attention deficit hyperactivity disorder
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at·ten·tion def·i·cit hy·per·ac·tiv·i·ty dis·or·der (ADHD),[MIM*143465]
Attention deficit disorder, with or without hyperactivity, is a common, chronic behavioral disorder, most evident in children but often persisting through adolescence and into adulthood. The prevalence among children of school age is 3-15%, depending on how stringently diagnostic criteria are applied. As many as two thirds of patients continue to meet diagnostic criteria in adulthood, and it is estimated that 4% of the adult U.S. population is affected. Strong evidence suggests a genetic predisposition: about 25% of patients have at least one parent with the disorder, and it is about eight times more common in males than in females. Children with this disorder have a higher incidence of anxiety, depression, oppositional defiant disorder, academic underachievement, antisocial behavior, and substance abuse. Affected adults may manifest social and occupational maladjustment, chronic anxiety, substance abuse, and bipolar disorder. The diagnosis is strictly clinical. Central nervous system stimulants (dextroamphetamine, methylphenidate, pemoline) and the selective norepinephrine reuptake inhibitor atomoxetine administered regularly improve symptoms in about 80% of patients, but a positive response to these agents does not confirm the diagnosis of ADHD.
attention deficit hyperactivity disorder
attention deficit hyperactivity disorder (ADHD)
attention deficit hyperactivity disorderA condition characterised by the inability to control one’s own behaviour due to difficulty in processing neural stimuli, resulting in increased motor activity and decreased attention span.
Epidemiology ADHD is the most commonly diagnosed neurobehavioural disorder of childhood, with a prevalence of 2% to 18% depending on defining criteria; in children, the male:female ratio is 2:1; in adults, 1:2.
Clinical findings Impulsiveness and distractibility, variably accompanied by hyperactivity and/or aggressiveness, immaturity, and emotional lability. While ADHD is considered idiopathic, neurochemistry and genetics play a role.
Diagnosis ADHD is a diagnosis of exclusion and, per many workers, vastly overdiagnosed.
• MRI Some data suggests that ADHD brains may have slightly smaller anterior frontal cortices, right caudate, and globus pallidus.
• PET ADHD patients have greater temporal blood flow, and lower glucose metabolism, especially in the premotor cortex and superior prefrontal cortex (brain regions involved in control of attention and motor activity).
Management Stimulants (methylphenidate/Ritalin®, dextroamphetamine, pemoline); antidepressants (desipramine, imipramine, bupropion); alpha-adrenergic agonists (clonidine).
DiffDx Sensory deficit, receptive language disorder, learning disability, seizures, emotional problems, oppositional defiant disorder, conduct disorder, problems of parent-child interaction, mental retardation. Family stresses (e.g., divorce, parental death, depression and sickness) must be evaluated before labelling a child “hyperactive”.
Molecular pathology Parents and sibs of children with ADHD are 2 to 8 times more likely to develop ADHD. The mean heritability of ADHD is 76%, making it one of the most heritable of all psychiatric disorders. Vulnerability to ADHD may be due to multigenetic effect linked to dopamine receptors or serotonin products—e.g., DRD4, DRD5, DAT, DBH, 5-HTT, and 5-HTR1B. The risk of ADHD is significantly increased in the presence of 1 risk allele,DRD2; odds ratio (OR) of 7.5, which increases in DRD2 homozygotes to 55. ADHD patients may have a blunted response to dopamine signals and less inhibited behaviour due to a defect in the D4 dopamine receptor gene (DRD4), the so-called novelty-seeking gene.
at·ten·tion def·i·cit hy·per·ac·tiv·i·ty dis·or·der(ADHD) (ă-ten'shŭn def'i-sit hī'pĕr-ak-tiv'i-tē dis-ōr'dĕr)
See also: attention deficit disorder
at·ten·tion def·i·cit hy·per·ac·tiv·i·ty dis·or·der(ADHD) (ă-ten'shŭn def'i-sit hī'pĕr-ak-tiv'i-tē dis-ōr'dĕr) [MIM*143465]
Patient discussion about attention deficit hyperactivity disorder
Q. What Is ADHD? I have heard parents talking about ADHD at my son’s school. What exactly is this syndrome?
Q. Is ADHD hereditary? I had ADHD as a young boy. Does this mean my children will have ADHD too?
Q. Is adhd an illness? what happens if not treated at all? can it just pass by itself?
Was it only discovered recently?