A comparison of the quality of intrusive memories in post-traumatic stress disorder and depression

Intrusive thoughts and memories in adolescents with major depressive disorder or post-traumatic stress disorder

OBJECTIVES

Research in adults suggests that intrusive memories and intrusive thoughts (often referred to as intrusive cognitions) are common in members of the general population and are often seen in clinical disorders. However, little is known about the experience of intrusive cognitions in adolescents, particularly in adolescents with major depressive disorder (MDD) and post-traumatic stress disorder (PTSD). The present study sought to gather fundamental data on these phenomena (i.e., frequency, characteristics and appraisals of intrusive cognitions) in adolescents with MDD and PTSD.

METHODS

Adolescents aged 11-18 with MDD (n = 11), PTSD (n = 13) and a non-clinical control group (n = 25) completed structured interviews concerning their intrusive memories and thoughts.

RESULTS

Intrusive thoughts were common in all three groups but were particularly frequently experienced in the MDD group. Intrusive memories were expectedly very common in the PTSD group but also experienced by over half of the adolescents with MDD. Both clinical groups reported more negative emotions in response to their intrusive thoughts or memories and appraised these cognitions more negatively than the non-clinical group.

CONCLUSION

Intrusive memories and thoughts are common experiences in adolescents with MDD and PTSD. Emotions and appraisals relating to these cognitions may be targets for psychological intervention in this age group. However, small sample sizes limit the conclusions that can be drawn. Replication is needed with larger numbers of clinical participants.

The prevalence of intrusive memories in adult depression: A meta-analysis

BACKGROUND

Intrusive memories have typically been associated with post-traumatic stress disorder (PTSD) but some studies have suggested they can also occur in depression-alone.

OBJECTIVE

This meta-analysis aimed to estimate the prevalence of intrusive memories in adult depression and to explore methodological and other factors that may moderate this prevalence.

METHOD

The databases PsycINFO, PsycARTICLES, MedLine, PubMed, CINAHL and Embase were searched for relevant articles, published up to and including July 2016. Studies measuring point prevalence of intrusive memories in adults aged 18 years or above with depression were included and assessed for quality. Meta-analysis was completed under a random effects model.

RESULTS

Seven studies measuring point prevalence of intrusive memories in adult depression were included. The overall pooled prevalence estimate calculated was 76.0% (95% CI 59.4-89.4%), reducing to 66.0% (95% CI 51.0-79.5%) when restricted to intrusive memories experienced within the week prior to assessment. Heterogeneity was high. Between-groups analyses indicated that adults with depression are as likely to experience intrusive memories as adults with PTSD, and more likely to experience intrusive memories than healthy controls (risk ratio of 2.94, 95% CI 1.53-5.67).

LIMITATIONS

The strength of conclusions is limited by the small number of studies included. Consideration of the relationship between depression, intrusive memories and trauma exposure is required.

CONCLUSIONS

Intrusive memories are experienced by a large majority of adults with depression and may therefore be an important target for cognitive intervention. Larger scale measurement of clinical outcome is needed with identification of individual factors predicting treatment response.

Investigation of the impact of total sleep deprivation at home on the number of intrusive memories to an analogue trauma

Sleep enhances the consolidation of memory; however, this property of sleep may be detrimental in situations where memories of an event can lead to psychopathology, such as following a traumatic event. Intrusive memories of trauma are emotional memories that spring to mind involuntarily and are a core feature of post-traumatic stress disorder. Total sleep deprivation in a hospital setting on the first night after an analogue trauma (a trauma film) led to fewer intrusive memories compared to sleep as usual in one study. The current study aimed to test an extension of these findings: sleep deprivation under more naturalistic conditions-at home. Polysomnographic recordings show inconsistent sleep deprivation was achieved at home. Fewer intrusive memories were reported on day 1 after the trauma film in the sleep-deprived condition. On day 2 the opposite was found: more intrusive memories in the sleep-deprived condition. However, no significant differences were found with the removal of two participants with extreme values and no difference was found in the total number of intrusive memories reported in the week following the trauma film. Voluntary memory of the trauma film was found to be slightly impaired in the sleep deprivation condition. In conclusion, compared to our eariler findings using total sleep deprivation in a hospital setting, in the current study the use of inconsistent sleep deprivation at home does not replicate the pattern of results on reducing the number of intrusive memories. Considering the conditions under which sleep deprivation (naturalistic versus hospital) was achieved requires further examination.

Association between intrusive negative autobiographical memories and depression: A meta-analytic investigation

The study investigated several associations between depression and intrusive negative autobiographical memories. A systematic literature search identified 23 eligible studies (N = 2,582), which provided 59 effect sizes. Separate meta-analyses indicated that depression was moderately, positively associated with intrusive memory frequency, memory distress, maladaptive memory appraisals, memory avoidance, and memory rumination. Intrusive memory vividness was not significantly associated with depression. There were insufficient data to examine the relationship between depression and memory vantage perspective. Between-study heterogeneity was high for intrusive memory frequency and memory avoidance, and the percentage of females in studies significantly moderated the relationship between these variables and depression. An additional exploratory meta-analysis (3 studies; N = 257) indicated that intrusive memories were experienced more frequently by those with posttraumatic stress disorder than those with depression. Overall, the findings suggest that intrusive memories warrant clinical attention as they may contribute to the maintenance of depressive symptomatology.

The impact of depression and PTSD symptom severity on trauma memory

Posttraumatic stress disorder (PTSD) and depression frequently co-occur following a traumatic event. Differences in the processing of autobiographical memory have been observed in both disorders in the form of overgeneralised memories and negative intrusive memories. The current study examined how symptoms of PTSD and depression influence the phenomenological characteristics of trauma memories. Undergraduate students who had experienced a traumatic event (n = 696) completed questionnaires online including measures of PTSD and depressive symptom severity. They rated their trauma memory on several phenomenological characteristics using the Memory Experiences Questionnaire [Sutin, A. R., & Robins, R. W. (2007). Phenomenology of autobiographical memories: The memory experiences questionnaire. Memory.]. Moderated multiple regression was used to examine how PTSD and depressive symptom severity related to each phenomenological characteristic. Symptoms of PTSD and depression were related separately and uniquely to the phenomenological characteristics of the trauma memory. PTSD severity predicted trauma memories that were more negative, contained higher sensory detail, and were more vivid. In contrast, depressive symptom severity predicted trauma memories that were less accessible and less coherent. These findings suggest that depressive and PTSD symptomatology affect traumatic memory differently and support a distinction between these two disorders.

Visual mental imagery and symptoms of depression - results from a large-scale web-based study

BACKGROUND

Mental imagery may influence the onset and maintenance of depression, but specific mechanisms have not yet been determined.

METHODS

Nine hundred twelve participants completed questionnaires on positive and negative mental images, as well as images of injury and death that lead to positive emotions ("ID-images"), and depressive symptomatology. The assessment was carried out online to reduce effects of social desirability.

RESULTS

Positive images were reported by 87 % of the sample, negative images by 77 %. ID-images were present in one-third of the sample. A connection with depression severity was found for the absence of positive mental images and the presence of negative images as well as ID-images. Higher depression scores were associated with more frequent and vivid negative images, greater imagery distress, and a higher proportion of negative relative to positive images.

CONCLUSIONS

Mental images are clearly related to depression. Future research should focus on ID-images and their connection to suicide-risk in depressed patients.

Psychological Effect of an Analogue Traumatic Event Reduced by Sleep Deprivation

STUDY OBJECTIVE

To examine the effect of sleep deprivation compared to sleep, immediately after experimental trauma stimuli on the development of intrusive memories to that trauma stimuli.

DESIGN

Participants were exposed to a film with traumatic content (trauma film). The immediate response to the trauma film was assessed, followed by either total sleep deprivation (sleep deprived group, N = 20) or sleep as usual (sleep group, N = 22). Twelve hours after the film viewing the initial psychological effect of the trauma film was measured and for the subsequent 6 days intrusive emotional memories related to the trauma film were recorded in daily life.

SETTING

Academic sleep laboratory and participants' home environment.

PARTICIPANTS

Healthy paid volunteers.

MEASUREMENTS AND RESULTS

On the first day after the trauma film, the psychological effect as assessed by the Impact of Event Scale - Revised was lower in the sleep deprived group compared to the sleep group. In addition, the sleep deprived group reported fewer intrusive emotional memories (mean 2.28, standard deviation [SD] 2.91) compared to the sleep group (mean 3.76, SD 3.35). Because habitual sleep/circadian patterns, psychological health, and immediate effect of the trauma film were similar at baseline for participants of both groups, the results cannot be accounted for by pre-existing inequalities between groups.

CONCLUSIONS

Our findings suggest that sleep deprivation on one night, rather than sleeping, reduces emotional effect and intrusive memories following exposure to experimental trauma.