Does neuroticism in adolescents moderate contextual and explicit threat cue modulation of the startle reflex?

Abstract

Background: This study evaluated the relationship between neuroticism (N), a probable risk factor for emotional disorders, and modulation of startle reflexes (SRs).

Methods: One hundred thirty-two adolescents with varying levels of N but without anxiety or depressive disorders were evaluated in contextual cue and explicit threat cue paradigms.

Results: Within the explicit threat cue paradigm, N potentiated SRs more in conditions that were intermediately associated with threat of an aversive biceps contraction than conditions that were the furthest from and conditions that were the closest to the same threat. Also, N potentiated SRs across the entire experiment, regardless of experimental conditions, in male and not in female subjects.

Conclusions: These results suggest that adolescents with high levels of N show greater sensitivity to contexts intermediately associated with threat. Results are discussed in comparison with other studies of groups at risk for anxiety and depressive disorders.

Figure 1

Figure 1a shows the overall experimental design. In the initial baseline and context conditions, 8 startle stimuli were delivered with a mean ISI of 22s (range 20–24s) as Ps focused on a white fixation cross. The baseline and context conditions were repeated after the explicit threat cue paradigm. The explicit threat cue paradigm included 8 safe (S) and 8 danger (D) phases presented in alternating order, with intervening rests periods of 5s, 15s or 25s showing the white fixation cross. Figure 1(b) shows that each 55 sec safe and danger phase contained two startle trials delivered at either 5 and 35 sec or 15 and 45 sec, with the order rotated every two phases. Startle trials at 45 sec were delivered during the 40–55 sec explicit threat period depicted on the progressing bar displayed on the computer screen. The muscle contraction was delivered at 50 sec during the fourth danger phase, resulting in 4 safe and 4 danger phases pre-contraction and a further 4 safe and 4 danger phases post-contraction. Grey indicates baseline and safe; black indicates context and danger.

Figure 2

Mean SR magnitude values (+SE) as a function of N at early (left panels) and late (right panels) startle trials during safe (top panels) and danger (bottom panels) phases in the explicit threat cue paradigm.