Sex differences in intrusive memories following trauma

<div><p>Background</p><p>A key mechanism thought to underlie Posttraumatic Stress Disorder (PTSD) is enhanced emotional memory consolidation. Recent evidence in healthy controls revealed that women have greater negative memory consolidation following stress relative to men. This study examined emotional memory consolidation in women and men with PTSD, and in trauma-exposed and non-trauma controls to test the hypothesis that emotionally negative memory consolidation would be greater in women with PTSD.</p><p>Method</p><p>One hundred and forty-seven men and women (47 with PTSD, 49 trauma-exposed controls, and 51 non-trauma controls) completed an emotional memory task where they looked at negative, neutral and positive images from the International Affective Picture System (IAPS). Delayed recall and an intrusive memory diary were completed two days later.</p><p>Results</p><p>Women displayed greater recall, and reported more negative intrusive memories than men. A gender x group interaction effect showed that both women with PTSD and trauma-exposed women reported more intrusive memories than women without trauma exposure or men.</p><p>Conclusion</p><p>This study provided preliminary evidence of sex differences in intrusive memories in those with PTSD as well as those with a history of trauma exposure. Future research should include measures of sex hormones to further examine sex differences on memory consolidation in the context of trauma exposure and PTSD.</p></div

Summary of Hierarchical Regression Models for Recall of Neutral Images.

<p><i>Note</i>. Males: Step 1 R² = −.03, Δ R² = .00. Step 2 R² = .00, Δ R² = .06. Step 3 R² = .20, Δ R² = .21. Step 4 R² = .21, Δ R² = .03.</p><p>Females: Step 1 R² = .08, Δ R² = 10. Step 2 R² = .14, Δ R² = .08. Step 3 R² = .14, Δ R² = .02. Step 4 R² = .17, Δ R² = .04.</p

Participant Characteristics and Stress Responses.

<p><i>Note.</i> Standard deviations appear in parentheses. sAA measured in μ/ml. Cortisol measured in nmol/dl.</p

Average salivary alpha amylase and cortisol levels at each experimental phase.

<p>Average salivary alpha amylase and cortisol levels at each experimental phase.</p

Free Recall and Intrusive Memory Responses.

<p><i>Note.</i> Standard deviations appear in parentheses.</p

Summary of Hierarchical Regression Models for Recall of Negative Images.

<p><i>Note.</i> Males: Step 1 R² = .01, Δ R² = .01. Step 2 R² = .02, Δ R² = .00. Step 3 R² = .09, Δ R² = .07, Step 4 R² = .09, Δ R² = .00.</p><p>Females: Step 1 R² = .31, Δ R² = .32. Step 2 R² = .29, Δ R² = .00. Step 3 R² = .31, Δ R² = .04. Step 4 R² = .29, Δ R² = .00.</p

Summary of Hierarchical Regression Models for Intrusions of Neutral Images.

<p><i>Note</i>. Males: Step 1 R² = .05, Δ R² = .07. Step 2 R² = .11, Δ R² = .09. Step 3 R² = .09, Δ R² = .00, Step 4 R² = .08, Δ R² = .01.</p><p>Females: Step 1 R² = −.02, Δ R² = .00. Step 2 R² = −.04, Δ R² = .00. Step 3 R² = .−.07, Δ R² = .00. Step 4 R² = −.07, Δ R² = .02.</p

Sex main effects at N100 and N200 amplitude to the “increase” instructional set.

<p>Sex main effects at N100 and N200 amplitude to the “increase” instructional set.</p

Sex Differences and Emotion Regulation: An Event-Related Potential Study

<div><p>Difficulties in emotion regulation have been implicated as a potential mechanism underlying anxiety and mood disorders. It is possible that sex differences in emotion regulation may contribute towards the heightened female prevalence for these disorders. Previous fMRI studies of sex differences in emotion regulation have shown mixed results, possibly due to difficulties in discriminating the component processes of early emotional reactivity and emotion regulation. The present study used event-related potentials (ERPs) to examine sex differences in N1 and N2 components (reflecting early emotional reactivity) and P3 and LPP components (reflecting emotion regulation). N1, N2, P3, and LPP were recorded from 20 men and 23 women who were instructed to “increase,” “decrease,” and “maintain” their emotional response during passive viewing of negative images. Results indicated that women had significantly greater N1 and N2 amplitudes (reflecting early emotional reactivity) to negative stimuli than men, supporting a female negativity bias. LPP amplitudes increased to the “increase” instruction, and women displayed greater LPP amplitudes than men to the “increase” instruction. There were no differences to the “decrease” instruction in women or men. These findings confirm predictions of the female negativity bias hypothesis and suggest that women have greater up-regulation of emotional responses to negative stimuli. This finding is highly significant in light of the female vulnerability for developing anxiety disorders.</p></div

Topographies of the Sex main effects at N100 and N200 amplitude, the Instruction main effect at P300 amplitude, and the Instruction×Site×Sex interaction for mean LPP amplitude to the ‘increase” instructional set (blue negative, red positive).

<p>Topographies of the Sex main effects at N100 and N200 amplitude, the Instruction main effect at P300 amplitude, and the Instruction×Site×Sex interaction for mean LPP amplitude to the ‘increase” instructional set (blue negative, red positive).</p