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ScienceWeek
MEDICINE: ADULT ATTENTION DEFICIT/HYPERACTIVITY DISORDER
The following points are made by Lynne Lamberg (J. Am. Med. Assoc. 2003 290:1565):
1) Although attention-deficit/hyperactivity disorder (ADHD) was long perceived as a disorder of children, it is now recognized as a chronic condition persisting into adulthood. But it is often undiagnosed in adults -- an unfortunate oversight, because appropriate treatment often can help those who have struggled with the effects of their condition for years. ADHD affects 3% to 7% of school-aged children, and it is now thought it affects approximately the same percentage of adults. But children and adults often manifest the disorder's core symptoms of hyperactivity, impulsivity, and inattention in different ways.
2) The hyperactive child squirms and fidgets, can't stay seated, and is constantly on the go. While hyperactivity lessens with age, adults with ADHD may experience subjective inner restlessness. Some become workaholics and have trouble relaxing. Impulsivity makes children with ADHD blurt out answers, interrupt others, and talk excessively. Adults with ADHD also are often incessant talkers, and may display impatience; studies reveal they change jobs more often, accrue more speeding tickets, and have more vehicle crashes than individuals without the disorder. As a group, adults with ADHD also have higher divorce rates and are more likely to smoke, have substance use disorders, and overeat more than other adults. Such behaviors often have serious medical consequences.
3) Inattention in children with ADHD is manifested by their propensity to not listen or follow through, as well as forgetfulness. Such tendencies have considerable impact as their lives unfold. Compared with peers of similar intelligence, for example, fewer enter college and fewer graduate. As inattentive adults, individuals with ADHD often find it hard to focus, plan, organize, and complete tasks at work and in their home lives. They generally advance more slowly at work than peers. Spouses complain that they neglect to pay bills or pick up the children at designated times, and misplace keys, glasses, and other items.
4) Some adults with ADHD harness their strengths, however, mobilizing intellectual curiosity, desire for novelty, and bountiful energy to achieve success as physicians, journalists, stockbrokers, lawyers, and sales people. Studies show that approximately one third of adults with ADHD become entrepreneurs by their 30s.
J. Am. Med. Assoc. http://www.jama.com
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ON BRAIN-VOLUME ABNORMALITIES IN CHILDREN AND ADOLESCENTS WITH ATTENTION-DEFICIT/HYPERACTIVITY DISORDER
The following points are made by F.X. Castellanos et al (J. Am. Med. Assoc. 2002 288:1740):
1) Attention-deficit/hyperactivity disorder (ADHD), the most common childhood psychiatric disorder, is thought to reflect subtle abnormalities in central nervous system functioning.(1) For this reason, ADHD is being studied increasingly with a variety of brain imaging techniques throughout the life span. Magnetic resonance imaging (MRI) is particularly suitable for the study of pediatric patients, providing high-resolution images without ionizing radiation. Previous MRI neuroimaging studies, most with small samples, have reported smaller anatomic areas and/or volumes in patients with ADHD in regions of the corpus callosum,(2-5) smaller volumes and/or hypoactivation of prefrontal brain, basal ganglia, and cerebellum. However, a recent study noted inconsistencies in the ADHD neuroimaging literature and concluded that specific abnormalities have not yet been convincingly demonstrated.
2) The authors report a study to compare regional brain volumes at initial scan and their change over time in medicated and previously unmedicated male and female patients with ADHD and healthy controls. The case-control study was conducted from 1991-2001 at the National Institute of Mental Health, Bethesda, Md, of 152 children and adolescents with ADHD (age range, 5-18 years) and 139 age- and sex-matched controls (age range, 4.5-19 years) recruited from the local community, who contributed 544 anatomic magnetic resonance images. Using completely automated methods, the main outcome measures were initial volumes and prospective age-related changes of total cerebrum, cerebellum, gray and white matter for the 4 major lobes, and caudate nucleus of the brain were compared in patients and controls.
3) Results: On initial scan, patients with ADHD had significantly smaller brain volumes in all regions, even after adjustment for significant covariates. This global difference was reflected in smaller total cerebral volumes (-3.2%) and in significantly smaller cerebellar volumes (-3.5%). Compared with controls, previously unmedicated children with ADHD demonstrated significantly smaller total cerebral volumes (-5.8%) and cerebellar volumes (-6.2%). Unmedicated children with ADHD also exhibited strikingly smaller total white matter volumes (F2,288 = 11.65) compared with controls (-10.7%) and with medicated children with ADHD (-8.9%). Volumetric abnormalities persisted with age in total and regional cerebral measures (P = .002) and in the cerebellum (P = .003). Caudate nucleus volumes were initially abnormal for patients with ADHD (P = .05), but diagnostic differences disappeared as caudate volumes decreased for patients and controls during adolescence. Results were comparable for male and female patients on all measures. Frontal and temporal gray matter, caudate, and cerebellar volumes correlated significantly with parent- and clinician-rated severity measures within the ADHD sample (Pearson coefficients between -0.16 and -0.26; all P values were < .05).
4) The authors conclude: Developmental trajectories for all structures, except caudate, remain roughly parallel for patients and controls during childhood and adolescence, suggesting that genetic and/or early environmental influences on brain development in ADHD are fixed, nonprogressive, and unrelated to stimulant treatment.
References (abridged):
1. Tannock R. Attention deficit hyperactivity disorder: advances in cognitive, neurobiological, and genetic research. J Child Psychol Psychiatry. 1998;39:65-99.
2. Hynd GW, Semrud-Clikeman M, Lorys AR, et al. Corpus callosum morphology in attention-deficit hyperactivity disorder: Morphometric analysis of MRI. J Learn Disabil. 1991;24:141-146.
3. Giedd JN, Castellanos FX, Casey BJ, et al. Quantitative morphology of the corpus callosum in attention deficit hyperactivity disorder. Am J Psychiatry. 1994;151:665-669.
4. Semrud-Clikeman M, Filipek PA, Biederman J, et al. Attention-deficit hyperactivity disorder: magnetic resonance imaging morphometric analysis of the corpus callosum. J Am Acad Child Adolesc Psychiatry. 1994;33:875-881.
5. Baumgardner TL, Singer HS, Denckla MB, et al. Corpus callosum morphology in children with Tourette syndrome and attention deficit hyperactivity disorder. Neurology. 1996;47:477-482.
J. Am. Med. Assoc. http://www.jama.com
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