpretation [21]. Retrospective self-report measures suffer from memory bias and incomplete recall [22]. However, demanding school records as gatekeeping often serves administrative cost-cutting rather than clinical purposes [23].

Report cards from third grade matter more than adult recollections of third grade struggles.

Limitations of Self-Report Questionnaires

Standalone self-report questionnaires risk false-positive diagnoses through negative response bias [24]. Without validity checks, 65% of adults demonstrating questionable response patterns would receive incorrect ADHD diagnoses based purely on interviews and rating scales [6].

Self-report measures fluctuate with temporary factors—mood changes, fatigue, time of day, sleep quality [22]. Rating scales provide data points, not diagnostic conclusions. A high ASRS score confirms symptom endorsement, not ADHD presence. My role involves understanding what drives those endorsed symptoms.

When Neuropsychological Testing Helps (and When It Doesn't)

Neuropsychological testing in ADHD sparks ongoing debate [9]. Barkley argues against performance-based executive function tests, citing poor validity, high false negative rates, and limited diagnostic differentiation [9]. Thorough psychiatric evaluation remains the gold standard for ADHD diagnosis [25].

Testing offers complementary cognitive efficiency data, while rating scales measure real-world goal achievement [9]. Neuropsychological assessment can clarify ADHD subtypes, inform treatment approaches, and identify intervention targets [9]. Combined with clinical assessment, testing may improve adult ADHD diagnostic accuracy [26].

I order testing when clinical interviews leave diagnostic uncertainty, or when cognitive data would guide treatment decisions. Testing isn't required for ADHD diagnosis, but results must integrate with comprehensive clinical evaluation [25].

Clear clinical pictures need less testing. Murky presentations benefit from objective cognitive data.

Documentation: Building a Defensible Case for F90.2

Documentation elevates clinical impressions to legally defensible diagnoses. Proper documentation distinguishes F90.2 as a substantiated finding rather than clinical opinion.

Required Elements in Clinical Documentation

A qualified professional must conduct the evaluation, with credentials clearly documented including licensure, certification, and specialty areas . Family member documentation cannot be accepted due to professional and ethical standards .

The evaluation report requires a comprehensive diagnostic interview addressing history of presenting ADHD symptoms, relevant developmental history, medical and medication history, psychosocial history and interventions, and educational background . Clinical summary of objective historical information must establish ADHD symptomatology throughout childhood in multiple settings, adolescence, and adulthood using transcripts, report cards, teacher comments, and past psychoeducational testing .

Documentation stays current. Testing should occur within the past three years using adult-based norms . Students under 18 require testing within two years .

Alternative diagnoses require exclusion. Given high comorbidity rates, evaluators must investigate dual diagnoses and alternative or coexisting mood, behavioral, neurological, personality disorders, and other health conditions that may confound diagnosis . This process includes exploring possible alternative diagnoses, medical and psychiatric disorders, plus educational and cultural factors potentially affecting diagnosis .

Sample Clinical Note Template for F90.2

Following comprehensive clinical interview, childhood history review (patient reports teacher comments on inattention since elementary school documented in grade 3-5 report cards), and spousal collateral confirming chronic patterns, patient's inattention, impulsivity, and restlessness symptoms are chronic, pervasive, and not better explained by current mood, anxiety, or substance use disorders. Diagnosis: Attention-deficit hyperactivity disorder, combined type (F90.2).

How to Document Ruling Out Other Diagnoses

I document statements showing elimination or exclusion of alternative diagnoses that might explain the symptoms . Symptoms do not occur exclusively during schizophrenia or another psychotic disorder and are not better explained by another mental disorder .

Critical Risk Warnings in F90.2 Diagnosis

Four diagnostic traps compromise every F90.2 diagnosis I make. Each represents a distinct failure in clinical reasoning that leads directly to patient harm.

Risk of Overdiagnosis: When Everyone Looks Like ADHD

Trauma exposure creates symptoms nearly identical to ADHD, yet clinicians default to ADHD explanations when children show behavioral and attention problems [30]. Time-pressured clinicians often skip trauma history entirely [30]. Communities with high violence exposure show inflated ADHD diagnosis rates, potentially missing trauma indicators [30].

The ASRS screening tool produces 7 to 10 times over-identification in general populations, with 90% of positive screens representing false positives [5]. The United States lacks professional guidelines for adult ADHD assessment, creating wild diagnostic variability between practitioners [5]. Screening instruments prioritize sensitivity over specificity, causing overdiagnosis when misused as diagnostic tools rather than screening aids [5].

Risk of Underdiagnosis: Missing True ADHD in Complex Cases

True adult ADHD gets missed frequently. Fewer than 20% of adults with the condition receive proper diagnosis and treatment [10]. Women face particularly high risk because predominantly inattentive presentations appear subtle and mask easily [10].

Adults create sophisticated compensatory strategies—arriving early to appointments, avoiding challenging situations, developing elaborate organizational systems [10]. Healthcare professionals trained primarily on hyperactive boys often miss how adult presentations differ fundamentally [10].

Risk of Relying Solely on Adult Self-Report

Adult retrospective self-reports correlate only moderately with childhood parent ratings [31]. Even adults with confirmed childhood ADHD diagnoses falsely deny childhood symptoms 22% to 37% of the time [31].

The Dunedin study showed only 23% of adults with verified childhood ADHD had parents who correctly recalled core symptoms before age 12 [31]. False-negative recall occurred in 77% of confirmed childhood cases [31]. College students self-referring for ADHD evaluation exaggerated symptoms between 25% and 48% of cases [5]. Nearly one-third of adults failed credibility assessments during ADHD evaluations [5].

Risk of Ignoring the Childhood Onset Criterion

Retrospective childhood ADHD diagnosis carries a positive predictive value of only 0.27—meaning only 27% of adults given this diagnosis would be correctly identified [32]. DSM criteria changes from age 7 to age 12 cutoffs expanded the pool of qualifying patients significantly [5].

Ignoring age-based requirements enables overdiagnosis easily [5]. Retrospectively diagnosing developmental conditions in adulthood introduces bias based on current functioning levels rather than historical patterns [5].

Compliance Steps: How to Avoid Diagnostic Errors

Five compliance steps reduce diagnostic error rates when evaluating suspected ADHD combined type in adults.

Step 1: Always Obtain Collateral History

Contact parents or long-term partners who can validate childhood symptom onset. When collateral sources are unavailable, document this limitation explicitly in the clinical note [33]. Adults with genuine ADHD underreport symptoms, while those without the condition often overreport [34].

Step 2: Rule Out Medical Causes First

Order TSH, hemoglobin A1c, and CBC before finalizing an ADHD diagnosis [12]. Thyroid dysfunction, diabetes, and sleep disorders mimic ADHD symptoms closely enough to cause frequent misdiagnosis [35] [36]. A sleep evaluation questionnaire screens for obstructive sleep apnea [12].

Step 3: Document Symptom Timeline Clearly

Establish when symptoms began, whether they preceded major life stressors, and if childhood impairment existed before age 12 [34]. If symptom onset coincides with trauma, substance use, or medical illness, eliminate ADHD as the primary diagnosis [34].

Step 4: Use Structured Rating Scales Appropriately

Administer the ASRS or CAARS as screening tools, not diagnostic instruments [37] [38]. The ASRS overidentifies ADHD by 7 to 10 times in general populations [38]. Rating scales validate symptom presence but require clinical interview to determine causation [39].

Step 5: Consider Comorbidities Without Defaulting to ADHD

Screen for anxiety, depression, bipolar disorder, and substance use disorders that frequently coexist with or mimic ADHD [40]. When both conditions exist, determine which is primary and whether treating one resolves symptoms attributed to the other [41].

Disclaimer and Clinical Judgment Considerations

Clinical judgment remains the cornerstone of F90.2 diagnosis because no laboratory test, brain scan, or single questionnaire can definitively confirm or exclude ADHD [1]. Only trained healthcare providers can diagnose or treat ADHD [11]. Qualified professionals include licensed mental health professionals and physicians such as clinical psychologists, psychiatrists, neurologists, family doctors, nurse practitioners, and clinical social workers [42]. The professional's level of knowledge and expertise about adult ADHD often matters more than the type of degree held [42].

Assessments must be conducted via direct consultation, either face-to-face or through video-conferencing, as patients need probing to elicit their subjective experiences in real-life situations [43]. Open-ended questions avoid leading the patient [43]. Risk assessments should always be completed, particularly considering risks from other mental health issues, substance abuse, and potential medication misuse or diversion [43]. ADHD is an established risk factor for alcohol and substance misuse, which impacts management [43].

Primary care physicians should develop comfort with diagnosing and treating ADHD while consulting specialists when necessary [44]. Referrals may result in lost treatment opportunities [44]. However, complex cases with significant differential diagnosis challenges warrant specialist consultation [13].

Patient honesty during evaluation determines the accuracy of diagnosis and treatment recommendations [42]. This article reflects clinical experience and interpretation of diagnostic guidelines for educational purposes, not as a substitute for formal training or clinical supervision.

FAQ

What makes F90.2 (ADHD Combined Type) different from anxiety or trauma-related symptoms?

The key difference lies in the nature and origin of symptoms. In ADHD, difficulty concentrating stems from boredom or external distractibility and has been present since childhood. With anxiety, concentration problems arise from intrusive worrying thoughts that improve when the person is calm. Trauma-related symptoms are linked to specific events and involve hypervigilance or preoccupation with intrusive memories, whereas ADHD symptoms are chronic and pervasive across all situations.

What criteria must be met to diagnose F90.2 ADHD Combined Type in adults?

Adults must display at least five symptoms from both the inattention category and the hyperactivity-impulsivity category. These symptoms must have persisted for at least six months, been present before age 12, and cause clear functional impairment in two or more settings such as work, home, or social situations. Both symptom dimensions must be met simultaneously for a combined type diagnosis.

How can clinicians distinguish between ADHD and PTSD when symptoms overlap?

The primary discriminator is the relationship to trauma and the pattern of symptoms. PTSD involves avoidant behavior, hypervigilance, and re-experiencing trauma through intrusive memories or flashbacks. A person with PTSD is distractible because they're scanning for threats, while someone with ADHD is generally distractible regardless of context. Additionally, ADHD symptoms must have been present since childhood, whereas PTSD symptoms emerge after a traumatic event.

Why is collateral information important when diagnosing adult ADHD?

Third-party reports from parents, siblings, or long-term partners are more accurate than adult self-reports. Research shows that young adults with genuine ADHD often underreport their symptoms due to lack of self-awareness, while those without ADHD tend to overreport. Collateral sources provide objective insights into long-term behavioral patterns and help validate whether symptoms were present before age 12, which is essential for accurate diagnosis.

What are the main risks of misdiagnosing ADHD in adults?

Overdiagnosis occurs when clinicians rely solely on screening tools or fail to rule out trauma, anxiety, or medical conditions that mimic ADHD symptoms. Underdiagnosis happens when compensatory mechanisms mask symptoms, particularly in women with predominantly inattentive presentations. Relying exclusively on adult self-report is problematic since studies show 77% of individuals with confirmed childhood ADHD have parents who cannot accurately recall symptoms, and up to 48% of self-referred adults exaggerate their symptoms.