Circannual pattern of hypothalamic–pituitary–thyroid (HPT) function and mood during extended antarctic residence

• Published in: Psychoneuroendocrinology 2001-05, Vol.26 (4), p.421-431
• Main Authors: Palinkas, Lawrence A, Reed, H.Lester, Reedy, Kathleen R, Do, Nhan Van, Case, H.Samuel, Finney, Nancy S
• Format: Article
• Language: English
• Subjects: Adult; Affect; Anger; Antarctic Regions; Antarctica; Behavioral psychophysiology; Biological and medical sciences; Circannual rhythms; Cold; Confusion; Depression; Fatigue; Female; Fundamental and applied biological sciences. Psychology; Hormones and behavior; Humans; Hypothalamus - physiology; Male; Military Personnel; Mood; Periodicity; Pituitary Gland - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Seasonal Affective Disorder - physiopathology; Seasons; Space life sciences; Thyroid; Thyroid Gland - physiology; Thyrotropin - blood; Thyrotropin-releasing hormone; Thyroxine - blood; Triiodothyronine - blood
• ISSN: 0306-4530; 1873-3360
• DOI: 10.1016/S0306-4530(00)00064-0

The seasonal variation in thyroid function and mood was examined in 10 men and two women who spent the 1997 or 1998 austral winter at McMurdo Station, Antarctica. Serum samples of TSH, free T 3 and free T 4 were collected each month over a 10-month period (October–August), along with responses to the Profile of Mood States (POMS) and the Center for Epidemiologic Studies — Depression (CES-D) Scale. Both TSH and mood (a summary score created from the POMS depression, anger, fatigue and confusion subscales) exhibited a circannual pattern with peaks during the months of November and July and a trough during the months of March and April. High levels of tension-anxiety and confusion were preceded by declines in free T 3 and T 4. However, increases in tension-anxiety and total mood disturbance also preceded a decline in free T 3 levels, suggesting a feedback of mood on T 3 levels. Levels of free T 4 were independently associated with preceding increases in anger scores. These results support the hypothesis that the symptoms characteristic of the winter-over syndrome is a state of relative CNS hypothyroidism. This model of seasonal variation in thyroid function and mood also has implications for an understanding of potential mechanisms underlying the association between latitude and SAD or S-SAD.