The long term objective of this research program is to determine whether adaptation to repeated stressors is impaired in depression.
The specific aims of the first pilot study are: (1) to find an effective acute stressor that will reliably elicit stress responses in both normal and depressed subjects using a variety of biochemical/hormonal measures (cortisol, NE, E, ACTH and beta endorphin) and subjective ratings of stress, (2) to determine, for purposes of control, the rhythmic pattern for basal hormone/neurotransmitter secretion during the time of day when we will be testing subjects, (3) to find out if there is adaptation to the laboratory situation itself by comparing basal levels of the outcome measures for separate sessions before exposure to any of the stressors and after exposure to three sessions of different stressors and (4) to find out if there are differences between normal and depressed subjects in their responses to acute stressors. The three stressors that will be examined in Study I are: (1) The cold pressor test in which one foot is immersed in ice water for 2 minutes, (2) a difficult mental arithmetic task performed while the subject listens to a tape recording of a crying infant which contains numbers embedded in it and (3) films of trauma scenes such as automobile accidents. During sessions in which basal measurements are taken blood will be drawn six times while the subject sits quietly in a chair. During each of the three stress sessions subjects will have blood drawn during a baseline rest period and at several points during and after the stressor. They will be asked to rate their subjective experience of the severity of the stressor. The Profile of Mood States will be administered before and after the stressor to assess changes in mood associated with it.
The specific aims of the second pilot study are (1) to determine the pattern of adaptation to a repeated stressor in normal subjects and (2) to find out whether depressed subjects have an abnormal pattern of adaptation to repeated stress. The methodology of Study II will be essentially the same as in Study I except that subjects will be exposed to five sessions of the same stressor. The information that will be obtained in the proposed studies should eventually lead to increased understanding of the relationship between stress and depression and could aid in designing better treatments for depression in the future.
