The influence of cochlear implantation on aggression behaviors in children

It has been suggested that children with higher degree of hearing loss may show more severe externalizing (e.g., aggression) and internalizing (e.g., depression and anxiety) behavioral problems compared to that of their normally hearing peers. The purpose of this study was to investigate the influence of sound amplification through cochlear implants (CIs) on aggressive behaviors in Persian children.

During a prospective study design, 72 children (40 girls, 32 boys) who underwent unilateral implantation and 72 (40 girls, 32 boys) age-matched normally hearing children (control group) participated. All CI children had age of <4 years at the time of implantation. The Aggression Scale for Preschoolers (ASFP) was utilized to measure various types of aggression including verbal aggression, physical aggression, relational aggression, and impulsive anger. The speech performance of children was also evaluated using Speech Intelligibility Rating (SIR). The ASFP and SIR measurements were conducted at the pre-implantation phase and at 6, 12, and 18 months post-implantation period.

A repeated measures analysis of variance showed significant reduction in ASFP scores from "pre-operation" to "post-operative" conditions in CI group. However, aggression level in CI recipients were significantly higher than children in control group. In the analyses of ASFP subscales, we found a reduction and a consequent improvement in verbal aggression, physical aggression and impulsive anger. However, no significant difference was found in relational aggression across various time intervals. Furthermore, children who received CI before 2 years old exhibited better aggression level than children who received their devices at later ages. The significantly negative correlation (r = -0.76, p < 0.001) was found between the SIR and ASFP scores, so that lower speech intelligibity ability scores were associated with more aggressive behavior problems.

This study suggests that young children with noticeable degree of hearing loss may experience higher level of aggression compared to normally hearing peers. However, when they undergo early implantation and attend at regular post-operative rehabilitation programs, their aggression status will improve seriously.