La. Palinkas et al., Circannual pattern of hypothalamic-pituitary-thyroid (HPT) function and mood during extended antarctic residence, PSYCHONEURO, 26(4), 2001, pp. 421-431
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 eac
h month over a 10-month period (October-August), along with responses to th
e Profile of Mood States (POMS) and the Center for Epidemiologic Studies -
Depression (CES-D) Scale. Both TSH and mood (a summary score created from t
he POMS depression, anger, fatigue and confusion subscales) exhibited a cir
cannual pattern with peaks during the months of November and July and a tro
ugh during the months of March and April. High levels of tension-anxiety an
d confusion were preceded by declines in free T-3 and T-4. However, increas
es 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 fr
ee T-4 were independently associated with preceding increases in anger scor
es, These results support the hypothesis that the symptoms characteristic o
f the winter-over syndrome is a state of relative CNS hypothyroidism. This
model of seasonal variation in thyroid function and mood also has implicati
ons for an understanding of potential mechanisms underlying the association
between latitude and SAD or S-SAD. (C) 2001 Elsevier Science Ltd. All righ
ts reserved.