title: Environmental influences on hypothalamic-pituitary-thyroid function and behavior in Antarctica.
abstract: We examined the physiological and psychological status of men and women who spent the summer (n=100) and/or winter (n=85) seasons in Antarctica at McMurdo (latitude 78.48 S, elevation 12 m) and South Pole (latitude 90 S, elevation 3880 m) stations to determine whether there were any significant differences by severity of the stations' physical environment. Physiological measures (body mass index, blood pressure, heart rate, tympanic temperature), serum measures of thyroid hormones, cortisol, and lipids and plasma catecholamines were obtained at predeployment (Sep-Oct) and the beginning of the summer (November) and winter (Mar-Apr) seasons. Cognitive performance and mood were assessed using the Automatic Neuropsychological Assessment Metric - Isolated and Confined Environments (ANAM-ICE), a computerized test battery. South Pole residents had a lower body mass index (p<0.05) and body temperature (p<0.01) and higher levels of plasma norepinephrine (p<0.05) in summer and winter than McMurdo residents. Upon deployment from the United States and during the summer, South Pole residents experienced significantly higher thyroid hormone values (free and total T(3) and T(4)) (p<0.01) than McMurdo residents; in summer they also experienced lower levels of triglycerides (p<0.01) cortisol (p<0.05) and LDL (p<0.05). In winter, South Pole residents also experienced a 39% decrease in serum TSH compared with a 31.9% increase in McMurdo (p<0.05). South Pole residents also were significantly more accurate (p<0.05) and efficient (p<0.01) in performance of complex cognitive tasks in summer and winter. Higher thyroid hormone levels, combined with lower BMI and body temperature, may reflect increased metabolic and physiological responses to colder temperatures and/or higher altitude at South Pole with no apparent adverse effect on mood and cognition.
authors.affiliation: School of Social Work, University of Southern California, 669 W. 34th Street, Los Angeles CA, 90089-0411, USA. palinkas@usc.edu
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Palinkas
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Reedy
authors.forename: Marc
authors.initials: M
authors.lastname: Shepanek
authors.forename: Mark
authors.initials: M
authors.lastname: Smith
authors.forename: Mihai
authors.initials: M
authors.lastname: Anghel
authors.forename: Gary D
authors.initials: GD
authors.lastname: Steel
authors.forename: Dennis
authors.initials: D
authors.lastname: Reeves
authors.forename: H Samuel
authors.initials: HS
authors.lastname: Case
authors.forename: Nhan Van
authors.initials: NV
authors.lastname: Do
authors.forename: H Lester
authors.initials: HL
authors.lastname: Reed
mesh_terms: D000223:Adaptation, Psychological; D000864:Antarctic Regions; D001519:Behavior / Q000502:physiology*; D002395:Catecholamines / Q000097:blood; D015331:Cohort Studies; D003081:Cold Climate; D004777:Environment; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008055:Lipids / Q000097:blood; D008297:Male; D010907:Pituitary Hormones / Q000097:blood; D010913:Pituitary-Adrenal System / Q000502:physiology*; D012189:Retrospective Studies; D012621:Seasons; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D002395:Catecholamines; D008055:Lipids; D010907:Pituitary Hormones; D013963:Thyroid Hormones; D006854:Hydrocortisone