Attentional Bias to Activity in the Abdomen in Children with Functional Abdominal Pain (FAP).

RAP affects about 0.3 to 19% of children in Western countries (Chitkara, Rawat,
& Talley, 2005). For most children, no organic abnormalities can be found to
explain the pain. In those cases, the pain is considered to be functional
(FAP). Children with FAP may experience significant school absenteeism, family
disruption and withdrawal from social activities (Youssef, Murphy, Langseder &
Rosh, 2006). FAP has been associated with a high comorbidity of anxiety (about
80%) and depression (about 40%). Many children with FAP go through potentially
risky and possibly unnecessary hospitalizations, tests and procedures, thus
placing a heavy burden on the medical community (Dufton et al., 2009). To treat
these children effectively and prevent further (psycho)pathology, it is very
important to learn more about the etiology of FAP.
A promising explanatory theory for FAP is that of attention bias. According to
the symptom perception hypothesis and empirical findings (Watson & Pennebaker,
1989; Whitehead, & Palsson, 1998), children with many somatic complaints might
selectively direct their attention to ambiguous physical sensations and
interpret them more readily as signs of disease. Children who focus their
attention on pain may not only perceive more pain, but also have fewer
attentional resources available to engage in adaptive coping strategies to deal
with their pain (Compas & Boyer, 2001). One previous study focused on the
presence of a selective attention bias in children with RAP (Boyer et al.,
2006). However, this study has two major limitations. First, it does not
include a control group, which makes it impossible to draw any conclusions on
the specificity of this attention bias for children with RAP. Second, this
study used words as stimuli to measure an attentional bias, whereas it is
questionable whether an attentional bias for words draws on the same processing
mechanisms in the brain as an attentional bias for physical sensations.
Therefore, the current study will follow the research design of Boyer and
colleagues, while correcting for these two major limitations.

The objective of this study is to determine if children with FAP demonstrate
subliminal and supraliminal attentional biases to assumed activity of the
abdomen compared to healthy children and if children with FAP interpret the
assumed activity as pain.

Approximately 30 children with FAP and 30 healthy children will be included.
The study has a between subject design including two conditions: children with
FAP and healthy children that match the age, gender and ethnicity of children
with FAP. The duration of the study will be approximately 12 months. Children
will perform a dot probe task to measure selective attention for physical
stimuli.

Dot probe:
In a visual dot probe task, participants are shown a pair of stimuli for a
short time at two different spatial locations on a screen. One of the stimuli
is threatening, the other stimulus is neutral. After the offset of these
stimuli, a dot probe emerges at the location of the threatening stimulus
(congruent presentation) or at the location of the neutral stimulus
(incongruent presentation). The allocation of attention is measured by the time
needed to respond to the dot probe (Koster et al., 2004).
In this study the threatening stimuli are assumed activity in parts of the body
(abdomen and heart). The neutral stimulus is assumed activity of the computer
on which the task is done. Another neutral but personally relevant stimulus is
activity in the legs. Stickers that are attached to the computer will be put on
the breast and stomach of the children. Straps will be put on the legs. The
participants will be told that the stickers and the straps measure the activity
in their heart (heartbeats), abdomen (bowel movements) and legs (blood
circulation). Every activity is translated in a schematic meter. The meter of
the neutral stimulus will measure the *activity* in the computer.
The participant will see a pair of stimuli, a threat related stimulus and a
neutral one (on the left and right of the computer screen) on subliminal level
for 20 ms. This will be followed by a scrambled picture (mask) for 1230 ms, to
ensure the stimuli are processed subliminally. On supraliminal level a pair of
stimuli will be seen for 1250 ms.

Participants complete questionnaires concerning abdominal pain, pain vigilance,
anxiety, depression, somatic complaints before and/or after the dot probe task.
Also, the children will answer a few questions concerning the influence of the
task on bodily sensations. After performing the dot probe and filling out the
questionnaires, the children will be debriefed about

There is no record of dot probe tasks being unsafe. They do not constitute a
heavy burden for participants and our experience is that children enjoy these
tasks. It is imperative that the study will be performed in children, as the
information processing systems of the brain might be very different in adults
due to maturation processes. Also, it is very important to include a healthy
control group, as without a comparison group, we cannot make any inferences
about whether the attention bias is specific for children with FAP. This
control group cannot constitute of adults but should be children, because of
the differences in information processing between children and adults as stated
above.