JMIR FORMATIVE RESEARCH

Thorarinsdottir et al

Original Paper

Reducing Intrusive Memories of Childhood Trauma Using a
Visuospatial Intervention: Case Study in Iceland
Kristjana Thorarinsdottir1, MSc; Emily A Holmes2,3, Prof Dr; Johann Hardarson1, MSc; Unnur Hedinsdottir1, MSc;
Marie Kanstrup3, PhD; Laura Singh2,4, PhD; Arna Hauksdottir5, Prof Dr; Thorhildur Halldorsdottir1,5, PhD; Berglind
Gudmundsdottir6,7, Prof Dr; Unnur Valdimarsdottir5,8,9, Prof Dr; Edda Bjork Thordardottir5, PhD; Beau Gamble2,
PhD; Andri Bjornsson1, Prof Dr
1

Department of Psychology, University of Iceland, Reykjavik, Iceland2

Department of Psychology, Uppsala University, Uppsala, Sweden

3

Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden

4

Swedish Collegium for Advanced Study, Uppsala, Sweden

5

Centre of Public Health Sciences, University of Iceland, Reykjavik, Iceland

6

Faculty of Medicine, University of Iceland, Reykjavik, Iceland

7

Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland

8

Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden

9

Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, United States

Corresponding Author:
Kristjana Thorarinsdottir, MSc
Department of Psychology
University of IcelandSæmundargata 12
Reykjavik, 101
IcelandPhone: 354 6942001
Fax: 354 6942001
Email: kth35@hi.is
Related Article:
This is a corrected version. See correction statement in: https://formative.jmir.org/2021/11/e34897/

Abstract
Background: Additional interventions are needed for survivors of psychological trauma because of several barriers to andlimitations of existing treatment options (eg, need to talk about the trauma in detail). Case studies are an important step in exploring
the development of novel interventions, allowing detailed examination of individual responses to treatment over time. Here, we
present a case study that aims to test a novel intervention designed to disrupt memory reconsolidation, taking a single-symptom
approach by focusing on intrusive memories of a traumatic event.
Objective: This study aims to examine a novel brief cognitive intervention to reduce the number of intrusive memories oftrauma in an Icelandic setting and to extend previous studies by examining long-term effects for up to 3 months. The intervention
was guided by a clinical psychologist and comprised a brief memory reminder, followed by Tetris gameplay with mental rotation,
targeting one memory at a time in each session.
Methods: This was a single case study in Iceland with a woman in her 50s (drawn from an epidemiological study of trauma)with subthreshold posttraumatic stress disorder and a diagnosis of obsessive-compulsive disorder and social anxiety disorder.
The participant had four different intrusive memories from a traumatic event that happened in her childhood. The primary outcome
was the change in the number of intrusive memories from baseline to intervention phase and to follow-ups. The number of
intrusions was monitored in a daily diary for 4 weeks preintervention, 8 weeks during the intervention, and 1 week at 1-monthand 3-month follow-ups. Intrusions were targeted one by one over six intervention sessions, creating four repetitions of an AB
design (ie, length of baseline A and intervention phase B varied for each memory). We examined changes in both the total number

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Thorarinsdottir et alof intrusions (summed across all four memories) and individually for each memory. In addition, we explored whether having
fewer intrusive memories would have an impact on functioning, posttraumatic stress, and depression or anxiety symptoms.
Results: The total number of intrusions per week was 12.6 at baseline, 6.1 at the intervention phase (52% reduction frombaseline), 3.0 at the 1-month follow-up (76% reduction), and 1.0 at the 3-month follow-up (92% reduction). Reductions in thesymptoms of posttraumatic stress and depression were observed postintervention. Sleep, concentration, stress, and functioning
improved. The participant considered the gameplay intervention acceptable and helpful in that she found that the memories
disappeared while she was playing.
Conclusions: This guided brief cognitive intervention reduced the number of intrusive memories over the intervention phaseand follow-ups. The brief memory reminder was well tolerated, removing the need to discuss trauma in detail. The next steps
require an extension to more cases and exploring remote delivery of the intervention.
(JMIR Form Res 2021;5(11):e29873) doi: 10.2196/29873
KEYWORDS
psychological trauma; intrusive memories; case report; visuospatial interference task; Tetris gameplay; mental imagery; mobile
phone

Introduction
Background
Psychological trauma (eg, disasters, accidents, or interpersonal
violence) is experienced by most people at some point during
their lifetime [1,2]. Many individuals who have been exposedto trauma (approximately 1 in 4) go on to develop posttraumaticstress disorder (PTSD) [3,4]. The core clinical symptom of
PTSD is intrusive memories related to traumatic events [1,5].
Other symptoms of PTSD include avoidance of stimuli
associated with trauma, along with negative alterations in
cognition, mood, arousal, and reactivity [1]. Approximately
half of those diagnosed with PTSD do not spontaneously recover
within 40 months of diagnosis [6]. PTSD, even whensubthreshold, is associated with substantial distress, functional
impairment, and comorbidities [1,7]. Although many patients
respond well to current PTSD treatments, approximately
one-third of patients who enter psychological treatment for
PTSD still meet the diagnostic criteria for the disorder following
treatment [8].
Current evidence-based treatments for PTSD include
individualized trauma-focused cognitive behavioral therapy
interventions and eye movement desensitization andreprocessing [3,8]. However, there are some limitations toexisting psychological treatment options for PTSD, including
the limited number of qualified therapists, geographic distances
to such clinical expertise (eg, in rural areas), high cost oftreatment, and stigma being a barrier to individuals seeking
treatment [9]. Dropout rates from PTSD treatment are high,approximately 18% overall (ranging from 0%-48%) in clinical
trials and are thought to be even higher in clinical practiceoutside of clinical trials [10-12]. Furthermore, only a minorityof those who need PTSD treatment receive it [13]. The common
denominator in existing treatment options is a requirement forpatients to recall and talk about the traumatic experience indetail, which many trauma survivors are reluctant to do [9].
Many therapists are also reluctant to deliver trauma-focused
therapies, such as prolonged exposure, because of fear ofexacerbation of symptoms or concerns with patient dropout[12].
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Another barrier to treatment is the lack of service provision [9].
Iceland, for instance, is one of many countries that lack themental health services capacity to offer treatment to all trauma
survivors. New, briefer approaches that reach more people orcan be delivered to remote places in geographically dispersed
countries via the internet are needed [9]. Moreover, people who
do not meet the full diagnostic criteria for PTSD are typicallyunable to access existing services, meaning that treatments fortrauma survivors with subthreshold but impairing symptoms
are needed.
Overall, these limitations and barriers create the need for
additional complementary approaches to current treatments.
One option that has been suggested is to focus on reducing one
single, tractable symptom (here, the core clinical symptom)
rather than a full diagnosis of PTSD [5,14]. Intrusive memories(ie, criterion B1 as defined in the Diagnostic and Statistical
Manual of Mental Disorders, Fifth Edition [DSM-5]) arerepeated and unwanted memories of scenes from a traumatic
event, and they are predominantly visual [15-17]. They canevoke the same emotions experienced during the traumatic event[16] and often have a sense of nowness, that is, as if they are
happening in the present rather than in the past [15]. Intrusive
memories can cause significant distress and interfere witheveryday functioning, making them an important target fortreatment [17].
A relatively simple and brief intervention to reduce the numberof intrusive memories after trauma has recently been developed,
building on principles from cognitive science [14,18,19]. It is
in line with calls to develop new therapeutic approaches for
PTSD, such as those that target memory reconsolidation [20].
The intervention comprised a brief memory reminder for a
specific intrusive memory of trauma, practice in mental rotation(ie, actively playing the game by rotating the blocks in one’s
mind; for further details, see Holmes et al [21], chapter 11),
followed by Tetris gameplay with mental rotation for 25
minutes, guided in person by a researcher.
Initial work toward clinical translation was for recent memoriesof trauma [22-24]. For older, intrusive memories of trauma, theeffect has been explored using case study and case series
approaches [19,25,26]. Kessler et al [19] conducted a case series
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of inpatients (n=20) with complex PTSD and trauma memories
from childhood. The intervention comprised a memory reminder(here, writing a brief description of the memory, then shreddingit) followed by Tetris gameplay with mental rotation for 25
minutes for one intrusive memory at a time. Memories (here,
many different memories) were targeted one by one, that is,each intrusive memory in a different session, and memories
were tracked individually in a diary. The results showed thattargeting a specific intrusion was followed by a drop in thefrequency of that intrusion (some to zero). The frequency oftargeted intrusions reduced by 64% overall from baseline topostintervention, whereas the frequency of nontargeted intrusive
memories reduced by 11%.
Kanstrup et al [25] adapted the intervention for a new target
group—people who were refugees (n=4) and used it to target
already established trauma memories such as of war. The
memory reminder used here was a brief list of intrusive
memories (ie, hotspot sheet) where participants were asked tobriefly describe in a few words the imagery content of theirintrusions, either by writing it themselves or by telling the
researcher what to write. The intervention was delivered in acommunity setting, such as a library. All 4 participants showeda decrease in the number of intrusive memories (again targeted
one by one) after the intervention and reported improved
functioning. For example, participant 1 had a decrease from 10
memories at baseline to 0 after the first intervention week, andfor participant 3, the 28 memories at baseline decreased to 14
after the first intervention week.

Study Design and Aims
Given the small-scale but promising results of thissingle-symptom intervention approach for older memories oftrauma, we were interested in adapting it for women with atrauma history in Iceland. Thus, in this case study (n=1), we
aim to investigate the effects of the intervention adapted to
Iceland for a woman from a population-based sample
experiencing intrusive memories of childhood trauma, delivered
with guidance from a clinical psychologist and seen in auniversity research setting. Importantly, we aim to extend theprevious literature testing this intervention by including asignificantly longer follow-up period than previous studies (ie,1 month and 3 months postintervention) to examine whether
effects are maintained in the long term.
When evaluating the efficacy of novel interventions and refining
intervention protocols, single-case designs are a crucial step
[27,28], giving researchers the chance to examine individual
variability over time [29]. The N-of-1 trials are also gaining
popularity as modern medicine moves toward individualized
patient-centered care [30]. Typically, a replication of AB(ABAB) is considered necessary to establish intervention effects[27]. However, Kanstrup et al [25] argued that a classic ABAB
design was not optimal for evaluating this specific interventionas, unexpectedly, the effects lasted after one intervention session
and did not rebound (ie, could not be reduced again, as assumed

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Thorarinsdottir et alby a classic ABAB). Kanstrup et al [25] instead recommended
a within-person multiple baseline AB design, as in the study by
Kessler et al [19]. In this approach, if a person has more than
one different intrusive memory, then each specific intrusive
memory is targeted one at a time, with separate intervention
sessions allowing focused assessment of the effect of eachintervention on each memory over time. This is the design
adopted in this study. However, to avoid confusion with othercase series designs (such as those with multiple randomized
baselines), we refer to this design as a repeated AB design.
We predict that our participant (here with four different intrusive
memories of trauma) would report fewer intrusive memories(primary outcome) during the intervention phase than in thepreceding baseline phase and that the reduction in the numberof intrusions would be maintained at the 1-month and 3-monthfollow-ups. We also aim to explore whether having fewer
intrusive memories would be associated with improvements ingeneral functioning and reductions in symptoms of PTSD,
depression, and anxiety (secondary outcomes). In addition, we
aim to explore the feasibility and acceptability of theintervention (similar to Holmes et al [31]).

Methods
Participants
Women who took part in a substudy of thestress-and-gene-analysis (SAGA) cohort study were screened
for eligibility. The SAGA cohort study is a population-based
longitudinal cohort study of Icelandic women who completed
an extensive questionnaire on trauma history and mental health(baseline data collection finished on July 1, 2019). The substudy(the Social Trauma Project) involves comparing two samples
of women from the SAGA cohort study with either likely PTSD
(ie, having a score on the PTSD Checklist-5 [PCL-5; see theMeasures section] of ≥33) or not likely PTSD (ie, scores in thelowest one-fifth on the PCL-5), using clinical interviews. Whentaking part in the substudy, two semistructured interviews wereadministered (ie, the Mini International NeuropsychiatricInterview [MINI], also used to assess the exclusion criteria forthis study, and the Clinician Administered PTSD Scale [CAPS];
see the Measures section). When taking part in the substudy,
women were screened for the presence of intrusive memoriesof trauma. The screening included a short description of thesymptom, followed by questions about the presence of thesymptom to assess their eligibility for this study. A total of 4
women from the substudy who provided consent to be contacted
regarding additional research were assessed for inclusion in thiscase study. A total of 3 women did not meet the inclusion criteria(CONSORT [Consolidated Standards of Reporting Trials]
diagram in Figure 1). The included participant was a woman inher 50s who had four different intrusive memories from a single
traumatic event involving physical violence in childhood (ie,occurring around four decades previously).

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Figure 1. Adapted Consolidated Standards of Reporting Trials participant flow diagram for this study. SAGA: Stress and Gene Analysis.

The inclusion criteria were as follows: (1) having experienced
criterion A trauma as defined by DSM-5 [6]; (2) having at least
one intrusive memory that occurs at least three times per week
for the last 4 weeks; (3) being able and willing to attend three
to eight sessions with the researcher; (4) being able and willingto monitor intrusive memories in daily life; (5) having accessto a smartphone; and (6) being able to speak Icelandic and readstudy materials in Icelandic. Exclusion criteria were as follows:(1) current psychotic disorder; (2) current manic episode; and(3) being acutely suicidal. Exclusion criteria were assessed with
the MINI.
The participant reported clinically significant past-month PTSD
symptoms from physical violence experienced in childhood,with a total symptom severity score of 22 of 80 on the CAPS
and missing one symptom in the E cluster to meet full diagnostic
criteria (had five symptoms in cluster B, two in cluster C, three
in cluster D, and one in cluster E). This assessment took place
2 months before participation in this study as part of thesubstudy of the SAGA cohort using the CAPS (see the Measures
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section). The participant also met criteria for social anxiety
disorder and obsessive-compulsive disorder according to the
MINI diagnostic interview (see the Measures section). The
participant received psychological treatment in the past for
problems related to work but had never received trauma-related
psychological treatment. She reported not taking any
psychotropic medication in the 3 months before taking part.

DesignThis single case study took a specific single-symptom probe
approach, whereby each of the four intrusive memories wastargeted one at a time in different sessions [19]. Critical to thisapproach, the participant distinguishes the content of theirdifferent intrusive memories (here, for four intrusions, eg, (1)red curtain, (2) man’s face, (3) blood on floor, and (4) closed
door; these examples are fictitious to protect anonymity) andtracks the frequency of each intrusion over time. We describe
this design here as a repeated AB design, wherein the length ofbaseline (A, preintervention; monitoring only) and intervention(B) phases varied across each of the four intrusive memories,
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depending on when each memory was targeted. The baseline
phases for each individual memory are used as control periods
to compare their numbers before and after being targeted by theintervention.
The number of each intrusive memory was monitored in a daily
diary for 4 weeks preintervention, over 8 weeks of theintervention, and then for 1 week at the 1-month and 3-monthfollow-ups, that is, the participant monitored the occurrence ofher intrusive memories in a daily diary before each intervention
session to establish a baseline level of intrusion. This baseline
phase was intended to be 1 week; however, the diary was kept
for 4 weeks, as the participant was not able to meet with theresearcher when planned. The intervention phase lasted 8 weeks
rather than 6 weeks, as planned for the same reason. However,the participant did monitor the frequency of her intrusive
memories in these extended periods, and we included all thedata in the analyses. The daily diary was kept again for 1 weekat the 1-month and 3-month follow-ups.
The participant’s four different intrusive memories were targeted
one by one over six intervention sessions guided by a clinicalpsychologist who specialized in trauma-focused cognitive
behavioral therapy. The design thus involved four repetitionsof an AB design. In addition to the six guided sessions, theparticipant could also self-administer the intervention at any
time after the first session if she so chose for memories alreadytargeted in the session. The primary outcome was the change
in the number of intrusive memories from baseline to theintervention phase and to long-term follow-ups (1 and 3
months). The participant also completed self-report measuresfor PTSD, depression and anxiety symptoms, and functional
impairment at baseline, the last intervention session, and the
1-month and 3-month follow-ups.

Procedure
Training
To promote adequate intervention delivery and protocol
adherence, the researcher delivering the intervention (JPH, alicensed clinical psychologist and specialist in trauma therapy)
received training and clinical supervision from experienced
researchers or clinical psychologists who had expertise indelivering the novel intervention (EAH and MK). Training
included two in vivo workshops for 3 days and thenapproximately 6 months later for 2 days. Workshops covered
theoretical and practical aspects of intervention delivery andincluded role-plays with trainers until adequate performance
was reached. Training also included how to explain and capture
the primary outcome measure (intrusive memory diary). During
data collection, the researcher received continued supervision,
adherence checks, and support regarding any adaptations
necessary from a clinical supervisor via telephone after sessions
with the participant and weekly supervision meetings. The
researcher also participated in remote group training meetings
twice a month with other researchers using the intervention.

Thorarinsdottir et althat include sensory impressions such as sight and sound; arepredominantly visual in form, similar to pictures or a film clip
in the mind’s eye; and are distressing and occur involuntarily).
The participant identified her different intrusive memories bybriefly describing them to the researcher using only a few words
to indicate their visual content; the researcher wrote thedescription on a hotspots sheet that was clearly visible to theparticipant. The participant did not talk about the trauma withthe researcher or about the intrusive memories in detail. The
participant labeled each of her intrusive memories with a symbol(ie, first memory labeled A and second memory labeled B) and
was instructed on how to monitor the daily frequency of themin a diary (primary outcome measure). When indicating
experiencing a memory, the participant noted the symbol
corresponding to that specific memory in a specific time frameof that day. Each diary included 7 days and four periods eachday (see the Measures section).

Intervention Sessions
In each of the intervention sessions (six sessions), the participant
selected one memory at a time to target that week and completed
the intervention procedure, guided by the clinical psychologist.
The intrusion selected first can be the one that is mosttroublesome or frequent or one for any other reason theparticipant wishes to try reducing first. The intervention
consisted of a brief memory reminder (ie, briefly thinking about
the intrusive memory to bring the image to mind without it
becoming emotionally overwhelming; this approach is different
from the memory reminder used by Kessler et al [19]). Afterthe memory reminder, the participant was trained in mental
rotation, followed by Tetris gameplay for 25 minutes with anemphasis on mental rotation (see Holmes et al [21], chapter 11).
The Tetris gameplay was delivered with the videogame Tetris
DS in the Nintendo DS, set to marathon mode and ghost pieceoff, on a 10.1-inch screen. Between sessions, the participant
was invited to self-administer the intervention using a Tetrisapp [32] on her smartphone, that is, to repeat the intervention
for already targeted intrusions (instructed to play in the same
way as in session when the intrusion came to mind
involuntarily). Only one intrusion was targeted per session;
when the next intrusion was targeted, the participant again (notthe therapist) selected the memory to target. At the start of thelast intervention session, the participant also completed thesecondary outcome measures.

Follow-up
At the 1-month and 3-month follow-ups, the participant recorded
the number of intrusions in the diary daily for 1 week andcompleted secondary outcomes. All data were recorded on alaptop computer using the REDCap (Research Electronic Data
Capture) database, an encrypted electronic software, and stored
on secure servers [33]. At the 1-month follow-up, the participant
was in quarantine because of the COVID-19 pandemic, andthus, all follow-up measures were administered remotely throughthe REDCap platform; see the Procedure section.

Baseline Session
In the first session, the participant answered baseline
questionnaires (relating to secondary outcomes), and theresearcher explained what intrusive memories are (ie, memories
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MeasuresEligibility Assessments (Part of the SAGA Cohort
Substudy)
The CAPS-5 is a 30-item semistructured interview used to assess
symptoms of PTSD from physical violence in childhood andsymptom severity in the past month, according to the DSM-5[1]. Each item is scored on a 5-point Likert scale (0=mild or
subthreshold; 4=extreme or incapacitating) with a threshold
symptom rating of 2 (ie, moderate) for a possible diagnosis.
Frequency and intensity of each symptom were assessed andrated separately. The CAPS-5 has excellent internal consistency(Cronbach α=.88) and test-retest reliability (0.83), along withgood convergent validity (0.83 [34]), making it a useful toolfor diagnosing PTSD.
The MINI is a structured diagnostic interview that assesses axis
1 psychiatric disorders according to the DSM-4. The MINI has
been shown to have good sensitivity and specificity for mostdiagnoses [35]. Interrater and test-retest reliability has beenshown to be good, with kappa values in the high to very highrange (κ=0.79-1.00 [36]).

Primary Outcome Measure
The intrusive memory diary was adapted from previous studies[22,25]. Each diary included a daily pen-and-paper record offour timeframes per day (morning, afternoon, evening, andnight) for 7 days. Instructions on how to use the diary included
a definition of intrusive memories of trauma as mental images(in the form of pictures or a film clip in the mind’s eye) that are
distressing and occur involuntarily. The participant was
instructed not to record voluntary thoughts or verbal thoughts
about the trauma without sensory content. The participant
monitored the occurrence of her intrusive memories in a daily
diary for 4 weeks before any intervention sessions, for 8 weeks
while intervention sessions were administered, and again for 1
week at the 1-month and 3-month follow-ups. Throughout this,the participant noted which of the four different memories each
intrusion was, allowing us to examine changes in each memory
individually. The primary outcome was the change in thenumber of intrusive memories from baseline to the intervention
phase and to long-term follow-ups (1- and 3-month follow-ups).

Secondary Outcome Measures
PTSD symptoms were assessed with the PCL-5, a 20-item
self-report scale used to assess the severity of PTSD symptoms
in the past month from physical violence in childhood,corresponding to the DSM-5 criteria for PTSD [34]. Eachsymptom is rated on a 4-point Likert scale (0=not at all;
4=extremely). The PCL-5 has strong internal and test-retest
reliability, with good convergent and discriminant validity [37].
The Icelandic translation of the PCL-5 had excellent internalconsistency in the SAGA cohort study (α=.95). Assessment ofclinical significance is not yet clear for the PCL-5; however, ascore of 33 is likely to correspond to a DSM-5 PTSD diagnosis,
and a score of ≤24 posttreatment is likely to represent clinicallysignificant change [38].
Depression symptoms were assessed with the Patient Health
Questionnaire-9 (PHQ-9), a nine-item self-report measure of
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Thorarinsdottir et al
depressive symptoms and their severity in the prior 2 weeks[39]. Each item is rated on a 4-point Likert scale (0=not at all;3=nearly every day). The PHQ-9 has excellent internal reliability(Cronbach α ranging from .86 to .89) and good test-retest
reliability (r=0.84 [39]). The Icelandic version had good internalconsistency in the SAGA cohort study (α=.89). A five-pointchange in the PHQ-9 score is considered clinically significant[40].
Anxiety symptoms were assessed with the Generalized Anxiety
Disorder-7 (GAD-7) scale, a brief self-report questionnaire used
as a screening tool for GAD symptoms and their severity in theprior 2 weeks [41]. Each item is rated on a 4-point Likert scale(0=not at all; 3=nearly every day). The GAD-7 has excellent
internal consistency (Cronbach α=.92) and good test-retest
reliability (r=0.83 [41]). The GAD-7 has been reported to be
useful in screening for anxiety disorders in general [42]. The
Icelandic version had good internal consistency in the SAGA
cohort study (α=.90). A four-point change in the total score isconsidered clinically significant on the GAD-7 [43].
Functional impairment was assessed with the Sheehan Disability
Scale (SDS), a self-report measure designed to assess functional
impairment in the prior week across three domains: (1) workor school, (2) social, and (3) family life [44]. These domains
are measured on an 11-point scale (0=not at all; 10=extremely).
The scale was adjusted to assess functional impairment
associated with intrusive memories. This scale has been shownto have good psychometric properties [44]. A three-point change
in the SDS score has been used as a measure of treatment
response [45]. The Icelandic version has good internalconsistency in clinical groups (α=.70-.84 [46]).
Self-guided adherence to the use of the gameplay intervention
in daily life was assessed with a question regarding how often
Tetris was played after experiencing an intrusive memory(11-point scale; 0=not at all; 10=every time).
Feasibility and acceptability rating for using the smartphone
gameplay intervention was assessed with two self-rated items:
whether the participant would recommend the intervention toa friend and whether she thought gameplay was an acceptable
way to reduce intrusive memories. Scores could range from 0
to 10, with higher scores indicating greater acceptability or
feasibility. Two open-ended questions were also asked: “How
did you feel about playing Tetris after you had an intrusive
memory?” and “Did you find the intervention helpful? If yes,how?”
The impact of intrusive memories on concentration, sleep, andstress was assessed with six self-rated items about the past week:
two items assessing concentration difficulties in general andbecause of intrusive memories (11-point scale; high scoresindicating more difficulties); one item assessing duration of
disruption after experiencing intrusive memories (five response
options ranging from <1 minute to >60 minutes); two items
assessing sleep disturbances because of intrusive memories(sleep in general and nightmares; 11-point scale; higher scoresindicating more sleep disturbance); and one item assessing thedegree to which intrusive memories affected stress levels (0=not
at all; 10=affected very much).
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Ratings of the general impact of intrusive memories wereobtained with two items: one assessing distress caused byintrusive memories and the other assessing how vivid they werein the past week, both rated on an 11-point scale (0=not at all;10=very distressing or vivid).
Intrusion diary adherence was assessed with one item addressing
the accuracy of filling out the diary (0=not at all; 10=very
accurately).
The impact of intrusive memories on daily functioning wasassessed with two items. One question was open-ended: “Howhave the intrusive memories affected your ability to function
in your daily life in the past week?” The other question was
self-rated: “Have the intrusive memories affected your ability
to function in your daily life?” (11-point scale, a higher scoreindicating a greater impact on functioning).

Data Analysis
Changes in the Total Number of Intrusive Memories
The primary outcome was change in the number of intrusive
memories from baseline to the intervention phase and tolong-term follow-ups (1 month and 3 months). We firstexamined the primary outcome in terms of the total number of
intrusions (before examining separately for each memory). For
this, we summed the number of all intrusions occurring acrossthe 4-week baseline period, then across the 8-week intervention
period, and then at each of the 1- and 3-month follow-ups. Given
that these periods differed in duration, we calculated the total
number of intrusions per week to generate a measure that wascomparable across periods. Missing data were dealt with by
excluding these time points from calculations. For example, thebaseline period was 29 days, but data were present for 22.25
days; thus, the total number of intrusions per week was
calculated as 40 intrusions/22.25 days × 7=12.6 intrusions per
week at baseline.
To examine changes over time, we calculated the percentage
reduction in total intrusions per week from baseline to the otherperiods. For example, as there were 6.1 intrusions per week in
the intervention phase, this was calculated as (1−[6.1/12.6]) ×
100=52% reduction in the intervention phase compared withbaseline.

Change in the Number of Each of the Four SpecificIntrusive Memories

Thorarinsdottir et alphase for each individual memory is used as a control period
to compare its number before and after being targeted by theintervention. There is a different baseline (A) and intervention(B) phase per memory, depending on which session it was
targeted. The percentage reduction in each intrusion after being
targeted was calculated as 1−(mean number per week during
intervention phase/mean number per week during baseline) ×100. Percentage reductions were then calculated in the sameway for the 1- and 3-month follow-ups compared with baseline.

Other Symptoms and Functioning
We also used a descriptive approach to investigate whether there
were clinically significant changes over time in the overall
symptoms of PTSD, depression, anxiety, and functional
impairment.

Ethics Statement
The study was approved by the National Bioethics Committeeof Iceland (Number VSNb2017110046/03.01). The participant
provided written and informed consent. All sessions followed
a written protocol. No adverse events were reported by theparticipant.

Open Science Statement
This single case study was not preregistered but precedes andis similar to the design and procedures of a case series (n=5)
that we later registered on ClinicalTrials.gov (NCT04209283)
on December 4, 2019. All anonymized summary-level data arereported in this manuscript. Study materials may be madeavailable upon reasonable request with an appropriate materials
transfer agreement with University of Iceland. It should be notedthat the delivery of this intervention requires extensive training
and supervision (see the Procedure: Training section).

Results
Overview
The participant had four different intrusive memories that were
all predominantly visual and tracked each intrusion over time.
All her intrusive memories were from a single traumatic eventthat took place roughly four decades before participation. Allfour intrusive memories were targeted with the intervention at
different time points during the intervention phase (Figure 2).

Next, we examined the data per intrusive memory. Here, each
intrusion acts as its own control, that is, the specific baseline

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Figure 2. Graph for visual inspection of primary outcome data (total number of intrusive memories) on the y-axis as total per day. Days since enrollment
is shown on the x axis, which includes baseline (gray), intervention (white), and follow-up periods (light gray). Dashed colored vertical lines show wheneach intervention session was administered and which specific memory (memories A, B, C, or D) was targeted (eg, session 1; memory A in green).
Memories are labeled in the order of when they were targeted (eg, memory A was targeted in the first intervention session). Solid black vertical lines
show the 1-month and 3-month follow-ups. Gaps in the time series in the baseline and intervention periods reflect the missing data (for each specificintrusive memory data, see Figure 3).

One memory (memory A) was targeted three times (reported
as the most distressing and frequent by the participant), and theother memories were targeted once. The participant readily
understood the instructions given and successfully completed
the intervention sessions and procedures. Intrusive memory
diary data were missing for days 8-12 and 21-22 during thebaseline phase and for days 40-41, day 49, days 57-63, and day
71 during the intervention phase; the diary was fully completed
at follow-ups. Most missing diary data were because of extra
days passing in between sessions, that is, when the participant
had completed their current diary (covering a period of only 1week) but had not received their next diary. No attempt wasmade to retrieve data for the missing days. In total, the diary

was completed successfully for 82% (81/99 days) of the study
period.

Primary Outcome
Change in the Total Number of Intrusive Memories
Across the 4-week baseline period, the total number of intrusions
was relatively stable and approximately 12.6 per week (summed
across all four memories). This number reduced to 6.1 per week
across the 8-week intervention phase (52% reduction frombaseline), to 3.0 per week at 1-month follow-up (76% reduction),and to 1.0 per week at the 3-month follow-up (92% reduction;
Table 1).

Table 1. Number of intrusive memories per week at baseline, intervention, 1-month follow-up, and 3-month follow-up, and relative reduction (inpercentage) from baseline for total intrusions and for each memory separately (n=1).
Intrusions

Baseline (A;number per
week)

Intervention (B;number per week)

Reduction (%)

1-month follow-up Reduction (%)(number per week)

3-month folReduction (%)
low-up (number
per week)

Totala

12.6

6.10

52

3.0

76

1.0

92

Memory A

3.8

2.0

46

1.0

74

1.0

74

Memory B

3.6

0.5

86

0

100

0

100

Memory C

2.4

1.0

59

1.0

59

0

100

Memory D

1.4

1.0

26

1.0

28

0

100

a

Total intrusions are not equal to the sum of the intrusions for each memory. This is because the length of the baseline and intervention phases differ
across memory and the total. See the Data Analysis section for more details on how these numbers were calculated.

Figure 2 displays the total number of intrusive memories perday (summed across all four intrusive memories) throughout
all phases. Visual inspection indicated that after the second
intervention session, the total number of intrusions reduced.
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The number of intrusive memories remained relatively stablebetween sessions 2 (day 43) and 5 (day 73) when a further drop
in frequency was evident, maintained at the 1-month follow-up,
and then continued to drop further at the 3-month follow-up.
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Change in the Number of Each of the Four SpecificIntrusive Memories
Figure 3 displays the frequency of each intrusive memory during
all phases (baseline, intervention, and 1-month and 3-monthfollow-ups). All four intrusive memories dropped in number

Thorarinsdottir et al
per week after being targeted, that is, reductions of 46%, 86%,
58%, and 26% for memory A, B, C, and D, respectively, fromtheir specific baselines to intervention periods. Three of the four
intrusions were eliminated completely at the 3-month follow-up(Table 1).

Figure 3. Graph for visual inspection of the number of intrusive memories (on the y-axis as number per day) for each of the four specific intrusive
memories reported by the participant (memories A, B, C, and D). Days since enrollment is shown on the x-axis, which includes baseline (gray),intervention (white), and follow-up periods (light gray). Different baseline and intervention lengths for each memory reflect that this is a repeated AB
design. Dashed colored vertical lines show when each intervention session was administered and which specific memory was targeted (eg, session 1:
memory A in green). Memories are labeled in the order of when they were targeted (eg, memory A was targeted in the first intervention session). Solidblack vertical lines show the 1-month and 3-month follow-ups. Gaps in the time series in the baseline and intervention periods reflect missing data.

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Thorarinsdottir et al

Memory A was targeted in intervention sessions 1, 2, and 5 atthe participant’s request. Visual inspection of Figure 3 showsa drop in frequency in the week after intervention session 1 anda further decrease in the week after session 2. The reduction
appears to be stable at the 1-month and 3-month follow-up.
However, there appears to be an increase in frequency between
days 65 and 73, which resulted in that intrusion being targetedagain. In session 5, the participant disclosed that she had comeacross a person who was present during the traumatic experience(ie, seeing the person triggered that memory).
Memory B was targeted in session 3, and a drop in frequency
was evident in the subsequent week, which was maintained
throughout the follow-ups. A drop in frequency for memory C
was shown in the week after intervention session 1 (memory A
targeted), and the frequency reduction remained stable atfollow-up. Less changes in frequency were visible for memory

D throughout the intervention phase (targeted in intervention
session 6), whereas there was a reduction in frequency at the
3-month follow-up.

Secondary Outcomes
Ratings of Adherence and General Impact of Intrusive
Memories
Table 2 shows that the participant rated her intrusions in general
as becoming less vivid and distressing over the intervention andfollow-up phases. Ratings of self-guided adherence to Tetris
gameplay between sessions are also shown in Table 2, indicatingthat it was most used during the intervention period, andself-reported accuracy for completing the intrusive memory
diary was high throughout the study period (mean 8.25, SD
0.5).

Table 2. Ratings of adherence to intrusive memory diary and general impact of intrusive memories (n=1).

a

Item

Session 1

Session 2

Session 3

Session 4

Session 5

Session 6

1-month follow-up 3-month follow-up

Diary accuracya

8

9

8

9

8

9

7

8

Intrusions vividnessb

7

8

6

9

8

6

4

3

Intrusions distressc

6

6

4

8

5

4

3

1

Tetris gameplayd

N/Ae

4

10

5

2

4

1

0

How accurately did you fill out the diary? 0=not at all; 10=very accurately.

b

During the last week, how vivid were your intrusive memories? 0=not at all; 10=very vivid.

c

During the last week, how distressing were your intrusive memories? 0=not at all; 10=very distressing.

dHow often did you manage to play Tetris after you experienced an intrusive memory? 0=never; 10=every time.

e

N/A: not applicable.

Feasibility and Acceptability for Using a Smartphone
Gameplay Intervention
The participant rated whether she would recommend theintervention to a friend as 10/10 (meaning she would certainly
recommend it). She also rated whether she considered gameplay
to be an acceptable way to reduce intrusive memories as 10/10(very acceptable). When asked how she felt about playing Tetris
after she had an intrusive memory, she reported the intervention
to be “very good,” and when asked if she found the intervention
helpful, she said, “Yes, I forgot time and place and the memory
went away immediately.”Self-report Measures on PTSD, Depression and Anxiety
Symptoms, and General Functioning

was clearly clinically significant at the 3-month follow-up, witha score of only 6 [38]. Depression symptoms were reduced frommoderate levels (PHQ-9; 10-14) at baseline to mild (5-9)
postintervention, indicating a clinically significant change [40].
Depression symptoms were further reduced to minimal (0-4)
at the 3-month follow-up. At baseline, the participant reported
mild levels of anxiety (GAD-7; 5-10) and did not report aclinically significant change in symptoms until the 3-monthfollow-up, when her symptoms were reduced to little or noanxiety (GAD-7; 0-4) [43]. Functional impairment (as measured
by the SDS) improved clinically significantly in the follow-up
period [45]. The score was 15 at baseline and reduced to zeroat the 3-month follow-up (Table 3).

Initial high levels of PTSD symptoms (a PCL-5 score of 51)
were reduced by over half at postintervention, and the reduction

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Table 3. Self-report measures for secondary outcomes (posttraumatic stress disorder, depression and anxiety symptoms, and general functioning) and
impact of intrusive memories on concentration, sleep, stress, and daily functioning (n=1).

a

Item

Baseline interview

Postintervention

1-month follow-up

3-month follow-up

PCL-5a

51

35

30

6

PHQ-9b

13

7

8

2

GAD-7c

9

7

7

2

SDSd

15

15

5

0

Concentratione

5

3

3

1

General concentrationf

7

3

5

3

Duration of disruptiong

4

2

2

1

Sleeph532

0Nightmaresi

4

6

2

0

Stressj

5

3

3

1

Daily functioningk

5

1

3

0

PCL-5: Posttraumatic Stress Disorder Checklist; scores ranging from 0 to 80.

b

PHQ-9: Patient Health Questionnaire-9; scores ranging from 0 to 27.

c

GAD-7: Generalized Anxiety Disorder scale-7; scores ranging from 0 to 21.

d

SDS: Sheehan Disability Scale; scores ranging from 0 (unimpaired) to 30 (highly impaired).

e

In the past week, how much did your intrusive memories disrupt your concentration? 0=not at all disruptive; 10=extremely disruptive.

f

In the past week, how much difficulty did you have concentrating generally? 0=no concentration difficulty at all; 10=extreme concentration difficulty.

gWhen you had an intrusive memory, how long did it disrupt your concentration (in minutes) in the past week? 0 (<1 minutes) to 5 (>60 minutes).

h

Did your intrusive memories interfere with sleep during the night in the past week? 0=not at all; 0=interfered very much.

i

Did you experience any nightmares that interfered with your sleep during the night in the past week? 0=did not experience any nightmares; 10=experienced
many nightmares.
j

In the past week, did your intrusive memories affect how stressed you felt? 0=not at all; 10=affected very much.

k

Have the intrusive memories affected your ability to function in your daily life? 0=not at all; 10=very much affected.

Impact of Intrusive Memories on Concentration, Sleep,
Stress, and Daily Functioning
Table 3 shows ratings of the impact of intrusions on
concentration, sleep, and stress. Critically, the impact of
intrusive memories on concentration reduced from 5 at baseline
to 1 at the 3-month follow-up, and estimated duration ofconcentration disruption per intrusion reduced from 4 (30-60
minutes) at baseline to 1 (1-5 minutes) at follow-up. The impact
intrusions had on sleep reduced from 5 at baseline to 0 at the
3-month follow-up. The impact intrusions had on stress reduced
from 5 at baseline to 1 at the 3-month follow-up. The impact
intrusive memories had on the participant´s ability to functionin her daily life reduced from 5 at baseline to 1 postintervention
and was 0 at the 3-month follow-up.
At baseline, the participant responded to an open question on
how her intrusive memories had affected her ability to function
in daily life: “I don’t sleep very well, and that leads to fatigue
which interferes with my daily functioning.” In the lastintervention session, she said, “It took some energy to try not
to think about them, but they bother me very little anymore,”
and at the 1-month follow-up she reported, “I can´t concentrate
when I have an intrusive memory, but the memories don’t reallybother me anymore even though I have been in quarantine.
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Usually when I am not busy that has meant more memories.”
She also said, “I have not needed to play Tetris, but it’s nice toknow that I can if I have an intrusive memory.” At the 3-monthfollow-up, she responded, “They have not been bothering mein the past weeks. It is a little uncomfortable that they may come,but they bother me very little.”

Discussion
Principal Findings
In this single case study, we investigated the effects of a brief
visuospatial intervention designed to disrupt memory
reconsolidation, thereby reducing the number of intrusive
memories of trauma. Different intrusive memories were targeted
one by one over six sessions, guided by a clinical psychologist.
The intervention stemmed from earlier laboratory studies [18,47]
as well as clinical studies [19,25]. The total number of intrusive
memories per week (primary outcome) was approximately
halved from baseline to the intervention phase, similar to what
Kessler et al [19] found in a study involving inpatients withcomplex PTSD. Of particular interest in this study is that the
reduction in the number of intrusions continued to 76% at the
1-month follow-up and to 92% at the 3-month follow-up,
meaning that three of the four intrusions were eliminated entirely
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JMIR FORMATIVE RESEARCH
at 3 months. This critically extends previous studies by
examining the long-term effects at 3 months postintervention
and, in this case, at least suggests that symptoms may continue
to improve in the long term rather than rebound. This is perhaps
because of the fact that the intervention is simple to use
independently once it has been learned so that the participant
can self-administer booster doses if needed.
The specific symptom probe design allowed us to zoom in on
the effect of each intervention session on each of theparticipant’s four intrusive memories. All four memories
reduced after being targeted, with reductions ranging between
26% and 86% (from baseline to intervention phase). By the
3-month follow-up, only the most distressing intrusive memory(memory A) was still present, occurring only once during thepast week. This quantitative reduction was mirrored in theparticipant’s qualitative feedback, with her noting that the
intrusive memories bothered her very little at this time.
Symptoms of PTSD (subthreshold for this participant) werereduced postintervention, and the same pattern was observed
for symptoms of both depression and anxiety. This change wassimilar to the results reported by Kessler et al [19]. Interestingly,
symptoms of PTSD, depression, and anxiety continued todecrease along with the number of intrusive memories and wereminimal at follow-up.
The intrusive memories affected the participant’s generalfunctioning at baseline, for example, it affected her sleep,
leading to fatigue, which affected her daily functioning. Afterthe intervention, her functioning improved as the intrusions nolonger interfered with her day-to-day life at the 3-monthfollow-up. Her concentration improved considerably frombaseline to postintervention and further at follow-up. The
participant, in effect, gained back hours during which herconcentration was not disrupted by intrusive memories. Bothsleep and stress improved postintervention and continued to
improve at follow-up.
Importantly, the participant found the gameplay to be a very
acceptable way to reduce the frequency of intrusive memories,
similar to the Holmes et al [31] study with refugees. The
participant also indicated that the intrusive memory diary wasstraightforward and not burdensome to complete. Most diary

Thorarinsdottir et aldata were successfully recorded, although some days in thebaseline and intervention phases were missing, mostly becauseof extra days passing in between sessions where the participant
had not received the next diary provided in sessions.
This intervention approach (currently under development, notevidence based), intended not to treat the whole of PTSD but
rather a single symptom, is unlike existing treatment options
and potentially removes some common barriers to them. For
example, barriers include a sparse number of qualified
psychological therapists in Iceland (particularly in rural areas)
as well as the high cost of treatment and high dropout rates,
stigma, and patients' reluctance to talk about the traumatic
experience [10-12].
This intervention removes patients' need to talk about anddescribe the trauma in detail, is low cost, and because of its
simplicity, it may be delivered by nonexperts after training. It
is important to explore further how this intervention approach
can address other common barriers in existing treatments. Future
research should explore remote delivery of the intervention (eg,communication via web-based platforms) instead of in-person
meetings [48]. This would remove geographical constraints andmake it possible to reach people even when immobilized or
isolated (eg, in quarantine because of the COVID-19 pandemic),
which is increasingly important in today’s uncertain
circumstances [49].

Conclusions
Overall, the results of this single case study indicate that theintervention is promising, showing initial signs of effectivenessin reducing the frequency of intrusive memories of trauma that
had occurred 4 decades ago and improving mental health andfunctioning in an Icelandic setting at least for the firstparticipant. The intervention was well tolerated and acceptable,
and the effects of the intervention may even continue after theintervention phase. The next step will be to examine whether
such effects extend to other participants (eg, in a case series)
and to explore remote delivery of the intervention, to explore
whether it is possible to deliver by nonclinicians, and to further
tailor the intervention to this setting based on feedback fromtarget users.

Acknowledgments
The authors would like to thank Johanna Motilla Hoppe and Elin Sjofn Stephensen for their administrative assistance. EAH
received funding from the Oak Foundation (OCAY-18-442) and from the Swedish Research Council (2020-00873) in supportof this study; EAH also received funding from AFA Insurance (200342) and the Lupina Foundation. AB received funding fromthe Icelandic Research Fund (11709-0270). UV received funding to establish the stress and gene analysis (SAGA) cohort fromthe European Research Council (StressGene, grant 726413) and the Icelandic Research Fund (grant 163362-051). EBT reports
funding from the Icelandic Research Fund (185287-051). LS received funding from the Swiss National Science Foundation(P2BEP1_184378) and a Thunberg Fellowship from the Swedish Collegium for Advanced Study.

Conflicts of Interest
EAH reports serving on the board of the charity MQ: Transforming Mental Health (UK). She also receives book royalties from
Oxford University Press (Imagery and Cognitive Therapy) and Guilford Press (Imagery-Based Cognitive Therapy for Bipolar
Disorder and Mood Instability) and occasional fees from clinical workshops and conference keynotes.

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Abbreviations
CAPS: Clinician Administered PTSD ScaleCONSORT: Consolidated Standards of Reporting Trials
DSM: Diagnostic and Statistical Manual of Mental Disorders
GAD-7: Generalized Anxiety Disorder–7
MINI: Mini International Neuropsychiatric Interview
PCL-5: Posttraumatic Stress Disorder Checklist-5
PHQ-9: Patient Health Questionnaire-9
PTSD: posttraumatic stress disorder
REDCap: Research Electronic Data Capture
SAGA: stress and gene analysis
SDS: Sheehan Disability Scale

Edited by G Eysenbach; submitted 23.04.21; peer-reviewed by J Hoogervorst; comments to author 20.05.21; revised version received
11.06.21; accepted 05.07.21; published 04.11.21
Please cite as:Thorarinsdottir K, Holmes EA, Hardarson J, Hedinsdottir U, Kanstrup M, Singh L, Hauksdottir A, Halldorsdottir T, Gudmundsdottir
B, Valdimarsdottir U, Thordardottir EB, Gamble B, Bjornsson A
Reducing Intrusive Memories of Childhood Trauma Using a Visuospatial Intervention: Case Study in Iceland
JMIR Form Res 2021;5(11):e29873
URL: https://formative.jmir.org/2021/11/e29873
doi: 10.2196/29873
PMID: 34734830©Kristjana Thorarinsdottir, Emily A Holmes, Johann Hardarson, Unnur Hedinsdottir, Marie Kanstrup, Laura Singh, Arna
Hauksdottir, Thorhildur Halldorsdottir, Berglind Gudmundsdottir, Unnur Valdimarsdottir, Edda Bjork Thordardottir, BeauGamble, Andri Bjornsson. Originally published in JMIR Formative Research (https://formative.jmir.org), 04.11.2021. This is an
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