Anxiety disorders. ADHD shares symptoms of inattention with anxiety disorders. Indi- viduals with ADHD are inattentive because of their attraction to external stimuli, new activities, or preoccupation with enjoyable activities. This is distinguished from the inat- tention due to worry and rumination seen in anxiety disorders. Restlessness might be seen in anxiety disorders. However, in ADHD, the symptom is not associated with worry and rumination.
Depressive disorders. Individuals with depressive disorders may present with inabil- ity to concentrate. However, poor concentration in mood disorders becomes prominent only during a depressive episode.
Bipolar disorder. Individuals with bipolar disorder may have increased activity, poor concentration, and increased impulsivity, but these features are episodic, occurring sev- eral days at a time. In bipolar disorder, increased impulsivity or inattention is accompa- nied by elevated mood, grandiosity, and other specific bipolar features. Children with
ADHD may show significant changes in mood within the same day; such lability is dis— tinct from a manic episode, which must last 4 or more days to be a clinical indicator of bi- polar disorder, even in children. Bipolar disorder is rare in preadolescents, even when severe irritability and anger are prominent, whereas ADHD is common among children and adolescents who display excessive anger and irritability.
Disruptive mood dysregulation disorder. Disruptive mood dysregulation disorder is characterized by pervasive irritability, and intolerance of frustration, but impulsiveness and disorganized attention are not essential features. However, most children and adoles- cents with the disorder have symptoms that also meet criteria for ADHD, which is diag- nosed separately.
Substance use disorders. Differentiating ADHD from substance use disorders may be problematic if the first presentation of ADHD symptoms follows the onset of abuse or fre- quent use. Clear evidence of ADHD before substance misuse from informants or previous records may be essential for differential diagnosis.
Personality disorders. In adolescents and adults, it may be difficult to distinguish ADHD from borderline, narcissistic, and other personality disorders. All these disorders tend to share the features of disorganization, social intrusiveness, emotional dysregulation, and cognitive dysregulation. However, ADHD is not characterized by fear of abandonment, self—injury, extreme ambivalence, or other features of personality disorder. It may take extended clinical observation, informant interview, or detailed history to distinguish im- pulsive, socially intrusive, or inappropriate behavior from narcissistic, aggressive, or dom- ineering behavior to make this differential diagnosis.
Psychotic disorders. ADHD is not diagnosed if the symptoms of inattention and hyperac- tivity occur exclusively during the course of a psychotic disorder.
Medication-induced symptoms of ADHD. Symptoms of inattention, hyperactivity, or impulsivity attributable to the use of medication (e.g., bronchodilators, isoniazid, neuro- leptics [resulting in akathisia], thyroid replacement medication) are diagnosed as other specified or unspecified other (or unknown) substance—related disorders.
Neurocognitive disorders. Early major neurocognitive disorder (dementia) and/or mild neurocognitive disorder are not known to be associated with ADHD but may present with similar clinical features. These conditions are distinguished from ADHD by their late onset.
In clinical settings, comorbid disorders are frequent in individuals whose symptoms meet criteria for ADHD. In the general population, oppositional defiant disorder co-occurs with