Tag Archives: methods

Biomarkers

In previous posts I have discussed the use of self-report questionnaires to measure aspects of health, for example stress and depression. In this post, I will describe two methods for measuring “biomarkers” which are characteristics that are objectively measured and evaluated as an indicator of biological processes. As part of my research in the Bribri village of Yorkin, Costa Rica, I would like to measure health in the village in order to show that because of their initiation of an ecotourism project, which has allowed them to work in the village rather than in plantain and banana plantations, their overall health has improved. In order to accomplish this, I have chosen two biomarkers to examine health which are relatively easy to conduct in the field in minimally invasive. The first biomarker is blood pressure, which is one of the principal vital signs used in many healthcare settings. Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels. High blood pressure can be a warning sign for hypertension which can lead to strokes and various heart conditions. The second biomarker I intend to use is the level of the stress hormone cortisol (CORT), which provides a measure of hypothalamic-pituitary-adrenal axis (HPA) system activity or more simply, physiological stress. Prolonged periods of physiological stress have been found to have negative health effects including impaired cognitive performance, suppress thyroid function, blood sugar imbalances, higher blood pressure, immunity impairment, and increased abdominal fat.

To measure blood pressure in the field I will use an automatic blood pressure monitor, the OMRON HEM-711, one of which we have in the Human Behavioral Ecology Research Group HBERG lab run by Dr. Chris Lynn at the University of Alabama. Similar OMRON models have proved adequate for measuring blood pressure (Wan et al. 2010). To use this instrument, the cuff is placed on the left arm above the elbow at approximately heart level. It is suggested that the participant has remained seated for 10 minutes before taking the measurement and the person should not have consumed tobacco or caffeine for at least 30 minutes before the measurement is taken. Researchers suggest taking multiple measurements, for example three, and then calculating the mean of these measurements (Wan et al. 2010). Below is a video describing the use of the automatic blood pressure monitor.

To measure the stress hormone cortisol I intend to use the hair extraction method. Cortisol is slowly incorporated into the hair of humans and other mammals and allows for the measurement of physiological stress over several months. The process involves first obtaining a sample of hair from a participant. A portion of hair up to the width of a pencil is first secured with a clip or rubber band and then cut as close to the scalp as possible with sterilized scissors. The sample is taken from the posterior vertex portion of the skull. To examine the distribution of cortisol over time, the hair sample can be cut into 1 cm segments, the segments furthest from the scalp being the oldest. The samples can then be placed into a paper envelope and then secured in a container. Upon returning from the field, the samples can then be taken into the lab, I plan to use Dr. Jason DeCaro’s lab here at the University of Alabama, to be analyzed. The samples are washed in an alcohol solution, dried, ground, and then the cortisol is extracted and analyzed. The above procedures were described in an article by Meyer et al. (2014). Below is a video provided by the same authors describing the methodology.

http://www.jove.com/video/50882/extraction-and-analysis-of-cortisol-from-human-and-monkey-hair

I have chosen these two measurements of health because they will be logistically easy to perform in the field, require no more special instruments, and do not require refrigeration. By combining these two biomarkers with self-report measurement scales, I believe I will be provided with a robust survey of health in the village.

Meyer, J., Novak, M., K. Rosenberg, and A. Hamel 2014 Extraction and Analysis of Cortisol from Human and Monkey Hair. Journal of Visualized Experiments (83).

Wan, Y., C. Heneghan, R. Stevens, R. J. McManus, A. Ward, R. Perera, M. Thompson, L. Tarassenko, and D. Mant 2010 Determining which Automatic Digital Blood Pressure Device Performs Adequately: A Systematic Review. Journal of Human Hypertension 24(7):431-438.

“Depresión”: What does it mean?

During my stay in Yorkin this past summer, it was mentioned by one of the women that there used to be a lot of “depresión” in the village before they started their ecotourism project. My initial reaction was, “I wonder what exactly they mean by “depresión”?” And then I started thinking about administering the CES-D, which is a depression scale that has been used in many contexts internationally, in the community. I also knew that some way, somehow, I would have to get at exactly what they mean by “depresión” but I was a little unsure of how to do this.

After my presentation of my pre-dissertation research in Yorkin, our new faculty member in the department of anthropology here at the University of Alabama, Lesley Jo Weaver, turned me on to an article she had just had published (Weaver and Kaiser 2014) describing the methodology that I was looking for. In this article she describes how a researcher can accomplish two major agendas of psychological anthropology, the first being the comparison of mental health between sites using standard measurement tools and the second focusing on identifying locally specific ways of discussing mental illness. In this paper she lays out the methodology used in two research sites which identified local idioms of distress, developed a locally derived mental health scale, evaluated the scale, and contextualized the findings with ethnographic data.

The first phase of this methodology involves ethnography. In this phase field notes and interviews are coded for themes and terms used to describe mental health and the frequency of usage is recorded. Also as part of the ethnographic work, participants were asked to create free lists of symptoms and characteristics which accompany particular idioms of distress, for example in the case of the Bribri, depresión. From this ethnographic data a survey questionnaire can then be developed asking participants to rate on a Likert scale the accuracy and frequency of various terms used to describe an idiom of distress. From this data, a scale can be created which reflects local terminology and understanding of culturally salient mental health domains, again in the case of the people in Yorkin, depresión.

In the next phase, the locally derived scale can be administered along with a standard scale, for example the CES-D for measuring depression. Quantitative analysis can then be administered; examining correlations between the results of the two scales, checking for internal consistency using Cronbach’s alpha, and using principal components analysis to examine those factors in the scale which are most relevant.

The authors suggest “This research agenda respects culturally defined illnesses and acknowledges the contextuality of all illness experiences while still maintaining the comparative enterprise of cross-cultural psychiatry” (Weaver and Kaiser 2014:12). I foresee using this methodology in my research in phase 2, after using participant observation to learn about and describe their ecotourism project while also collecting hair samples which will be used to examine levels of cortisol (as a biomarker for stress) among community members.

Weaver & Kaiser 2014
Weaver & Kaiser 2014