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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Retrospectively registered

Titles & IDs
Public title
An investigation to modulate odour perception, food-attention and appetite with non-invasive peripheral nerve stimulation
Scientific title
The effect of non-invasive, median nerve stimulation on the interaction of odour and food-attention using a modified odour probe-dot task in healthy-adult male and female populations.
Secondary ID [1] 301690 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 318648 0
Condition category
Condition code
Diet and Nutrition 316664 316664 0 0

Study type
Description of intervention(s) / exposure
Healthy adult participants, male and female of age 21-39 years, were tested on an appetite questionnaire and a simple probe-dot, attention task with food imagery and odour delivery, before and after non-invasive, stimulation of the median nerve for ten minutes, with the recording of an ECG throughout the whole experiment.
The participants will perform a simple reaction time task and fill in subjective ratings of appetite, before- and after median nerve stimulation. There is a baseline period of 5mins of ECG recording, followed by 15-20minutes of pre-stim tests then a 10 min stimulation period then again 15-20mins post-stim tests, total of approx. 45-55 minutes. The TENS electrodes are placed on the left forearm, and the stimulation is set to be above the motor threshold but not inducing any pain or discomfort for the participant.
The duration of each session is roughly 45-55minutes and each session occurs on different days. The sessions are not required to be consecutive.
The intervention will be applied by a member of the research staff and each intervention will be identified by a key of P1-12.
ECG recordings, probe-dot tests and VAS scales (where participants rate subjective appetite) also have raw data files which can be checked for fidelity if needed.
Visual analogue scales (VAS) are used for subjective appetite and hunger scales, which are very well-validated in the literature. Probe-dot test is also stable in food-attention research and is considered superior to the previously used Stroop test design. Our only modification with the probe-dot test is the delivery of odour throughout some of the probe-dot test blocks with the use of an olfactometer.
The only change in the four different sessions (male) and eight different sessions (female) was the frequency of stimulation (40Hz, 80Hz, 120Hz, control-placebo). Females were tested on both stages of the menstrual cycle (follicular and luteal stages).
Intervention code [1] 318356 0
Treatment: Devices
Comparator / control treatment
Placement of the electrodes on the same site of median nerve stimulation, but no stimulation used for placebo,
Control group

Primary outcome [1] 324793 0
Statistical change in food perception-odour
Timepoint [1] 324793 0
The difference between the reaction times between pre-stimulation and post-stimulation "probe-dot test" will be used to assess results the odour and non-odour blocks.
Repeated-measures ANOVA using a 4x2x2x2 design (4-conditions ‘40Hz, 80Hz, 120Hz, Control’, 2-stage ‘pre-stimulation, post-stimulation’, 2-blocks ‘odour, non-odour’, 2-trial-type ‘target vs non target, control vs non target’).
Primary outcome [2] 325421 0
Statistical change in appetite (Subjective)
Timepoint [2] 325421 0
Subjective appetite will be analysed with the aid of visual analogue scales (The difference between the VAS at the pre-stimulation and post-stimulation).
Secondary outcome [1] 385757 0
Heart Rate Variability
Timepoint [1] 385757 0
The ECG recordings will be analysed to demonstrate Heart Rate Variability(beat-to-beat variation) as an immediate post-stimulation response following the 10 minutes of stimulation

Key inclusion criteria
Inclusion criteria for the study include healthy (no neurological or cognitive impairments, no impairments in smell, vision or hearing) male and females (not on hormonal contraceptives) of 21-39 years of age, non-smokers, of Caucasian (NZ-European descent), of a healthy BMI range (18.5-24.9). In the screening form before each session, participants are also asked to disclose any medication use, physical fitness levels, computer use levels, following of any specific diets, alcohol intake (if within 48 hours of the experiment), caffeine intake (if any within 2 hours of the experiment) and food intake (if any within 2 hours of the experiment).
Minimum age
21 Years
Maximum age
39 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
No consumption of food or caffeine within two hours of the experiment, no use of deodorant on the day of experiment and no consumption of alcohol or performance of weight training/heavy exercise on the day or within 24 hours of the experiment.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Compusense software codes each participant session (1-4 for males and 1-8 for females) with a random 3-digit number, therefore, the allocation for each participant to each of their sessions (40Hz,80Hz,120Hz, CTR) is concealed. The same goes for the sequence of the olfactometer. For the probe-dot, the order of the counterbalance of images can only be seen post-process at data analysis so therefore, the order is concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Use of William James design through software ‘Compusense’
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Use of paired sample t-test/ Wilcoxon Sign rank test (dependent on normal sample distribution) to observe the changes in appetite (use of visual analogue scales) before and after the stimulation stage, and changes in HRV in ECG before and after stimulation stage.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 22857 0
New Zealand
State/province [1] 22857 0

Funding & Sponsors
Funding source category [1] 306127 0
Name [1] 306127 0
Department of Anatomy, School of Biomedical Sciences University of Otago
Address [1] 306127 0
270 Great King Street, Dunedin Central, Dunedin 9016
Country [1] 306127 0
New Zealand
Primary sponsor type
University of Otago
School of Biomedical Sciences, Department of Anatomy, Lindo Ferguson Building, 270 Great King Street, Dunedin Central, 9016, Dunedin
New Zealand
Secondary sponsor category [1] 306594 0
Name [1] 306594 0
Address [1] 306594 0
Country [1] 306594 0

Ethics approval
Ethics application status
Ethics committee name [1] 306343 0
University of Otago Human Ethics Committee (Health)
Ethics committee address [1] 306343 0
University of Otago Human Ethics Committee (Health),
Scott Shand House, 1st Floor
90 St David's Street
Dunedin 9016
Ethics committee country [1] 306343 0
New Zealand
Date submitted for ethics approval [1] 306343 0
Approval date [1] 306343 0
Ethics approval number [1] 306343 0

Brief summary
Study objectives: to observe the effects of specific frequencies of median nerve stimulation on food attention and subjective and physiological appetite.
Intervention: use of non-invasive electrical stimulation (Transcutaneous electrical nerve stimulation) on the median nerve at the inner forearm region for ten minutes using a frequency of 40hz, 80hz or 120hz and placebo (electrodes placed but no stimulation passed) on four different days for males and eight different days for females(four days per menstrual period of follicular and luteal stages).
Hypothesis: median nerve stimulation using different frequencies will reduce subjective and physiological measures of appetite and reduce the effect of odour on the food attention task.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 103558 0
Dr Yusuf Ozgur Cakmak
Address 103558 0
Department of Anatomy, School of Biomedical Sciences, University of Otago,270 Great King Street, Dunedin 9016
Country 103558 0
New Zealand
Phone 103558 0
+64 34794030
Fax 103558 0
Email 103558 0
Contact person for public queries
Name 103559 0
Dr Yusuf Ozgur Cakmak
Address 103559 0
Department of Anatomy, School of Biomedical Sciences, University of Otago,270 Great King Street, Dunedin 9016
Country 103559 0
New Zealand
Phone 103559 0
+64 34794030
Fax 103559 0
Email 103559 0
Contact person for scientific queries
Name 103560 0
Dr Yusuf Ozgur Cakmak
Address 103560 0
Department of Anatomy, School of Biomedical Sciences, University of Otago,270 Great King Street, Dunedin 9016
Country 103560 0
New Zealand
Phone 103560 0
+64 34794030
Fax 103560 0
Email 103560 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
What supporting documents are/will be available?
No other documents available
Summary results
No Results