Factor analysis of neuropsychological domains in a preschool clinic.

INTRODUCTION: The clinical practice of preschool neuropsychology assumes that our assessment tools are measuring underlying neuropsychological functions, and that these functions are negatively impacted by early life neurological injury, disease, and disorder. This study hypothesized that general intellectual capacity and specific cognitive skills, both "broad" neuropsychological domains and "specific" subdomains within those broader clusters, would be differentiable in a preschool-age clinical population.

METHODS: Using neuropsychological data from 580 children (6 and 71 months) seen for a clinical neuropsychological evaluation in the Preschool and Infant Neuropsychological Testing (PINT) Clinic, exploratory factor analyses (EFA) were conducted. Results: A one-factor model provided a good fit when considering verbal, nonverbal, and adaptive functions. Consideration of one- versus two-factor solutions for broad neuropsychological domains indicated that a 2-factor solution provided a significantly better fit for the data. Factor 1 was defined by motor, language, and nonverbal reasoning abilities; Factor 2 was defined by inhibitory control and attention. Further consideration of specific neuropsychological functions also supported a 2-factor solution. Factor 1 ("thinking") was defined by nonverbal reasoning, receptive language, and expressive language; Factor 2 ("processing") was defined by impulse control, inhibitory control, inattention, visual-motor integration, and visuo-constructional abilities. Motor skills cross-loaded onto both factors. Secondary analyses suggest these models provide the best fit for preschool-aged children with > 70 overall intellectual functioning and no comorbid medical diagnosis.

CONCLUSIONS: In a clinical sample of preschool-age children, neuropsychological assessment data appears to assess a general level of intellectual capacity or functioning. Further differentiation between assessing "thinking" (knowledge and reasoning skills) and "processing" (cognitive attention and processing of information) can be considered clinically. Next steps include more recent clinical sample replication, consideration of whether neuropsychological profiles are detectable in the preschool-age range and whether the results of early life assessment are predictive of future functioning.