Study design
This study is designed as a single-center, prospective parallel-group, double-blinded, randomized controlled clinical trial. The intervention consists of 4 weeks of real rTMS or sham rTMS in which fear extinction and sleep quality are analyzed in insomnia patients. The study protocol will be conducted in accordance with the guidelines for randomized clinical trials: Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines[21]. Ethical approval has been granted by the ethics committee of Zhenjiang mental health center (2023K02), and the trial is prospectively registered at ChiCTR (ChiCTR2300076097).The study detailed flowchart is illustrated in Fig.1. The trial schedule is listed in Fig.2.
Participants
Recruitment
We will post recruitment advertisements on community boards and online social media (WeChat) to recruit participants who report clinically significant insomnia. Patients, who are interested in this study, will fill in the information about the purpose of the study and a survey on the presence of conditions related to the inclusion criteria through a QR code. Researchers will use background data to screen applicants for eligibility. Eligible participants will receive an informed consent form and will be informed about the trial procedure, intervention, benefits, and potential adverse events by a blinded and trained evaluator. All participants will sign informed consent forms before collecting data and randomization.
Inclusion criteria
1.Meeting the diagnostic criteria for insomnia disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition;
2.Age 18–65years (male or female);
3.Pittsburgh Sleep Quality Index (PSQI) scale score > 7 points;
4.Sign informed consent forms for this study;
5.Have not received medications and physical therapy such as rTMS, transcranial direct current stimulation for improving insomnia within 4 weeks prior to enrollment in the study.
Exclusion criteria
1.History of mental illness;
2.History of alcohol and drug abuse;
3.Presence of insomnia caused by medical diseases including nervous system, cardiovascular system and respiratory system and other serious physical diseases;
4.Pregnant or breastfeeding women;
5.Received physical therapy such as rTMS, tDCS in the last months.
Sample size
Sample size estimation is based on the primary outcome changes of PSQI score. According to preliminary experiments, a mean difference of 2.87 with a standard deviation of 3.20 between the real rTMS groups and control group.Then a sample size of 27 patients per group were required to detect a significant difference (power = 0.9, α = 0.05, two-sided) using two-sided,two-sample t-tests assuming equal variance. Considering a 15% patients per group dropout rate, the actual participants in this study will be at least 62.
Randomization and allocation concealment
This study will use simple randomisation method. The random allocation sequence will be carried out using Statistical Analysis Software (version 9.3, SAS Institute Inc., Cary, NC, USA). After baseline measures, the eligibility participants will be randomly adivided into either the real rTMS group or sham rTMS group in a ratio of 1:1. The randomization number will be sealed in a computer-generated opaque envelopes with sequence numbers printed on the outside of the envelopes. After the patient has been screened eligible and given informed consent, the envelopes will be opened by the researchers.
Blinding
It will be impossible to blind the trained operators who operate rTMS and therefore will be excluded from assessments and data processing. The unblinded researchers will inform participants of group allocation and monitor completion of assessments. Participants, data analysts, and outcome assessors will be blinded to allocation. Unblinding should only be performed in case of an emergency, such as any serious adverse events.
Intervention
All participants will receive 20 sessions of rTMS (30min each session, five sessions per week for 4 weeks). The operators who operate rTMS will be well trained to ensure consistent rTMS technique on all participants. Patients will be prohibited from receiving any other relevant treatments including drugs that can improve sleep during the trial period. We attempted to improve adherence to interventions by strategies (i) Emphasizing to participants the importance of their attendance at follow-up assessments even if they were no longer compliant with the intervention, (ii) During the follow-up period, investigators will be arranged to respond to patient inquiries. (iii) Investigators will contact patients 2 (±1) days before each visit via letters and telephone contact.
Real rTMS treatment
rTMS treatment will be performed using a "8" shape coil matched with a high focusing capability using the MagVenture x100 TMS stimulator (MagVenture,Farum,Denmark). According to the 10-20 standard lead localization system, the mPFC brain region is located at the Fpz site. Before the first treatment session, the motor threshold (RMT) of the extensor halusis brevis muscle of the participant’s toes will be measured by single-pulse TMS.RMT is defined as the minimum intensity, which elicited 3 motor evoked potential (MEP) responses in 6 attempts. Treatment parameters will be 1Hz and stimulation intensity will be 80% of RMT. Each sequence will be stimulated for 10 s, the interval between sequences will be 5 s, the number of sequences per treatment will be 120. The daily stimulation time will be 30 min. rTMS will be treated once a day, 5 days a week for 4 weeks.
Sham rTMS treatment
The sham rTMS group will receive no-magnetic stimulation with sham coils designed to induce same "click" sound and scalp sensations during treatment, which the subject could not distinguish.The parameters will be set the same as that for the active stimulation group.
Fear conditioning and extinction procedure
Fear conditioning and extinction will be using electric shocks as the unconditioned stimulus (US) paired with two neutral square stimuli with different colors (blue and red) to be the conditioned stimulus (CS). The shock intensity will be determined according to subjects’ feeling as highly uncomfortable but not painful. The CS will be presented in a counter-balanced order. For the habituation phase, six blue square stimulus (CS-) and six red square stimulus (CS+) presented 5s duration and separated by a 6–10s inter-trial interval with no shock delivery will be shown on the screen. For the fear acquisition phase, CS+ will be coupled to 60% of electric shocks which will apply for a duration of 200ms before CS+ ended.It will consist of 24 CS+ and 24 CS-. The extinction phase will be followed after fear acquisition phase with no instructions at the begining. The procedures will same with fear acquisition phase except that the CS+ during extinction will be no longer followed by electrical stimulation.
Outcomes
Study results will be assessed at baseline (week 0), post-intervention (week 4) and 8-week follow-up (week 8). Outcomes will still be measured for all participants who will be withdraw from the study.
Primary outcome
The Primary outcome measure in this study will be mean change scores of PSQI from baseline to post-intervention. The PSQI consist of seven components, including sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disorders, hypnotic medication, and daytime dysfunction. The higher score reflects the worse sleep quality.
Secondary outcome measures
Secondary outcome measures of this study will be mean change values of skin conductance responses (SCR) and fear expectation during fear extinction, PSQI, Insomnia Severity Index (ISI), Zung Self-Rating Anxiety Scale (SAS), and the Zung Self-Rating Depression Scale (SDS) to evaluate the fear extinction, insomnia and emotional state of ID patients between the baseline, post-intervention, and 8-week follow-up. SCR will be recorded using Ag- AgCl electrodes connected to the BioPac System. Electrodes will be placed on the second and the third finger of the left hand. SCR data will be calculated as the difference between the maximum and minimum response amplitude in a time-window of 0.5 and 4.5s after CS onset. The raw SCR data will be initially square-root-transformed and if the untransformed SCR data is negative, the negative sign will be retained after calculating the square root of the absolute value of the SCR data. Participants will be asked to rate the extent to which they will receive an electric shock during every CS presentation using fearfulness scale that ranged from 1 (‘not at all’) to 7 (‘certainly’). Participants will be instructed to give these ratings quickly since the rating scale would disappear from the screen 5 s after CS onset. The scales evaluation will be self-administered by ID patients according to their actual condition.
Safety monitoring
Any adverse event, including mild headache, memory impairments, and seizures ,will be reported by patients and researchers at each patient visit. rTMS treatment have no anticipated harm for participants.
Criteria for discontinuing study participation
1.For patients with worsening state;
2.Treatment needs to be discontinued due to serious adverse events such as headache, memory impairments, and seizures;
3.Patients with other serious physical diseases during the trial;
4.Investigator considers it necessary to terminate the investigator for medical and ethical reasons;
5.Withdrawal of informed consent;
6.Unwilling to continue or lack of interest;
7.Participants who show differential response to the CS+ and CS- (CS->CS+) during fear acquisition stage.
Data Collection and Management
This study will utilize case report form (CRF) to collect and organize data. In addition, two trained data management personnels who will be blind to the allocation will double enter the data from the CRFs under the study management team which is set up to take charge of quality control
and supervise the research process. The scales evaluation will be self-administered by ID patients according to their actual condition. Fear conditioning, extinction procedure and SCR monitoring and electric shocks protocol will be conducted by professionals in the Sleep Rehabilitation Center of Zhenjiang Mental Health Center. To protect the privacy of the participants, there information will be collected through numbers.
Dissemination plans
The results of this trial will be published in a peer reviewed journal.
Quality control
To ensure high quality of the trial, the research personnel will be trained before conducting formal trials to guarantee consistent practices. The training will include diagnoses, inclusion and exclusion criteria,treatment regimen, rTMS operation, data collection and management, adverse event reporting and recording and completion of the CRF. The study management team will monitor and examine clinical data management once a week.
Statistical analysis
Descriptive characteristics of baseline will be analyzed using independent sample t-tests for normally distributed continuous variables or Mann-Whitney U test for non-normally distributed continuous variables. A chi-square test will be used to assess sex differences. Statistical significance will be set at a p-value less than 0.05 for a two-tailed test. An efficacy analysis will be conducted based on the intention-to-treat principle with no interim analysis. According to the intention-to-treat principle, the missing data will be replaced by the last observation carried forward’ method. Independent t-tests between the two groups and a repeated-measures analysis of variance (ANOVA) will be used to compare the effect of rTMS. The factors are treatment time (baseline, post-intervention, and follow-up) and groups (treatment and sham) and their interaction term.
The mediation hypothesis will be conducted using modern causal inference methods. If the efficacy analysis is significant differences between the two groups in scores of PSQI at 4 weeks, then parametric regression models will be used to test the indirect effect of sleep quality (PSQI) on secondary fear extinction outcomes at 4 weeks, and the residual direct effect of treatment on fear extinction outcomes at 8 weeks. The indirect effects will be calculated by multiplying relevant pathways and valid standard errors will be produced using bootstrapping. Since mediation analyses are potentially biased by measurement error in mediators and hidden confounding between mediators and outcomes, we will investigate the sensitivity of the estimates. Stata will be used for statistical analysis.