Problem behavior in a community sample of 14- and 19-month-old children: common versus uncommon behaviors, structure, and stability.

Few studies have examined the presence, structure, and stability of behavior problems in a community sample of 14- and 19-month-old infants. A questionnaire with items on emotional, attentional, and impulsive behavior and social communication was completed by the parents of 6,491 infants aged 14 months and 1,803 infants aged 19 months. Particularly externalizing behavior problems were reported to present sometimes or often for 50% of more of the sample and could be considered as common. In contrast, social communication problems were reported to be present in less than 10% of the sample. Overall, boys showed more problem behaviors than girls. Principal component analysis at the 14 months data revealed seven factors, which could all be replicated in the 19 months data. Pearson correlations between scores at 14 months and 19 months were highest for oppositional and attention factors (0.68 and 0.63) and lowest for the inhibiton factor (0.38). More than 50% of those scoring in the top 10% for total problem score at 14 months were in the top 10% at 19 months. These results will facilitate the recognition of psychopathology at very early age and the study of its development over time