Abstract. Data from the 2001 National Household Education Survey were examined to estimate the prevalence of comorbid AD/HD and LD among school-aged children in the United States and assess how this comorbidity was associated with selected parent-reported behavioral and academic outcomes. The observed prevalence of comorbidity coincided with estimates in previous studies. Parents of children with comorbid AD/HD + LD were significantly more likely than parents of children with LD-only to be contacted by teachers about behavioral problems at school. Additionally, students with comorbid disorders were more likely than students with AD/HD-only to show impaired academic outcomes. However, when compared to children with AD/HD-only, children with comorbidity did not show significantly impaired behavioral outcomes; and when compared to children with LD-only, they did not show significantly impaired academic outcomes.
Attention-deficit/hyperactivity disorder (AD/HD) is a neurobiological disorder characterized by a chronic pattern of inattention and/or hyperactivity-impulsivity. This behavior pattern is exhibited more frequently and is more serious in nature than behavior displayed by individuals at a comparable developmental level (American Psychiatric Association [APA], 2000).
Three subtypes of AD/HD have been identified: (a) AD/HD with a significant pattern of inattentiveness (AD/HD, predominantly inattentive type); (b) AD/HD with significant symptoms of both hyperactivity and impulsivity (AD/HD, predominantly hyperactive-impulsive type); and (c) AD/HD with significant symptoms of inattentiveness, hyperactivity, and impulsivity (AD/HD, combined type) (APA, 2000). AD/HD has been described as "one of the most important disorders that child and adolescent psychiatrists treat" (p. 978) because of its persistence, interference with typical development and functioning, and prevalence (Cantwell, 1996).
Children and adolescents with AD/HD experience tremendous difficulty in academic performance and achievement (APA, 2000; Barkley, 2006; Biederman, Newcorn, & Sprich, 1991; Hechtman et al., 2004). In addition, AD/HD is associated with difficulties or deficits in behavioral performance (APA, 2000; Miranda, Presentacion,& Soriano, 2002). Indeed, Barkley, one of the leading researchers on AD/HD has stated "evidence that behavioral disinhibition, or poor effortful regulation and inhibition of behavior, is in fact the hallmark of this disorder is so substantial that it can be considered fact" (2006, p. 81).
Recent estimates of the prevalence of AD/HD among school-aged children include 3-6% (DeVeaugh-Geiss et al., 2002), 3-5% (U.S. Department of Health and Human Services, 1999), 6.8% (U.S. Department of Health and Human Services-Centers for Disease Control and Prevention [DHHS-CDCP], 2002), and 7.5% (Leibson, Katusic, Barbaresi, Ransom, & O'Brien, 2001). These rates emphasize that AD/HD is a common disorder of childhood.
Another disorder that commonly occurs in children and adolescents is a learning disability (LD). As defined by the Individuals with Disabilities Education Improvement Act of 2004 (IDEA, 2004), the federal law governing special education and related services in the United States, a specific learning disability is:
a disorder in one or more of the basic psychological
processes involved in understanding or in using
language, spoken or written, which disorder may
manifest itself in the imperfect ability to listen,
think, speak, read, write, spell, or do mathematical
In general, reading is the most common problem among students with LD (Bell, McCallum, & Cox, 2003). Some students experience difficulties in only one academic area, such as written communication (Mayes, Calhoun, & Crowell, 2000) or math (Mazzocco, 2005). Most of these students, however, have difficulties that span the entire range of academic as well as social areas (C. …