[Attention deficit hyperactivity disorder: intellectual profile and the freedom from distraction factor]

Attention deficit hyperactivity disorder (ADHD) usually presents a neuropsychological profile in which the freedom from distraction factor (FDF) is affected to a greater extent than the verbal comprehension factor (VCF) and the perceptual organisation factor (POF).

To determine the intellectual profile of clinical cases with ADHD through a specific analysis of the FDF, in which we evaluated the differences compared with the VCF and the POF, between types of ADHD and with WISC-R criteria, as well as the variables that affect the probability of FDF < VCF and POF.

Our study involved a clinical sample of 167 cases of ADHD between 6 and 16 years of age. The cases were defined according to DSM-IV criteria and the evaluation was performed using WISC-R, the Child Symptom Inventory and the social and occupational activity assessment scale. Both descriptive and exploratory statistics were used. Means were compared using ANOVA and/or t tests. Alpha was accepted if it was equal to or below 0.05 and a logistic regression method was used (alpha model parameters below or equal to 0.05). In each factor a 95% confidence interval and odds ratio were determined.

The criterion FDF < VCF and FOP accounted for 71.3% of the cases with ADHD and FDF < (VCF + POF) / 2 represented 81.4% (sensitivity: 81.4%). The FDF is significantly lower than both the mean that corresponds to factorial criteria derived from the WISC-R and the VCF and POF in the cases that were analysed. The mean FDF scores were significantly higher in ADHD-H (a type in which hyperactive-impulsivity predominates) than in ADHD-C (combined type) and ADHD-I (inattentive type). Comorbidity, social or school activity and intellectual quotient do not have a significant influence on the probability that FDF < VCF and POF.

The FDF is a neuropsychological dimension that is useful in evaluating ADHD.