Differentials
Learning/language disorder
SIGNS / SYMPTOMS
Of note, many ADHD patients have comorbid learning disorders.[32]
INVESTIGATIONS
Neuropsychological testing +/- educational psychologic assessment.
Oppositional defiant disorder
SIGNS / SYMPTOMS
More hostile behavior, anger, open defiance (at home and school), openly rebellious. Most behaviors are directed at an authority figure. The diagnosis of oppositional defiant disorder is not assigned if symptoms exist along with mood or psychotic disorder. May often precede conduct disorder.[100]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist should be considered.
INVESTIGATIONS
Diagnosis is clinical. The Conners rating scale and the Child Behavior Checklist both have oppositional defiant disorder domains.
Depression
SIGNS / SYMPTOMS
Depression may also cause poor concentration, but this is typically associated with other symptoms of depression.
Patients with major depressive disorder will report depressed mood or loss of interest or pleasure for at least 2 weeks in addition to 4 of the following symptoms: impaired sleep, feelings of worthlessness or guilt, low energy, poor concentration, psychomotor slowing, cognitive impairment, anorexia, suicidal ideation.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist may be considered according to location of practice, but note that in the US many primary care physicians will provide initial assessment and treatment for children with mild to moderate depression.
INVESTIGATIONS
Diagnosis is clinical.
The Patient Health Questionnaire.
PHQ-9 is a valid rating scale to help detect depression in children.[101]
Bipolar disorder
SIGNS / SYMPTOMS
Bipolar disorder may cause impulsivity or inattention, but this is typically associated with other symptoms of bipolar disorder. It is uncommonly seen before puberty. Bipolar disorder is characterized by symptoms of depression and symptoms of mania.[1]
Manic symptoms include a persistently elevated, expansive, or irritable mood lasting at least 1 week and 3 additional symptoms including grandiosity, decreased sleep, very rapid speech, disorganized and rapidly shifting thoughts, increased goal-directed activities, psychomotor agitation, and excessive pursuit of pleasurable activities despite negative consequences.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist should be strongly considered.
INVESTIGATIONS
Diagnosis is clinical.
Anxiety
SIGNS / SYMPTOMS
Anxiety disorders may cause inattention due to worry and rumination. Symptoms of anxiety consist of restlessness, tiring easily, difficulty concentrating, irritability, muscle tension, and sleep disturbance.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist should be considered according to location of practice, but note that in the US many primary care physicians will provide initial assessment and treatment for children with mild to moderate anxiety disorders.
INVESTIGATIONS
Diagnosis is clinical. The screen for child anxiety-related emotional disorders (SCARED) is commonly used to evaluate anxiety symptoms in children and adolescents. Clinical Tools Opens in new window
Psychosis
SIGNS / SYMPTOMS
Psychotic disorders such as schizophrenia include a mixture of positive symptoms (delusions, auditory or visual hallucinations, disorganized speech) and negative symptoms (thought blocking or slowed thinking, flat facial expression) that persist for a significant amount of time during a 1-month period.
Psychotic disorders are associated with marked social, academic, or occupational dysfunction.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist is indicated.
INVESTIGATIONS
Diagnosis is clinical.
Autism spectrum disorder
SIGNS / SYMPTOMS
ASD may also cause social difficulties and peer rejection, but in contrast to ADHD, this is typically due to social disengagement, isolation, and difficulties in interpreting facial and tonal communication. Other overlapping features may include emotional outbursts ("meltdowns") caused by a change in the expected routine, in contrast to ADHD, where emotional outbursts are more likely to be due to impulsivity or difficulties with self-control. The most striking feature of patients with autism spectrum disorders (ASD) is impaired social interaction, a restricted range of interests, and difficulty adapting to new situations. Language development is often significantly delayed, though social impairment can be the most prominent delay for some children with ASD.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist, neurologist, or developmental-behavioral pediatrician should be considered. ADHD may be comorbid with ASD.
INVESTIGATIONS
Diagnosis is clinical, and typically involves use of a diagnostic assessment tool as part of a comprehensive assessment, for example, the Autism Diagnostic Observation Schedule-Generic (ADOS-G).
Intellectual disability (intellectual developmental disorder)
SIGNS / SYMPTOMS
Defined by deficits in intellectual and adaptive functioning that occur during the developmental period.[1]
Intellectual disability can be distinguished from ADHD by its greater impairment in areas other than inattention, hyperactivity, or impulsivity.
INVESTIGATIONS
Referral to a psychologist for testing of intellectual and adaptive functioning, and neuropsychological tests.[1]
Genetic testing may be performed if there is a high degree of suspicion based on dysmorphism or organ involvement (e.g., Down syndrome). Genome-wide microarray and fragile X testing have been recommended as standard practice.
Imaging, thyroid function tests, and metabolic work-up may help elucidate the cause of the disorder.
Conduct disorder
SIGNS / SYMPTOMS
Conduct disorder is a repeated pattern of violating the rights of others or society's rules. These include 4 main groups of behavior: aggression that hurts people or animals, destruction of property, lying or stealing, and serious rule violations.[1]
Careful history and mental status exam with collateral information will help to distinguish from ADHD.
Referral to a psychiatrist should be considered.
INVESTIGATIONS
Diagnosis is clinical.
Lead toxicity
SIGNS / SYMPTOMS
Blood lead level should be obtained in high-risk children such as those living in poverty, recent immigrants, and children with developmental delay.[102]
INVESTIGATIONS
Blood lead level
Iron deficiency anemia
SIGNS / SYMPTOMS
Iron deficiency anemia can lead to pallor, fatigue, irritability, and anorexia. Skin findings include angular stomatitis (cracking at the corner of the mouth), glossitis (tongue inflammation), and spooning of the fingernails. Neurocognitive deficits can also occur and may be irreversible.
INVESTIGATIONS
CBC will show microcytic anemia (MCV <80 femtoliters).
Iron deficiency can be demonstrated by lower transferrin saturation (serum iron/total iron-binding capacity x 100), lower serum ferritin, or higher soluble transferrin receptor.[103]
Fetal alcohol spectrum disorder
SIGNS / SYMPTOMS
Fetal alcohol spectrum disorder (FASD) is a spectrum of disorders that includes FASD with and without sentinel facial features, fetal alcohol syndrome, partial fetal alcohol syndrome, alcohol-related neurodevelopmental disorder, and alcohol-related birth defects.[104]
Prenatal exposure to alcohol can have toxic effects on the fetal brain and lead to impaired cognitive development and higher levels of ADHD.
In contrast to ADHD, however, patients with fetal alcohol spectrum disorder may have a distinct facial appearance (smooth philtrum, thin upper lip, upturned nose, epicanthal folds) and may have microcephaly and shorter stature.[105]
Physical exam may detect facial abnormalities.
INVESTIGATIONS
Diagnosis is clinical. Prenatal history of alcohol exposure can be obtained by screening mothers with the T-ACE questions (tolerance, annoyance, cut down, eye opener).[106]
Neurocutaneous syndromes
SIGNS / SYMPTOMS
These are a group of heterogeneous disorders that cause tumors to develop primarily in the skin and central nervous system, although it can affect other organs.[107] Diagnosis is based on physical exam as well as neurologic workup, which may include genetic testing and imaging.
INVESTIGATIONS
Genetic testing and imaging based on possible syndrome.
Hyperthyroidism
SIGNS / SYMPTOMS
People with hyperthyroidism also have other signs of hypermetabolism such as sweating, significant weight loss, palpitations, and frequent bowel movements.[108] History and physical exam can help distinguish.
INVESTIGATIONS
Free T4 and thyroid-stimulating hormone are obtained for screening.
Auditory or visual impairment
SIGNS / SYMPTOMS
In infants and toddlers, inattentiveness may be secondary to hearing and vision problems.
INVESTIGATIONS
Referral for auditory and visual testing (but screening testing may be available in primary care, depending on local service arrangements).
Child abuse or other environmental stressor
SIGNS / SYMPTOMS
Psychosocial deprivation and stress are associated with increased risk of ADHD, but not all abused or neglected children have ADHD.[80][81] When abuse is suspected, it is critical to screen children separately from their parents. A physical exam may assist in the diagnosis. Child protective services must be notified and will gather collateral information.
INVESTIGATIONS
Diagnosis is clinical, requires clinical assessment and collateral information gathering.
Seizure disorder
SIGNS / SYMPTOMS
Absence seizures can lead to episodic impairment of attention and focus. Drugs used to treat epilepsy can impair alertness.
History can help distinguish from ADHD.
INVESTIGATIONS
EEG.
Central nervous system infection/trauma
SIGNS / SYMPTOMS
People who have had a traumatic brain injury often have acute symptoms and long-term impairments that vary by the region of injury.
Those who have acute central nervous system infections will display altered mental status and may have delirium, headache, and fever.
INVESTIGATIONS
LP, head imaging.
Medication adverse effects
SIGNS / SYMPTOMS
Certain medications can have cognitive adverse effects and this can be recognized by reviewing the medication list for suspect medication (e.g., antihistamines, sympathomimetics, benzodiazepines, theophylline, and anticonvulsant drugs).
INVESTIGATIONS
Serum levels of some medications can be obtained (e.g., carbamazepine, theophylline, and phenobarbital).
Substance use disorder
SIGNS / SYMPTOMS
Intoxication or withdrawal from substances can mimic some of the hyperactivity, impulsivity, and inattentiveness of ADHD. ADHD typically has onset before 12 years of age and is present throughout development and even into adulthood, while experimentation with substances occurs generally in adolescence and adult life. Careful history and physical exam can distinguish isolated substance use from ADHD, although the two are often comorbid.
INVESTIGATIONS
Urine and serum toxicology screens.
Sleep disorders
SIGNS / SYMPTOMS
Sleep disorders (e.g., obstructive apnea, periodic limb movement disorder, restless legs syndrome, psychophysiological insomnia, sleep-wake cycle disorders including inadequate sleep) affect 25% to 50% of children with ADHD, so it is difficult to distinguish a sleep disorder from ADHD with sleep problems. People with sleep disorders can be inattentive or hyperactive.[109]
A careful sleep history including review of time to sleep onset, loud snoring, observed apnea, awakenings at night, and poor sleep hygiene may identify a sleep disorder.
INVESTIGATIONS
Sleep studies can give a more definitive diagnosis.
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