An explorative and experimental study to assess the feasibility, acceptability and effectiveness of four imagery intervention techniques in the treatment of auditory vocal hallucinations

Auditory vocal hallucinations are the most common hallucinations of psychosis
(American Psychiatric Association, 2013; Sommer et al., 2012) and do also often
occur in in patients with various other psychiatric disorders, such as
Post-Traumatic Stress Disorder (PTSD), anxiety disorders, mood disorders,
eating disorders or personality disorders (Laroi et al., 2012; van Os &
Reininghaus, 2016; Waters et al., 2018). It remains open to debate whether
theories about auditory vocal hallucinations are sufficient enough to explain
the full spectrum of psychosis, since effects of both pharmacological
(Carpenter & Davis, 2012) and psychological (Janssen et al., 2021; van der
Gaag et al., 2014; Wykes et al., 2008) therapies for auditory vocal
hallucinations are in the small to modest range. The missing link and a
potential target for treatment might be the transdiagnostic phenomenon mental
imagery, as as few studies showed that patients with psychosis experience
intrusive images associated with their psychotic symptoms (Morrison et al.,
2002; Schulze et al., 2013). In addition, psychological interventions targeting
mental imagery in several other mental disorders with overlapping features with
psychosis has yielded promising results (Ehlers et al., 2005; Hales et al.,
2018; Holmes et al., 2016; Wild & Clark, 2011). Also, few experimental
studies investigating the effects of a few imagery interventions in addition to
cognitive behavioral therapy (CBT) for patients with psychosis showed promising
results (Ison et al., 2014; Morrison, 2004; Serruya & Grant, 2009).
However, the working mechanism behind these interventions is not fully
understood. Moreover, there is no specific imagery enhanced CBT protocol for
working with auditory vocal hallucinations. Indeed, it is not known which
imagery intervention techniques are feasible for patients with hallucinations.
The aim of the current study is to assess the acceptability and feasibility of
four imagery interventions for auditory vocal hallucinations and to assess
effects of these interventions on the level of auditory vocal hallucinations
and mental imagery.

The main objective of this study is to assess the feasibility, acceptability,
and effectiveness of four imagery intervention techniques adapted from the
protocol of Holmes (2019) for auditory vocal hallucinations. We are primarily
interested in whether these imagery intervention techniques would be associated
with a decrease in auditory vocal hallucinations and imagery symptoms. Also, we
are interested in whether these imagery intervention techniques would be a
feasible and acceptable intervention for patients with a disorder in the
transdiagnostic psychosis and suffering from auditory vocal hallucinations.
Secondly, we aim to assess the effects on the level of delusions, visual
hallucinations and social and occupational functioning. Lastly, we aim to
explore the working mechanisms of imagery, affective symptomatology, and
auditory vocal hallucinations by three times daily measuring these symptoms for
a period of seven weeks.

The present research proposal concerns four single case series A-B-A within
subject designs. Assessments consists of clinical questionnaires and three-time
daily questions about hallucinations (both auditory and visual), delusions,
imagery and affective symptoms (anxiety and depression).

This protocol consists of four different studies assessing four imagery
intervention techniques (metacognitive imagery intervention, imagery
rescripting, promoting positive imagery and competing imagery task).

Risks for patients participating in this study are minimal. Similar
interventions have been successfully tested in feasibility trials for patients
with psychosis suffering from delusions and auditory vocal hallucinations. The
results of these studies suggests that these interventions are well tolerated
and received by patients. All patients, during the baseline period, during the
treatment phase and during follow-up, have regular appointments with their
psychiatrists or general nurse practitioner to monitor medication use, mental
and daily functioning. Also, risks for patients with suicidal related auditory
vocal hallucinations are minimal since the urge to act on suicidal thought or
imperative auditory vocal hallucinations does not increase after talking about
these thoughts. On the contrary, it seems to have a protective effect (Dazzi et
al., 2014). This is the same for the use of imagery interventions in the
treatment of suicidal ideations (Rahnama et al., 2013). Psychological therapy
for psychosis belongs to standard care. The extra burden for participants is
the daily self-monitoring, that requires participants to complete a
questionnaire (5-10 min) at three at equidistant time points with a 4-hour
interval in between for 49 consecutive days, the first assessment in which
participants sign the informed consent and a researcher administer a clinical
interview (+/- 60 minutes) and the self-report questionnaires at T0-T1-T2
(25-35 minutes).