Procedure

3.3.1. Time table

Potential participants were screened in a telephone interview and an introductory session was scheduled to sign consent forms and allow the women to adapt to the setting in which the experiment would take place. The study consisted of two sessions scheduled one week apart.

Table 1 shows measures and sampling schedules for the study both for the questionnaires as well as physiological data.

Table 1: Flow chart of assessments conducted for the study in order to obtain background variables, control variables, self-report data and family history information.

Variables Telephone

interview Visit 1 Home Visit 2

Inclusion/exclusion criteria z Background variables

Ethnicity z

Marital status z

Living arrangement z

Education z

Employment z

Income z

Control variables

Age z

Height, weight, BMI z

Sleep, caffeine, nicotine, alcohol z

Menstrual cycle phase z

Self-report variables

Visual Analog Scales z

Beck Depression Inventory (BDI) z

Perceived Stress Scale (PSS) z

Brief Symptom Inventory (BSI) z

Family History Questionnaire z

Physiological data

Cardiovascular z

Endocrine z

Visit 1

All participants came to the laboratory for a brief initial visit (20 minutes) to provide informed consent and to fill in a series of questionnaires. During this session, a small blood sample was obtained and any questions the women might have had were answered. The blood sample was collected for the purpose of another study and the results are not reported here. This introductory session served to allow the women to habituate to the laboratory environment and meet the primary experimenter who would be present during the experimental session.

This visit 1 was introduced into the protocol in order to minimize the level of baseline distress at the experimental session. It was further used to collect self-report data and hand out a packet of questionnaires that the participants were asked to fill in at home and bring back for the next session. Participants received financial compensation of US$20 at the end of this visit for their time and effort.

Visit 2

On the day of the stress test, subjects reported to the laboratory between 8:00 AM and 10:00 AM. This session was rescheduled when the participants reported any symptoms indicative of a cold or flu in the past three days. They were asked to refrain from drinking more than two alcoholic drinks the night before and more than one cup of coffee in the morning of the session.

Furthermore, they were asked not to take any medication in the 24 hours prior to the stress test. Upon arrival in the laboratory, an IV catheter was placed in the non-dominant arm. The catheter was kept patent with saline drip during the experimental session. Subsequently, an ambulatory blood pressure monitor was hooked up and an inflatable cuff was put on the participant’s dominant arm. The monitor was started and the subjects were allowed a habituation period of 20 minutes to reduce the effect of the IV line and cuff placement on the outcome variables. Blood samples were drawn at baseline, immediately after stressor termination (15 minutes post baseline), as well as 30 and 45 minutes after baseline for hormone measurement. Figure 4 shows the sampling schedule for cardiovascular and endocrine assessments.

Figure 3: Time course of assessments during the experimental session

3.3.2. Randomized group assignment

The FR- group was randomly assigned to either the stress (n=36) or control condition (n=30) while all FR+ subjects underwent the acute psychological stressor (see below). This was necessary because of the relatively small number of subjects with Claus scores above 11 that could be recruited for this study. The unequal group sizes in the FR- sample are due to

STRESSOR

catheter-20’

insertion

VAS0’

Cardio Blood

VAS15’

Cardio Blood

Blood30’ 45’

Blood

missing data after randomization in the cardiovascular, endocrine, or self-report measures. For the analyses, all subjects were included in order to increase statistical power.

3.3.3. Experimental stressor Speech Task and Mental Arithmetic

The stress test was a modified version of the Trier Social Stress Test (TSST, Kirschbaum et al., 1993), comprising a 5 min speech task and a 5 min mental arithmetic test with harassment.

The test that has been introduced into psychobiological research by Kirschbaum and Hellhammer is one of the most widely used experimental paradigms in human stress research.

Studies from the Trier Lab as well as other groups using it have consistently found reliable elevations in cortisol and catecholamines (see Biondi & Picardi, 1999, for review). As noted above, a recent meta-analysis (Dickerson & Kemeney, 2002) concluded that stressors like the TSST, which include a social component, are most likely to produce a stress response in the HPA axis.

For the speech task, participants were asked to imagine they had been caught for a traffic violation and had to defend themselves at the traffic court. They were allowed three minutes for preparation and two minutes for delivery. Speeches were delivered in front of a video camera, and the women were told that their performance would later be rated by experts for content and style. During the following mental arithmetic task, subjects had to add numbers out loud at the pace set by an audiotape (duration 5 minutes). This task requires speed as well as concentration from the participant. A series of one-digit numbers is presented to the subjects, who have to add the value of the new number to the previous one. This task is specifically demanding since the most salient stimulus is the solution of the addition rather than the new number. Throughout the task, the experimenter interjected standardized comments to the women participating in the study that they needed to work harder or faster.

Control Task

The sampling schedule and procedure for the non-stress control group (control FR-) was exactly the same as in the two groups undergoing the stress condition except for the nature of the task. The control condition was included in order to ensure that the stressor worked in our hands and produced a reliable stress response in self-report (VAS) as well as cardiovascular and neuroendocrine parameters. It consisted of two 5 min sessions of a non-stressful reading assignment, in which the women were told they could read the material provided by the experimenter at their leisure and would not be tested later on.