Published online by Cambridge University Press: 31 August 2009
Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous disorder. DSM-IV (Diagnostic and Statistical Manual of Mental Disorders-IV) recognizes three subtypes of ADHD: a predominantly inattentive subtype, a predominantly hyperactive–impulsive subtype, and a combined subtype (American Psychiatric Association, 1994). These categories acknowledge clinical heterogeneity and reflect a change in emphasis from earlier definitions that stressed motoric symptoms to current nosology in which inattention is emphasized. ADHD is one of the major clinical and public health problems because of its associated morbidity and disability in children, adolescents, and adults. Its impact on society is enormous in terms of financial cost, stress to families, impact on academic and vocational activities, as well as negative effects on self-esteem. Data from cross-sectional, retrospective, and follow-up studies indicate that children with ADHD are at risk for developing other psychiatric difficulties in childhood, adolescence, and adulthood including antisocial behaviors, substance use disorders, and mood and anxiety symptoms and disorders.
The pathophysiology of ADHD
ADHD is a heterogeneous disorder of unknown etiology. An emerging neuropsychologic and neuroimaging literature suggests that abnormalities in frontal networks or fronto-striatal dysfunction is the disorder's underlying neural substrate, and that catecholamine dysregulation is its underlying patho-physiologic substrate. The pattern of neuropsychologic deficits found in ADHD children implicates executive functions and working memory; this pattern is similar to that which has been found among adults with frontal lobe damage, which suggests that the frontal cortex or regions projecting to the frontal cortex are dysfunctional in at least some ADHD children.
To save this book to your Kindle, first ensure firstname.lastname@example.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.