Attention Deficit Hyperactivity Disorder

Overview

Definition

Attention-deficit hyperactivity disorder is a neuropsychiatric condition marked by a pattern of decreased attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment and hyperactivity or impulsivity.

Epidemiology

• Affects about 8%–12% of children 
• 70% will carry the disease into adolescence and 50% into adulthood.
• Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency in adulthood is 4%–5%.
• Male:female prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: 5:1 
• Risk factors:
  • 1st-degree relative who had a similar disease
  • Exposure to lead in early childhood
  • Maternal exposure to drugs, alcohol, or cigarette smoke
  • Premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis birth and associated perinatal hypoxic injury
  • Acquired traumatic brain injury Traumatic brain injury A form of acquired brain injury which occurs when a sudden trauma causes damage to the brain. Le Fort Fractures
  • Environmental risk factors:
    • Low socioeconomic status
    • Parental mental disorder

Classification

Major subtypes:

• Predominantly inattentive:
  • Most common among girls
  • Deficient in attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment to activities
  • Disorganized 
  • Leave tasks rapidly
  • Lack of focus
  • Does not follow instructions
• Predominantly hyperactive/impulsive:
  • Most common among boys
  • Restless or fidgety (nervous)
  • Impulsive
  • Excessive talking
  • Disruptive behavior
• Combined:
  • Most common form
  • Variety of symptoms from both inattentiveness and impulsivity

Etiology and Pathophysiology

Etiology

• Genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics and mutations: 
  • Children born to affected parent have 2x–8x risk of developing the disease.
  • 55%–90% monozygotic twin concordance
  • Possible genetic mutations Genetic Mutations Carcinogenesis in dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS receptors Receptors Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors (DRD4, DRD5, DAT, DRH, 5-HTT, and 5 HTR1B)
  • Genetic syndromes with increased risk:
    • Klinefelter syndrome Klinefelter syndrome Klinefelter syndrome is a chromosomal aneuploidy characterized by the presence of 1 or more extra X chromosomes in a male karyotype, most commonly leading to karyotype 47,XXY. Klinefelter syndrome is associated with decreased levels of testosterone and is the most common cause of congenital hypogonadism. Klinefelter Syndrome
    • Turner syndrome Turner syndrome Turner syndrome is a genetic condition affecting women, in which 1 X chromosome is partly or completely missing. The classic result is the karyotype 45,XO with a female phenotype. Turner syndrome is associated with decreased sex hormone levels and is the most common cause of primary amenorrhea. Turner Syndrome
    • Fragile X syndrome Fragile X syndrome Fragile X syndrome (FXS), also known as Martin-Bell syndrome, is a genetic condition with X-linked inheritance. Both boys and girls may be affected, but the severity is much worse in boys. Characteristic features include a long face, prominent forehead and chin, large ears, flat feet, and large testes post-puberty for boys. Fragile X Syndrome
    • Neurofibromatosis type 1 Type 1 Spinal Muscular Atrophy
    • Williams syndrome Williams syndrome Williams syndrome (WS), also known as Williams-Beuren syndrome (WBS), is a genetic disease caused by a microdeletion on chromosome 7. Affected individuals have a characteristic elfin facies and short stature. Cognitive, developmental, and behavioral issues are common. Additionally, cardiovascular, connective tissue, endocrine, and renal anomalies may be present. Williams Syndrome
    • DiGeorge syndrome DiGeorge syndrome DiGeorge syndrome (DGS) is a condition caused by a microdeletion at location q11.2 of chromosome 22 (thus also called 22q11.2 syndrome). There is a defective development of the third and fourth pharyngeal pouches, leading to thymic and parathyroid hypoplasia (causing T-cell immunodeficiency and hypocalcemia, respectively). DiGeorge Syndrome
• Neurotransmitter deficiency: 
  • Decrease in dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS and norepinephrine Norepinephrine Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus. Receptors and Neurotransmitters of the CNS in areas of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification responsible for attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment and control of activity and behavior ( frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy and prefrontal cortex)
  • Supported by positive response to stimulant medications and functional magnetic resonance imaging (fMRI) studies showing reduced neurotransmission Neurotransmission The communication from a neuron to a target (neuron, muscle, or secretory cell) across a synapse. In chemical synaptic transmission, the presynaptic neuron releases a neurotransmitter that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across electrical synapses. Synapses and Neurotransmission in these areas
• Structural brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification changes:
  • Changes in areas that control attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment, behavior, and emotions ( basal ganglia Basal Ganglia Basal ganglia are a group of subcortical nuclear agglomerations involved in movement, and are located deep to the cerebral hemispheres. Basal ganglia include the striatum (caudate nucleus and putamen), globus pallidus, substantia nigra, and subthalamic nucleus. Basal Ganglia: Anatomy and cerebellum Cerebellum The cerebellum, Latin for “little brain,” is located in the posterior cranial fossa, dorsal to the pons and midbrain, and its principal role is in the coordination of movements. The cerebellum consists of 3 lobes on either side of its 2 hemispheres and is connected in the middle by the vermis. Cerebellum: Anatomy): smaller anterior cingulate gyrus Cingulate gyrus One of the convolutions on the medial surface of the cerebral hemispheres. It surrounds the rostral part of the brain and corpus callosum and forms part of the limbic system. Limbic System: Anatomy and dorsolateral prefrontal cortex 
  • May be due to perinatal hypoxic-ischemic injury that destroys converging glutaminergic neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology, or fetal circulatory insufficiency

Pathophysiology

• Exact pathophysiology is unknown.
• Associated with functional and cognitive deficits related to structural changes in brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification:
  • Areas of brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification involved include:
    • Frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy cortex
    • Subcortical structures
    • Anterior cingulate gyrus Cingulate gyrus One of the convolutions on the medial surface of the cerebral hemispheres. It surrounds the rostral part of the brain and corpus callosum and forms part of the limbic system. Limbic System: Anatomy
• Involves dysregulation of dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS and norepinephrine Norepinephrine Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus. Receptors and Neurotransmitters of the CNS in brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification

Clinical Presentation

Differs depending on age of child:  

• Preschool:
  • Hyperactive
  • Impulsive
  • Inflexible
  • May be aggressive with peers
  • Decreased sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep 
• Elementary school:
  • Struggles with listening in class
  • Poor organizational skills
  • Struggles with social interaction
  • Difficulty functioning independently
• Adolescence:
  • Academic demands become overwhelming.
  • Struggles with attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment, learning, executive functioning

Diagnosis

Symptoms

• Onset of symptoms before the age of 12
• Symptoms occur in 2 or more settings, e.g., school, home, or work.
• Duration: > 6 months 
• Symptoms cause decline in function or development.

Symptoms of inattention:

Six or more of the following symptoms in childhood (5 symptoms sufficient in adolescents and adults):

• Lack of attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment to details, repeatedly making careless mistakes
• Inability to focus or remain on task
• Inattention when spoken to
• Inability to follow instructions and failing to finish work on time
• Disorganization in completing tasks
• Avoidance of tasks that require continuous mental effort or attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment (e.g., homework)
• Frequent misplacement and loss of personal things (e.g., pencil, books)
• Frequently forgetting to complete daily activities

Symptoms of hyperactivity and impulsivity:

Six or more of the following symptoms in childhood (5 symptoms sufficient in adolescents and adults):

• Fidgeting and restlessness  
• Leaving seat in situations where remaining seated is expected (e.g., in classroom)
• Running or climbing in inappropriate situations
• Difficulty engaging in activities
• Uncomfortable with remaining still (often “on the go,” acting as if “driven by a motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology”)
• Excessive talking 
• Excessive outbursts (shouting out answers before completion of question)
• Difficulty standing in line or waiting their turn
• Often interrupts others

Mental status and physical exam

• Children with hyperactivity are more likely to be referred for evaluation than those with the inattentive type. 
• Obtaining interviews from teachers as well as school reports is critical.
• History taking should include detailed records from parents to screen for risk factors (e.g., substance use or their own symptoms of ADHD).
• Initial clinical evaluation should include height/weight, blood pressure, and pulse. 
• Validated rating scale Scale Dermatologic Examination, such as Vanderbilt ADHD rating scale Scale Dermatologic Examination, may be used to assist with diagnosis.

Exclusion of other causes

Rule out other potential causes for abnormal behavior.

• Symptoms due to other psychiatric disorder:
  • Oppositional defiant disorder Oppositional Defiant Disorder Oppositional defiant disorder is a pediatric psychiatric disorder characterized by a continuous pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness directed at adults or other authority figures. Symptoms must be present for at least 6 months to make a diagnosis of ODD. Oppositional Defiant Disorder (ODD)
  • Schizophrenia Schizophrenia Schizophrenia is a chronic mental health disorder characterized by the presence of psychotic symptoms such as delusions or hallucinations. The signs and symptoms of schizophrenia are traditionally separated into 2 groups: positive (delusions, hallucinations, and disorganized speech or behavior) and negative (flat affect, avolition, anhedonia, poor attention, and alogia). Schizophrenia
  • Major depressive disorder Major depressive disorder Major depressive disorder (MDD), commonly called depression, is a unipolar mood disorder characterized by persistent low mood and loss of interest in association with somatic symptoms for a duration of ≥ 2 weeks. Major depressive disorder has the highest lifetime prevalence among all psychiatric disorders. Major Depressive Disorder
  • Bipolar Bipolar Nervous System: Histology disorder
  • Anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder disorder
  • Tourette syndrome Tourette Syndrome A neuropsychological disorder related to alterations in dopamine metabolism and neurotransmission involving frontal-subcortical neuronal circuits. Both multiple motor and one or more vocal tics need to be present with tics occurring many times a day, nearly daily, over a period of more than one year. The onset is before age 18 and the disturbance is not due to direct physiological effects of a substance or another medical condition. The disturbance causes marked distress or significant impairment in social, occupational, or other important areas of functioning. Tics and Tourette Syndrome
  • Dissociative disorder
  • Personality disorder
  • Substance intoxication Substance Intoxication A condition or physical state produced by the ingestion, injection, inhalation of or exposure to a deleterious agent. Substance-Related and Addictive Disorders or withdrawal
• Screen for specific learning disability Disability Determination of the degree of a physical, mental, or emotional handicap. The diagnosis is applied to legal qualification for benefits and income under disability insurance and to eligibility for social security and workman’s compensation benefits. ABCDE Assessment to ensure that symptoms are not due to failure to understand tasks or instructions.
• For those with inattentive symptoms, evaluation for petit mal epilepsy Petit mal epilepsy A seizure disorder usually occurring in childhood characterized by rhythmic electrical brain discharges of generalized onset. Clinical features include a sudden cessation of ongoing activity usually without loss of postural tone. Rhythmic blinking of the eyelids or lip smacking frequently accompanies the seizures. The usual duration is 5-10 seconds, and multiple episodes may occur daily. Juvenile absence epilepsy is characterized by the juvenile onset of absence seizures and an increased incidence of myoclonus and tonic-clonic seizures. Epilepsy is recommended. 
• Neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant is not recommended or required for diagnosis. 

Management

Pharmacotherapy

• Stimulant medication: 
  • 1st-line therapy in school-aged children
  • More effective than non-stimulant
  • Includes: methylphenidate Methylphenidate A central nervous system stimulant used most commonly in the treatment of attention deficit disorder in children and for narcolepsy. Its mechanisms appear to be similar to those of dextroamphetamine. Stimulants, amphetamines Amphetamines Analogs or derivatives of amphetamine. Many are sympathomimetics and central nervous system stimulators causing excitation, vasopressin, bronchodilation, and to varying degrees, anorexia, analepsis, nasal decongestion, and some smooth muscle relaxation. Stimulants 
  • Mechanism of action:
    • Blockage of dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS and norepinephrine Norepinephrine Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus. Receptors and Neurotransmitters of the CNS transporters 
    • Reduction of monoamine oxidase Oxidase Neisseria activity 
  • Preparations with sustained release are preferred due to less of a need for interruptions for medications, as well as avoiding periods of rebound or irritability. 
  • Side effects:
    • Decreased appetite, insomnia Insomnia Insomnia is a sleep disorder characterized by difficulty in the initiation, maintenance, and consolidation of sleep, leading to impairment of function. Patients may exhibit symptoms such as difficulty falling asleep, disrupted sleep, trouble going back to sleep, early awakenings, and feeling tired upon waking. Insomnia, headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
    • Potentially significant increases in blood pressure and/or heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology
    • Modest stunting in growth 
    • May exacerbate comorbid tics Tics Habitual, repeated, rapid contraction of certain muscles, resulting in stereotyped individualized actions that can be voluntarily suppressed for only brief periods. They often involve the face, vocal cords, neck, and less often the extremities. Examples include repetitive throat clearing, vocalizations, sniffing, pursing the lips, and excessive blinking. Tics tend to be aggravated by emotional stress. When frequent they may interfere with speech and interpersonal relations. Conditions which feature frequent and prominent tics as a primary manifestation of disease are referred to as tic disorders. Tics and Tourette Syndrome 
    • Has potential for misuse
    • Recommend obtaining electrocardiogram Electrocardiogram An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) prior to start, especially for patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with personal or family history Family History Adult Health Maintenance of cardiovascular disease 
• Non-stimulant medications:  
  • No potential for misuse and do not cause euphoria Euphoria An exaggerated feeling of physical and emotional well-being not consonant with apparent stimuli or events; usually of psychologic origin, but also seen in organic brain disease and toxic states. Hepatic Encephalopathy, unlike psychostimulants 
  • Selective norepinephrine Norepinephrine Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus. Receptors and Neurotransmitters of the CNS reuptake inhibitors:
    • Include: atomoxetine, viloxazine
    • Usually 2nd-line therapy 
    • Indicated with comorbid anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder, tic disorder, or insomnia Insomnia Insomnia is a sleep disorder characterized by difficulty in the initiation, maintenance, and consolidation of sleep, leading to impairment of function. Patients may exhibit symptoms such as difficulty falling asleep, disrupted sleep, trouble going back to sleep, early awakenings, and feeling tired upon waking. Insomnia 
    • Side effects: increased suicidal ideation Suicidal ideation A risk factor for suicide attempts and completions, it is the most common of all suicidal behavior, but only a minority of ideators engage in overt self-harm. Suicide
  • Alpha agonists:
    • Include: guanfacine, clonidine Clonidine An imidazoline sympatholytic agent that stimulates alpha-2 adrenergic receptors and central imidazoline receptors. It is commonly used in the management of hypertension. Sympathomimetic Drugs
    • Efficacy significantly lower than psychostimulants 
    • Used if patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship cannot tolerate stimulants Stimulants Stimulants are used by the general public to increase alertness and energy, decrease fatigue, and promote mental focus. Stimulants have medical uses for individuals with ADHD and sleep disorders, and are also used in combination with analgesics in pain management. Stimulants or develop new-onset tics Tics Habitual, repeated, rapid contraction of certain muscles, resulting in stereotyped individualized actions that can be voluntarily suppressed for only brief periods. They often involve the face, vocal cords, neck, and less often the extremities. Examples include repetitive throat clearing, vocalizations, sniffing, pursing the lips, and excessive blinking. Tics tend to be aggravated by emotional stress. When frequent they may interfere with speech and interpersonal relations. Conditions which feature frequent and prominent tics as a primary manifestation of disease are referred to as tic disorders. Tics and Tourette Syndrome
    • Side effects: drowsiness, dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome), headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
• Antidepressants: 
  • 3rd-line therapy
  • May be used for adults with comorbid substance use or mood disorders
  • Bupropion Bupropion A propiophenone-derived antidepressant and antismoking agent that inhibits the uptake of dopamine. Other Antidepressants commonly used

Psychotherapy Psychotherapy Psychotherapy is interpersonal treatment based on the understanding of psychological principles and mechanisms of mental disease. The treatment approach is often individualized, depending on the psychiatric condition(s) or circumstance. Psychotherapy

• 1st-line treatment for preschool-aged children (4–5 years of age) 
• Involves education for family/teachers, as well as patient, to reach short- and long-term goals 
• Educational accommodation Accommodation Refractive Errors can be helpful in terms of academic performance.
• Psychotherapy Psychotherapy Psychotherapy is interpersonal treatment based on the understanding of psychological principles and mechanisms of mental disease. The treatment approach is often individualized, depending on the psychiatric condition(s) or circumstance. Psychotherapy supplements, but may not replace, medication therapy.

Differential Diagnosis

• Specific learning disorder: neurodevelopmental disorder with both environmental and genetic factors that causes an impairment of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification‘s ability to perceive or process either verbal or nonverbal information. The disorder is an umbrella of diagnoses that includes academic difficulties in domains such as reading, writing, and mathematics. Specific learning disorders may be present alongside ADHD. Key difference from ADHD is a lack of inattention or hyperactivity. 
• ODD: Continuous pattern of angry/ irritable mood Irritable mood Abnormal or excessive excitability with easily triggered anger, annoyance, or impatience. Oppositional Defiant Disorder, argumentative/ defiant behavior Defiant behavior Oppositional Defiant Disorder, or vindictiveness Vindictiveness Oppositional Defiant Disorder that is present for at least 6 months. The diagnosis is frequently found in those with ADHD. While ADHD is present in numerous settings and among peers, symptoms of ODD are mostly directed toward authority Authority Medical Ethics: Basic Principles figures, such as parents or teachers.  
• Major depressive disorder Major depressive disorder Major depressive disorder (MDD), commonly called depression, is a unipolar mood disorder characterized by persistent low mood and loss of interest in association with somatic symptoms for a duration of ≥ 2 weeks. Major depressive disorder has the highest lifetime prevalence among all psychiatric disorders. Major Depressive Disorder (MDD): a mood disorder marked by depressed mood, sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep disturbance, anhedonia Anhedonia Inability to experience pleasure due to impairment or dysfunction of normal psychological and neurobiological mechanisms. It is a symptom of many psychotic disorders (e.g., depressive disorder, major; and schizophrenia). Schizophrenia, feelings of guilt or worthlessness, loss of energy, reduced ability to concentrate, weight or appetite changes, psychomotor retardation or agitation Agitation A feeling of restlessness associated with increased motor activity. This may occur as a manifestation of nervous system drug toxicity or other conditions. St. Louis Encephalitis Virus, and suicidal ideation Suicidal ideation A risk factor for suicide attempts and completions, it is the most common of all suicidal behavior, but only a minority of ideators engage in overt self-harm. Suicide. While the decrease in concentration overlaps in both diagnoses, ADHD is distinguished from MDD by the lack of other depressive mood features.