Pathophysiology of ADHD

Question 1

Subtypes of ADHD in DSM-5

Answer 1

DSM-5 no longer conceptualizes ADHD as three separate types; it is seen as a single disorder that can vary in the relative severities of its two symptom dimensions. This can change over time; therefore there are three “presentations” rather than subtypes.

Question 2

Change in hyperactivity-impulsivity symptoms over time

Answer 2

These symptoms decline; in older adults, 4 items places them above the 93rd percentile in the distribution. These adults continue to show functional impairment. The 5-item cutoff shoudl probably be 4 symptoms on either symptom list (Barkley 2015). Adults can outgrow the DSM criteria but not the disorder.

Question 3

Dimensional vs. categorical nature of ADHD

Answer 3

ADHD is presented as a categorical condition in DSM, but it is actually a dimensional disorder whose symptoms vary in severity across the population and produces impairment at excessive levels of severity.

Question 4

Is ADHD a disorder of executive functioning?

Answer 4

Reviews of psychometric tests of EF have typically concluded that only a minority of individuals with ADHD are impaired on these tests (Willcutt, Doyle, Nigg, Faraone, & Pennington 2005). However, rating scales of EF show that the vast majority of children and adults with ADHD are so impaired.

Question 5

The executive function that correlates with inattention.

Answer 5

Metacognition

Question 6

The executive function rating that corresponds to hyperactivity / impulsivity

Answer 6

Behavioural disinhibition or self-restraint.