Implicit processes in the treatment of trichotillomania

Many people suffer from unwanted habits. Six unwanted habits are included in
the section impulse control disorders of the DSM-IV-TR (APA, 2000). One of
these is trichotillomania. People suffering from trichotillomania pull out
their hair until bald spots become visible. Hair pulling can occur on all
bodyparts. The disorder is fairly common: life-time prevalence rates are 3.4%
for women and 1.5% for men. Behaviour therapy has shown to be effective (e.g.,
Keijsers et al., 2006b; Lerner, Franklin, Meadows, Hembree, & Foa, 1998; Van
Minnen, Hoogduin, Keijsers, Hellenbrand, & Hendriks, 2003). Unfortunately,
relapse rates up to 70% are common (e.g., Keijsers et al., 2006b).
We expect that standard behaviour therapy insufficiently affects implicit
processes. Bargh and colleagues(1990, 1997) assume that stimulus-response
associations that lead to behaviour, are mediated by implicit processes.
Several studies have shown that these implicit processes are related to
unwanted behaviour. Implicit processes can be subdivided into three categories:
action tendencies, attention and evaluation.
It has even been shown that implicit processes can be trained. In two studies
by Wiers and collegues with alcoholics (2010, 2011) it was found that training
people with a joystick task leads to behavioural change. In this task
alcohol-related stimuli have to be pushed away with a joystick, whereas stimuli
representing a healthier alternative, in this case soda, have to pulled. Wiers
found that people drank less alcohol in a subsequent taste taste. In a patient
population it was even found that patients that received this training showed
significantly less relapse than patients that received a placebo training.
We want to replicate this study in a population of trichotillomania patients to
find out whether this training also works in this disorder to reduce relapse.

The objective of this study is to find out whether adding an implicit training
to standard behaviour therapy can improve long-term treatment outcome in TTM.
We are especially interested to find out whether this added training can reduce
relapse rates.
The second goal is to find out which implicit processes underly
trichotillomania to get a better understanding of this disorder. With this
knowledge future therapy can be improved.

This study is double-blind randomized controlled study.

Patients first receive six sessions of computer training. One half of the
patients receives a control training in which hair pulling-related stimuli are
pushed and pulled with the joystick an equal amount of times. The other half of
the patients receives a training in which patients push stimuli related to hair
pulling all the time to create an avoidance bias.

After this all patients receive 6 sessions manual-based behaviour therapy.
After one and three months a follow-up session takes place.

The computer training as well as the behaviour therapy takes about an hour per
participant each session. The computer training will take place during the time
patients normally have to wait until they are assigned to a therapist. The
waiting list at the Ambulatorium (the time between the first intake and the
assignment to a therapist) normally is around three weeks. We extend this
period with approximately one week. The computer training and the bahaviour
therapy take place at the same location. In our view there are no risks
involved in participation.