Contents

1 Attention-Deficit/Hyperactivity Disorder

ADHD is a behavioral disorder characterized by inattention, hyperactivity, and impulsivity. Sir Alexander Crichton appears to be the first to describe a disorder among boys of ‘mental restlessness’ in 1798, which has since been described by many others with many names, including most recently: hyperkinetic disorder of childhood, minimal brain damage (i.e. not obvious by then current scanning technology or gross anatomy), attention deficit disorder, and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) term ADHD [2, 5]. The essential feature of ADHD is a “persistant pattern of inattention and/or hyperactivity-impulsivity that is more frequently displayed and more severe than is typically observed in individuals at a comparable level of development” [2]. Diagnosis with ADHD is associated with higher incidence of criminal behavior, alcohol abuse, and problematic drug use [6, 7].

Over the years, critics have suggested that ADHD and other previous diagnostic terms are used to label difficult children whose behavior is at the extreme end of the normal range, but are not ill [5]. Current diagnostic requirements state that some symptoms must be present before age 7, although many are first diagnosed after symtoms have been present a number of years. Symptoms must be considered impairing in multiple settings, and there should be evidence of interference with developmentally appropriate social, academic, or occupational functioning, which is not better accounted for by another mental disorder [2].

2 How big is ADHD?

ADHD affects 8 % to 12 % of children worldwide [3, 4].

2.1 Male/Female disparity

The disorder is more frequent among males than in females, with male-to-female ratios ranging from 2:1 to 9:1 depending on the subtype and setting [2, 4]. The male-to-female ratio is greater in clinical studies than in community studies, indicating that females are less likely to be referred for treatment than male individuals [3].

2.2 Under- and Over-Diagnosis

If diagnosed on symptom load alone, the prevalence of ADHD is as high as 16.1 %, but only 6.8 % if functional impairment was required, as is now the case in the DSM-IV. Community studies commonly find a large percentage of children who meet DSM-IV criteria for ADHD, but who have never been diagnosed nor treated, and usually a similar percentage (3 % to 5 %) who did not meet criteria for ADHD, yet had been treated with stimulants [1, 4].

2.3 Demographics

National studies in the USA have not observed a difference in rates of ADHD by income, or have identified income-related differences among boys but not girls; however, the poorest children were least likely to receive ADHD medication treatment [4]. While these national studies have shown lower rates of reported ADHD diagnoses in children from minority backgrounds, other studies found no difference in DSM-IV-based ADHD rates in non-Hispanic white and African American children [4]. Mexican American children had lower overall rates of ADHD, and non-Hispanic white children had higher rates of ADHD inattentive subtype than Mexican American or African American children [4]. Female sex, minority status, and low income predict failure to diagnose and treat children with the disorder. While minority children with ADHD were less likely to be pharmacologically treated, pharmacological treatment rates were not different in minority children with other psychiatric disorders [8]. Among those meeting DSM-IV criteria, less than half of caregivers reported that their child had received an ADHD diagnosis by a health-care professional. Significant predictors of prior ADHD recognition included non-Hispanic white race, male sex, older age, and health insurance coverage of the child. Income and ADHD subtype were not associated with prior diagnosis among children meeting DSM-IV criteria [4]. Of the children who met DSM-IV criteria, 38.8 % had received medication to treat inattention, hyperactivity, or overactivity within the past year [4].

ADHD

attention-deficit/hyperactivity disorder

APA

American Psychiatric Association

DSM-IV

Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition

References