Distressing visual mental images in depressed patients and healthy controls – Are they one and the same?

Author’s Accepted Manuscript Distressing visual mental images in depressed patients and healthy controls – are they one and the same? Charlotte Weßlau, Klara Lieberz, Viola OertelKnöchel, Regina Steil www.elsevier.com/locate/psychres

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S0165-1781(15)30737-X http://dx.doi.org/10.1016/j.psychres.2016.09.034 PSY9968

To appear in: Psychiatry Research Received date: 24 November 2015 Revised date: 16 September 2016 Accepted date: 20 September 2016 Cite this article as: Charlotte Weßlau, Klara Lieberz, Viola Oertel-Knöchel and Regina Steil, Distressing visual mental images in depressed patients and healthy controls – are they one and the same?, Psychiatry Research, http://dx.doi.org/10.1016/j.psychres.2016.09.034 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Distressing visual mental images in depressed patients and healthy controls

Distressing visual mental images in depressed patients and healthy controls – are they one and the same? Charlotte Weßlau , Klara Lieberz , Viola Oertel-Knöchel * & Regina Steil Goethe University, Department of Clinical Psychology and Intervention, Institute of Psychology, Varrentrappstr. 40-42, 60486 Frankfurt Main, Germany Laboratory of Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe-University, Frankfurt/Main, Germany * Department of Clinical Psychology and Intervention, Institute of Psychology, Goethe University Frankfurt, P.O. Box 11 19 32-120, 60054 Frankfurt Main, Germany Telephone: +49 - 69 - 798-23971, Fax: +49 - 69 - 798-23459 E-mail: [email protected] a*

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Abstract Negative mental images are common in a range of mental disorders. So far, only inconclusive evidence has been obtained for depression specificity. We assessed the disparities and similarities of a variety of imagery characteristics in 17 patients suffering from depressive disorders and 17 healthy matched controls who all reported negative mental images. The number of intrusive images, their frequency, and the associated distress were significantly greater for the depressed individuals. Compared with non-depressed controls, negative images during depression were more frequently triggered by internal factors and led to depression-related emotions. Approximately 30 percent of the images in the depressed group did not consist of actual memories of real-life events. No significant differences in vividness or perceived controllability were observed, but the depressed patients experienced significantly more bodily symptoms during the intrusions than the healthy controls. The results indicate that the central characteristics of the negative mental images of depressed and non-depressed individuals are distinguishable, despite some similarities, and may contribute to depressive symptoms.

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Keywords Visual imagery; mental images; depression; maintenance of depressive symptoms

 Introduction Recently, mental imagery has increasingly become a focal topic in research on underlying factors in mood disorders. Negative mental images in depression have been found to be associated with emotional distress (Newby and Moulds, 2011a), to trigger and be triggered by depressive rumination (Birrer et al., 2007; Pearson et al., 2008) and lead to dysfunctional coping strategies like suppression or avoidance (Brewin et al., 1999). As they seem to be easily reactivated during remission (Brewin et al., 1999), they may constitute a vulnerability factor for depressive relapses (Weßlau and Steil, 2014). Visual mental images have been found in a variety of mental disorders, such as posttraumatic stress disorder (PTSD) (Hackmann et al., 2004), social phobia (Hackmann et al., 2000) and bipolar disorder (Holmes et al., 2008). Research has shown that distressing mental imagery in individuals with depression is not as distinct from the distressing mental imagery formed by individuals with PTSD as has been assumed in the past (Birrer et al., 2007). Intrusive memories seem to be common even in non-clinical populations (Bywaters et al., 2004). Content seems to be one of the few distinguishing factors across disorders. Intrusions in depression frequently address loss and interpersonal crisis, whereas the traumatic memories in PTSD primarily concern personal injury or assault (Wheatley and Hackmann, 2011). Although some studies have revealed no differences between depressed individuals and non-depressed individuals in the

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prevalence of intrusive memories (Newby and Moulds, 2011a; Spenceley and Jerrom, 1997), other studies found significant differences in, for example, the number of intrusive memories (Brewin et al., 1998). So far, existing studies concentrated mostly on intrusive memories in depressed and non-depressed controls (Brewin, 1998; Brewin et al., 1998; Newby and Moulds, 2011a; Spenceley and Jerrom, 1997) or on the influence of depression on mental imagery in other disorders (Karatzias et al., 2009). We extended previous research on possible depression-specific imagery by including memory- as well as non-memory-based negative mental images and focused on primarily visual imagery – other sensory modalities could still be present, but the visual modality was the necessary and sufficient condition. Studying visual mental imagery, which has been found to use similar neural mechanisms as actual visual perception (Ganis et al., 2004), is of particular importance, as the vividness of visual images seems to be connected to more sensory detail of past or future mental representations in general (D’Argembeau and Van der Linden, 2006); also visual recollections of events are perceived as more distressing (Ehlers and Steil, 1995) and are more common than intrusions represented in other sensory modalities (Hackmann et al., 2004). In this study, we compared the features and impact of negative visual mental images of individuals with current depressive disorder and those of non-depressed individuals. The aim of this study was to determine whether the negative imagery of depressed patients is inherently different from that of healthy controls. Previous studies have identified areas of disparity and similarity in the range of negative mental images when comparing depressed individuals with non-depressed individuals. Specifically, the negative imagery associated with depression seems to be perceived as more distressing and vivid (Newby and Moulds, 2011a). Based on previous research, the current study investigated the following hypotheses regarding differences between depressed patients (DPs) and matched healthy controls (HCs): 1) DPs would report a greater number of negative mental images than HCs. 2) In DPs, the

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most significant negative image would have occurred more frequently in the previous two weeks compared with HCs. 3) Both groups would perceive the negative image to be distressing and vivid, but DPs would consider the image to be significantly more distressing and vivid. 4) DPs’ perceived controllability would be significantly lower than that of HCs; meaning that negative mental imagery in the depressed group would be experienced as more intrusive and thus experienced as a less voluntary event 5) Because DPs would report greater imagery vividness, the image would accompanied by a greater range of sensory modalities compared with the image of HCs. To test these hypotheses, we assessed imagery characteristics in 17 patients suffering from diagnosed depression (DPs) and compared their reports to the reports of 17 healthy controls who were matched on a group level for age, gender, and education (HCs). In addition to these hypotheses, we assessed triggers for intrusions, the accordance of the image with real-life events, vantage point, image-related emotions and image content within and between the two groups. 2. Method 2.1 Participants For the depressed group, the inclusion criteria were a current depressive disorder – (recurrent) Major Depressive Disorder (MDE), Dysthymia, or both – and age between 18 and 65 years. An inclusion criterion for both groups was the experience of negative mental images. The DPs and HPs were matched for age, gender, and educational level. For both groups, people with schizophrenic spectrum disorders and substance-related mental phenomena were excluded to avoid collecting data on hallucination-like mental images. PTSD and social phobia were set as exclusion criteria as we aimed to assess predominantly

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depression-specific visual mental images and the named disorders have been found to be strongly associated with distinct mental imagery. Because our aim was to assess unipolar depression, patients with depressed and (hypo)manic phases were excluded. For the HCs, a lifetime or current depressive disorder was an additional exclusion criterion; one participant suffered from a specific (spider) phobia but the image was not phobia-related; all others reported no diagnoses. N = 26 participants were initially examined for the depressed group; n = 3 patients were excluded (not satisfying the criteria of a depressive disorder: n = 2; acute suicidality: n = 1) or did not want to participate (n = 6). N = 30 participants were examined for the control condition; n = 4 participants were excluded due to a current depressive disorder, and the remaining 26 participants were eligible as matched partners for the depressed patients. A total of 34 participants were matched and included in the final sample, with 17 participants in the depressed group and 17 participants in the non-depressed group. 2.2 Procedure Depressed participants between the ages of 18 and 65 years were recruited via the waiting list of the cognitive behavior therapy (CBT)-based outpatient center at GoetheUniversity in Frankfurt, Germany and the local Department of Psychiatry, Psychosomatic Medicine and Psychotherapy Goethe-University Frankfurt, Germany. Patients with depressive symptoms according to the initial clinical interview at the treatment center who had given their approval regarding their participation in clinical studies were contacted via phone. They underwent a telephone screening concerning the inclusion and exclusion criteria and were given a general overview of the procedure of the study. In this screening, information on negative mental images was also provided and all participants were asked whether they knew this type of imagery, how often it occurred and whether or not they would

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be able to describe such an image in detail (“In this study we would like to know more about visual negative mental images that some people have about themselves, the surrounding world or even the future. Mental images are images that appear before our “mind’s eyes” – either in the form of photo-like ‘snapshots’ or moving film-like scenes. They can be based on memories, alterations of those or may have their roots in imagination or fantasy – thus they can refer to past or future events and even ‘unrealistic’ content. […]”) Patients with a positive screening who were interested in participating were invited for a diagnostic session, in which participants were administered the German version of the SCID-I (Wittchen, 1997) to determine axis I diagnoses and the SCID-II (Fydrich and First, 1997) to assess personality disorders. All interviews were administered by the first author (CW). The patients who fulfilled the inclusion criteria and did not display the exclusion criteria were invited to a second session. In this session, the Interview on Negative Mental Images (INMI, Weßlau & Steil, unpublished) was conducted. The patients were asked to complete the German BDI-II (Hautzinger et al., 2006) to determine the severity of their selfreported depression and the Questionnaire on Negative Mental Images (QNMI, Weßlau & Steil, unpublished) at home after the second session. In the third session, the Hamilton Depression Rating Scale (Hamilton, 1960) was administered to obtain a clinical rating of the patients’ depression severity. The patients were also informed of their diagnoses. The non-depressed control group was recruited via flyers that were distributed in supermarkets, hospitals, the university and online platforms. The non-depressed participants underwent the same procedure, with the exception that only two of the three sessions were required for the diagnostic assessments; they received a monetary compensation of 40 Euros. These assessments were performed by the second author (KL) after extensive training

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(conducted by the first author) to ensure comparability of the diagnostic process. The study was approved by the local ethics committee. 2.3 Materials 2.3.1 Interviews. Interview on Negative Mental Images. This interview (INMI, Weßlau & Steil, unpublished) contains questions on qualitative and quantitative characteristics of the most prominent negative mental image. This imagery interview as well as the questionnaire were developed on the basis of previous studies of mental images (Hackmann et al., 2000; Holmes et al., 2007) and all participants were given a definition of the term visual image (see (Weßlau and Steil, 2014) for a detailed description). So far, no standardized imagery interview has been published or validated. Participants are asked to describe their negative image in as much detail as possible (instruction: “as if you would describe a film or a picture to someone who cannot see it”). Additional questions include the time reference of the image (past, present, future, or fantasy-based image), age at the time of the first occurrence, frequency of the intrusions, imagery distress, and vividness, controllability, concomitant sensory experiences (olfactory, gustatory, etc.) and vegetative symptoms (tachycardia, trembling, nausea, etc.), intrusion triggers and the influence on the participants’ mood. We inquired about the frequency in the following ways: days within the past two weeks and incidence on those days. Thoughts during and about the negative mental image and imageryrelated emotions are assessed. Participants are also asked the extent to which the images depict an actual life event. In the current study, the negative mental images described in the INMI were categorized by two independent raters into the following categories derived from existing literature about imagery content in depression (refer to (Patel et al., 2007): interpersonal problems (disputes or conflicts with significant social partners and termination

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of intimate relationships); injury, illness or death of oneself; injury, illness or death of other people; and assault or threat of assault to oneself. An unspecific (“miscellaneous”) category was added for images that were not classifiable as one of the previously mentioned contents. Cohen’s kappa was calculated to assess inter-rater reliability, with κ = 0.96 (p < 0.001); the raters reached agreement for 33 of the 34 images. For additional descriptions, the mismatched image was assigned to the miscellaneous category by the first author. Structured Clinical Interview for DSM-IV (SCID-I and SCID-II). The German version of the SCID-I interview (Wittchen, 1997) is an extensively used clinician-administered structured interview that assesses a variety of Axis I disorders, such as major depression, PTSD, and social phobia. The SCID-II (Fydrich and First, 1997) assesses the presence or absence of the eleven DSM-IV (American Psychiatric Association, 2000) personality disorders. No quality criteria have been specifically published for the German versions of the SCID-I and SCID–II; however, the inter-rater reliability was moderate to excellent for Axis I disorders and excellent for Axis II (personality) disorders in a non-German sample (Lobbestael et al., 2011). 2.3.2 Questionnaires. Beck Depression Inventory II. The severity of depressive symptoms was assessed using the German Beck Depression Inventory (BDI-II; (Hautzinger et al., 2006). The BDI-II is a well-known and reliable self-report instrument that is frequently employed in clinical and nonclinical samples. The inventory has adequate content validity and sufficient retestreliability, with Cronbach’s α ≥ 0.84 (Kühner et al., 2007). Hamilton Depression Rating Scale. The Hamilton Depression Rating Scale (HDRS; (Hamilton, 1960) is a commonly employed instrument for the external assessment of

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depressive symptoms. The German version reveals acceptable internal consistency (0.73 to 0.91; (CIPS, 2005). Questionnaire on Negative Mental Images. This questionnaire (QNMI, Weßlau & Steil, unpublished) is based on the Intrusion Questionnaire by Hackmann and colleagues (2004); it is the self-report counterpart to the INMI and refers to the past two weeks. All participants were instructed to describe the negative mental image which was most significant to them and then asked a range of questions regarding this specific image (e.g. regarding intrusion frequency, distress, vividness, controllability, triggers etc.). Participants can select a different negative mental image from that selected in the imagery interview if they consider it to be more distressing and meaningful to them at the time of measurement. For this reason, the images that are described in the questionnaire can differ from those described in the interview. In addition to the QNMI, the current study employed the INMI to obtain a more detailed description of the most significant negative images than can be attained using only the questionnaire.

2.4 Statistical analyses Independent samples t-tests were performed for the majority of the group comparisons. Chi-square tests were employed to assess the nominal distribution of gender, image triggers, real life vs. fantasy-based images, imagery perspective (first-person vs. thirdperson) and photo-like vs. film-like images between the two groups. An ANOVA was used to analyze the differences between imagery vantage point and distress and vividness. Data were analyzed using IBM SPSS Statistics for Windows (Version 20.0. Armonk, NY: IBM Corp). Statistical significance was set at an alpha of .05. The effect sizes are reported when possible.

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3. Results 3.1 Sample characteristics The total sample comprised 34 participants with a mean age of 35.9 (SD = 7.8; range = 24 -53); 79.4 percent of the participants were female. In the independent samples t-test comparisons, no group differences in age, t(1,32) = 0.65, p > 0.05, or educational level in years, t(1,32) = 1.23, p > 0.05, were detected. The chi-square test revealed no differences in the gender distribution (χ2 = .18, p > 0.05). As expected, highly significant differences in depression severity (HDRS: t(1,19.8) = -8.61, p < 0.001, d = 3.2; BDI-II: t(1,24.4) = -10.66, p < 0.001, d = 3.98) were obtained. None of the participants fulfilled criteria for any DSM-IV personality disorder. Table 1 presents the sample characteristics for both groups. If not otherwise indicated, the following results refer to the data derived from the QNMI regarding the most relevant negative image.

insert table 1 here 3.2 Frequency, distress, controllability and vividness. The HC group experienced 1.9 (SD = 1.4) different negative mental images. The DP group experienced 3.8 (SD = 1.7) distinct images, t(1,32) = -3.36, p = .002, d = 1.3. Table 2 lists the characteristics of the most significant negative images for the participants in both groups. The frequency of the days on which the negative image occurred was more than three times higher in the DP group than in the HC group, t(1,22.3) = -2.66, p < 0.05, d = 0.9. The image occurred an average of 0.9 times per day in the HC group, compared with 2.4 times per day in the DP group, t(1,22.3) = -2.66, p < 0.05, d = 0.9. A low level of imagery distress was

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observed for both groups – 13.2 out of 100 in the non-depressed group and 35 out of 100 in the depressed group – with a significantly higher distress level in the individuals suffering from depression, t(1,26.7) = -2.31, p <0.05, d = 0.8. No significant group differences in controllability, t(1,32) = 0.99, p > 0.05, d = 0.3, or vividness, t(1,32) = -1.22, p > 0.05, d = 0.4, of the negative image were observed.

insert table 2 here

3.3 Accompanying bodily symptoms and sensory experiences. The participants were asked whether the negative image was accompanied by (vegetative) symptoms of anxiety (shortness of breath, tachycardia, chest pain, trembling, nausea, feeling dizzy, fear of dying, choking feeling, de-personalization or de-realization, numbness or tingling sensation, hot or cold flashes, sweating, fear of losing control or “going crazy”, dry mouth, or muscle tension). The depressed group reported more than twice as many of these symptoms (M = 2.9, SD = 3.2) as the non-depressed group (M = 1.1, SD = 1.4), t(1,22.0) = -2.16, p <.05, d = 0.75. Nearly half of the HCs reported no bodily symptom (47.1 percent, median = 1.0) as compared to 29.4 percent in the DP group (median = 2.0). In addition to the visual component, 23.5 percent of the control group reported another sensory modality (tactile, auditory, olfactory, or gustatory), compared with 35.3

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percent of the depressed group (n = 16 due to missing data). All chi-square group comparisons for the different sensory modalities were non-significant.

3.4 Exploratory analyses. Intrusion Triggers. The role of situations, thoughts, (bodily) feelings, and memories as internal or external triggers for the negative image was explored (multiple answers possible). The number of different types of triggers did not differ between the groups. The depressed group reported a mean of 1.8 (SD = 1.1) different triggers, and the non-depressed participants reported M = 1.3 (SD = 0.8) triggers, t(1,32) = 0.12, p > 0.05. Of the participants, 70.6 percent in the non-depressed group and 58.8 percent in the depressed group named an external situation as a trigger for their negative images (χ2 = .52, p > 0.05). Additionally, no group difference in memories of real-life events as internal triggers (depressed group: 47.1 percent, non-depressed group: 41.2 percent; χ2 = .12, p > 0.05) was observed. Thoughts were considered to be triggers of visual intrusions in only 17.6 percent of the non-depressed individuals, compared with 47.1 percent of the depressed patients (χ2 = 3.36, p = 0.07). None of the non-depressed participants named (bodily) feelings as intrusion triggers, compared with 29.4 percent of the depressed group (χ2 = 5.86, p = 0.02). In addition, 11.8 percent of the non-depressed participants and 17.6 percent of the depressed patients were unable to identify specific intrusion triggers (χ2 = .23, p > 0.05). Accordance with a real-life event. A total of 70.5 percent of the depressed group indicated that their image corresponded with a real-life event, compared with 58.8 percent of the non-depressed group. The difference was nonsignificant (χ2 = .52, p > 0.05). The level of conformity (scale from 0 (not at all) to 100 (totally)) between the mental image and the reallife experience was M = 55.6 (SD = 47.7) for the depressed group and M = 58.2 (SD = 37.5)

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for the non-depressed group. The group difference was nonsignificant, t(1,30.3) = 0.18, p > 0.05. Vantage point and film-like vs. photo-like image. Two participants in the non-depressed group reported that the image ‘switched’ from the first-person to the third-person perspective; n = 6 individuals in the depressed group and n = 6 individuals in the non-depressed group indicated that they only viewed the image from the third-person perspective. The remainder of the participants reported viewing the image from the first-person perspective. The group comparison was nonsignificant (χ2 = 2.20, p > 0.05). No significant differences in the vantage points and imagery distress, F(2,31) =0.961, p > 0.05, were observed. Regarding vividness, the total comparison was also nonsignificant, F(2,31)=1.812, p > 0.05, but post-hoc contrasts revealed a significantly greater level of vividness for the two participants who reported a ‘switch’ between the vantage points compared with those who reported the use of the firstperson perspective, t(20) = -6.66, p < 0.001, or the third-person perspective, t(10) = -2.24, p < 0.05. Most participants characterized their intrusion as a moving film-like image (n = 22). Comparing the groups, 29.4 percent of the non-depressed group described their image as a still photo-like image, compared with 11.8 percent of the depressed group. Only the depressed patients reported a combination of both still and moving images. The distribution between the groups (χ2 = 6.47, p < 0.05) significantly differed, with the combination being the only answer with a significantly different distribution between the groups. Image-related emotions. The emotions (on a scale from 0 to 100) that were most strongly associated with the negative image in the depressed group included the feelings of sadness (M = 83.5, SD = 19.7), paralysis (M = 79.4, SD = 24.5), helplessness (M = 77.9, SD = 22.2), and loneliness (M = 67.7, SD = 37.1). In the non-depressed group, the most prominent

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emotions were fear (M = 57.9, SD = 35.8), helplessness (M = 55.9, SD = 35.7), sadness (M = 38.2, SD = 42.3), and nervousness (M = 26.5, SD = 33.7). Image content. In the depressed group, 41.2 percent of the images referred to “interpersonal problems”, compared with only 11.8 percent in the non-depressed group. Of the participants, 17.6 percent of the depressed patients reported an image in the category “injury, illness or death of oneself” (11.8 percent in the non-depressed group) and 11.8 percent of the depressed patients reported an image in the category of “injury, illness or death of others” (58.8 percent in the non-depressed group). “Assault or threat of assault to oneself” described 11.8 percent of the depressed group and 11.8 percent of the non-depressed group. Only 5.9 percent of images in the non-depressed group were assigned to the “miscellaneous” category, compared with 17.6 percent of the images in the depressed group. The distribution showed a trend toward a significant difference between the groups (χ2 = 9.31, p = 0.05). The category “injury, illness or death of others” was the only category for which the DCs and HCs significantly differed from each other. Table 3 lists examples of the imagery categories. insert table 3 here

4. Discussion This study aimed to determine differences in the characteristics of the negative mental images of individuals with and without a current depression (all of the participants reported distressing images in front of their “mind’s eye”). The depressed group obtained a mean BDIII score of 24.8, which ranged from medium to severe depression, whereas the non-depressed group obtained a mean score of 3.2, which fell below the cut-off for clinical depression. Comparable group differences were obtained for the clinician rating for depression using the HDRS. The depression scores of the current depressed sample were comparable to those

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obtained by Newby and Moulds (2011a), and the scores of the current non-depressed group were slightly lower than those of Newby and Mould’s never-depressed participants (M = 28.60 and M = 6.03, respectively). Significant differences in imagery characteristics were observed between depressed individuals and non-depressed individuals. All participants suffered from at least one negative image, but the number of distinct visual images was twice as high in the depressed group compared to the non-depressed group. Although the mean depression scores were lower than those in the study by Patel et al. (2007), the number of negative mental images was significantly greater in our sample of depressed patients (M = 3.8) compared to M = 2 (composite score of 1.71 (N = 17) different memories and an additional 1.25 different images (n = 4)) in the study by Patel et al., which was more similar to the results for our nondepressed group (M = 1.9). A comparably low number was also obtained by Reynolds and Brewin (1999) (i.e., a mean of 1.1) - however, it is unclear whether participants without any negative image were included in the analysis of the mean score. An explanation for the higher number in our study may be that Reynolds and Brewin only included autobiographical memories; our results showed that only 70% of the images in our depressed group corresponded to a real-life event. It might still be the case that depressed individuals report more negative memories due to a higher number of distressing life-events (Weßlau and Steil, 2014). Confirming our hypothesis, the frequency of the visual intrusions was more than three times higher in the depressed as compared to the non-depressed group. Because other factors such as age, gender and education were evenly distributed between the groups, depression severity seems to be a major factor in the large number of negative mental images and the more frequent occurrence of the most significant image in the past two weeks.

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Contrary to our expectations, imagery distress was low throughout the sample; however, the negative image was perceived as significantly more distressing in participants with depression. Avoidance or the retrospective questioning may account for the low levels of distress. No significant group differences in imagery vividness or perceived controllability were detected. As the effect sizes were small to medium, the lack of statistical significance was quite likely due to a lack of power. Another explanation might be the retrospective rating of imagery vividness in our study. Although we did not observe any differences in general imagery vividness, the DPs experienced approximately twice as many bodily symptoms during the intrusions compared with the HCs. These symptoms may not be a significant contributor to vividness. Other factors, such as richness in detail, may cause a greater level of vividness; this finding should be assessed in future studies. On the other hand, the accompanying physical symptoms could be experienced by an individual as a sign of imagery vividness, if not necessarily visual vividness, and could be part of the image itself rather than a secondary response to it – a factor which could be targeted in therapeutic interventions. As distressing imagery in the depressed group was more often triggered by internal factors, it can be hypothesized that bodily symptoms may also represent triggers of mental imagery rather than being a consequence or just an imagery component. Future research could adopt experimental manipulation paradigms to address this relationship and to refine intervention techniques – for example assessing temporal connections between somatic experiences and mental images, or using interventions targeting physical symptoms to examine if a reduction in for example heartrate influences the occurrence of mental imagery. Other than the visual modality, depressed individuals did not report a significantly greater number of additional sensory modalities compared with the HCs. The comparable number of sensory modalities may explain the lack of differences in vividness.

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In addition to the examination of our hypotheses, we assessed imagery characteristics on an exploratory basis. Triggers for intrusive images were comparable between the groups, with the exception of a significantly greater number of depressed individuals who named (bodily) feelings as triggers. If (negative) emotional states can specifically induce negative mental images in depression, which produce negative emotions such as sadness, visual mental imagery may be an important factor in the acute “downward spiral” and the long-term maintenance of depressive disorders. DPs and HCs did not differ regarding the relation of the image to a real-life event or the vantage point from which the image was viewed (first-person perspective vs. third-person perspective). Previous studies have shown that the observer-perspective is associated with greater imagery distress in negative intrusive memories (Moulds et al., 2012). Our results did not reveal any differences in the vantage points in regards to the level of distress in our sample. Regarding the prevalence of negative mental images reported in other studies (Brewin et al., 1998; Newby and Moulds, 2011a; Reynolds and Brewin, 1999), our results have demonstrated that non-memory-based images should be considered to prevent a general underestimation of mental imagery. The non-depressed group viewed their image as a non-moving picture significantly more frequently than did the depressed patients. This finding hypothesizes that still pictures may be associated with lower distress. Mental imagery might also function as an emulating process whereby individuals can (voluntarily or involuntarily) simulate past or future events in their mind, a phenomenon termed mental time travel (Berntsen and Jacobsen, 2008; D’Argembeau and Van der Linden, 2006).

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Non-depressed participants experienced fear as their main image-related emotion, whereas depressed individuals ranked feelings of sadness, paralysis and helpless as their predominant emotional reactions. In a depressed state, mood-congruent imagery might be induced and in turn these images could contribute to depression severity by eliciting depression-related emotions such as sadness or helplessness. For the non-depressed group, images mostly involved “injury, illness or death of others” – thus situations in which an individual might be scared or concerned for someone else which can elicit a fear-response. Visual intrusions during depression were accompanied by a significantly greater number of vegetative symptoms. This result may indicate negative appraisals of the intrusions (e.g., “This means that something bad is going to happen”), which have been found in currently depressed patients (Newby and Moulds, 2010). Furthermore, dysfunctional metacognitive beliefs may predict future depressive symptoms (Newby and Moulds, 2011b; Papageorgiou and Wells, 2003). Changing dysfunctional appraisals or ‘intrusion-based reasoning’ (Berle and Moulds, 2014), for example, via metacognitive therapy can lead to a significant reduction in symptoms, as demonstrated for PTSD (Wells et al., 2014). Mindfulness-based cognitive therapy (MBCT) has also been successful in changing the adverse approach of intrusive images (McManus et al., 2014). Nearly 50 percent of the images in the depressed group referred to “interpersonal problems”, whereas “injury, illness or death of others” was the predominant content in the non-depressed group. This variation in image topics may explain the difference in imagerelated emotions between the two groups. Non-depressed individuals primarily “feared for” harm of others in their mental images, whereas the depressed patients suffered from visual intrusions of social conflicts with significant social partners. In interpreting the study results, the study limitations must be considered. First, although the two groups were matched on central sociodemographic variables, the sample

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size was relatively small. Therefore, some differences in imagery characteristics may have reached significance levels in a larger sample. Second, QNMI and INMI are both retrospective measures: information about negative images, their frequency or distress at the time of occurrence may be distorted by memory bias. Future studies could address this problem using ambulatory assessment methods (e.g., Ebner-Priemer and Trull, 2009). An additional limitation is that we did not acquire detailed descriptions of all images, as noted by a participant. Therefore, the results for the content of the most important negative image may not be representative of all negative images. Also, an experimenter effect might be present, as the two groups were assessed by two different clinicians. We aimed to investigate the properties of distressing images, including but not limited to intrusive memories in depressed and non-depressed individuals, and to extend previous research, such as studies by Newby and Moulds (2011) and Patel and colleagues (2007). In summary, negative visual mental images can be found in depression as well as healthy individuals. Although both groups were matched with regard to relevant sample characteristics, they differed with regard to a large number of imagery characteristics. Negative mental images were more numerous and occurred more frequently in depressed individuals compared with non-depressed individuals, and negative mental images seemed to be perceived differently (e.g., distress, accompanying physical symptoms, internal triggers, and associated emotions) by the two groups. Despite being a common phenomenon, negative visual imagery differs in a range of aspects between depression individuals and nondepressed individuals. The current results show that negative mental images occur frequently in depression and are significantly more distressing for depressed individuals than for healthy individuals, which have implications for the maintenance and treatment of depressive disorders. Imageryrelated distress can be targeted using imagery modification techniques (Wheatley and

Distressing visual mental images in depressed patients and healthy controls

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Hackmann, 2011). During depression, these visual intrusions are frequently triggered by internal factors and produce core depressive symptoms, such as sadness. Reducing the number of intrusive images via imaginal exposure (Kandris and Moulds, 2008) or reducing safety behaviors that are employed to control or suppress intrusions (Moulds et al., 2008) are potential approaches to reducing the possible depression-maintaining effect of visual intrusions in depression (refer to Weßlau and Steil, 2014 for an overview).

Acknowledgements: We thank Dipl.-Psych. Pia Bornefeld-Ettmann and Dipl.-Psych. Clara Dittmann for their ratings of the negative mental images.

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Highlights



We assessed negative imagery in matched depressed and non-depressed individuals.



Negative visual imagery is more frequent and distressing in depression.



Visual intrusions in depression are more often triggered by internal factors.



Distressing imagery can produce depressive symptoms and may maintain depression.



Imagery vividness and perceived controllability were comparable between the groups.

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Table 1 Sample characteristics DPs

HCs

(n = 17)

(n = 17)

35.8 (7.8)

36 (8)

Gender (female)a, n.s.

14

13

Education (years) n.s.

17.7 (3.2)

19 (3.2)

Single

11

8

Engaged

0

2

Married

4

6

Divorced

2

1

BDI-II**

24.8 (7.4)

3.2 (3.9)

HDRS**

15.4 (6.1)

1.2 (2.1)

Agen.s.

Marital Status

Note. BDI-II = Beck Depression Inventory, HDRS = Hamilton Depression Rating Scale. Standard deviation (SD) in parentheses. Except where noted, values refer to mean scores. Group differences (ttests) in the matching variables and depression scores are reported. n.s.

a

non-significant.

chi-square test.

**p < 0.001.

Table 2 Characteristics of the most significant negative image DPs

HCs

(n = 17)

(n = 17)

Distressing visual mental images in depressed patients and healthy controls

Frequency Days in the last two weeks*

3.9 (3.6)

1.4 (1.6)

Per day*

2.4 (2.5)

0.9 (0.9)

Vividness n.s.

65 (28.2)

52.7 (30.7)

36.8 (31.6)

47.7 (32.5)

35 (33)

13.2 (20.4)

Tactile n.s.

5.9

11.8

Auditory n.s.

23.5

17.6

Olfactory n.s.

0

5.9

Gustatory n.s.

0

5.9

23.5

29.4

11.8

0

Controllability n.s.

Distress*

Sensory Modalities (% yes)a

Vegetative Symptoms (% yes) Palpitations, pounding heart or accelerated heart rate Sweating

5.9 5.9 5.9 5.9 Trembling or shaking

11.8 5.9

Dry mouth Feeling short of breath, or a

41.2

25

Distressing visual mental images in depressed patients and healthy controls sensation of smothering

23.5

17.6

Feeling of choking

35.3

5.9

Chest pain or discomfort

26

5.9

Nausea or abdominal

17.6

distress

11.8

Feeling dizzy, unsteady,

29.4

light-headed or faint

0

Derealisation or

17.6

depersonalisation

0

Fear of losing control or

11.8

going crazy

11.8

Fear of dying

5.9 5.9

Numbness or tingling

23.5

sensations

23.5

Chills or hot flushes

0 11.8

Muscle Tension Note. If not otherwise specified, values refer to mean and (standard deviation) scores. Group differences (t-tests) are reported. Vividness and distress were rated on a visual analog scale from 0 to 100. Controllability: Values above 50 indicate “rather controllable”; values below 50 indicate “rather uncontrollable”. *p < 0.05. n.s.

a

non-significant.

divergent sample size: HCs: n = 17, DPs: n =16.

Table 3 Description of mental images category interpersonal problems

example Bullying at work. I can see my boss. He is offering me a

Distressing visual mental images in depressed patients and healthy controls

27

redundancy pay and gives me notice of my instant dismissal. I can see him with a smile on his face. We are sitting at the table. He holds a knife in his hands. injury, illness or death of

I can see myself, blood, and fire. I cannot stop the car fast enough.

oneself

The others misjudge the situation and hit my truck from behind. I am about to die and will not be able to say goodbye to my children.

injury, illness or death of other

Operation at work (crime-scene of a stabbing) – I am at an

people

apartment building. Drops of blood are on the floor at the house entrance. The higher you go in the house, the greater is the amount of blood. Blood in the elevator; the walls are full of blood. Dim light. “What happened?”

assault or threat of assault to

I can see myself from the outside in our bathroom, where I am

oneself

forced to go to the toilet in front of my mother’s eyes, right before she flips down the toilet lid, sits down and puts me over her knee, bare-bottomed, and spanks me with a cooking spoon.

miscellaneous

I am standing alone in a large living room of a detached house in the middle of the open countryside. I am looking at the garden through a large window at the front of the house, where I can see a meadow that is bounded by a forest in the background. It is completely quiet; nothing is moving. The colors seem faint. Despite the time of day (probably late afternoon), there is only a little light inside and outside. A feeling of loneliness and emptiness spreads within me.