2002-2003 Science Planning Summary

Biology & Medicine

Dr. Polly Penhale
Program Manager

BO-321-M/S

NSF/OPP 00-90343
Station: McMurdo and South Pole Stations
RPSC POC: Steve Alexander
Research Site(s): McMurdo, South Pole

Prevention of environment-induced decrements in mood and cognitive performance
Dr. Lawrence A. Palinkas
University of California San Diego
Department of Family and Preventive Medicine
lpalinkas@ucsd.edu

Deploying Team Members: Kathleen Reedy . Mark J Smith
Research Objectives: Cognitive performance degrades with residence in Antarctica, and mood alteration fits a seasonal pattern during extended residence. Although these changes suggest psychological responses to physiological adaptations to cold and dim light, the exact mechanisms are poorly understood.

The first objective is to determine whether long-term exposure to cold temperatures and/or to dim light is associated with significant changes in cognitive performance and emotional well-being:

Is physiological adaptation to cold and/or adaptation to dim light independently or synergistically associated with decrements in cognitive performance and emotional well-being?

Do personnel at South Pole Station experience greater physiological adaptation and decrements than personnel at McMurdo Station?

This group will also determine whether these decrements can be prevented or minimized by pharmacologic interventions and/or phototherapy:

What are the effects of combining liothyronine sodium with levothyroxine sodium versus supplementation with tyrosine (a precursor to both thyroid hormone and catecholamines) and daily phototherapy?

Is phototherapy used in combination with a pharmacologic agent more effective than either intervention used alone.

In phase I, project team members will establish computer-testing protocols, develop an effective placebo capsule, package the necessary drugs, and test the validity and reliability of computer-administered cognition and mood protocols with 30 hypothyroid outpatients on constant thyroid hormone replacement and 30 age- and sex-matched healthy controls in New Zealand.

In phase II, 50 members of the 2002 winter (v) crews, 35 at McMurdo Station and 15 at South Pole Station, will be randomized in a double-blind crossover design into 1 of 2 treatment groups (20 subjects in each group) and 1 control group (10 subjects). Baseline measurements will be conducted, and treatment groups will be switched after a 1-month washout period. Mood and memory testing will comprise 5 assessments over 12 months. Treatments consist of 50 micrograms (mcg) of levothyroxine sodium plus 12.5 mcg of liothyronine per day, 150 milligrams per kilogram of tyrosine per day, and a placebo.

In phase III, a similar design will be used to evaluate the effectiveness of phototherapy, alone and in combination with the more effective of the two pharmacologic interventions.

This research will lead to an improved understanding of the specific environmental conditions and physiological mechanisms that affect behavior and performance in the Antarctic, help develop countermeasures for circannual oscillations of mood and cognitive performance, and contribute to a reduction in accidental injuries at high latitudes.


Field Season Overview:
During the austral summer, researchers will measure participants' height, weight, blood pressure, heart rate and 24-hour records of core and skin temperature. Volunteers will be asked to provide blood samples for analysis of thyroid hormones, catecholamines, cortisol melatonin, and plasma lipids. The winter-over physicians at McMurdo and South Pole Stations will conduct similar assessments. At each assessment, study participants will also perform self-administered computerized psychological tests that assess mood and cognitive performance.