The interaction between infant negative emotionality and cognition predicts ADHD-related behaviors in toddlerhood.

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent disorder commonly identified in childhood. Affective and cognitive characteristics that are identifiable as early as infancy could be signals of risk for developing ADHD. Specifically, the interplay between emotionality and cognition may be important in predicting early symptoms of ADHD. This study examined the independent and interactive effects of infant negative emotionality and cognition on the development of inattention and hyperactivity/impulsivity in toddlerhood among infants at high and low familial likelihood for ADHD. Participants were 64 infants (M = 8.7, SD = 1.8) at high (n = 32) and low (n = 32) familial likelihood for ADHD, defined as at least one parent with ADHD or two parents without ADHD, respectively. Negative emotionality and cognition in infancy were assessed using the Infant Behavior Questionnaire and the Bayley's Scales of Infant and Toddler Development, and ADHD symptoms were assessed at toddler follow-up (M= 20.0, SD= 3.2) using the Child Behavior Checklist. Accounting for the quality of parent-child interaction, infants' negative emotionality (β = .033, p = .938) and cognition (β = .006, p = .884) did not independently predict toddlers' ADHD-related behaviors, but their interaction did (β = .110, p = .019). For infants with higher levels of cognition (>95th percentile), higher negative emotionality predicted more ADHD-related behaviorss. For infants with lower levels of cognition (<11th percentile), higher negative emotionality predicted fewer ADHD-related behaviors. There may be two affective-cognitive pathways to inattention and hyperactivity/impulsivity in toddlerhood. The combination of higher levels of negative emotionality and cognition may result in greater frustration when goals are blocked, resulting in the expression of dysregulated behaviors (i.e., ADHD symptoms). Alternatively, low levels of negative emotionality and cognition combined may lead to dysregulation that is primarily cognitive in nature (such as the inattention symptoms of ADHD). Investigating affective and cognitive processes simultaneously may be important for increasing understanding of the early signals of ADHD risk.