What conditions should be ruled out when evaluating a patient for Attention Deficit Hyperactivity Disorder (ADHD)?

Conditions to Rule Out When Evaluating for ADHD

When evaluating a patient for ADHD, clinicians should systematically screen for multiple comorbid and mimicking conditions that can affect diagnosis, treatment approach, and outcomes. 1

Emotional and Behavioral Conditions

• Anxiety disorders (generalized anxiety disorder, social anxiety, separation anxiety) - anxiety can cause inattention and restlessness that mimics ADHD symptoms 1
• Mood disorders (depression, bipolar disorder) - these can present with concentration difficulties, irritability, and psychomotor agitation that may be mistaken for ADHD 1
• Oppositional defiant disorder and conduct disorders - these frequently co-occur with ADHD but can also present with similar behavioral symptoms 1
• Substance use disorders - particularly important to screen for in adolescents and adults, as certain substances (e.g., marijuana) can produce symptoms that mimic ADHD 1
• Trauma-related conditions - posttraumatic stress disorder (PTSD) and toxic stress can present with hypervigilance, concentration problems, and emotional dysregulation 1

Developmental Conditions

• Learning disorders - difficulties with reading, writing, or mathematics can lead to apparent inattention in academic settings 1
• Language disorders - may cause children to appear inattentive when they have difficulty processing verbal instructions 1
• Autism spectrum disorders - social difficulties, restricted interests, and sensory sensitivities can overlap with ADHD symptoms 1
• Developmental coordination disorder - motor clumsiness and coordination difficulties often co-occur with ADHD 1
• Borderline intellectual functioning - should be ruled out as it can present with academic difficulties similar to those seen in ADHD 1

Physical Conditions

• Sleep disorders - including sleep apnea, restless leg syndrome, and hypersomnolence can cause daytime inattention and behavioral problems 1, 2
• Seizure disorders - certain types of seizures can present with attention lapses or behavioral changes 1
• Tic disorders - frequently co-occur with ADHD and may complicate treatment decisions 1
• Thyroid dysfunction - can affect energy levels, concentration, and mood 3
• Hearing or vision problems - sensory deficits can lead to apparent inattention 3

Special Considerations for Different Age Groups

Adolescents (12-18 years)

• Prioritize screening for substance use, anxiety, depression, and learning disabilities 1
• Be aware that adolescents may feign symptoms to obtain stimulant medications for performance enhancement 1
• Consider that adolescents have multiple teachers and parents may have less opportunity to observe behaviors 1
• Verify onset of symptoms before age 12 as required by DSM-5 criteria 1

Adults

• Screen for comorbid substance use disorders, which are very common in adults with ADHD 2
• Evaluate for mood and anxiety disorders, which occur in approximately 80% of adults with ADHD 2
• Consider personality disorders, especially borderline and antisocial personality disorder 2
• Note that hyperactivity in adults is often internalized as restlessness rather than external motor activity 2
• Be aware that well-developed compensation strategies may mask symptoms until life demands increase 2, 3

Diagnostic Approach

• Use validated assessment tools with input from multiple observers (home, school, community) 4
• For adults, obtain collateral information when possible, as self-reporting may be inaccurate 5
• Consider that emotional dysregulation and executive function difficulties, while not part of formal diagnostic criteria, are common in ADHD 2
• When evaluating patients with a previous ADHD diagnosis, review the original diagnostic process thoroughly 4
• Remember that there is no objective laboratory-based test that can definitively establish an ADHD diagnosis 6, 5

Pitfalls to Avoid

• Failing to obtain information from multiple settings (home, school, work) 1, 5
• Overlooking the requirement for symptom onset before age 12 1
• Attributing symptoms to ADHD when they are better explained by another condition 1
• Missing comorbid conditions that may alter treatment approach 1
• Relying solely on subjective reports without systematic assessment 6

By thoroughly screening for these conditions, clinicians can ensure accurate diagnosis and develop appropriate treatment plans that address both ADHD and any comorbid conditions, ultimately improving outcomes for patients.