The Impact Of Mental Visual Imagery Programme On Episodic Future Thinking

Introduction

The ability to simulate events that may take place in the personal future is named Episodic Future Thinking (EFT). Studies show that limitations in the ability to extract details of past experiences from episodic memory are associated with an inability to generate detailed simulations of future events, supporting the hypothesis that episodic memory serves as the basis for episodic future thinking (Szpunar & Radvansky, 2015). It is easy to imagine that the ability to mentally project oneself into a future scenario could be valuable for optimal real-world functioning. Every day is filled with tasks that need to be completed. Mentally placing oneself into a vivid future scenario could potentially aid in the anticipation of obstacles and facilitate taking steps to overcome such obstacles. EFT impairment has been reposted in various clinical conditions such as in Alzheimer’s disease (Addis, Sacchetti, Ally, Budson, & Schacter, 2009), semantic dementia (Irish, Addis, Hodges, & Piguet, 2012; Viard et al. , 2014), behavioral variant of frontotemporal dementia (Irish, Hodges, & Piguet, 2013), depression (Williams et al. , 1996), Schizophrenia (D’Argembeau, Raffard, & Van der Linden, 2008) or in relapsing-remitting multiple sclerosis (RR-MS) patients (Ernst et al. , 2014). Previous studies suggest that episodic foresight is disrupted in individuals who regularly use Cannabis (Mercuri et al, 2018). Regular cannabis users, in particular, show a substantial deficit in their capacity to generate episodic details when asked to imagine novel future scenarios.

As a result of such studies which reported EFT impairment in different clinical conditions, the importance of using a cognitive rehabilitation programme which specifically targets and enhances EFT performance, has increased. An episodic future thinking intervention may allow individuals to achieve optimal functioning since findings show that episodic future thinking is associated with functional abilities. The goal of an episodic future thinking intervention would be to help individuals mentally project themselves into the future in a vivid way to aid in successful completion of daily activities. Among all the cognitive rehabilitation programs known to us so far, Ernst, Blanc, de Seze, and Manning (2015) were the first to develop a cognitive rehabilitation programme that aimed at alleviating EFT impairment specifically. This programme was developed to tackle executive function-related EFT impairment in relapsing-remitting multiple sclerosis (RR-MS) patients (Ernst et Al, 2016). The Mental Visual Imagery (MVI) intervention relies on the critical role of mental visual imagery (MVI) in autobiographical memory (the ability to mentally re-experience personal past events) retrieval and vividness of memories (Greenberg & Rubin, 2003). The aim of this programme is to make use of the cueing role of MVI, that is the use of visual details as cues to activate additional visual information. Goals and Hypotheses The purpose of this study is to understand the impact of a Mental Visual Imagery (MVI) cognitive facilitation programme, on the episodic future thinking (EFT) of chronic Cannabis users.

Furthermore, the primary goal of this study is to investigate how the MVI programme has an impact on an individual’s EFT, and how it differs in Cannabis user individuals and non-user healthy individuals, according to the structural and functional changes in their brain using functional magnetic resonance imaging (fMRI). Using a short-term version of MVI based programme, we expect an improvement in Cannabis users EFT functions and that this clinical benefit would be accompanied by functional and structural changes within the EFT brain networks which has been detected in a few studies and are consisted of: the medial temporal lobe, the medial prefrontal cortex, the posterior cingulate cortex, the retrosplenial cortex, anterior and lateral temporal lobe, precuneus, and posterior parietal lobe (Buckner & Carroll, 2007; Schacter & Addis, 2007; Schacter, Addis, & Buckner, 2007; Schacter et al. , 2008; Schacter, Addis, et al. , 2012; Szpunar, 2010; Verfaellie, Race, & Keane, 2012). We hypothesis that the changes we expect in the MVI experimental group would not be observed in the control programme group, where no EFT improvement is expected. We believe that the results of the current study will be consistent with the results suggesting by prior research showing cannabis- related deficits in related future-oriented cognitive abilities, such as prospective memory (Bartholomew et al. , 2010; Fisk and Montgomery, 2007; Montgomery et al. , 2012) and planning (Harvey et al. , 2007; Montgomery et al. , 2012). To our current knowledge there are only two other studies to assess episodic foresight in the context of chronic substance abuse, one in long-term opiate users which identified significant impairments (Mercuri et al. , 2014) and also a study showing that regular cannabis use can disrupt the capacity for mental time travel into the past and the capacity for episodic foresight (Mercuri et al. , 2018).

Method Participants

Participants include 30 people, 20 Cannabis using adults (18-60 years of age) both male and female, assigned to two groups of experimental and control, and 10 healthy (non-user) adults. Cannabis user participants must meet DSM-5 criteria for at least moderate cannabis use disorder. Participants must be right-handed (should they? !) and Persian speaking.

Inclusion Criteria

• Participants must be able to provide informed consent and function at an intellectual level, sufficient to allow accurate completion of all assessment instruments.
• Participants must be physically healthy as determined by a comprehensive physical examination.
• Participants must be able to read and write for filling the demographic forms and subjective information needed for the study.
• Participants must be between ages of 18 and 60.
• Participants must have used Cannabis at least 10 times in the past three months or at least 50 times in life.
• Participants must have a positive UDS (Urine Drug Screening) for Cannabis during their enrollment visit and confirm that they are regular users.
• Participants must be mentally stable as determined by a psychological evaluation. Exclusion Criteria
• Participants must not test positive for any substance other than Cannabis (except Nicotine) on UDS during their enrollment visit.
• Participants must not meet moderate or severe use disorder of any other substance with the exception of Nicotine use disorder.
• Participants must not have any unstable general medical conditions and must not be on medications that have CNS effects.
• Participants must not have magnetically active irremovable prosthetics, plates, pins, permanent retainer, bullets, cardiac pace maker, etc.
• Participants must not have Claustrophobia or other medical condition preventing them for lying in the MRI for approximately 1 hour.
• Participants must not have severe vision problems.
• Participants with a MoCA score, less than 21 will be excluded from the study.

Recruitment

Participants are recruited from the community, clinics, and the social media advertisements. Online flyers are posted in social media such as Instagram, face book, etc. adults using cannabis are invited to participate in the study for an exchange of … amount of money. 10 non-user participants are also recruited from the community and are matched with the users group by age, gender and education. Screening An initial screening is done by the researcher on the phone, in response to the volunteers who call the researcher for taking part in the study as subjects. The information asked by the researcher in the initial screening phone session is about participant’s age, language spoken, MRI contraindications, vision and hearing problems, reading abilities, yes/no questions about psychiatric history and yes/no questions about substance use. Participants are instructed to refrain from use of alcohol or illicit drugs in the 24 hours prior to testing.

Participants will be sent a reminder text message at least 24 hours prior to their testing time and abstinence should be confirmed via self-report and Urine Drug Screening on the day of testing. Participant’s demographic information is recorded by means of CDAP version I (Clinical Drug Addiction Profile) (Mokri, Ekhtiari & Farhoudian, 2011). The information consists of Gender, date of birth, Marital status, Education (in years), Occupation (Job), Drug abuse profile (age onset and the amount of drug consumption in the last 30 days), History of Overdose, amount of money spent on drugs (per month). A Persian version of Montreal Cognitive Assessment (MoCa) test (Nasreddine et al, 2005) is done after the demographic information acquisition. Individuals with the score less than 21 will be excluded from the study. Design The study will involve one visit lasting about 3 hours. Participants will have an initial assessment about their Demographic information, a neuropsychological assessment (MoCA), and provide Urine samples before beginning the study, done by the researcher. Participants will have two Functional Magnetic Resonance Imaging (FMRI) Brain scans done for Pre-test and Post-test.

The Pre-test scanning also includes the Brain Structural imaging at its beginning. Cannabis user subjects are randomly assigned in the experimental (Mental visual imagery group) or in the control group and should be blind to their allocation. fMRI tasks The fMRI task encompasses an EFT condition, which includes imagination and visualization of unique personal future events based on adapted Autobiographical Interview (AI) instructions (Addis et al. ,2007) and a control task. The control task is adapted from (Addis et al. ,2007) which includes pairs of words which the subject has to make a sentence for the construction phase ( e. g. pink dress : she is wearing a pink dress). Then during the elaboration phase, the subject has to keep the sentence’s same structure, replacing the two given cue-words by words of the same semantic category (e. g. she is wearing a yellow shirt).

For both tasks (construction and elaboration), each trial has a fixed duration of 20 s modulated by subject’s response. Once the event has generated, the subject presses a button on the response box to show the end of the construction phase. Then a central fixation indicates the elaboration phase, which lasts during the remaining time. Subjects are instructed to press the button only if an event comes to their mind.

During the scanning session, 24 future event trials are presented randomly across the entire scanning session. Each trial is 35 s in duration and begins with a 20 s construction and elaboration phase. There are totally 6 runs consisting of 4 trials each 35 secs plus a 20 s at its beginning for the construction and elaboration phase. Trials are separated by a rest period during which a fixation cross is presented for a mean duration of 4 s (varying between 2-6 s). Immediately prior to scanning, patients should complete a computerized practice trial for the tasks to ensure that the participants understand the experimental design and the timing of presentation of the stimuli. The event does not have to strictly involve the object named by the cue. Participants are encouraged to freely associate so that they are successful in generating the event. Events are required to be temporally and contextually specific, occurring over minutes and hours, but not more than one day (i. e. episodic events). Examples should be provided to illustrate this requirement (remembering a 2-week trip to France versus visiting the Eiffel tower on one specific day, or imagining one’s future child versus imagining the birth of one’s child).

Future events should also be novel (not been previously experienced by the participant) and plausible given the participants plans for the future, to ensure the projection of the self over time. (If one isn’t planning to have children in the future, they shouldn’t imagine giving birth). Further, participants were instructed to experience events from a field perspective (i. e. , seeing the event from the perspective of being there) rather than from an observer perspective (i. e. , observing the self from an external vantage point). Once the participant finishes the imagination, they have to press a button on the response box. The cueing slide remains on the screen for the entire 20 s duration. All stimuli are presented with black text on white background which is projected on a screen viewed by the participant in a mirror attached to the head coil. E-Prime 2 software will be used for presentation and the timing of stimuli and the collection of response data. Responses are made on an MR-compatible five-button response box. It is also important that, the same procedure should be followed for the two fMRI sessions (in pre- and post-test scanning). Each task should be developed in two versions, and presented in a counterbalanced order across pre and post scanning sessions. Patients should also be instructed not to provide the same events as those previously mentioned during the adapted Autobiographical interviews or during the first fMRI session and this absence of events repetition should also be verified by the subject on the post-scan questionnaire. Heart Rate Measurement Heart Rate (HR) responses are measured during both fMRI scanning sessions for monitoring the amount of the subject’s arousability. An MRI-compatible Electrocardiogram (ECG or EKG) is the used technique in acquiring HR information in the current study. The three ECG electrodes are placed in proximity to the heart on the left side of the chest.

Post Scan Questionnaire

In the post-scan questionnaire which is provided to the subjects immediately after the fMRI scanning, For each event, subjects should indicate the type of future events (unique, repetitive, extensive, semantic or absent). The different types of events are defined as follows: 1) unique: specific or particular occurrence of events, within a specific time and place frame, no longer than one day; 2) repetitive: events that are usual and repeated, and thus lack being episodic; 3) extended: includes events whose duration is longer than one day (e. g. my whole week of holidays in Tehran), without the mention of a specific incident; 4) semantic: including general, semantic associations with the cue-words not self-relevant (i. e. this winter will be colder than the last year); (v) absent: corresponds to the absence of response in the scanner (i. e. no button press to end the construction phase). Participants also rate each event for personal significance on a five point scale (1 = insignificant, did not change my life; 5 = personally significant and life-changing event) and provided their approximate age at the time of the event imagined. They also should rate the vividness, presence of the details, emotional intensity, overall arousal or energy level at time, of each event on a Likert (5-point) scale.

Cognitive Intervention

The cognitive facilitation programme consists of Mental Visual Imagery (MVI) (created by Manning, 2016) and is based on the ability to mentally construct scenes. It is organized in 3 steps done in one session of approximately 40 minutes. The first pre-intervention step is to explain carefully the aim of the programme, its content and how it is supposed to help the memory impairment. This introduction is important to help promote its further use in daily life. The first step in the intervention is the “external visualization” which includes 10 names of objects to be imagined and described. (10 isolated items to imagine and describe in as much details as possible like their shape, colour, size, etc. , with the complementary visualisation of an action made with the item. ) The second step is the “construction phase” consists in figuring out complex scenes, bringing into play several characters. Five verbal items are proposed with for each one, a first training step and a subsequent scene, sharing thematic similarities (imagine and visualize more complex and dynamic scenes). The third and last “self-visualization” step follows the same procedure, but participants are asked to imagine themselves within a given scenario as they are living the scene. The procedure is exactly the same than in the previous step, with the only difference that the participant is the main character in the scene. The participant is asked to visualise him/herself within the given scenario, to imagine it as he/she is actually living the scene, with the description of every kind of details, sensations or feelings that come to their mind. The external-visualization and the self-visualization steps consist of 5 scenes each to be visualized.

Control Programme

The control programme follows the same procedure but focuses on the narrative structure, which plays a minor role in autobiographical memory relative to Mental Visual Imagery (Greenberg & Rubin, 2003). The common theme is to construct discussions about texts, going from discussion about the form, to the theme of the text, with a final focus on the patient’s personal opinion, with a particular emphasis on the organization of information. Three steps should be proposed: (1) The external discussion which relies on the identification of influent variables on text understanding related to its form (e. g. , clarity, vocabulary used) and comprises 20 texts. This step is very short and corresponds to the MVI external visualization programme. (2) The discussion construction contains five items, with a training and a construction step for each item, with two texts thematically related to enable reliance on the first to construct the second (e. g. , a first text dealing with a trip to Shiraz was followed by a text about a trip to Isfahan). (3) The self-involved discussion is similar to the previous step, with the addition of questions about the participant’s own opinion (e. g. , a first text about taxing sodas to reduce their consumption was followed by a second text concerning the usefulness of anti-smoking campaigns).