Effects of rTMS on Impulsivity and Empathy
Condition: Impulsive Behavior; Empathy
MeSH terms: Impulsive Behavior
Study type: Interventional

Summary: 
      Impulsivity describes the tendency to make risky and unplanned decisions, to pick immediate
      reward over a bigger reward after a period of time or to not be able to resist the urge to do
      something. Empathy refers to the ability to be sensitive to and vicariously experience other
      people's feelings and to create working models of emotional states. Recent neuroscientific
      research have found that the right frontal part of the brain (left dorsal lateral frontal
      cortex, LDLPFC) is important in the control of impulsive behaviour and empathy. Self-report
      questionnaires have been proven valid measures at assessing impulsivity and empathy.
      Repetitive Transcranial Magnetic Stimulation (rTMS) is a widely used non-invasive brain
      stimulation procedure; stimulation can be applied at different brain regions depending on the
      administration method. It temporally changes the way that this part of the brain functions,
      providing us a further understanding of how this part works. Recent research has found that
      rTMS on the LDLPFC changes performance-based tasks measuring different types of impulsivity
      and empathy. This study aims to investigate this further to look at the RDLPFC stimulation
      and its effects on empathy and two different types of impulsivity. Of interest is also how
      innate impulsive personality type and empathy trait relate to performance on these tasks.
    

Detailed description: 
      Background Impulsivity describes the tendency to make risky and unplanned decisions, to pick
      immediate reward over a bigger reward after a period or to not be able to resist the urge to
      do something. Empathy refers to the ability to be sensitive to and vicariously experience
      other people's feelings and to create working models of emotional states. Recent
      neuroscientific research have found that the left frontal part of the brain (left dorsal
      lateral frontal cortex, RDLPFC) is important in the control of impulsive behaviour and
      empathy. Self-report questionnaires have been proven valid measures at assessing impulsivity
      and empathy. Repetitive Transcranial Magnetic Stimulation (rTMS) is a widely used
      non-invasive brain stimulation procedure; stimulation can be applied at different brain
      regions depending on the administration method. It temporally changes the way that this part
      of the brain functions, providing us a further understanding of how this part works. Recent
      research has found that rTMS on the LDLPFC changes performance based tasks measuring
      different types of impulsivity and empathy. This study aims to investigate this further to
      look at the LDLPFC stimulation using the newer form of high-frequency rTMS, intermittent
      theta burst stimulation (iTBS) and its effects on empathy and two different types of
      impulsivity. Of interest is also how innate impulsive personality type and empathy trait
      relate to performance on these tasks.

      Aims The specific purposes of this study are to (i) examine whether iTBS is an effective
      technique for modulating impulsivity and empathy, and to (ii) examine the relationship
      between the modulatory effects of the iTBS and baseline self-reported impulsivity and
      empathy.

      The key objectives of this study are to examine whether the specific iTBS protocol at RDLPFC
      can effectively modulate two subtypes of impulsivity (delayed discounting and reflection
      impulsivity) and empathy, and to examine whether the participant's baseline self-reported
      impulsivity and empathy scores mediate the modulatory effects of the iTBS on impulsivity and
      empathy respectively in normal healthy young adults. The secondary objectives of this study
      are to examine whether the self-reported measures of impulsivity and empathy correlate with
      their performance-based counterparts.

      Experimental protocol and methods The proposed study will be a single-centre, crossover
      design study, taking place at Queens Medical Centre, Nottinghamshire NHS Trust. Participants
      (male students or staff) will be recruited from the University of Nottingham. A potential
      participant will be asked to complete the TMS screening questionnaire to ensure that there
      are no contraindications to using TMS. After the written informed consent is obtained, he
      will then be asked to complete an online questionnaire (Barratt Impulsiveness Scale -version
      11, BIS-11) measuring self-report impulsivity. The scores obtained from BIS-11 will be one of
      the screening criteria. If the potential participant is eligible for taking part in the
      study, he will be invited to the two laboratory sessions. He will then be asked to perform
      three computerised tasks assessing impulsivity and empathy before and after the iTBS
      administration. Each session of iTBS will apply 600 pulses to the LDLPFC, with 20 2-second
      trains and an 8-second inter-train interval for a total stimulation time of 190 seconds. Sham
      iTBS condition will be administered with the same methodology used for active iTBS condition
      with a sham coil mimicking noises and vibrations without delivery of magnetic pulses.
      Participants will be asked to guess which rTMS condition is real after completing the whole
      study to ascertain that whether the sham manipulation is successful or not. Participants will
      be monitored if they experience any adverse events during the rTMS session and instructed to
      report any experience of adverse events after each rTMS session. Tolerability will be
      presented as the number of reported adverse events and the number of dropouts due to adverse
      events.

      Measurable end points/statistical power of the study To detect the change in impulsivity and
      empathy resulted from the iTBS intervention, G*Power 3.1.9.2 was used to estimate sample size
      required in consideration of interaction effect (impulsivity group × iTBS conditions) of
      repeated measure ANOVA. The following parameters were selected: effect size f = 0.20
      (equivalent to d = 0.40, estimated from the results of previous meta-analyses), alpha error
      probability = .05, power = (1- β error probability) = .80, number of groups = 2, number of
      measurements = 2 and correlation among repeated measurements = 0.6. A minimum of total sample
      size of 42 subjects will be required. Considering the dropout rate of 0.20 (according to
      previous rTMS studies), 54 subjects will be required for the study, including 27 high
      impulsivity participants and 27 low impulsivity participants.
    

Intervention name(s): repetitive transcranial magnetic stimulation
Intervention type(s): Device
Intervention description(s): Each session of iTBS will apply3 trains of 600 pulses to the RDLPFC, with 20 2-second trains and an 8-second inter-train interval. Sham iTBS condition will be administered with the same methodology used for active iTBS condition with a sham coil mimicking noises and vibrations without delivery of magnetic pulses.
Other intervention name(s): intermittent theta burst stimulation
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: crossover (real and sham stimulation) design with randomised allocation of outcome examination
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: transcranial magnetic stimulation; theta burst stimulation; impulsivity