The characteristics of attention deficit hyperactivity disorder can depend on specific genetic and environmental determinants. Factors that influence how the characteristics are manifested are the setting, such as a classroom and playground, age, cognitive development, comorbidities and gender differences. When comparing the many possible factors with each other, the three most common dominant characteristics that show up are inattention, hyperactivity and poor impulse control.
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Someone with ADHD who primarily exhibits as the inattentive type can show behaviors and emotions that seem withdrawn and unaware of their surroundings. A child or adult with this sub-type may easily forget tasks, may become distracted by simple annoyances and may become quickly bored with projects that do not involve his constant attention. A person diagnosed with inattentive-type ADHD is distinct, because he rarely exhibits the other two main types, hyperactivity and impulsivity. For example, the National Institute of Mental Health states that someone with an inattentive-type diagnosis may be able to sit quietly, not bother other people and appear to be working but still not understanding the work or classroom directions and tasks.
People who fall primarily into the hyperactive type of this disorder will show specific signs that are more physical and action-oriented. Children and adults who are in the hyperactive group will often overlap into the characteristics of the impulsive group as well. Characteristic examples of this group include fidgeting or squirming while sitting, constant talking, moving from chair to chair or jumping out of his seat and major difficulty performing tasks that involve quiet strategic planning. The revised fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders" states that a diagnosis requires that these types of behaviors occur for at least six months.
The impulsive sub-type of ADHD has its own set of characteristics as well. For example, a person with ADHD may act impatiently, shout out comments that are inappropriate in context or timing and show major deficits in understanding delayed gratification. A child may also show difficulty waiting in line or taking turns during game play. A child or adult may be characterized as impulsive only or may fall into a combination of both hyperactivity and impulsivity. The impulsive subtype may also play a role in gender differences regarding appropriate classroom behavior. Boys are more than twice as likely as girls to be diagnosed with ADHD, according to a 2002 large-scale national survey conducted by the Center for Disease Control.
Additional Diagnostic Characteristics
When looking at official diagnostic characteristics of ADHD, the first three subtypes must also include other factors. The revised fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders" states that a person must have shown significant impairments before the age of 7. In addition, it states that she must show impairment in more than one setting. There also must be evidence of impairment in multiple function areas, such as social settings, school and work. Lastly, it must be demonstrated that the condition can not be accounted for by another medical condition, such as a developmental disability, schizophrenia or dissociative identity disorder.