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Original Article
August 2005

Instability of the DSM-IV Subtypes of ADHD From Preschool Through Elementary School

Author Affiliations

Author Affiliations: Department of Psychiatry, University of Chicago, Chicago, Ill (Drs Lahey and Lee); Department of Psychology, State University of New York at Buffalo, Buffalo (Dr Pelham); Department of Psychiatry, State University of New York at Stony Brook, Stony Brook (Dr Loney); Department of Psychology, University of Colorado, Boulder (Dr Willcutt).

Arch Gen Psychiatry. 2005;62(8):896-902. doi:10.1001/archpsyc.62.8.896

Context  The DSM-IV definition of attention-deficit/hyperactivity disorder (ADHD) distinguished 3 subtypes that had not been extensively studied.

Objective  To determine whether the ADHD subtypes are stable enough over time to be valid.

Design  Longitudinal study with a greater-than 89% retention rate in 7 assessments over 8 years.

Setting  Outpatient clinics.

Participants  Volunteer sample of 118 4- to 6-year-olds who met DSM-IV criteria for ADHD, including impairment in 2 settings in at least 1 assessment.

Main Outcome Measure  Meeting DSM-IV criteria for the subtypes of ADHD during years 2 through 8.

Results  The number of children who met criteria for ADHD declined over time, but most persisted. Children who met criteria for the combined subtype (CT, n = 83) met criteria for ADHD in more subsequent assessments than children in the predominantly hyperactive-impulsive subtype (HT, n = 23). Thirty-one (37%) of 83 CT children and 6 (50%) of 12 children in the predominantly inattentive subtype (IT) met criteria for a different subtype at least twice in the next 6 assessments. Children of the HT subtype were even more likely to shift to a different subtype over time, with HT children who persisted in ADHD mostly shifting to CT in later assessments. The subtypes exhibited consistently different mean levels of hyperactive-impulsive symptoms during years 2 through 8 that corresponded with their initial subtype classifications, but initial subtype differences in inattention symptoms diminished in later years.

Conclusions  In younger children, the CT and IT may be stable enough to segregate groups for research, but they seem too unstable for use in the clinical assessment of individual children. Children rarely remain in the HT classification over time; rather, they sometimes desist from ADHD but mostly shift to CT in later years. Using continuous ratings of hyperactivity-impulsivity symptoms as a diagnostic qualifier should be considered as an alternative to classifying nominal subtypes of ADHD in DSM-V.