Introduction to ADHD
Attention Deficit Hyperactivity Disorder (ADHD) is the most common psychiatric disorder of childhood affecting 5-12% of school-aged children. Approximately 8-10% of males and 3-4% of females under the age of 18 years have ADHD. Approximately 80% of children with ADHD continue to meet the diagnostic criteria for ADHD in adolescence and over 60% will maintain some core symptoms of ADHD into adulthood. Although there are some differences in symptomatology and comorbidity between males and females, the impact of the disorder on patients and their families are about the same.
Core Symptoms and Subtypes
The three core symptom domains of ADHD are inattention, hyperactivity and impulsivity. Other main symptoms and associated symptoms are related to these core symptom areas. The various subtypes of ADHD are diagnosed based on meeting the symptom thresholds according to the Diagnostic and Statistical Manual- TR Edition (DSM-TR: American Psychiatric Association). The Subtypes of AD/HD are: a) Predominantly Inattentive type (sometimes referred to in the lay public as ADD or ADD-non H); b) Predominantly Hyperactive-Impulsive type and, if thresholds for a) and b) are met, then c) Predominantly Combined type.
The symptoms and subtypes of ADHD and associated comorbid disorders change dramatically throughout the lifecycle. Hyperactivity and impulsivity may decrease as patients get older but the demands on their attention and other cognitive skills may increase. The Predominantly Inattentive Subtype may be more obvious by adulthood as they tend to not be disruptive and obvious during grade school. Many of these patients are females suggesting that the prevalence rates may be higher in females during childhood but that they are not being picked up.
ADHD and Comorbid Disorders
ADHD is a very important comorbid disorder in a wide variety of psychiatric disorders such as Specific Learning Disabilities, Developmental Disabilities, Mental Retardation, Conduct Disorder, Oppositional Defiant Disorder, Anxiety Disorders, Mood Disorders, Tic Spectrum Disorders and possibly Autism Spectrum Disorders. Only one out of five patients do not present with a comorbid disorder. In adulthood, many patients with Antisocial Personality Disorder and possibly other personality, mood and anxiety disorders have a high risk of having ADHD. The prevalence of ADHD is dramatically different in various psychiatric disorders. For example, over 80% of children with Bipolar Disorder and Conduct Disorder also meet the diagnostic criteria for ADHD, mostly for the Predominantly Combined subtype.
ADHD is likely a genetically transmitted and highly disabling medical illness that requires early diagnosis and intervention. If it persists into adulthood, the likelihood of associated comorbid psychiatric syndromes is high, leading to even more impairment.