compiled by Teresa Binstock for
Generation Rescue
June 2008
ADHD & ADD: Epidemiologies
1. Epidemiology of ADHD [in US, UK, AU]
By National Health and Medical Research Council Government of Austrailia
The National Health and Medical Research Council of Austrailia
http://www.mental-health-matters.com/articles/article.php?artID=651
There have been widely different prevalence rates reported in both the
United States and the United Kingdom for the hyperkinetic disorder,
attention deficit disorder with hyperactivity (ADDH) and attention
deficit hyperactivity disorder (ADHD). For example the draft ICD-10
(WHO 1988) criteria in the United Kingdom were based on a study by
Taylor, Sandberg, Thorley et al (1991), which found a prevalence of 1.7
per cent for hyperkinetic disorder in boys. Hyperkinetic disorder was
defined as a score of 1.5 or greater on the hyperactivity-
inattentiveness criteria of the Conners Teacher Rating Scale (TRS),
together with a score of 1.0 or greater on the hyperactivity scale of
the Parent Account of Children's Symptoms (PACS).
In the United States, ADHD, as defined by the third DSM edition
(DSM-III) (American Psychiatric Association 1980), which required
observations of symptoms by a parent or teacher, had a prevalence of 6
per cent. ADHD, as defined by the revised third edition, DSM-III-R
(American Psychiatric Association 1987) which also allowed a diagnosis
at home or at school, was thought likely to have a higher prevalence
rate.
The diagnostic criteria of the most recent classifications for ADHD in
DSM-IV (1994), and the research diagnostic criteria of ICD-10 (1993),
are almost identical. Both require observation of symptoms in two or
more settings (home/school/clinic) and should provide similar
prevalence rates in the United Kingdom and the United States (estimated
by DSM-IV to be 3-5 per cent). The multiple diagnoses possible in
DSM-IV in the presence of co-morbid conditions, compared to the
compound diagnoses of ICD-10, may affect prevalence rates. Even small
differences in diagnostic procedures can affect rates, which in turn
have a powerful effect on the predictive value of diagnostic tests. The
advent of DSM-IV Îpredominantly inattentive types of attention deficit
disorder (ADD) could, for example, increase trait prevalence rates.
One reason for the above United States/United Kingdom differences in
prevalence rates is that prevalence estimates are arrived at using at
least two different methods (Glow 1980; Quay 1979), using either a
categorical or a trait (or empirical) approach to diagnosis.
Australian studies have shown prevalence rates ranging between 2.3 per
cent and 6 per cent (Glow 1980) depending on the methodology used.
Current epidemiological studies will need to take account of newest DSM
edition, DSM-IV (American Psychiatric Association 1994).
Age and gender difference
In general, boys are rated higher on disruptive behaviour scales (Werry
and Hawthorne 1976). Also, incidences of hyperactive problems are
usually reported as being 49 times as common in boys than in girls
depending on the setting (community or clinic) (DSM-IV 1994). Age
differences in DSM-IV subtypes of ADHD have been postulated by Barkley
(1995a), but data are not currently available.
Key points - epidemiological data
Epidemiological data remain imprecise and are influenced greatly by the
method of ascertainment. Also, as DSM-IV and ICD-10 have only recently
been published, epidemiological data based on these classification
systems are not currently available. Most studies show a considerably
higher incidence of ADHD in males than in females.
© 2001-2007 National Health and Medical Research Council Government of Austrailia. All Rights Reserved.
2. The epidemiology of attention-deficit/hyperactivity disorder (ADHD): a public health view
Rowland AS, Lesesne CA, Abramowitz AJ.
Ment Retard Dev Disabil Res Rev. 2002;8(3):162-70.
Attention-deficit/hyperactivity disorder (ADHD) is the most common
neurodevelopmental disorder of childhood. However, basic information
about how the prevalence of ADHD varies by race/ethnicity, sex, age,
and socio-economic status remains poorly described. One reason is that
difficulties in the diagnosis of ADHD have translated into difficulties
developing an adequate case definition for epidemiologic studies.
Diagnosis depends heavily on parent and teacher reports; no laboratory
tests reliably predict ADHD. Prevalence estimates of ADHD are sensitive
to who is asked what, and how information is combined. Consequently,
recent systematic reviews report ADHD prevalence estimates as wide as
2%-18%. The diagnosis of ADHD is complicated by the frequent occurrence
of comorbid conditions such as learning disability, conduct disorder,
and anxiety disorder. Symptoms of these conditions may also mimic ADHD.
Nevertheless, we suggest that developing an adequate epidemiologic case
definition based on current diagnostic criteria is possible and is a
prerequisite for further developing the epidemiology of ADHD. The
etiology of ADHD is not known but recent studies suggest both a strong
genetic link as well as environmental factors such as history of
preterm delivery and perhaps, maternal smoking during pregnancy.
Children and teenagers with ADHD use health and mental health services
more often than their peers and engage in more health threatening
behaviors such as smoking, and alcohol and substance abuse. Better
methods are needed for monitoring the prevalence and understanding the
public health implications of ADHD. Stimulant medication is the
treatment of choice for treating ADHD but psychosocial interventions
may also be warranted if comordid disorders are present. The treatment
of ADHD is controversial because of the high prevalence of medication
treatment. Epidemiologic studies could clarify whether the patterns of
ADHD diagnosis and treatment in community settings is appropriate.
Population-based epidemiologic studies may shed important new light on
how we understand ADHD, its natural history, its treatment and its
consequences. Copyright 2002 Wiley-Liss, Inc.
PMID: 12216060
3. Epidemiology of ADHD in school-age children
Scahill L, Schwab-Stone M.
Child Adolesc Psychiatr Clin N Am. 2000 Jul;9(3):541-55, vii.
Attention-Deficit/Hyperactivity Disorder is a relatively common
condition of childhood onset and is of significant public health
concern. Over the past two decades there have been 19 community-based
studies offering estimates of prevalence ranging from 2% to 17%. The
dramatic differences in these estimates are due to the choice of
informant, methods of sampling and data collection, and the diagnostic
definition. This article provides a critical review of the
community-based studies on the prevalence of ADHD in children and
adolescents. Based on the 19 studies reviewed, the best estimate of
prevalence is 5% to 10% in school-aged children. The review also
examines age and gender effects on the frequency of ADHD. The article
closes with a discussion of psychosocial correlates and patterns of
comorbidity in ADHD.
PMID: 10944656
4: CDC: ADHD: A Public Health Perspective Conference
http://www.cdc.gov/ncbddd/adhd/dadphra.htm
5. Have there been changes in children's psychosomatic symptoms? A 10-year comparison from Finland
Santalahti P et al.
Pediatrics. 2005 Apr;115(4):e434-42.
http://pediatrics.aappublications.org/cgi/content/full/115/4/e434
OBJECTIVES: The aims of the study were to determine whether the
prevalence of children's somatic symptoms, such as headache, abdominal
pain, other pain, and nausea and vomiting, changed from 1989 to 1999
and to study the similarity of parents' and children's reports of the
child's symptoms. Furthermore, the aims were to explore possible
comorbidity in somatic symptoms and to investigate the associations
between somatic and psychiatric symptoms. METHODS: Two cross-sectional,
representative samples were compared. All children born in 1981 (1989
sample, n = 985) and 1991 (1999 sample, n = 962) and living in selected
school districts in southwest Finland served as study samples. The
response rate for the 1989 sample was 95% and that for the 1999 sample
was 86%. Both children and parents were asked about the children's
somatic symptoms, whereas parents, children, and teachers were asked
about psychiatric symptoms. To study psychiatric symptoms, the
Children's Depression Inventory and Rutter's parent and teacher scales
were used. RESULTS: The prevalence of frequent headaches and abdominal
pain increased somewhat from 1989 to 1999. Parents often failed to
recognize their children's psychosomatic problems. Child-reported
somatic symptoms were associated with conduct and hyperactivity
symptoms, in addition to a previously well-documented association with
depression. In associations between somatic symptoms and psychiatric
symptoms, there were some differences between the 1989 and 1999
samples. CONCLUSIONS: In clinical work, questions about somatic and
psychiatric symptoms should also be addressed to children themselves,
because parents and teachers do not always recognize children's
symptoms. When somatic problems are being evaluated, psychiatric
symptoms should be asked about, and vice versa. More research is needed
to explore the reasons for the increased prevalence of somatic symptoms
and their associations with psychiatric symptoms.
PMID: 15805346
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