The effect of cognitive bias modification of interpretive bias in the treatment of dental phobia

In the last years, a rapid increase took place of studies in the field of
cognitive bias modification (CBM). CBM seems to be an effective intervention to
modify cognitive biases in order to reduce psychological complaints. Moreover,
the method is not strainful to the patients. Interpretive bias is one of the
most important cognitive biases, especially in anxiety disorders. Anxiety
symptoms can be reduced by a cognitive bias modification training of
interpretive bias (CBM-I). For instance, this effect has been shown in
generalized anxiety disorder, chronic rumination, and social anxiety. However,
no studies are known that investigate the effect of CBM-I on dental phobia. In
the present study, the effect of CBM-I on specific anxiety complaints will be
investigated in patients with dental phobia. These patients will receive the
CBM-I training prior to the treatment-as-usual (exposure therapy). We
hypothesize that patients who received CBM-I training will start their exposure
therapy with lower anxiety levels, and that their anxiety levels will reduce
faster compared to patients that receive a placebo training.

Investigation of the effect of interpretive bias modification on anxiety levels
in dental phobia. If CBM-I indeed has positive effects in the treatment of
dental phobia, it could be integrated in the treatment-as-usual as an
additional intervention.

Double-blind randomized controlled trial (N = 2x 24). A power analysis with a
power=0.8, α= .05 shows that a sample size of 45 patients is required
(calculated a priori for a medium effect size). Because of equal group sizes,
and to account for some drop-out, we choose to include 48 patient (2x 24). In a
similar study (Bowler, 2012), 21 participants per group were included.

The CBM-I training consists of short scenarios of initially ambiguous dental
situations. A word is left out of the final sentence of the scenario. In the
positive CBM-I group the missing word will give a positive meaning to the
ambiguous situation, and participants are trained to make positive emotional
interpretations. For the placebo group, only neutral meanings are given to the
scenarios that are similar to those in the experimental group. All participants
receive the training four times: two times per week, 20 minutes per session, 20
trials (scenarios) per session, during two weeks prior to the exposure therapy
(the treatment-as-usual).

Participants receive four training sessions (20 minutes each, two sessions per
week) during the two weeks prior to the exposure therapy. This is an online
training which the participant can perform at home. There will be no treatment
delay; instead, the waiting weeks between the intake session and the first
exposure therapy session will be usefully filled in. The training modifies the
interpretive bias in a positive direction. This is considered a positive effect
(a negative interpretive bias is associated with anxiety symptoms, whereas
healthy, non-anxious individuals interpret ambiguous information in a positive
direction. The CBM-I training corrects the negative interpretive bias towards a
positive outcome or stimulates a positive bias). The placebo group receives a
neutral computer task, similar to the CBM-I training (without stimulation
towards a positive or negative direction). Both tasks are not psychological or
physical strainful. There are no risks for the patients. Patients participate
in the research fully voluntarily, they may withdraw from the research at any
moment and without any consequences, and data will be handled anonymously.