ADHD may be seen as one or more continuous traits found normally throughout the general population. It is a developmental disorder in which certain traits such as impulse control lag in development. Using magnetic resonance imaging of the prefrontal cortex, this developmental lag has been estimated to range from 3 to 5 years. A diagnosis of ADHD does not, however, imply a neurological disease. ADHD is classified as a disruptive behavior disorder along with oppositional defiant disorder, conduct disorder and antisocial disorder.
ADHD has three subtypes:
- Predominantly hyperactive-impulsive
- Most symptoms (six or more) are in the hyperactivity-impulsivity categories.
- Fewer than six symptoms of inattention are present, although inattention may still be present to some degree.
- Predominantly inattentive
- The majority of symptoms (six or more) are in the inattention category and fewer than six symptoms of hyperactivity-impulsivity are present, although hyperactivity-impulsivity may still be present to some degree.
- Children with this subtype are less likely to act out or have difficulties getting along with other children. They may sit quietly, but they are not paying attention to what they are doing. Therefore, the child may be overlooked, and parents and teachers may not notice symptoms of ADHD.
- Combined hyperactive-impulsive and inattentive
- Six or more symptoms of inattention and six or more symptoms of hyperactivity-impulsivity are present.
- Most children with ADHD have the combined type.
ADHD Signs and symptoms
Inattention, hyperactivity, and impulsivity are the key behaviors of ADHD. The symptoms of ADHD are especially difficult to define because it is hard to draw the line at where normal levels of inattention, hyperactivity, and impulsivity end and clinically significant levels requiring intervention begin.To be diagnosed with ADHD, symptoms must be observed in two different settings for six months or more and to a degree that is greater than other children of the same age.
The symptom categories of ADHD in children yield three potential classifications of ADHD—predominantly inattentive type, predominantly hyperactive-impulsive type, or combined type if criteria for both subtypes are met:
Predominantly inattentive type symptoms may include:
- Be easily distracted, miss details, forget things, and frequently switch from one activity to another
- Have difficulty maintaining focus on one task
- Become bored with a task after only a few minutes, unless doing something enjoyable
- Have difficulty focusing attention on organizing and completing a task or learning something new or trouble completing or turning in homework assignments, often losing things (e.g., pencils, toys, assignments) needed to complete tasks or activities
- Not seem to listen when spoken to
- Daydream, become easily confused, and move slowly
- Have difficulty processing information as quickly and accurately as others
- Struggle to follow instructions.
Predominantly hyperactive-impulsive type symptoms may include:
- Fidget and squirm in their seats
- Talk nonstop
- Dash around, touching or playing with anything and everything in sight
- Have trouble sitting still during dinner, school, and story time
- Be constantly in motion
- Have difficulty doing quiet tasks or activities.
and also these manifestations primarily of impulsivity:
- Be very impatient
- Blurt out inappropriate comments, show their emotions without restraint, and act without regard for consequences
- Have difficulty waiting for things they want or waiting their turns in games
Most people exhibit some of these behaviors, but not to the degree where such behaviors significantly interfere with a person’s work, relationships, or studies—and in the absence of significant interference or impairment, a diagnosis of ADHD is normally not appropriate. The core impairments are consistent even in different cultural contexts.
Symptoms may persist into adulthood for up to half of children diagnosed with ADHD. Estimating this is difficult as there are no official diagnostic criteria for ADHD in adults.ADHD in adults remains a clinical diagnosis. The signs and symptoms may differ from those during childhood and adolescence due to the adaptive processes and avoidance mechanisms learned during the process of socialisation.
A 2009 study found that children with ADHD move around a lot because it helps them stay alert enough to complete challenging tasks.