Teacher-reported prevalence rates for attention-deficit hyperactivity disorder (ADHD) using DSM-IV and DSM-III-R criteria were compared in a middle Tennessee county during the 1993-94 academic year and analysed by subtypes at Vanderbilt University, Nashville, TN. Rating scales for 8258 children were completed by 398 teachers. Prevalence rates were 7.3% for ADHD using DSM-III-R diagnostic criteria; 5.4% for ADHD, inattentive type (AD); 2.4% for hyperactive-impulsive type(HI); and 3.6% for combined type (CT) using DSM-IV criteria. Boys outnumbered girls with a 4:1 ratio for ADHD-HI and 2:1 for ADHD-AD. The number of children meeting criteria for the total of all three DSM-IV subtypes (11.4%) was 57% greater than those with ADHD DSM-III-R criteria. Children with ADHD-CT had the highest rate of comorbid conditions, 55% having ODD, 29% CD, and 29% ANX/DEP. ADHD-AD was associated with much lower rates of ODD and CD than other subtypes. Anxiety or depression rates were highest for ADHD-CT types and lowest with ADHD-HI. Behavioral problems predominate in ADHD-HI types and academic problems predominate in ADHD-AD. The use of DSM-IV in place of DSM-III-R criteria increased the prevalence of the diagnosis of ADHD in this community, and the new subtypes better characterized the heterogeneity of the disorder. 
COMMENT. The new diagnostic criteria in DSM-IV which include two new subtypes are likely to increase the prevalence of ADHD when compared to DSM-III-R criteria. The ADHD inattentive subtype (AD) is characteristic of children with predominant academic problems and fewer behavioral complaints, and it occurs more frequently in females than do other subtypes. ADHD hyperactive-impulsive type (HI) is characterized by behavioral problems, with fewer academic problems, and a low rate of anxiety or depression. ADHD combined type (CT) criteria are close to the the original DSM-III ADD with hyperactivity.
Validity of DSM-IV ADHD subtype diagnoses in relation to previous DSM III and DSM-III-R diagnoses. ADHD-AD and ADHD-CT diagnoses corresponded with DSM-III ADD/WO and ADD/H diagnoses, respectively, in a study at the University of Georgia, Athens, GA . For the ADHD-AD, predominantly inattentive type, diagnosis the child must have 6 of 9 inattentive symptoms but less than the specified number of HI symptoms.
These frequent and sometimes premature modifications of the DSM criteria for diagnosis of ADHD are certainly leading to confusion and have prompted a rash of articles and studies attempting to clarify the dilemma.