What are the signs and symptoms of inattentive Attention Deficit Hyperactivity Disorder (ADHD)?

Signs of Inattentive ADHD

Inattentive ADHD is characterized by at least 5 specific symptoms (6 for those under age 17) persisting for at least 6 months, causing functional impairment across multiple settings, with onset before age 12. 1

Core Inattentive Symptoms

The following 9 symptoms define the inattentive presentation of ADHD:

• Poor attention to detail - making careless mistakes in work or other activities 1
• Difficulty concentrating or sustaining attention on tasks - unable to maintain focus during activities 1
• Seems preoccupied - difficulty shifting focus even when spoken to directly, appearing not to listen 1
• Difficulty completing tasks - gets distracted or side-tracked before finishing 1
• Organizational challenges - resulting in chronic lateness for appointments or deadlines, messiness, disorganized work 1
• Reluctance to engage in tasks requiring sustained mental effort - such as preparing reports or reviewing lengthy papers 1
• Difficulty keeping track of personal belongings - frequently loses items required for task completion 1
• Easily distracted - attention pulled away by extraneous stimuli 1
• Frequently forgetful - in daily activities 1

Diagnostic Requirements Beyond Symptoms

For a formal diagnosis, symptoms must meet specific criteria beyond just being present: 1

• Duration: Symptoms must persist for at least 6 months 1
• Childhood onset: Several symptoms must have been present before age 12 years 1, 2
• Cross-situational: Symptoms must occur in 2 or more settings (home, work, school) 1
• Functional impairment: Clear evidence that symptoms interfere with or reduce quality of functioning in interpersonal, occupational, or academic domains 1
• Not better explained by: Other mental disorders such as depression, anxiety, psychotic disorders, personality disorders, or substance use 1

Predominantly Inattentive Type Classification

A diagnosis of predominantly inattentive ADHD requires 5 or more inattentive symptoms for at least 6 months, but fewer than 5 hyperactive-impulsive symptoms. 1 This distinguishes it from the combined type (which requires 5+ symptoms in both domains) and the predominantly hyperactive-impulsive type. 1

Clinical Presentation Patterns

Adults with ADHD are more likely to present with predominantly inattentive symptoms rather than hyperactivity. 1 Women are disproportionately affected by the inattentive subtype and may be underdiagnosed because they lack the externalizing hyperactive behaviors that typically prompt evaluation. 3

The inattentive subtype typically has a later age of onset and referral compared to combined type, and is much less likely to be associated with oppositional defiant disorder or conduct disorder. 3

Screening Approach

When inattentive ADHD is suspected, use the Adult ADHD Self-Report Scale (ASRS-V1.1) Part A as the first-line screening tool. 1, 2 A positive screen is defined as checking "often" or "very often" for 4 or more of the 6 questions. 1, 2

If the screen is positive, further assessment should include:

• Part B of the ASRS to comprehensively document symptom patterns 2, 4
• Collateral information from someone who knows the patient well (spouse, parent, friend) to gain external perspective on symptoms and their impact 2, 4
• Functional impairment assessment using tools like the Weiss Functional Impairment Rating Scale-Self (WFIRS-S) to measure ADHD-specific impairment across life domains 1, 4

Common Pitfalls in Recognition

Inattentive symptoms overlap substantially with depression, anxiety, and other psychiatric conditions, making differential diagnosis critical. 2 Major depressive disorder explicitly includes difficulty concentrating and decision-making as core DSM-5 symptoms, which directly overlap with ADHD presentation. 2

Adults with ADHD often have poor insight and underestimate the severity of their symptoms and resulting impairments, making collateral information essential for accurate diagnosis. 2 The inattentive subtype may be particularly challenging to diagnose because symptoms present without externalizing behaviors and may be accompanied by learning problems, depression, or anxiety. 3

ADHD is a chronic condition that precedes other episodes, unlike depression which is typically episodic. 1 Approximately 10% of adults with recurrent depression or anxiety have underlying ADHD, and treating depression alone will likely be inadequate without addressing the ADHD. 1