Reducing depressive intrusions via a computerized cognitive bias modification of appraisals task: Developing a cognitive vaccine
Introduction
The distressing experience of negative intrusive memories is a cognitive feature of depression, and maladaptive appraisals of such memories are associated with symptom persistence. To date, research in this area has been correlational. In contrast, the aim of the current study was to use a computerized cognitive bias modification (CBM) of appraisals paradigm to experimentally manipulate appraisals about depressive intrusions. We tested the effects of this appraisal bias manipulation on the frequency of depressive intrusions for a standardized event (a depressing film).
Whilst intrusive negative memories do not form part of the diagnostic criteria for depression (American Psychiatric Association, 1994), or traditional formulations of cognitive therapy, growing evidence has demonstrated that these types of memories are commonly experienced by depressed patients (Birrer et al., 2007, Carlier et al., 2000, Kuyken and Brewin, 1994). Specifically, in some samples, up to 90% of depressed patients report negative intrusive memories (Birrer et al., 2007, Brewin et al., 1996). Not only are such memories common across a range of psychopathologies (Holmes et al., 2007, Holmes and Hackmann, 2004), they also appear to be as frequently experienced and to prompt the same degree of cognitive avoidance in individuals with PTSD and depression. For example, Brewin, Watson, McCarthy, Hyman, and Dayson (1998) reported that depressed cancer patients endorsed levels of intrusion and avoidance of their intrusive memories (measured by the Impact of Event Scale) that were equivalent to patients with PTSD. Birrer et al. (2007) reported that “the intrusive images were associated with as much distress in PTSD patients as in depressed patients with or without trauma” (p. 2060). They further commented that it is “surprising that intrusive images have received more attention in PTSD than in depression” (p. 2062). Patel et al. (2007) suggested that intrusive memories play a key role in maintaining depressed mood. This suggestion accords with evidence that levels of intrusion frequency and avoidance are associated with depression severity (Kuyken & Brewin, 1994) and are predictive of depression over six months (Brewin, Reynolds, & Tata, 1999).
Recent clinical studies have examined the potential benefits of targeting intrusive memories in the treatment of depression. Kandris and Moulds (2008) completed a clinical case study that suggested the utility of imaginal exposure in reducing intrusive memories and depression symptoms. At posttreatment and six-month follow-up, the patient no longer met diagnostic criteria for depression. Wheatley et al. (2007) conducted two case studies in which they employed imagery rescripting techniques to reduce intrusive memories in patients with depression. Their findings were promising: they reported significant reductions in depressive symptoms that were maintained at 12-month follow-up.
Negative, maladaptive appraisals of intrusive memories (e.g., having intrusive memories means I'm crazy) have been studied more extensively in PTSD than in depression. Cognitive models of PTSD (e.g., Ehlers & Clark, 2000) propose that when an individual assigns maladaptive appraisals to intrusive memories, the experience of these memories results in more distress, and, secondarily, prompts the use of avoidant strategies such as thought suppression. These strategies paradoxically result in the increase in the frequency of intrusions (Ehlers and Clark, 2000, Ehlers and Steil, 1995). From this perspective, maladaptive appraisals are thus a major driver in the maintenance of PTSD symptoms (Brewin and Holmes, 2003, Ehlers and Clark, 2000, Ehlers and Steil, 1995). Evidence for the role of appraisals has been provided by retrospective studies that showed significant associations between negative interpretations of intrusive memories and PTSD severity (Clohessy & Ehlers, 1999; Dunmore et al., 1999, Steil and Ethlers, 2000), and longitudinal prospective studies in which maladaptive appraisals predicted PTSD severity over time, beyond initial symptom levels (Bryant and Guthrie, 2007, Dunmore et al., 2001). Critical support for the importance of maladaptive appraisals was provided by Bryant and Guthrie's (2007) prospective study of trainee firefighters. They demonstrated that maladaptive appraisals [specifically the self-subscale of the Posttraumatic Cognitions Inventory (Foa, Ehlers, Clark, Tolin, & Orsillo, 1999)] endorsed prior to trauma exposure (i.e., fire fighting) predicted PTSD severity at a four-year follow-up.
Negative appraisals of intrusive memories have been studied more recently in the context of depression. Maladaptive appraisals (e.g., having this memory means that I am weak) have been proposed to maintain intrusive memories, and in turn, depressive symptoms (Starr and Moulds, 2006, Williams and Moulds, 2008). Starr and Moulds (2006) and subsequently Williams and Moulds (2008) showed that maladaptive appraisals of intrusions were associated with levels of depressive symptoms. Further, these associations held after controlling for the severity of the memory content and intrusion frequency. The strongest predictor of depression in these studies was the negative appraisals of the intrusions. Given their proposed role in intrusion persistence (i.e. maintaining the presence of negative intrusive memories), such maladaptive appraisals present a potential target for intervention. With this in mind, the current study experimentally tested the immediate and downstream effects of manipulating maladaptive appraisals of intrusive memories.
An experimental tool with which to manipulate cognitive biases such as appraisals of intrusive memories is the CBM paradigm. CBM is a computerized technique that was developed to systematically modify biases by repeated exposure to stimulus examples (Mathews & Mackintosh, 2000). The paradigm has predominantly been used to experimentally modify interpretations of ambiguous situations (Holmes et al., in press, Holmes et al., 2006, Mathews and Mackintosh, 2000, Salemink et al., 2007). Recently, Mackintosh, Woud, Potsma, Dalgleish, and Holmes, submitted for publication. extended the application of the CBM paradigm beyond ambiguous external information, and targeted the interpretation of internal cognitions; specifically, appraisals of intrusive trauma memories in a non-clinical sample. The negative training incorporated maladaptive appraisals associated with PTSD (Foa et al., 1999). The positive training condition consisted of the opposite, adaptive counterpart to each of the negative items. The impact of the CBM was tested on a standardized analogue traumatic event known to generate intrusions – a traumatic film. Participants who completed positive CBM rated their intrusive memories of the traumatic film (over one week) as less distressing (in Experiment 1) and less frequent (in Experiment 2) than those who completed negative CBM.
For the current study, a new CBM paradigm was developed specifically to target maladaptive appraisals of intrusive memories that are associated with depression. We identified and employed the precise maladaptive appraisals endorsed by people with depressive symptoms by drawing on data from previous studies (Freeston et al., 1992, Obsessive Compulsive Cognitions Working Group, 2001, Williams and Moulds, 2008). Stimuli in the negative condition utilized maladaptive appraisals such as “Intrusive memories mean that I am coping badly”. The positive condition utilized a corresponding opposite/adaptive version (i.e., “Intrusive memories mean that I am coping well”). This paradigm was tested in response to a depressive (as opposed to trauma) film that was compiled to provide an analogue of a depression-related negative event.
The aim of the current study was to test the utility of this newly developed CBM paradigm to modify depressive appraisals of intrusive memories. We predicted that: compared to the negative CBM condition, positive CBM would produce: (1) a more positive appraisal bias, as indexed by the recognition test, and (2) reduced levels of intrusions of a depressing film, as indexed by three convergent measures: (i) a one-week intrusion diary, (ii) the Impact of Event Scale (IES; Horowitz, Wilner, & Alvarez, 1979), and (iii) an intrusion provocation task.
Section snippets
Participants
The 40 participants comprised 19 males and 21 females, with a mean age of 27.67 years (SD = 9.95). Participants were recruited through multiple sources: via online advertisements, posters displayed on campus, and voluntary sign-up during orientation week at two Oxford universities. For ethical reasons, the material that was used for recruitment included information that warned participants that the experiment involved viewing distressing film clips. Participants were paid a nominal amount to
Comparison of participants in positive and negative conditions at baseline
There were no significant differences between the groups in terms of gender (χ2 [1, N = 48] = 0.33, p = .56). The conditions were also comparable in terms of age, trait depression (BDI-II), trait anxiety (STAI-T), hopelessness (BHS), the tendency to use imagery (SUIS), and state positive and negative affect (PANAS) (ts < 1.05, ps > .30) (see Table 1).
Film ratings and diary compliance
There was no significant difference between conditions in the attention paid to the films (M = 90.17, SD = 9.91), t(46) = 0.46, p = .64, or diary compliance, with
Discussion
The current study sought to examine whether maladaptive appraisals about intrusive memories of a negative event could be altered by computerized CBM techniques. Our novel CBM paradigm was developed to encourage changes in maladaptive responding to intrusions. Our critical results were that as predicted, compared to participants who underwent negative CBM, participants who underwent positive CBM produced: 1) a greater positive appraisal bias and 2) reduced levels of intrusions evident by
Acknowledgements
Tamara Lang is supported by the University of Oxford Department of Psychiatry Bursary for Overseas Students. Michelle Moulds is supported by a Fellowship from the Australian Research Council (DP0984791). Emily Holmes is supported by a Royal Society Dorothy Hodgkin Fellowship and in part by a grant from the Economic and Social Research Council (RES-061-23-0030) and a John Fell OUP Grant (PRAC/JF).
We would like to thank Dr Bundy Mackintosh for her helpful discussion. We would also like to thank
References (48)
- et al.
Intrusive images in PTSD and in traumatised and non-traumatised depressed patients: a cross-sectional clinical study
Behaviour Research and Therapy
(2007) - et al.
Psychological theories of posttraumatic stress disorder
Clinical Psychology Review
(2003) - et al.
Intrusive memories and depression in cancer patients
Behaviour Research and Therapy
(1998) - et al.
Cognitive factors involved in the onset and maintenance of posttraumatic stress disorder (PTSD) after physical or sexual assault
Behaviour Research and Therapy
(1999) - et al.
A prospective investigation of the role of cognitive factors in persistent posttraumatic stress disorder (PTSD) after physical or sexual assault
Behaviour Research and Therapy
(2001) - et al.
A cognitive model of posttraumatic stress disorder
Behaviour Research and Therapy
(2000) - et al.
Cognitive intrusions in a non-clinical population. II. Associations with depressive, anxious, and compulsive symptoms
Behaviour Research and Therapy
(1992) - et al.
Imagery rescripting in cognitive behaviour therapy: images, treatment techniques and outcomes
Journal of Behavior Therapy and Experimental Psychiatry
(2007) - et al.
Inducing and modulating intrusive emotional memories: a review of the trauma film paradigm
Acta Psychologica
(2008) - et al.
Positive interpretation training: effects of mental imagery versus verbal training on positive mood
Behavior Therapy
(2006)