[Acral rewarming. II: Comparison of healthy probands and depressed patients]

The effect of local cooling on acral rewarming function was measured in healthy subjects and depressed patients. Although group comparison showed that acral rewarming is significantly slower in depressed patients, this parameter cannot be considered as specific for thermoregulatory disturbances in depression since there is marked overlap between groups. Comparison of the annual course was more informative. Annual variations in acral rewarming rate with sex specific differences were found in both groups. However, the variation with time of year was of greater amplitude in depressed patients. Furthermore, in the patient group an annual rhythm was present even in basal finger temperature. Significant March and October troughs in rewarming efficiency after local cooling were found in women (both groups). The greater proportion of depressed women, and the higher spring and autumn incidence of affective illness, may thus have a physiological correlate. The results are discussed in view of the relevance of the acral rewarming test in psychiatric practice and research, the seasonal changes in thermoregulatory measures in the light of a chronobiological approach to depression.