F90 vs F84
F84 — Pervasive developmental disorders
Distinguish attention/activity regulation difficulty (F90) from a pervasive developmental disorder (F84), using the presence or absence of the qualitative social-interaction/communication/restricted-behaviour triad — a cross-block boundary check, since inattention and overactivity frequently co-occur with F84 and can be coded alongside it when both are genuinely present.
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Show overlap — what both share
Autistic children very often show inattention, overactivity, and impulsiveness that can superficially resemble F90, and a child with F90 can show narrow interests or social difficulties arising from impulsivity and inattention that superficially resemble F84's triad, so either category's core presentation can be mistaken for the other's.
Show decisive evidence
- F90 is defined by inattention, overactivity, and impulsiveness, evident before age 6 and pervasive across settings, without requiring the qualitative F84 triad (abnormal social interaction, communication, and restricted/repetitive behaviour).
- F84 is defined by that qualitative triad, assessed relative to the person's own developmental level, and is not defined by attention or activity regulation difficulty as such.
- Social difficulty that is well explained by impulsivity and inattention (for example, interrupting others or missing social cues due to distractibility), without qualitative abnormality in reciprocal social interaction itself, favours F90 alone.
- Qualitative abnormality in social interaction and communication, together with restricted or repetitive behaviour, evident independent of attention or activity level, favours F84 — whether or not attention/activity difficulties are also present and separately coded.
What weakens F90: The presence of the full qualitative triad (social interaction, communication, restricted/repetitive behaviour) weakens F90 as a complete explanation and favours also considering F84; conversely, attention/activity difficulty without that triad weakens F84 as the primary classification.
Show duration / course
F90 requires onset before age 6 and cross-situational persistence; F84's specific subtypes carry their own onset and course requirements (see the F84 category record), generally including early developmental onset as well.
Show exclusions / context
Per F90's own exclusions_distinctions entry, overactivity and social/communication difficulty together with restricted, repetitive behaviour is directed to F84 as the more accurate classification, with attention/activity difficulties able to be coded alongside it when genuinely present.
Show information still needed
Whether the qualitative F84 triad (social interaction, communication, restricted/repetitive behaviour) is independently present, or whether the presentation is fully explained by attention and activity regulation difficulty alone.
Show the common trap
Assuming a restless, inattentive, socially awkward child must have either F90 or F84 exclusively, without checking whether both patterns are genuinely present and should be coded together.
Mini challenge — practise this distinction
Apply the discriminating evidence above to a fresh case before checking the full feedback.