Increased fear-potentiated startle in major depressive disorder patients with lifetime history of suicide attempt

Abstract

Background: Suicide is a common reason for psychiatric emergency and morbidity, with few effective treatments. Anxiety symptoms have emerged as potential modifiable risk factors in the time before a suicide attempt, but few studies have been conducted using laboratory measures of fear and anxiety. We operationally defined fear and anxiety as increased startle reactivity during anticipation of predictable (fear-potentiated startle) and unpredictable (anxiety-potentiated startle) shock. We hypothesized that a lifetime history of suicide attempt (as compared to history of no suicide attempt) would be associated with increased fear-potentiated startle.

Methods: A post-hoc analysis of fear- and anxiety-potentiated startle was conducted in 28 medication-free patients with Major Depressive Disorder (MDD) divided according to suicide attempt history.

Results: The magnitude of fear-potentiated startle was increased in depressed patients with lifetime suicide attempts compared to those without a lifetime history of suicide attempt (F(1,26)=5.629, p=.025). There was no difference in anxiety-potentiated startle by suicide attempt history.

Limitations: This is a post-hoc analysis of previously analyzed patient data from a study of depressed inpatients. Further replication of the finding with a larger patient sample is indicated.

Conclusions: Increased fear-potentiated startle in suicide attempters suggests the role of amygdala in depressed patients with a suicide attempt history. Findings highlight the importance of anxiety symptoms in the treatment of patients at increased suicide risk.

Keywords: Fear-potentiated startle; Major depressive disorder; Suicide.

Figure 1

Schematic representation of sequences of stimulus presentation during each condition in one block of the NPU-threat test. The top of the figure represents a complete block, including two P (predictable), two U (unpredictable) and three N (no shock) conditions (order U-N-P-N-P-N-U as shown; or, alternatively administered as P-N-U-N-U-N-P). The remaining figure shows each condition, including cues (8-s duration), startle probes presented during cues (grey arrow pointing up) or during cue-free periods (dark arrow pointing up), and shocks. Image originally adapted from reference (Grillon et al., 2009) and taken from Grillon et al. 2013.

Figure 2

Startle Response during NPU (T-Scores) by Lifetime History of Suicide Attempt