The factor structure of ADHD items in DSM-III-R: internal consistency and external validation

Area of Science:

• Child and Adolescent Psychiatry
• Neurodevelopmental Disorders
• Psychometrics

Background:

• Previous factor analyses of DSM-III Attention Deficit Disorder with Hyperactivity (ADDH) symptoms consistently supported a two-factor model.
• Revisions in the DSM-III-R diagnostic criteria for ADHD and the inclusion of new items raised questions about diagnostic comparability.

Purpose of the Study:

• To investigate the factor structure of DSM-III ADDH and DSM-III-R ADHD symptoms.
• To determine if the revisions in ADHD diagnostic criteria impact the underlying symptom dimensions.
• To externally validate the identified factors using cognitive performance measures.

Main Methods:

• Teacher ratings of DSM-III ADDH and DSM-III-R ADHD items were collected from 85 nonreferred school children.
• Factor analysis was employed to determine the underlying factor structures of both diagnostic scales.
• Factor scores were correlated with cognitive test battery results.

Main Results:

• A similar two-factor solution emerged for both the DSM-III ADDH and DSM-III-R ADHD symptom ratings.
• The identified factors corresponded to inattention and hyperactivity-impulsivity constructs.
• Hyperactivity-impulsivity factor scores correlated with response inhibition measures, while inattention-disorganization scores correlated with attention and visual search measures.

Conclusions:

• The study supports a consistent two-factor model (inattention and hyperactivity-impulsivity) for ADHD symptoms across diagnostic revisions.
• External validation through cognitive testing supports the objective reality of these symptom dimensions.
• Findings have implications for the assessment and diagnosis of ADHD.