The purpose of this study is to examine how hormonal changes that occur during stressful
situations affect thought and emotions. Results from this study may lead to treatments that
can alleviate the psychological effects of trauma.
Levels of cortisol and norepinephrine increase in response to stress; these hormones also
influence thought processes. This study will give hydrocortisone and/or yohimbine (a
stimulator of central norepinephrine) to healthy adults in order to model the stress
response and to better understand the way people process information during traumatic
This study comprises two experiments in which the stress response is pharmacologically
modeled. Participants in the study will have two study visits. During Visit 1, participants
will undergo a psychiatric assessment, complete neuropsychological tasks, and have their IQ
measured. During Visit 2, participants will be given hydrocortisone and/or yohimbine. Blood
will be collected before and during this. Participants will then perform two experiments. In
one experiment, participants will hear a story with emotional and non-emotional segments; in
a second experiment, participants will view both emotional and non-emotional stimuli.
Memories for traumatic events are fundamentally different from typical memories. Individuals
who witness or are involved in an extremely stressful event, such as a robbery or a violent
act, retain highly accurate memories for the information directly related to the trauma
(e.g., a gun or verbal threat), while surrounding details are poorly remembered. This
so-called weapon focus phenomenon has been found in both naturalistic and laboratory studies
with humans. However, difficulties with the control of naturalistic studies and
approximating trauma in the lab limit the validity of these findings.
Neurophysiologically, cortisol and norepinephrine are principal mediators of the stress
response, and both influence memory function. In particular, cortisol improves memory at low
levels but impairs memory at higher doses. Similarly, some evidence indicates that
norepinephrine also enhances memory in low doses and either impairs or does not influence
memory at high doses. Much of the experimental work in this area has been conducted with
animals. Studies have recently begun to extend these paradigms to humans.
To better understand memory processing during trauma, hydrocortisone and/or yohimbine (a
stimulator of central norepinephrine) will be administered to healthy adults in two
experiments in order to pharmacologically model the stress response. Following infusion,
participants will hear a story with emotional and nonemotional segments in one experiment (N
= 80) and emotional as well as nonemotional stimuli (faces and scenes) in another experiment
(N = 80). It is predicted that relative to the placebo, hydrocortisone will impair memory
for both emotional and nonemotional information, yohimbine will improve memory for both
types of information, and the combination of hydrocortisone and yohimbine will enhance
memory for emotional aspects and impair memory for the nonemotional segments of the story.
Results from this study will permit a better understanding of how emotionally charged
memories are encoded and will potentially lead to treatments to mitigate the psychological
effects of traumatic exposure.
IQ: all subjects will have IQ greater than 85
Follicular cycle: Women will participate in the encoding task between days 3-10.
Only healthy individuals will participate; special attention will be taken to ensure that
no subject has: hypertension, glaucoma, cataracts, ulcers, renal insufficiency,
osteoporosis, hypothyroidism, cirrhosis, ocular herpes simplex and myocardial infarction.
Use of hormonal contraception
Use of glucocorticoids within past 3 years
Use of any psychoactive substance; current or past psychiatric diagnosis.
Irregular sleep pattern as defined as getting less than 6 hours of sleep per night, going
to sleep after 2:00 AM; waking up before 5:00 AM or after 11:00 AM
Weight that is 15% more or less than ideal body weight for sex and height
History of panic attacks or first degree relative with history of panic attacks