The TEMP II Study: the central and peripheral body temperature response after social stress: a follow up study

Rationale: Acute stress elicits an autonomic stress response, causing body
temperature to rise in all organisms (stress-induced hyperthermia, SIH). This
autonomic stress response also causes the heart rate and blood pressure to
increase, and plays an important part in the manifestation of anxiety
disorders, when it is activated inappropriately. Extensive animal research has
shown that this stress-induced temperature response can be robustly blocked
with a wide range of anxiolytic drugs. Furthermore, the SIH response has
excellent translational properties for anxiety research, because the parameter
is identical in animals as well as humans. So far, very little structural
research on the temperature response in humans has been carried out. The TEMP
study has shown that exposure to stress increased skin temperature on the upper
arm in male and female subjects, whereas it resulted in a small but
statistically significant decrease in intestinal core temperature in male
subjects only. Interestingly, the core temperature decrease correlated
significantly (R=-0.59) with the subjective stress increase. These results
indicate that a direct translation of the preclinical SIH paradigm to a human
version is possible but not without difficulty as the direction of
stress-induced temperature changes depends on the site of temperature
measurement. Therefore, the TEMP II study aims to extend these findings by
repeating and extending the finding that stress-induced central and peripheral
body temperature changes are present in healthy men and women exposed to
standardized social stress (the Trier Social Stress Test). In addition to the
central (intestinal) temperature and peripheral (upper arm skin) temperature
that were already measured in the TEMP study, we additionally measure auricular
and arterial core temperature using specialized thermometers as well as the
peripheral exposed skin temperature (facial and extremities) using an infrared
camera. This way, we may confirm and extend our earlier findings of the TEMP
study. Also, stress-induced changes in heart rate are monitored using an
automatic heart rate monitor. Furthermore, we aim to correlate the
stress-induced temperature response to subjective perceived anxiety levels in
humans by using a set of different anxiety and stress questionnaires. Saliva
cortisol levels are known to be increased after the Trier Social Stress Test.
Therefore, stress-induced saliva cortisol samples will be collected as a
positive control. The TEMP II study will lead to more information on the basal
SIH response and possible gender differences, and will serve as a basis for
future studies in which the effects of a registered anxiolytic drug on the SIH
response will be studied. The possibility to screen for anxiolytic effects
using temperature measurements could be of great value for the development of
new anxiolytic drugs, facilitating progress in anxiety research.

Study Objective:
Primary objectives:
1 To determine and confirm whether the Trier Social Stress Test will lead to a
stress-induced changes in body temperature increase in male and female
volunteers

Secondary objectives:

1 To determine whether stress-induced temperature changes correlate.
2 To determine whether stress-induced temperature changes correlate with
stress-induced increases in saliva cortisol.
3 To determine whether stress-induced temperature changes correlate with
subjective anxiety/stress questionnaires.
4 To determine whether the SIH response is comparable in male and female
volunteers.

Study Design: 24 adult volunteers (12 male and 12 female volunteers) will
participate in the TEMP II study in which they will be exposed to 10-min
lasting standardized social stress in the validated Trier Social Stress Test or
a placebo stress test. The stress test consists of a short public speech test
and an arithmetic test and does not lead to extreme perceived stress levels.
Body temperature will be measured before, during and after the stress exposure
using telemetry (an ingested pill and a dermal patch), an infrared camera and
an arterial and auricular thermometer. Also heart rate levels will be measured
throughout the study using a heart rate monitor. Also, saliva samples will be
taken throughout the experiment to determine cortisol levels. Subjects will
also complete anxiety/stress questionnaires before and after the Trier Social
Stress Test.

On each testing day (total: two testing days, day1 : TSST; day 2: placebo
stress test)

1 Telemetry pill
All participants receive and ingest a telemetry pill and attach a skin patch
(Vitalsense Minimitter, size 2.3 x 0.87 cm) on the day of the
TSST, at least 1 hour before commencing the TSST. Immediately after taking the
pill and attaching the patch, temperature data will be
checked to establish a good functioning of the telemetry pill. The pill will be
present until it leaves the
alimentary tract after an average passage time of 1 day. The pill will leave
the body without any known
hazard or discomfort. Details about the system and MDD/FDA approval are
included as an appendix.

2 Heart rate monitor
All volunteers will be equipped with an automatic heart rate monitor at least 1
hour before
commencing the TSST which will measure the heart rate continuously

3. Non-invasive Thermometer
Auricular and arterial temperature will be non-invasively measured from all
participants at discrete intervals using a tympanic thermometer and a temporal
artery thermometer. Moreover, temperature of the visible skin (extremities,
face and neck) will be continuously measured before, during and after the TSST
using infrared cameras (FlIR T360). After analysis, recordings will be
discarded.

4 Saliva samples
All volunteers will be asked to donate saliva at discrete intervals before,
during and after the experiment.
Saliva samples will be collected in tubes after arrival (-60 min), immediately
before the preparation phase
(pre-stress levels, -1 min), directly (+2 min) and 10, 20, 30, 45, 60 and 120
min after stress. Saliva samples
are kept at room temperature throughout the test session and are then stored at
-20 ° C. Free cortisol, the
biologically active fraction of cortisol will be assayed. Samples will be coded
with the participant number. After
analysis, saliva samples will be destroyed. Saliva samples will only be used to
determine cortisol levels.

5 Stress questionnaires
All participants will be asked to fill in several stress questionnaires twice.
The first time, questionnaires have
to be completed as a baseline before the Trier Social Stress Test. The second
time, questionnaires have to be
completed just after the Trier Social Stress Test and indicate a stress-induced
state. Questionnaires that will
be taken are the STAI-score (state-trait anxiety inventory) (Spielberger 1989),
the BIS/BAS test
and visual analog scales.

6 (placebo) Trier Social Stress Test
The Trier Social Stress Test will be taken in the morning since body
temperature and cortisol levels are subject
to circadian rhythmicity. The Trier Social Stress Test consists of a
standardized public speaking test as well as
a short arithmetic task which will take around 10 minutes (excluding 2 minute
explanation and 3 minute
preparation time). For a precise protocol of the (placebo) Trier Social Stress
Test we refer to the attached stress
protocol.

7 Urine sample
A urine sample will be obtained at arrival to conduct a drug test (MDMA,
barbiturates, cannabinoids,
benzodiazepines, cocaine and opiates) and to test for nicotine use.

8. Wake up call
Alle participants receive a wake up call at least 1 hour before commencing the
study.

Risks for volunteers are minimal. The ingestion of a telemetric pill is not
associated with any known risks. The
stress test consists of a short public speech test and an arithmetic test and
does not lead to extreme
perceived stress levels. The time spent in the laboratory is limited, and
participants have sufficient time for
breaks. No direct benefits are present for volunteers