Is taxing working memory effective in reducing dental anxiety?

The aim of this study is to determine whether level of dental anxiety reduces
when people who suffer from dental phobia play the computer game Tetris®. For
this study we recrute people who visit a Center for Special Dentistry.
Patients with dental phobia do not primarely suffer from distressing memories
and intrusive imagery from the past (i.e., flashbacks), but they mainly suffer
from distressing images of what might happen in the future (DSM-IV-TR, 2000;
Brewin et al., 2010). The idea of a confrontation with the dreaded object or
situation automatically evokes a fear response. A study of De Jongh and his
colleagues showed that dentally high-anxious patients are more likely to
experience negative, irrational thoughts, both during and prior to treatment,
than those with low anxiety (De Jongh et al., 1994). They also report to
experience less control about their negative thoughts than their low anxious
counterparts (De Jongh et al., 1996; Marteau & Bekker, 1992).
Nowadays, Eye Movement Desensitization and Reprocessing (EMDR) is widely used
as a first-line treatment for traumatic memories (Shapiro, 2001; De Jongh & ten
Broeke, 2011). A core feature of EMDR is that the patient is requested to hold
in mind a disturbing memory while engaging in sets of bilateral dual attention
stimuli (i.e., eye movements, taps or tones; Shapiro, 2001). One of the
theories for explaining the effectiveness of this treatment approach is the
working memory theory which is based on the notion that recalling an episode
depends on the working memory capacity which is limited (Baddeley, 2012). Since
a traumatic memory is inherently intense, vivid and emotionally charged, it
taxes working memory resources when it is recalled. If at the same time another
task (i.e., client*s eyes following the therapist's hand back and forth) is
executed during recall, fewer resources would be available for the memory
(Maxfield et al., 2008; Weitgarnter, 1984; Baddeley, 2012). This competition
within the working memory results in less memory resources for the vividness
and the disturbance or emotionality of the memory. Until now, a series of
experimental studies has been conducted that is supportive of a working memory
explanation of EMDR. Memories have been found to not only become less
disturbing and less vivid during execution of an eye movements task (e.g.,
Gunter & Bodner, 2008).
The working memory account predicts that tasks that tax working memory will
affect the intensity of both flashbacks and flashforwards. Indeed, it has been
found that a competing task for working memory resources will reduce not only
the emotionality of retrospective images but prospective images as well
(Engelhard et al., 2011; Butler et al., 1995). This interpretation is supported
by a study using Tetris® after viewing a traumatic movie. Individuals that
played Tetris® reported significantly less flashbacks of the traumatic images
after one week compared to a control group of subjects who did not play Tetris®
after having watched the same traumatic movie (Holmes et al, 2009; Homes et al,
2010). The effects of playing Tetris® seems to be comparable with that of using
eye movements (Engelhard et al, 2010). Although the effects of taxing working
memory with a dual-task on flashbacks and flashforwards has been supported by
prior studies (Holmes et al, 2009; Holmes et al, 2010; Engelhard et al, 2010;
Engelhard et al, 2011), it is not yet clear whether these effects can be
replicated in patients suffering from a specific phobia.
The question is whether playing the computer game Tetris® is capable of
exerting a positive effect on flashforwards of patients suffering from a severe
form of anxiety about dental treatment. To this end, playing a computer game
prior to undergoing dental treatment seems to be more practical than making
eye-movements according to the EMDR protocol since these must be applied by an
experienced and well-educated clinical psychologist. A computer game like
Tetris® can be played behind a PC, on a handheld console or even on a smart
phone that is accessible at any given time. Moreover, the game Tetris® can be
played solitary.

The purpose of this study is to determine whether playing the computer game
Tetris® prior to dental treatment is capable of reducing trait anxiety in
patients suffering from a severe form of dental anxiety. Patients who visist a
dental fear clinic are asked to think about one aspect of dental treatment that
they fear most. They focus on their mental representation of what might go
wrong (a so called *flashforward*). At the same time their working memory will
be taxed by playing the computer game Tetris®.

The following hypotheses are tested:
1. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces the vividness of their flashforward. (as
indexed by a Visual Analogue Scale (VAS), from 0 = 'not lively' to 100 =
"extremely lively").
2. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces the emotionality of a flashforward (as
indexed by a Visual Analogue Scale (VAS), from 0 = "not at all emotionally
charged" to 100 = 'extremely emotional').
3. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces trait anxiety in regard to the dental
treatment significantly, compared to the levels of three weeks prior. Level of
dental trait anxiety is measure at the start of the study using the K-ATB, and
is administered again when commencing dental treatment three weeks thereafter.
4. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces dental trait anxiety regarding the dental
treatment significantly more than it does for patients without intervention.
The difference between the scores of the K-ATB questionnaire at the start of
the study and measured three weeks later, will be compared with those of the
control group.
5. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces state anxiety level of patients during
treatment. Level of state anxiety will be determined by the VAS, which runs
from 0 = 'no fear' to 100 = "extreme fear". This will be measured at the start
of the study and after having playied Tetris®.
6. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces state anxiety level of patients during
treatment significantly more than of patients that did not get an intervention.
Level of state anxiety will be determined by the VAS which runs from 0 = 'no
fear' to 100 = "extreme fear". This will be measured at the start of the study
and at the start of a treatment appointment three weeks later. The difference
between these scores will be compared to those of the control group.
7. Taxing working memory of patients with fear of dental treatment by playing
the computer game Tetris® reduces the extent to which a flashforward can be
recalled signifcantly more than that of patients who do not receive this
intervention. The extent to which the flashforward can be recalled before and
after playing the computer game Tetris® will be measured with the Visual
Analogue Scale (VAS), which runs from 0 = "can not be recalled at al" to 100 =
'can be recalled extremely easy'.

Sixty patients with severe fear of dental treatment registered at a Center for
Special Dentistry (CBT), will be randomly allocated to two groups of 30
patients each, being the intervention group either the control group. Patients
in both groups will receive a necessary dental treatment that will consist of
administering a local anesthetic followed by the restoration of a tooth
affected by caries, an endodontic treatment or the extraction of a tooth. This
treatment will not exceed a duration of 60 minutes.
We expect that 24 to 30 months will be needed to recruit the required number of
participants.
To determine whether a specific phobia is present a clinical diagnostic
interview, the MINI Plus version 5.0.0. (Sheehan, 1998; van Vliet, the Beurs,
2007) will be administered. A trained dentist will conduct this interview. The
second instrument is a short questionnaire, called the 'Phobia checklist', and
consists of four questions that will be administered by the dentist (Oosterink
et al., 2009). This checklist screens for the presence of the DSM-IV-TR
criteria of a specific phobia (DSM-IV-TR, 2000). Subsequently, level of trait
anxiety and state anxiety will be determined. Patients will be requested to
fill out the K-ATB (Short version of the Dental Anxiety Inventory). The K-ATB
appears to be a reliable and valid instrument to assess level of dental anxiety
(Aartman, 1998).
Prior to treatment patients are asked to indicate the level anxiety they feel
at that particular moment using a Visual Analogue Scale (VAS) ranging from 0 to
100). Next, patients in the control group will receive a standard dental
treatment. The need for this dental treatment has previously been assessed and
will consist of administering a local anesthetic followed by the restoration of
a tooth affected by caries, an endodontic treatment or the extraction of a
tooth. Type of treatment and treatment time will be recorded by the
investigator and will not exceed 60 minutes. The treatment itself is not
adapted to the study and is equal to the treatments other patients receive.
Duration of treatment (defined as the time spent in the dental chair), type of
treatment (filling, extraction, endodontic treatment), number of treatment
(first treatment, second treatment, etc.), and the elapsed time between
treatments will be recorded and filled out on a patient-related data sheet.
The participants in the intervention group are told that they will play the
computer game Tetris ® on a console LCD Brick Game 999-in1 for a few minutes in
four periods of three minutes. Between each period there will be a break of 60
seconds. The consoles are issued out by the investigators.
Prior to playing Tetris the patients in the experimental group are asked to
bring up a picture in their heads of the following dental treatment. This so
called 'flashforward' will mainly consist of the most feared aspect of dental
treatment ("the catastrophe"). The dentist will ask questions to clarify the
flashforward for a detailed description: "Create a clear picture of this
situation and describe it briefly. What do you see tha tgoes wrong? What are
you doing? What is happening? What do you see? (On a scale of 0 to 10, how
anxious are you feeling now?)". The patients will be asked to recall their
picture for 20 seconds and indicate the vividness and emotional charge of it on
two 100 mm Visual Analogue Scale (VAS), which runs from 0 = 'not alive' to 100
= "extremely vivid" . It will be scored for how emotionally charged the picture
is and how difficult it is to recall, on a 100 mm VAS (0 = 'not disturbing' and
'not difficult', 100 = 'extremely emotional' and ' extremely difficult "). The
patients are asked to keep this picture in mind, while playing Tetris®. After
the last period of 180 seconds playing Tetris®, participants are again asked to
recall the image for 20 seconds and score it on vividness and emotional impact
using the VAS. This procedure is based upon the procedure described and used by
Van den Hout et al (2001) and Gunter and Bodner (2008). The VAS scores are used
to determine whether the computer game Tetris® provides an accurate taxing of
working memory.
Within 15 minutes after completing the VAS, a standard dental treatment will
start that is not adapted to the study and is equal to the treatment that other
patients receive. The criteria for this are identical to those of the control
group. After completing dental treatment the participants of both groups will
again be asked on a VAS from 0 to 100 to indicate how much anxiety they feel at
that moment.
After three weeks, all participants will again visit the center (the number of
days between the first and second appointment will be listed on a
patient-related data sheet). During this second appointment participants of
both groups, will be asked to again fill out a K-ATB questionnaire and to
indicate on a VAS from 0 to 100 the level of anxiety they feel at that moment.
The MINI Plus version 5.0.0. and 'Phobia' checklist' will be administered
again. The participants in the intervention group will be asked to recall
their "flashforward" for 20 seconds and to rate it on vividness and emotional
impact using a VAS. Immediately thereafter, within a maximum of 15 minutes,
participants of both groups will again receive a 'standard' dental treatment.

Prior to dental treatment, the participants in the intervention group are asked
about their most feared aspect of the dental treatment (catastrophe) and take
this image in mind as a flashforward. They will then play the computer game
Tetris ®. Playing the computer game Tetris ® will be done on a console LCD
Brick Game 9999-in1. There are four periods of each three minutes played, with
1 minute resting time in between. After the last period again vividness and
emotional impact are scored on a VAS. Within 15 minutes after playing the
computer game Tetris® a standard dental treatment will take place.

Participants who take part in the trial receive dental treatment that is in no
way adapted to the study. Their dental treatment will be equal to that which
other patients receive. Participation in the study requires completing
questionnaires and playing the computer game Tetris ®, which will take about 15
minutes. There are no risks associated with participation in the trail.