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

Symptoms of Attention Deficit Hyperactivity Disorder (ADHD)

ADHD manifests through two primary symptom clusters—inattention and hyperactivity-impulsivity—which must persist for at least 6 months, cause functional impairment across multiple settings, and have onset before age 12 years. 1

Core Symptom Categories

Inattentive Symptoms

Adults with ADHD predominantly present with inattentive symptoms rather than hyperactivity. 1 The following inattentive manifestations must be present:

• Poor attention to detail leading to careless mistakes in work or other activities 1, 2
• Difficulty concentrating or sustaining attention on tasks, making it challenging to maintain focus during activities 1, 3
• Seeming preoccupied with difficulty shifting focus even when directly spoken to 1, 3
• Failure to follow through on tasks or instructions, often leaving projects incomplete 2
• Poor organization, manifesting as chronic lateness, messiness, or disorganized work 3, 2
• Avoidance of tasks requiring sustained mental effort, showing reluctance to engage in effortful activities 3, 2
• Frequently losing things necessary for tasks or activities 2
• Easy distractibility by extraneous stimuli or becoming sidetracked 3, 2
• Forgetfulness in daily activities 2

Hyperactive-Impulsive Symptoms

These symptoms are more commonly observed in children but may persist or manifest differently in adults:

• Frequent fidgeting such as tapping hands or feet 1
• Difficulty sitting still for prolonged periods, often leaving seat when remaining seated is expected 1, 2
• Inappropriate running or climbing (in children) or feelings of restlessness (in adults) 2
• Difficulty with quiet activities, appearing to be "on the go" or driven by a motor 2
• Excessive talking 2
• Blurting out answers before questions are completed 2
• Inability to wait turn in conversations or activities 2
• Intrusive behavior, interrupting or intruding on others 2, 4

Diagnostic Thresholds and Subtypes

The number of symptoms required varies by age and determines the ADHD subtype:

• Adults (age 17+): Require 5 or more symptoms in either category 1
• Children and adolescents (under age 17): Require 6 or more symptoms 1

Three presentations exist based on symptom patterns:

1. Predominantly Inattentive Presentation: 5+ inattentive symptoms but fewer than 5 hyperactive-impulsive symptoms for at least 6 months 1
2. Predominantly Hyperactive-Impulsive Presentation: 5+ hyperactive-impulsive symptoms but fewer than 5 inattentive symptoms for at least 6 months 1
3. Combined Presentation: 5+ symptoms in both categories for at least 6 months 1

Essential Diagnostic Criteria Beyond Symptoms

Symptoms alone are insufficient for diagnosis. The following criteria must also be met:

• Onset before age 12 years: Several symptoms must have been present before this age, even if diagnosis occurs later 1, 2
• Pervasive across settings: Symptoms must be present in 2 or more settings (home, work, school, social situations) 1, 2
• Functional impairment: Clear evidence that symptoms interfere with or reduce quality of functioning in interpersonal, occupational, or academic domains 1
• Duration: Symptoms must persist for at least 6 months 1, 3
• Not better explained by other conditions: Symptoms cannot be better accounted for by oppositional behavior, other mental disorders (psychotic disorder, mood disorder, anxiety disorder, personality disorder), or substance use 1

Context-Dependent Symptom Variations

A critical pitfall is dismissing ADHD because symptoms are not observed during clinical examination. ADHD symptoms show relative context-dependency:

• Symptoms may be less severe or absent in unfamiliar environments, one-on-one situations, or when receiving direct attention and positive reinforcement 5
• Symptoms are more pronounced in high-stimulation environments (noisy classrooms, large groups) or during effortful, unrewarding tasks 5
• Individuals may show satisfactory attention during highly stimulating activities (video games, TV) while showing marked impairment in school or work tasks 5
• Symptoms often worsen during periods of increased demands, such as pregnancy, parenting, or major life transitions 1, 6

Associated Features and Functional Impacts

Beyond core symptoms, adults with ADHD commonly experience:

• Mood lability and quick temper 1, 7, 8
• Stress sensitivity and difficulty managing stress 7
• Disorganization affecting home management, appointment tracking, and daily routines 1
• Impaired time management and chronic lateness 1
• Difficulty managing children's schedules and parenting demands (particularly relevant postpartum) 1, 6
• Greater parental distress in the first year postpartum compared to parents without ADHD 1, 6

Screening and Assessment Tools

When ADHD is suspected, use the Adult ADHD Self-Report Scale (ASRS-V1.1) Part A as the initial screening tool. 1, 3 A screen is positive when a patient endorses "often" or "very often" for 4 or more of the 6 questions. 1, 3

If screening is positive, further assessment should include:

• ASRS Part B to elucidate additional symptoms 1
• Collateral information from someone who knows the patient well (parent, spouse) to assess how symptoms impact others 1
• Functional impairment scales such as the Weiss Functional Impairment Rating Scale-Self (WFIRS-S) to measure ADHD-specific impairment 1
• Childhood symptom documentation to establish onset before age 12 years 1

Critical Differential Diagnosis Considerations

Do not diagnose ADHD without ruling out conditions that mimic or co-occur with it:

• Depression and anxiety disorders (present in approximately 10% of adults with recurrent depression/anxiety who have undiagnosed ADHD) 1
• Bipolar disorder 1
• Substance use disorders 1
• Learning disabilities 1
• Personality disorders 1
• Sleep disorders (particularly sleep apnea) 1
• Trauma, posttraumatic stress disorder, and toxic stress 1
• Medical conditions affecting attention (thyroid disorders, neurological conditions) 1

A key clinical insight: Treatment of depression and anxiety will likely be inadequate to restore optimal functioning for those with unaddressed ADHD, as ADHD is a chronic condition requiring its own management. 1