Is aggressive behavior in Neurofibromatosis Type 1 due to dysregulated inhibitory control, difficulties in interpreting emotional cues, or both?

Abstract

Objective: Patients with Neurofibromatosis 1 (NF-1) have poor social functioning, problems with conduct and they may exhibit aggressive behavior. Two types of aggressive behavior exist. Reactive aggression rises in response to perceived threat or frustration and is regulated through inhibitory control and reading emotions on faces and in voices. Instrumental aggression is a means of controlling and dominating others and is regulated through understanding others' emotions. Here, we aimed at assessing aggressive behavior in NF-1 and at understanding whether they are due to difficulties in inhibitory control or/and the perception of emotions. Method: Twenty-six participants with NF-1 (age 5 to 16) and 34 matched controls completed one test assessing inhibitory control and three tests assessing the recognition of isolated facial expressions, the attribution of facial expressions to faceless characters in visually presented scenes depicting social interactions, and the attribution of facial expressions to voices of characters involved in social interactions. The intellectual level was also evaluated. Finally, the parents completed scales assessing reactive and instrumental aggression. Results: As compared to controls, participants with NF-1 had higher scores in both reactive (p < 0.02) and instrumental aggression (p < 0.04). Regression analyses showed that difficulties in identifying isolated faces explained instrumental aggression independently of the group, whilst reactive aggression was explained by difficulties in inhibitory control as a function of the group. Conclusions: Patients with NF-1 present with both reactive and instrumental aggressive behavior and, as expected through the literature on general population, this may contribute toward poor social functioning. However, increased aggressive behavior in NF-1 is due to poor inhibitory control, not to difficulties in reading emotions on faces and in voices, even though deficits of these functions are also present.