Clinical trial NCT05193383: Neural Mechanisms of Imaginal and in Vivo Exposure
Official title: Neural Mechanisms of Imaginal and in Vivo Exposure: Exploring the Differences Between Imaginal and in Vivo Exposure, Using fMRI and Psychophysiology
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Fear of Spiders
Keywords: Imaginal exposure
Exposure
Mental Imagery
Lead sponsor: Uppsala University
Sponsor class: OTHER
First posted: 2022-01-14
Enrollment: 87
Sex: ALL
Minimum age (years): 18
Maximum age (years): 60
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: Imaginal exposure is a widely used and effective psychological treatment technique. Recent research suggests that neural activations and emotional responses during imaginal exposure are similar to those elicited during in vivo exposure. However, to the investigators knowledge, no direct comparison between in vivo and imaginal exposure has been performed during neuroimaging. This study compares neural activations and emotional responses during imaginal and in vivo exposure. This study also explores the generalizability of fear reduction achieved through imaginal exposure to fear responses elicited by in vivo stimuli, and vice versa, in a follow-up session approximately one week later. A better understanding of the mechanisms behind both types of exposure could have significant clinical utility, as well as elucidate the differences between fear created from outward stimuli and fear created from inward stimuli, such as mental imagery.

Detailed description: The study includes participants fearful of spiders and entails two experimental sessions, roughly one week apart. The first session includes brain imaging using functional magnetic resonance imaging (fMRI). During the first session, participants will be randomized into one of two conditions - in vivo exposure or imaginal exposure. In the in vivo exposure condition, participants will be shown video clips of spiders (fearful stimuli) and leaves (neutral stimuli) in different situations. In the imaginal exposure condition, participants will be instructed to produce mental imagery of the corresponding stimuli used for in vivo exposure.

Previous research found that the brief exposure procedure used during session 1 produced a fear reduction when the procedure was repeated one week later. Thus, in order to conceptually replicate this finding, and to examine the generalizability of fear reduction, participants return roughly one week later for a follow-up session. In the follow-up session, participants undergo a similar exposure procedure as used in session 1, but with half of the stimuli in vivo and the other half of the stimuli as mental imagery. In this way, it can be studied whether fear reduction generalize from exposure modality to another. The effects of imaginal and in vivo exposure on avoidance behavior towards fear-provoking stimuli (spiders) will also be assessed using an approach-avoidance conflict paradigm, using pictures of spiders to probe spider fear.

The current study will also explore the impact of mental imagery vividness during imaginal exposure on fear reduction. Additionally, the study will assess if vividness level can predict the generalizability of the effects of imaginal exposure to fear-provoking stimuli (mental imagery of a spider) on subsequent fear responses to to in vivo stimuli (film clip of a spider) one week later.

Functional magnetic resonance imaging (7T) is used to measure neural activations (session 1). Skin conductance is used to measure arousal response (session 1 \& 2). Subjective fear and mental imagery vividness ratings will also be collected.

Eligibility criteria: Inclusion Criteria:

* Willing and able to provide informed consent and complete study procedures
* Fear of spiders

Exclusion Criteria:

* Current psychiatric disorder other than spider phobia
* Current use of psychotropic medication
* Current neurological conditions
* MRI-contraindications (i.e metal implants in skull)

Primary outcomes:
measure: Blood oxygen level dependent contrast (BOLD-signal) during exposure to fearful stimuli (in vivo or imaginal).
timeFrame: Day 1
measure: Physiological arousal response during exposure (in vivo or imaginal).
timeFrame: Day 1
measure: Physiological arousal response during follow-up exposure
timeFrame: One week after Day 1
measure: Ratings of subjective fear experienced during exposure to fearful stimuli and neutral stimuli
timeFrame: Day1
measure: Ratings of subjective fear experienced during exposure to fearful stimuli and neutral stimuli
timeFrame: One week after Day 1
Secondary outcomes:
measure: Ratings of subjective fear participants expect to experience during exposure to fearful stimuli
timeFrame: Day 1 & one week after Day 1
measure: Number of approach-avoidance decisions during an approach-avoidance behaviour task using fearful stimuli (spiders)
timeFrame: One week after Day 1
measure: Task-specific mental imagery vividness ratings to fearful and neutral stimuli during imaginal exposure, and follow-up exposure (not applicable during in vivo exposure).
timeFrame: Day 1 & one week after Day 1
measure: Spielberger State-Trait Anxiety Inventory (STAI-T)
timeFrame: One week after Day 1
measure: Vividness of visual imagery Questionnaire (VVIQ)
timeFrame: One week after Day 1
measure: Amount of watching film clips (not applicable during imaginal exposure).
timeFrame: Day 1 & one week after Day 1
Other outcomes:
Locations:
city: Lund
country: Sweden
facility: The Swedish 7T facility
Study officials:
affiliation: Uppsala University
name: Thomas Ågren, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Hoppe JM, Holmes EA, Agren T. Exploring the neural basis of fear produced by mental imagery: imaginal exposure in individuals fearful of spiders. Philos Trans R Soc Lond B Biol Sci. 2021 Feb;376(1817):20190690. doi: 10.1098/rstb.2019.0690. Epub 2020 Dec 14.