rTMS Response Trajectories in Depression
rTMS Response Trajectories in Depression
Previous studies on network mechanism of repetitive transcranial magnetic stimulation (rTMS)
 suggest that pretreatment resting-state functional magnetic resonance imaging (rs-fMRI)
 connectivity may serve as a predictive biomarker for antidepressant treatment response. In
 phase I of the study, the focus was on the predictive value of pretreatment connectivity
 between the left dorsolateral prefrontal cortex (DLPFC) and subgenual anterior cingulate
 cortex (sgACC). However, preliminary results indicated a more complex pattern. Additionally,
 accessibility to magnetic resonance imaging scanners is often limited and costly. Therefore,
 in phase II of the study, a more affordable way to measure the blood-oxygen-level-dependent
 signal was examined, known as functional near-infrared spectroscopy (fNIRS). The aims of this
 study are identifying biomarkers for predicting and monitoring treatment response to
 neuronavigated TMS in medication-resistant depression and examine the clinical utility of
 fNIRS.
Research Plan and Methodology

 i. Sampling Participants will be referred by psychiatrists from specialist outpatient clinics
 based in the regional hospitals of New Territories East Cluster under the Hospital Authority
 of Hong Kong. Written informed consents will be obtained from all participants according to
 the Declaration of Helsinki.

 ii. Pretreatment assessment A) Baseline clinical assessment At baseline (before treatment),
 subjects' age, level of education, handedness will be noted by research assistant. A research
 psychiatrist will administer MADRS1, HDRS2, DSM-IV SCID-I/II 3-4 to ascertain current/
 lifetime Axis I and II psychiatric diagnosis and score on Global Assessment of Functioning,
 age at onset of MDD and number of major depressive episodes, number of failed
 antidepressants, current life stressor(s) and the perceived severity on a visual analog scale
 of 0-10, and clinical global impression scale (CGI).5 Subjects are asked to complete
 self-administered questionnaires including 1) Beck Depression Inventory II 6 that has been
 validated in local Chinese dialect 7; 2) a 60-item NEO Five Factor Inventory that measures
 five personality traits on neuroticism, extraversion, openness to experience, agreeableness
 and conscientiousness;8 3) ruminative response subscale (Chinese version) (RRS) of the
 response style questionnaire, a 22-item questionnaire comprising of two distinct factors on
 brooding and reflection.9 Published data suggest rumination may be correlated positively with
 duration of depressive episode and predict onset of depressive episode10.

 B1) Structural Magnetic Resonance Imaging (MRI) of brain for neuro-navigated rTMS and resting
 state functional MRI (rs-fMRI) to map intrinsic functional connectivity (baseline, 2 weeks
 and 8 weeks post-treatment) A whole brain anatomical data set is acquired with T1-weighted
 sequence (repetition time(TR)/echo time(TE): 7.6/3.5ms, field of view 230mm, 250 contiguous
 slices, 0.6mm thickness, reconstruction matrix 224 x 224) for voxel-based morphometry (VBM)
 analysis and functional to anatomical image co-registration.

 A resting-state functional MRI will be taken for either six (phase I) or twelve minutes
 (phase II). Subjects will be instructed with written cues projected (for 5 seconds) on the
 screen to stay relaxed and look at the fixation cross hair. Stimuli are projected on a TV
 monitor equipped by MRI-compatible Esys (Invivo) system. Subjects view the screen through
 mirror glasses. The functional scans are acquired on a 3.0-T whole-body scanner (Achieva TX,
 Philips Healthcare, Best, the Netherlands) using PRESTO (principles of echo shifting with a
 train of observation) sequence (TR28ms, TE 12ms, flip angle 7°. Slab thickness 125mm, 230mm
 field of view, data matrix 80 x 51 x 25) with a nominal in-plane resolution of 2.8 x 2.8mm
 and a temporal resolution of 2.7 sec/scan. Slices will be tilted about 30º clockwise along
 the AC-PC plane to obtain better signal in the orbitofrontal cortex.

 All the functional and anatomical MRI data are transferred to an offline workstation for
 image analysis. MRI data will be preprocessed using the default pipeline of the CONN toolbox
 v18.b11, which is an open-source MATLAB (2019B, Mathworks, Natick, MA, USA) and SPM-based
 (Statistical Parametric Mapping, www.fil.ion.ucl.ac.uk/spm/) cross-platform software1. The
 preprocessing steps included realignment and unwarping, temporal slice time correction,
 functional outlier detection (ART-based identification of outlier scans), segmentation,
 normalization and smoothing (8 mm Gaussian kernel). The best way to denoise resting-state
 fMRI data is currently still a controversial topic12. Therefore, component based noise
 correction with and without global signal regression11,13. will be applied. For denoising
 with component based noise correction a principal component analysis was used to identify the
 time series data from the noise regions, including white matter and cerebrospinal fluid.
 Significant principal components are then introduced as covariates in the general linear
 model as an estimate of the physiological noise signal space. Regressors: white matter (10
 dimensions), cerebrospinal fluid (5 dimensions), realignment parameters (6 dimensions),
 scrubbing (61 dimensions). Further, a default temporal band-pass filter (.008-.09 Hz) and
 detrending. For global signal regression the same procedure was performed, but an additional
 regressor of the global signal (1 dimension) was added. The Subject-level correlation
 coefficients of the regions of interest and seed maps were converted to normally distributed
 Fisher-transformed Z scores to conform to the assumptions of generalised linear models. These
 connectivity values and statistical seed maps were subsequently used for the second-level
 analyses to examine group differences (responders versus nonresponders) and perform
 correlational analyses to examine whether either pretreatment connectivity or change in
 functional connectivity is associated with TMS treatment response.

 B2) Offline resting state FNIRS (baseline and serial measures) In a sub-sample of subjects
 who agree for extra brain mapping sessions, offline resting state FNIRS measures will be
 taken in pre-treatment phase (within 7-10 days before first rTMS session), week 2 and week 4
 in the course of rTMS treatment, 2 weeks and 8 weeks post-treatment.

 The FNIRS measurements will be taken in a specialized laboratory situated in the Center for
 Cognition and Brain Studies, Department of Psychology of CUHK (Sino Building of Chung Chi
 College), which is in close proximity to University MTR station and inside the same amenity
 as the CU Clinical Psychology Department.

 All subjects will be instructed to keep still with eyes closed, relax their mind and remain
 motionless for two blocks of 15-minute resting state session (totaling 30 minutes). The
 target mapping areas are bilateral fronto-parietal areas for their roles in default mode
 network (DMN). Optical signals will be recorded on a two-wavelength (690 and 830 nm, 110MHz)
 frequency-domain oximeter (Imagent, ISS Inc., Champaign, IL, USA).

 Offline mode is opted in this study as clinical applicability is our main concern.
 Simultaneous FNIRS-rTMS is theoretically possible but the set-up will substantially increase
 session time, compromising the tolerability of rTMS session and likely compliance. Aside,
 previous studies have shown the FNIRS signal changes are sustainable and detectable with
 offline measures after TMS.

 The FNIRS are measured with source fibers emitting light at the two different wavelengths
 that are co-localized as a pair, giving rise to 24 source locations. Photons that scatter
 through the head are collected by 16 detector fiber bundles connected to photomultiplier
 tubes (PMTs). These sources and detectors are held on the participants' scalp with a rigid
 custom-made head-mount system (montage).

 Sources and detectors are arranged in groups of two parallel rows (1.7 cm to 2.5 cm apart
 from each other) to create overlapping light channels so as to increase the spatial
 resolution and signal-to-noise ratio.

 Source-detector placement in each of the four mapping areas (left and right frontal, left and
 right parietal) is opted. After the montage is positioned, coordinates of 230 points on the
 scalp, including the locations of source-detector pairs and three fiducial points (nasion,
 left and right pre-auricular points), are digitized using ASA 4.5 software (ANT, Netherlands)
 in conjunction with an infrared camera and 3-dimensional digitization system (Visor, ANT BV,
 1mm spatial resolution). These points are used for calculation of the exact source-detector
 distance for data analysis and, more importantly, for co-registration of functional optical
 data with each participant's structural MRI.

 The individually co-registered data are then Talairach-transformed to permit comparison
 across subjects. The ISS Imagent control box is connected to a computer that controls and
 records the intensity of emitted and recorded signals. The sampling rate used in this study
 is 19.5Hz, giving rise to a 51.3ms sampling interval. During this interval, light sources are
 time multiplexed to allow different sources to be distinguished from each other. Light
 intensity and phase-delay data are computed and stored in ASCII format in the computer during
 the recording. Similar to fMRI analyses, predicted time series are generated by convolving
 the hemodynamic response function (SPM 8) with the impulse function for each event, i.e.,
 from the onset to the offset of one sequence trial.

 The pulse-corrected bandpass-filtered oxy-haemoglobin concentration change from each channel
 is then correlated with the predicted time series for repeated and random conditions
 separately for each recording block and each participant. The Beta weight for each condition
 is estimated, Fisher-transformed, and averaged across each recording block for each
 participant in each session. The averaged data are analyzed using Opt-3 for the generation of
 statistical maps. In Opt-3D, the optical signal, in this case, hemoglobin concentration
 change, for a given voxel is defined as the mean value of the channels that overlap at that
 particular voxel. Channels with source-detector distances shorter than 20mm and longer than
 60mm are excluded from statistical map analysis as the light path would be too short to have
 reached the cortical surface or too long to have enough light reaching the detector,
 respectively. Channels will be removed if the standard deviation of the phase delay data is
 greater than 230 picoseconds (i.e. the channel is excessively noisy).

 C) Neuro-navigated rTMS protocol rTMS treatment suite and personnel: the treatment facilities
 are based in Chen Wai Wai Vivien Foundation Therapeutic Physical Mental Exercise Centre,
 which is a CU clinical and research center sponsored by private funds where the physicians
 delivering the treatment (PI and co-PI) are serving on-site. The treatment center is equipped
 with resuscitation facilities. Full-time research staff and physiotherapists are available to
 handle medical and behavioral emergencies.

 Stimulator set-up: Neuro-navigated high-frequency rTMS over a specific area on left DLPFC
 (between BA9 and BA46, junction of middle and anterior two-thirds of the middle frontal
 gyrus) will be provided using Magstim Super Rapid2 (Phase I) or Neurosoft Neuro-MS/D Advanced
 Therapeutic Transcranial Magnetic Stimulator (Phase II) that both generate short duration
 biphasic pulses. A figure-of-eight coil will be held in place with a custom-made stand
 tangential to the scalp with the handle pointing back and away from the midline at 45
 degrees. The resting motor threshold will be determined Motor Evoked Potential or the
 standard visual method (whichever revealed the lowest motor threshold).

 Stimulation parameters Phase I: 10 hertz, 120% motor threshold, thirty trains of 5 seconds
 with 25 seconds between trains, 1500 pulses per day delivered 5 days per week, totaling 30000
 pulses over 4 weeks.

 Stimulation parameters Phase II: triplet 50 hertz, repeated at 5 hertz, 120% motor threshold,
 twenty trains of 2 seconds with 8 seconds between trains, 600 pulses per day delivered 5 days
 per week, totaling 12000 pulses over 4 weeks.

 Stimulation localization: The DLPFC coordinates of the stimulation target site is determined
 individually for each participant using a structural T1-weighted MRI scan. This area is
 defined around the junction of Brodmann area 9 and 46. To coregister the scan with the
 patient's head, advanced stereotactic techniques incorporated into Brainsight TMS (Rogue
 Research Inc., Canada) for phase I of the study and the Neural Navigator (Brain Science Tools
 BV, Netherlands) for phase II of the study were used.

 iv. Clinical follow-up and outcome assessments All participants are evaluated by a research
 psychiatrist who is blinded to the functional connectivity maps of the participants and other
 potential clinical predictors of response measured at baseline. Follow-up assessments are
 scheduled at the end of week 2, week 4, week 6, week 8, and week 12.

 Primary outcome measures are the percentage change in symptom scores on MADRS and CGI at week
 4, week 6, week 8, and week 12 compared to baseline. Secondary outcome measures include
 scores on GAF, BDI and RRS.

 Clinical response is defined as CGI= 2 and 50% reduction of MADRS score from baseline,
 respectively at the end of six weeks and twelve weeks.

 Clinical remission criteria is MADRS <7 and CGI of 1, respectively at the end of six weeks
 and twelve weeks.

 v. Management of decompensated mental states, serious adverse somatic reactions to rTMS and
 drop-outs The research psychiatrists (PI and co-I) are responsible for the detection of
 high-risk mental states (emergence of psychotic symptoms, catatonic state, suicide ideation,
 and para-suicide state) at the regular follow-up assessments. Physical adverse effects will
 be checked at each follow-up and evaluated on the severity. In times of emergent risky mental
 state and adverse somatic reactions, the research psychiatrists will work collaboratively
 with the participant and if necessary, the treating psychiatrists on the necessary
 psychiatric and medical management plans. All adverse effects will be reported to the
 "serious adverse effect monitoring sub-committee" under the local ethics committee. All
 drop-out participants will be assessed by phone followed by clinic-based interviews to work
 out the care plan as indicated clinically. At the end of the study, the subjects will receive
 the generic psychiatric service as they are originally entitled to. The research team will
 ensure seamless aftercare will be arranged for all participants.

 vi. Sample size estimation The sample size estimation is based on the parameter estimate that
 addresses the main objective. In our study, it is the expected Pearson correlation
 coefficient between functional connectivity of the ROIs and quantitative measure of clinical
 efficacy (percentage drop in MADRS score). In Fox et al's study (2012)14, the correlation
 coefficient is -0.355 (p<0.05 one-tailed). According to Friedman's partial power table, the
 required sample size is at least 58 at alpha=0.8 and Pearson r= 0.35. Taking into account the
 drop-out rate of 20% reported in the active rTMS group of a prior randomized controlled trial
 comparing the efficacy of neuro-navigated rTMS and conventional targeting protocol, the
 required sample size that is sufficiently powered to examine the main objective is adjusted
 to 128.

 vii. Data analyses Intention-to-treat analysis will be adopted with the last observation
 carried forward for participants with at least one post-baseline observation. To describe the
 trajectory of clinical response over the course of follow-up, survival analysis will be used
 to track the proportions of responders and remitters respectively at 2, 4, 6, 8, 10, 12
 weeks.

 To test the main objectives, we plan to perform:

 1. Group comparison of functional connectivity between ROIs between clinically defined
 responders and non-responders at 4 weeks, 6 weeks and 12 weeks, respectively. We
 hypothesize pre-treatment anti-correlation between the left DLPFC target and subgenual
 cingulate is stronger in responders than non-responders at the respective time points.

 2. Group comparison of functional connectivity between ROIs in clinically defined remitters
 and non-remitters at 4 weeks, 6 weeks and 12 weeks, respectively. We hypothesize
 pre-treatment anti-correlation between the left DLPFC target and subgenual cingulate is
 stronger in remitters than non-remitters at the respective time points.

 3. Correlations analyses of the functional connectivity between ROIs and percentage drop in
 MADRS scores at 4 weeks, 6 weeks and 12 weeks compared to baseline, respectively. We
 hypothesize larger percentage drop in MADRS from baseline correlates with greater
 anti-correlation between the left DLPFC target and subgenual cingulate, at the
 respective time points.

 4. multiple linear regression of functional connectivity between ROIs on percentage drop in
 MADRS score from baseline at 4 weeks, 6 weeks and 12 weeks respectively, in the presence
 of other baseline demographic and clinical characteristics. We hypothesize higher
 percentage drop in MADRS from baseline correlates with greater anti-correlation between
 the left DLPFC target and subgenual cingulate, at the respective time points after
 adjusting for baseline demographic and clinical characteristics.

 5. Correlate FNIRS signals in left DLPFC detected in week 1 and 2 with depressive symptom
 scores (MADRS) in week 6, 8, and 12 in order to look for early biomarkers for treatment
 response.

 6. Group comparison of FNIRS signals in left DLPFC detected 7-10 days before rTMS treatment
 in clinically defined responders and non-responders at 6 weeks and 12 weeks,
 respectively.

 Declaration:

 The research protocol fully complies with the Declaration of Helsinki and the guidelines of
 ICH-GCP.

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Inclusion Criteria:

 -  right-handed

 -  meet the Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition (DSM-IV)
 criteria for major depressive disorder

 -  at least moderate episode or with a score of >20 on Montgomery-asberg Depression
 Rating Scale (MADRS) and >18 on Hamilton Depression Rating Scale(HDRS) 17-item;

 -  has failed to respond adequately to at least one full course (>6 weeks) of
 antidepressant medication or medication intolerant.

 Exclusion Criteria:

 -  significant head trauma

 -  active abuse of alcohol or illegal substances

 -  current psychotic symptoms

 -  suicide ideation/recent suicide attempts

 -  other DSM-IV Axis I and II psychiatric diagnosis

 -  neurological disorders and contraindications to fMRI (e.g. pace makers, metal
 implants, pregnancy) or rTMS, or having undergone electroconvulsive therapy in the
 preceding year.