Intrusive memories in depression and posttraumatic stress disorder

This study compared the stressors and consequent intrusive memories reported by matched samples of patients with posttraumatic stress disorder (PTSD) and major depression. Although intrusive memories were slightly more common among PTSD patients, both quantitative and qualitative measures revealed few differences between the groups. PTSD patients were more likely to have experienced personal illness or assault, and depressed patients family deaths and illness, and interpersonal events. Factor analysis of the associated emotions and memory characteristics suggested the existence of specific links between fear and reliving, and helplessness and out-of-body experiences. Possible inhibitory relationships between fear and sadness, and between guilt and anger, were also noted.     

Characteristics of intrusive memories in a community sample of depressed, recovered depressed and never-depressed individuals

An accumulating body of evidence has revealed that intrusive autobiographical memories of negative events play a role in depression. Despite increasing understanding of the phenomenological experience of these memories, previous research in this area has been conducted in either nonclinical samples, or in clinical samples without an adequate control group. This study aimed to replicate and extend findings with dysphoric samples by comparing the content and characteristics of intrusive memories in clinically depressed (n = 25), recovered (n = 30) and never-depressed (n = 30) participants. Participants completed mood measures, and a battery of self-report questionnaires that indexed intrusive memory frequency, avoidance and characteristics. Intrusive memories were common and shared strikingly similar characteristics across the three groups. The key finding was that depressed participants reported higher levels of intrusion-related distress, associated emotions (especially sadness and helplessness), interference as a result of the memories and memory vividness compared to the never-depressed group. Despite similar levels of intrusion, there were group differences in avoidance such that depressed participants reported higher levels of avoidance than the never-depressed group. These results provide further support for the proposal that clinical interventions for depression could usefully incorporate components that aim to reduce intrusive autobiographical memories and target avoidance strategies.     

Autobiographical memory processes and the course of depression.

The authors report a 6-month follow-up study of clinically depressed patients. At baseline, 2 indexes of autobiographical memory functioning were assessed: the presence of spontaneous intrusive memories of stressful life events and performance on the Autobiographical Memory Test (J. M. G. Williams & K. Broadbent, 1986), which measures overgeneral memory. The index of overgeneral memory was associated with greater levels of spontaneous intrusion of stressful memories. Overgeneral memory did not predict outcome, but depression at follow-up was predicted by the amount of intrusion and avoidance of stressful memories, even after controlling for initial severity of psychiatric symptoms.     

Intrusive images and memories in major depression

Individuals with current major depression were interviewed to investigate the prevalence of distressing intrusive mental imagery among depressed patients and study the phenomenology of these intrusions. Of the 39 currently depressed patients, 17 experienced some form of repetitive intrusive imagery (i.e., either an intrusive memory or image), with intrusive memories being more common than images. The intrusive imagery was experienced as highly uncontrollable and interfered significantly with patients' everyday lives. The intrusions were experienced with a sense of 'nowness', as well as physical and emotional re-experiencing. Despite high levels of re-experiencing, levels of dissociation were very low. The intrusive imagery was in some patients part of a wider network of key defining autobiographical memories, consistent with the idea that it is likely to play a significant role in maintaining the patient's depressive mood. Interventions targeting these intrusions could potentially result in a positive shift in depressed mood.     

The characteristics of involuntary and voluntary autobiographical memories in depressed and never depressed individuals

This study compares involuntary and voluntary autobiographical memories in depressed and never depressed individuals. Twenty depressed and twenty never depressed individuals completed a memory diary; recording their reactions to 10 involuntary and 10 voluntary memories over 14-30days. Psychiatric status (Structured Clinical Interview for DSM-IV, SCID-1), psychopathology, rumination and avoidance were assessed. For both groups, involuntary memories more frequently lead to strong reactions than voluntarily memories. For both modes of retrieval, depressed individuals reported more frequent negative reactions than never depressed individuals and rated memories as more central to identity with higher levels of rumination and avoidance. Depressed individuals retrieved both positive and negative memories during involuntary retrieval. These findings support the view that involuntary memory retrieval represents a basic mode of retrieval during healthy and disordered cognition, and that during depression, both involuntary and voluntary memories are central to identity and associated with rumination and avoidance.     

Exploring self-defining memories in schizophrenia

Previous studies have shown that patients with schizophrenia are impaired in recalling specific events from their personal past. However, the relationship between autobiographical memory impairments and disturbance of the sense of identity in schizophrenia has not been investigated in detail. In this study the authors investigated schizophrenic patients’ ability to recall self-defining memories; that is, memories that play an important role in building and maintaining the self-concept. Results showed that patients recalled as many specific self-defining memories as healthy participants. However, patients with schizophrenia exhibited an abnormal reminiscence bump and reported different types of thematic content (i.e., they recalled less memories about past achievements and more memories regarding hospitalisation and stigmatisation of illness). Furthermore, the findings suggest that impairments in extracting meaning from personal memories could represent a core disturbance of autobiographical memory in patients with schizophrenia.     

Giving meaning to illness: An investigation of self-defining memories in patients with relapsing-remitting multiple sclerosis patients

Multiple sclerosis (MS) patients are often unable to adequately fulfill their established roles due to physical disabilities and cognitive changes, making this chronic illness particularly threatening to personal identity. Twenty-five MS patients and 25 healthy controls were asked to recall five self-defining memories (SDM). Overall characteristics of SDM did not differ between patients and controls; MS patients displayed preserved capacity to draw meaning upon past events. Moreover, almost two-thirds of MS patients mentioned at least one illness related SDM and about 25% of patients’ SDM referred to MS. These memories were experienced as more negative and associated with more tension than other SDM but led toward more positive emotion and less negative emotion over time; they were also more central and more integrated to the personal identity. We concluded that self-challenging events due to MS may trigger both cognitive and emotional processes enabling the integration of illness in patients’ self-representations.     

Intrusive and non‐intrusive memories in a non‐clinical sample: The effects of mood and affect on imagery vividness

We studied the number, valence, and vividness of intrusive and non‐intrusive memories in two groups (N = 20) of pre‐screened non‐depressed mood and depressed mood undergraduate participants. They were asked to generate as many intrusive memories (IMs) as possible from the prior 2 weeks, together with pleasant and unpleasant non‐intrusive memories from the same period. They subsequently formed images of these memories and rated them on measures of vividness, valence, arousal, and overall affect, while having their heart rate, skin conductance, and electromyogram monitored. IMs were common, with participants generating a mean of 1.15 pleasant IMs and 1.60 unpleasant IMs, and there was some evidence that they were mood‐congruent. IMs were more vivid than non‐intrusive memories, a difference not due to either valence or arousal. We conclude that IMs are a general feature of human memory rather than just a symptom of certain clinical disorders.     

Do intrusive memory characteristics predict depression at 6 months?

Two prospective studies have investigated whether the presence, intrusion, and avoidance of negative intrusive memories predict depression, and have reported conflicting findings. We aimed to replicate and extend these investigations by exploring the role of intrusion and avoidance of intrusive memories, as well as memory characteristics, in the prediction of depression prospectively. At Time 1 a mixed sample of community participants (N=85) were interviewed and completed self-report measures of depression, anxiety, and intrusive memory features. At Time 2 (6 months later, N=64) depression and anxiety symptoms were reassessed. Results were partly consistent with hypotheses for the sub-sample of participants who did not receive treatment between the baseline and follow-up assessments. Baseline levels of intrusion and some memory features (uncontrollability, distress, interference, numbness, detachment) predicted follow-up depression, controlling for baseline depression symptoms. Unexpectedly, avoidance of intrusive memories and other features (e.g., here and now quality) did not predict depression. Levels of intrusion and avoidance did not predict anxiety at follow-up. These results provide further evidence that intrusive memories are not simply an epiphenomenon of depression, but predict depression prospectively. Our results suggest that novel, depression-specific theories that emphasise the role of memory disturbances in the maintenance of depression are needed.     

Levels of specificity of autobiographical memories and of biographical memories of the deceased in bereaved individuals with and without complicated grief

Traumatized individuals experiencing posttraumatic stress have difficulty retrieving specific autobiographical memories to cue words on the Autobiographical Memory Test (AMT; J. M. G. Williams & K. Broadbent, 1986). This may represent a generalized, functional avoidance of the personal past. However, such individuals also often report specific intrusive memories of their trauma in the day-to-day. This raises the possibility that memories tied to the source of the person's distress are immune to this putative avoidance process. This was investigated in bereaved individuals with complicated grief (CG) who reported intrusive, specific memories from the life of their deceased loved one, and matched bereaved controls without CG. Participants performed the AMT and two Biographical Memory Tests (BMTs), cueing memories from the life of the deceased (BMT-Deceased) and from a living significant other (BMT-Living). To negative word cues, the CG group showed reduced specificity for the AMT and BMT-Living, relative to controls, but this effect was reversed on the BMT-Deceased. These data support the proposal that memories tied to the source of an individual's distress are immune to the processes that underlie the standard reduced specificity effect.     

Intrusive imagery in severe health anxiety: Prevalence, nature and links with memories and maintenance cycles

Increased understanding of the nature and role of intrusive imagery has contributed to the development of effective treatment protocols for some anxiety disorders. However, intrusive imagery in severe health anxiety (hypochondriasis) has been comparatively neglected. Hence, the current study investigates the prevalence, nature and content of intrusive imagery in 55 patients who met DSM-IV-TR (APA, 2000) criteria for the diagnosis of hypochondriasis. A semi-structured interview was used to assess the prevalence, nature and possible role of intrusive imagery in this disorder. Over 78% of participants reported experiencing recurrent, distressing intrusive images, the majority (72%) of which either were a memory of an earlier event or were strongly associated with a memory. The images tended to be future orientated, and were reliably categorised into four themes: i) being told ‘the bad news’ that you have a serious/life threatening-illness (6.9%), ii) suffering from a serious or life-threatening illness (34.5%), iii) death and dying due to illness (22.4%) and iv) impact of own death or serious illness on loved ones (36.2%). Participants reported responding to experiencing intrusive images by engaging in avoidance, checking, reassurance seeking, distraction and rumination. Potential treatment implications and links to maintenance cycles are considered.     

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

As in post-traumatic stress disorder (PTSD), intrusive memories (IMs) also play an important role in depression. Evidence about the comparative quality of IMs in PTSD and depression is limited and inconsistent. A total of 28 adults with PTSD, 29 with depression, and 30 controls identified intrusive and voluntary segments of narrative memories of key events. Self-report and language measures of memory quality were obtained. Depressed and PTSD participants reported higher frequency of IMs and higher IM-related interference than controls. IMs in PTSD participants were distinguished from depressed and control participants by higher self-rated distress, higher self-rated sensory quality, and a higher proportion of sensory words in the narrative. The depressed and control groups did not differ on IM quality. PTSD IM segments had more sensory content than voluntary segments and fewer temporal markers. The IM segments of the depressed and control groups had fewer temporal markers than the voluntary segments. Depression severity predicted fewer sensory words in the IM after considering peri-event dissociation and arousal but did not add to the prediction of other IM qualities. A strong sensory quality is a distinctive feature of IMs in PTSD but not in depression. Basic sensory processes contribute to the intrusiveness of remembering in PTSD but not in depression.     

Mindfulness-based cognitive therapy reduces overgeneral autobiographical memory in formerly depressed patients

Previous research on depressed and suicidal patients and those with posttraumatic stress disorder has shown that patients' memory for the past is overgeneral (i.e., patients retrieve generic summaries of past events rather than specific events). This study investigated whether autobiographical memory could be affected by psychological treatment. Recovered depressed patients were randomly allocated to receive either treatment as usual or treatment designed to reduce risk of relapse. Whereas control patients showed no change in specificity of memories recalled in response to cue words, the treatment group showed a significantly reduced number of generic memories. Although such a memory deficit may arise from long-standing tendencies to encode and retrieve events generically, such a style is open to modification.     

Cognitive avoidance of intrusive memories and autobiographical memory: specificity, autonoetic consciousness, and self-perspective

Autobiographical memory (AM) specificity is impaired in depression and post-traumatic stress disorder. Previous studies emphasised the role of cognitive avoidance of intrusive memories in this impairment. This study aimed to examine the association of cognitive avoidance of intrusive memories with specificity, autonoetic consciousness, and self-perspective. A total of 38 healthy participants were given the revised Impact of Event Scale (IES-R) and an AM task designed to assess positive and negative memories regarding specificity, autonoetic consciousness (remember/know procedure), and self-perspective (field/observer procedure). Taking into account age, verbal IQ, mood, harm avoidance, and executive resources, the IES-R avoidance subscale was negatively correlated with specificity and remember responses for positive memories, and with remember and field responses for negative memories. These findings suggest that cognitive avoidance of intrusive memories is associated with a decrease of the episodic components of AM retrieval.     

An investigation of the cognitive and experiential features of intrusive memories in depression

Intrusive autobiographical memories of negative past events are a clinical feature common to post-traumatic stress disorder (PTSD) and depression. Recent investigations provide increasing evidence that shared cognitive processes are linked to the maintenance of intrusive memories in both conditions. Still absent from the existing literature, however, is a systematic examination of the basic content and defining characteristics of intrusive memories in depression. This study sought to: (i) outline the content and features of intrusive memories in depression, and (ii) investigate whether intrusion characteristics linked to the persistence of intrusive memories in PTSD are also characteristic of intrusive memories in depression. A sample of undergraduate students (n=250) were interviewed and assessed for the presence of an intrusive memory in the past week, and completed a battery of measures that indexed cognitive and affective responses to the memory. Consistent with prediction, intrusive memories contained high levels of sensory experience and were marked by a sense of "nowness". In accord with studies with PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This pattern of findings was replicated in a dysphoric (BDI-II>or=12) sub-sample of participants. Our results underscore the value of drawing on theoretical conceptualisations and empirical findings from the post-traumatic stress literature to extend our understanding of intrusive memories in depression.     

An investigation of the cognitive and experiential features of intrusive memories in depression

Intrusive autobiographical memories of negative past events are a clinical feature common to post-traumatic stress disorder (PTSD) and depression. Recent investigations provide increasing evidence that shared cognitive processes are linked to the maintenance of intrusive memories in both conditions. Still absent from the existing literature, however, is a systematic examination of the basic content and defining characteristics of intrusive memories in depression. This study sought to: (i) outline the content and features of intrusive memories in depression, and (ii) investigate whether intrusion characteristics linked to the persistence of intrusive memories in PTSD are also characteristic of intrusive memories in depression. A sample of undergraduate students (n=250) were interviewed and assessed for the presence of an intrusive memory in the past week, and completed a battery of measures that indexed cognitive and affective responses to the memory. Consistent with prediction, intrusive memories contained high levels of sensory experience and were marked by a sense of “nowness”. In accord with studies with PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This pattern of findings was replicated in a dysphoric (BDI-II≥12) sub-sample of participants. Our results underscore the value of drawing on theoretical conceptualisations and empirical findings from the post-traumatic stress literature to extend our understanding of intrusive memories in depression.     

Reduced goal specificity is associated with reduced memory specificity in depressed adults

Models of autobiographical memory suggest a close association between memories, future imagination and setting specific personal goals. However this association has yet to be tested with depressed individuals. The aim of this study was to examine whether the specificity of remembering past and imagining future personal events is associated with the specificity of approach and avoidance goals in depressed individuals. Two samples comprising adults who met criteria for major depressive disorder (MDD; N=30) and adults who had no prior history or current depression (N=30) completed autobiographical memory and future event tests, and a personal goal task. In the depressed sample, the specificity with which participants remembered the past was significantly associated with the specificity with which they generated future goals. The depressed sample also elicited fewer specific approach and avoidance goals compared to the non-depressed sample. These findings suggest that an overgeneral memory deficit extends to impairments in goal specificity.