THE FACTOR STRUCTURE OF ADHD ITEMS IN DSM-III-R - INTERNAL CONSISTENCY AND EXTERNAL VALIDATION

Previous research employing factor-analytic procedures to study the un derlying dimensions of DSM-III attention deficit disorder with hyperac tivity (ADDH) symptoms have consistently supported a two-factor model. Revision of the structure of the ADHD diagnosis in DSM-III-R, as well as inclusion of new items, has raised the question of comparability o f the two diagnoses. To explore the significance of these changes, tea cher ratings of DSM-III ADDH items and DSM-III-R ADHD items of 85 nonr eferred school children were factor-analyzed to determine their underl ying factor structures. A similar two-factor solution was obtained for each. diagnostic scale. The factors consisted of items believed to re flect inattention and hyperactivity-impulsivity constructs. These fact ors were further evaluated against results of a cognitive test battery to ascertain whether objective, external validation could be demonstr ated. The hyperactivity-impulsivity factor scores were related to cont inuous performance test measures of response inhibition, while inatten tion-disorganization factor scores were related to measures of attenti on and visual search. Implications for assessment and diagnosis of ADH D are discussed.