The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) outlines specific criteria for the diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD). Here’s a summary of the key points:

1. Persistent Pattern of Inattention and/or Hyperactivity-Impulsivity
   Symptoms interfere with functioning or development and fall into two categories: Inattention and Hyperactivity-Impulsivity.
2. Symptoms Present Before Age 12
   There must be evidence that the symptoms were present before the age of 12.
3. Symptoms Present in Two or More Settings
   Examples: home, school, work, or social settings.
4. Symptoms Interfere with Functioning
   Symptoms must cause significant impairment in social, academic, or occupational functioning.
5. Symptoms Are Not Better Explained by Another Disorder
   For example, symptoms are not solely attributable to psychotic disorders, mood disorders, or substance use.

Presentations of ADHD:

• Predominantly Inattentive Presentation: Criteria for inattention are met, but not for hyperactivity-impulsivity.
• Predominantly Hyperactive-Impulsive Presentation: Criteria for hyperactivity-impulsivity are met, but not for inattention.
• Combined Presentation: Criteria for both inattention and hyperactivity-impulsivity are met.

Severity Levels:

• Mild: Few symptoms beyond the minimum required for diagnosis; minor impairment.
• Moderate: Symptoms and impairment between mild and severe.
• Severe: Many symptoms in excess of the diagnostic threshold; marked impairment.

Persistent Pattern of Inattention vs. Hyperactivity-Impulsivity:

 Understanding the Hyperactivity-Impulsivity Symptoms:

• Deficient motor inhibition (restless, hyperactivity)
• Impaired verbal inhibition (excessing talking, interrupting)
• Impulsive cognition (Difficulty suppressing task irrelevant thoughts, rapid decision making)
• Impulsive motivation (prefer immediate gratification, greater discounting of delayed consequences)
• Emotion dysregulation (impulsive affect; poor ´´top down´´ emotional self-regulation)
• Restlessness decreases with age, becoming more internal, subjective by adulthood 

Understanding the Inattention Symptoms: But 6 types of attention exist – not all are impaired in ADHD

Executive Attention (& Functioning)

• Poor persistence toward goals, tasks, and the future (can´t sustain attention/action over time)
• Distractible (impaired resistance to responding to goal-irrelevant external and internal events)
• Deficient task re-engagement following disruptions (skips across uncompleted tasks)
• Impaired working memory (forgetful in daily activities, cannot remember what is to be done)
• Diminished self-monitoring

What is Underlying Nature of the Disorder?

• Deficiencies in the brain´s executive functions – the suite of mental mechanisms that permit self-regulation and the cross-temporal organization of behavior toward the future
• They are types of self-directed behavior that modify automatic behavior so as to alter later consequences:
• Self-awareness
• Inhibition or self-restraint
• Working memory (nonverbal and verbal)
• Emotional self-regulation
• Self-motivation
• Planning and problem-solving