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ADHD
ADD 1980; ADHD 1987· Condition or disorder
Well replicatedStrong, repeated evidence.
A neurodevelopmental condition of persistent inattention, hyperactivity or impulsivity that starts in childhood and often continues into adulthood.
See it on the Psychology map →What it says
British doctor George Still described restless, impulsive children in 1902. DSM-III named 'attention deficit disorder' in 1980; the 1987 revision made it ADHD. Symptoms must appear before age 12 and cause problems in more than one setting. About 5 percent of children worldwide and 2 to 3 percent of adults qualify, though US diagnoses run higher. Heritability is about 75 percent. Stimulants such as methylphenidate (Ritalin) and amphetamines (Adderall) work well short term; coaching and parent training also help.
Why it matters
Untreated ADHD is linked to accidents, school failure and money trouble from impulsive spending. It is not caused by sugar or bad parenting.
The evidence
Twin and genome studies, the large US MTA treatment trial (1999), meta-analyses of drug trials, and Swedish registry studies linking medication to fewer accidents and crimes.
Open questions
Whether the surge in diagnoses, especially among adults since 2020, reflects better recognition or overdiagnosis is debated, as are medication's long-term benefits.
Connections (2)
▸Attention and its limits is hard to regulate in ADHDWell replicated
The connection
ADHD is less a lack of attention than trouble steering it: people struggle to sustain focus on dull tasks, filter distractions and stop impulses, yet may 'hyperfocus' on engaging ones. Lab tasks show weaker sustained attention and response inhibition, tied to prefrontal and dopamine networks.
Who showed it and when
Virginia Douglas in Montreal (1972) argued attention problems, not hyperactivity, were central, shaping the 1980 'attention deficit disorder' label; Russell Barkley later stressed self-control.
The evidence
Meta-analyses of lab tests show consistent group differences in attention and inhibition, though effects are moderate and many people with ADHD test normally.
Open questions
Whether attention, self-control, motivation or time sense is the core problem is still debated, and no single test diagnoses ADHD.
▸ADHD is a neurodevelopmental condition among Mental disorders: what they are and how commonWell replicated
The connection
DSM-5 groups ADHD with autism, intellectual disability and learning disorders as 'neurodevelopmental', conditions that begin in childhood as brain development diverges from typical. It is among the most common childhood conditions, and many adults with ADHD also have anxiety, depression or substance problems.
Who showed it and when
DSM-5 created the neurodevelopmental chapter in 2013 and made it easier to diagnose ADHD in adults.
The evidence
Brain imaging shows somewhat delayed cortical maturation in children with ADHD, and genetic studies show overlap with other neurodevelopmental conditions.
Open questions
Whether ADHD is a distinct condition or the extreme end of a normal trait, as many researchers now argue, is still debated.