Attention deficit hyperactivity disorder (ADHD) is a developmental condition of inattention and distractibility, with or without accompanying hyperactivity.
Signs and symptoms
According to the Diagnostic and Statistical Manual of Mental Health Disorders, Fifth Edition (DSM-5), the 3 types of attention deficit/hyperactivity disorder (ADHD) are (1) predominantly inattentive, (2) predominantly hyperactive/impulsive, and (3) combined. The current DSM-5 criteria are provided below. 
This must include at least 6 of the following symptoms of inattention that must have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level:
Often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities
Often has difficulty sustaining attention in tasks or play activities
Often does not seem to listen to what is being said
Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions)
Often has difficulties organizing tasks and activities
Often avoids or strongly dislikes tasks (such as schoolwork or homework) that require sustained mental effort
Often loses things necessary for tasks or activities (school assignments, pencils, books, tools, or toys)
Often is easily distracted by extraneous stimuli
Often forgetful in daily activities
This must include at least 6 of the following symptoms of hyperactivity-impulsivity that must have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level:
Fidgeting with or tapping hands or feet, squirming in seat
Leaving seat in classroom or in other situations in which remaining seated is expected
Running about or climbing excessively in situations where this behavior is inappropriate (in adolescents or adults, this may be limited to subjective feelings of restlessness)
Difficulty playing or engaging in leisure activities quietly
Unable to be or uncomfortable being still for extended periods of time (may be experienced by others as “on the go” or difficult to keep up with)
Blurting out answers to questions before the questions have been completed
Difficulty waiting in lines or awaiting turn in games or group situations
Interrupting or intruding on others (for adolescents and adults, may intrude into or take over what others are doing)
Onset is no later than age 12 years
Symptoms must be present in 2 or more situations, such as school, work, or home
The disturbance causes clinically significant distress or impairment in social, academic, or occupational functioning
Disorder does not occur exclusively during the course of schizophrenia or other psychotic disorder and is not better accounted for by mood, anxiety, dissociative, personality disorder or substance intoxication or withdrawal
See Clinical Presentation for more detail.
Psychometric and educational testing is often important for the diagnosis of ADHD. The patient's initial history may indicate a need for additional tests, as follows:
Examine children by using the Conners' Parent and Teacher Rating Scale and examine adolescents according to the Brown Attention Deficit Disorder Scale (BADDS) for Adolescents and Adults 
Assess impulsivity and inattention using timed computer tests such as the Conners’ Continuous Performance Test (CPT), the Integrated Visual and Auditory (IVA) CPT, or both
Assess girls using the Nadeau/Quinn/Littman ADHD Self-Rating Scale for Girls
Assess the patient's executive function by using various neuropsychological tests
Perform a learning disability evaluation (intelligence quotient [IQ] vs achievement)
See Workup for more detail.
Behavioral and pharmaceutical strategies are the 2 major components in the medical care of patients with ADHD.
Behavioral psychotherapy often is effective when used in combination with medication. [3, 4] Behavioral therapy or modification programs can help diminish uncertain expectations and increase organization. Working with parents and schools through behavioral parent training and behavioral classroom management to ensure environments are conducive to focus and attention is necessary.
Psychostimulants are effective in patients with ADHD. However, compliance is an issue, particularly in children. Therefore, the use of long-acting medications at once-a-day dosing to treat ADHD has been shown to have advances over shorter-acting drugs. Their use has been marked to higher rates of remission and better adherence, and they have been demonstrated to be less stigmatizing.
The term attention deficit is misleading. In general, the current predominating theories suggest that persons with attention deficit hyperactivity disorder (ADHD), attention deficit disorder (ADD), actually have difficulty regulating their attention; inhibiting their attention to nonrelevant stimuli, and/or focusing too intensely on specific stimuli to the exclusion of what is relevant. In one sense, rather than too little attention, many persons with ADHD (ADD) pay too much attention to too many things, leading them to have little focus.
Three basic forms of ADHD (ADD) are described in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) of the American Psychiatric Association (APA).  They are (1) predominantly inattentive, (2) predominantly hyperactive/impulsive, and (3) combined.
The major neurologic functions disturbed by the neurotransmitter imbalance of ADHD (ADD) fall into the category of executive function. The 6 major tasks of executive function that are most commonly distorted with ADHD (ADD) include (1) shifting from one mindset or strategy to another (ie, flexibility), (2) organization (eg, anticipating both needs and problems), (3) planning (eg, goal setting), (4) working memory (ie, receiving, storing, then retrieving information within short-term memory), (5) separating affect from cognition (ie, detaching one's emotions from one's reason), and (6) inhibiting and regulating verbal and motoric action (eg, jumping to conclusions too quickly, difficulty waiting in line in an appropriate fashion).
Contrary to some media accounts, ADHD (ADD) is not new. In the early 1900s, diagnosis emphasized the hyperactivity component. Today, hyperactivity, impulsivity, and inattention are the areas of focus. However, reports have alluded to disorders involving hyperactivity, impulsivity, and inattention in conjunction with distractibility and inappropriate arousal patterns throughout medical history. What is new is the enhanced awareness of ADHD (ADD) secondary to rapidly accumulating research findings and its addition to the DSM in 1980.
Findings from neuropsychological studies suggest that the frontal cortex and the circuits linking them to the basal ganglia are critical for executive function and, therefore, to attention and exercising inhibition. Many findings support this view, including those described below.
Executive functions are major tasks of the frontal lobes. MRI of the right mesial prefrontal cortex in persons with ADHD (ADD) strongly supports decreased activation (low arousal) during tasks that require inhibition of a planned motor response and timing of a motor response to a sensory cue. MRI in persons with ADHD (ADD) also strongly supports weakened activity in the right inferior prefrontal cortex and left caudate during a task that involves timing of a motor response to a sensory cue.
In an effort to explore neural correlates that mediate response inhibition deficits in children with ADHD, Spinelli, et al (2011) examined functional MRI brain activation patterns of children aged 8-13 years with and without ADHD on a go/no-go task. While lapses in attention preceded response inhibition errors in the children without ADHD, brain circuitry involved in response selection and control was activated prior to errors in the children with ADHD. 
The catecholamines are the main neurotransmitters with frontal-lobe function. Catecholamine controlled dopaminergic and noradrenergic neurotransmission appear to be the main targets for medications used to treat ADHD (ADD).
A 10-year study by National Institute of Mental Health (NIMH) demonstrated that the brains of children and adolescents with ADHD (ADD) are 3-4% smaller than those of children without the disorder, and that pharmacologic treatment is not the cause. The more severe patients' ADHD (ADD) symptoms were, as rated by parents and clinicians, the smaller their frontal lobes, temporal gray matter, caudate nucleus, and cerebellum were.
Data from 357 healthy subjects, obtained from the NIH MRI Study of Normal Brain Development, noted that a thinner cortex and slower cortical thinning was associated with higher attention problem scores, suggesting a link between attention and cortical maturation. 
In addition to the role of the neurotransmitters most commonly associated with the frontal lobes and the pathways mentioned above, some investigations have begun exploring a possible role for 5-hydroxytryptamine (5-HT). Although the brain’s motor regions are innervated by 5-HT projections, no connection between 5-HT and ADHD (ADD) motor pathology has yet been identified. However, connections have been made to attention-related processes. Altered 5-HT activity does appear to be at least part of the cause for difficulties with perceptual sensitivity and the appropriate recognition of the relative significance of stimulation.
The prevalence of ADHD (ADD) in children appears to be 3-7%. ADHD (ADD) is associated with significant psychiatric comorbidity. Approximately 50-60% of individuals with this disorder meet DSM-5 criteria for at least one of the possible coexisting conditions, which include learning disorders, restless legs syndrome, ophthalmic convergence insufficiency, depression, anxiety disorders, antisocial personality disorder, substance abuse disorder, and conduct disorder. The likelihood of a person having ADHD (ADD) if a family member has ADHD (ADD) or one of the disorders commonly associated with ADHD (ADD) is significant.
People with ADHD (ADD) have been identified in every country studied, with comparable frequency.
The morbidity for ADHD (ADD) widely varies. This range is a function of many factors, including the specific area of deficit, the patient's environmental response to and interaction with the deficits, the therapy provided, and the presence of coexistent conditions.
ADHD (ADD) is more frequently diagnosed in boys than in girls. Most estimates of the male-to-female ratio range between 3:1 and 4:1 in clinic populations. However, many community-based samples produce a ratio of 2:1. Recognition of ADHD (ADD) has improved over the last decade, and the male-to-female ratio has been decreasing; this may be the result of the increased recognition of inattentive ADHD (ADD).
Data concerning the likelihood that a child with ADHD (ADD) will also have the disorder as an adult are conflicting. As definitions of ADHD (ADD) subtypes improve, some subtypes that cause more adult dysfunction than others will likely be found.
Approximately 30-80% of children with ADHD (ADD) have the disorder as adults. Most experts believe that the rate is well above 50%.
Hyperactive symptoms may decrease with age because of developmental trends toward self-control and changes in brain composition (ie, pruning of abundant neural connections) that occur during late adolescence. However, persons with ADHD (ADD) developmentally mature later than the average population. Inattentive symptoms do not appear to have a similar developmental advantage and tend to remain constant into adulthood.
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