Depression, Involutional Clinical Trial
Official title:
An Investigation of a Pharmacologic Strategy to Bring About Rapid (Next Day) Antidepressant Effects
This study examines if Yohimbine, when given during the sleep cycle, will improve symptoms of
depression within a matter of hours.
Purpose: This study will examine whether the drug yohimbine, given at a specific time during
the sleep cycle, produces chemical changes in the brain similar to those that occur with
sleep deprivation. It will also see if yohimbine can induce rapid (next day) antidepressant
effects in patients with major depression. Total sleep deprivation for 36 hours improves mood
in most patients with major depression in a matter of hours, but the response is usually
short-lived. Understanding the chemical changes that occur in the body during sleep
deprivation may help in the development of a rapidly acting antidepressant.Patients with
major depressive disorder between 18 and 65 years of age may be eligible for this study.
Candidates are screened with a medical and psychiatric history, physical examination,
electrocardiogram, and blood and urine tests. Participants are hospitalized at the NIH
Clinical Center for the study, as follows: Drug-free period: Patients are tapered off their
anti-depression medications and remain drug-free for 1 week before beginning study phase 1.
Study phase 1: Patients undergo sleep deprivation for 36 hours. Those whose depression
improves with sleep deprivation initially and then worsens continue to phase 2. The day after
sleep deprivation, patients undergo a lumbar puncture (spinal tap). For this test, a local
anesthetic is given and a needle is inserted in the space between the bones in the lower back
where the cerebrospinal fluid circulates below the spinal cord. A small amount of fluid is
collected through the needle. Study phase 2: Patients spend 1 night in the sleep lab. A
catheter (plastic tube) is placed in a vein in each arm-one to give yohimbine and the other
to draw blood samples. A small monitor cuff is placed on a finger to measure the patient's
blood pressure and blood oxygen levels during the night. While asleep, the patient receives a
dose of yohimbine or placebo, given over 3 minutes. A lumbar puncture is done the following
morning. Patients receive no medications for 6 days, and then the sleep lab procedure is
repeated. Patients who received yohimbine in the previous experiment are switched to placebo,
and those who were given placebo are switched to yohimbine.
Sleep deprivation is one of the only interventions that have consistently been demonstrated
to produce rapid antidepressant effects. The mechanisms by which sleep deprivation brings
about rapid antidepressant effects remain to be elucidated. It is noteworthy, however, that
recent genomic and proteomic studies have shown that acute sleep deprivation rapidly brings
about an upregulation of several mediators of neuronal plasticity, most notably CREB and
BDNF. Intriguingly, these are the very same molecules that are upregulated by chronic
antidepressants, and are believed to underlie the delayed therapeutic effects of most
antidepressants. Additional investigation of the regulation of CREB and BDNF by sleep
deprivation has revealed that these changes are critically dependent upon the activation of
the noradrenergic system. This is particularly noteworthy, since the locus coeruleus (LC)
noradrenergic projection is quiescent only during rapid eye movement sleep (REM), when the
target tissues display their greatest sensitivity; indeed, the temporal dissociation between
the firing of the LC noradrenergic neurons, and the sensitivity of its postsynaptic targets
in the cortex may have considerable relevance for the antidepressant effects of sleep
deprivation. In this context, biological rhythms have the capacity to temporally dissociate
biochemical processes, and imposing a temporal coincidence on normally dissociated events can
have striking and unexpected effects. Thus, it is our hypothesis that activating the normally
quiescent noradrenergic system during REM sleep (i.e. when its postsynaptic target system
displays its greatest sensitivity) will robustly upregulate CREB and BDNF, thereby bringing
about a rapid antidepressant effect. We propose to activate the noradrenergic system during
REM sleep by infusing an alpha(2) antagonist, yohimbine. Since it is our hypothesis that
activating the noradrenergic system during REM sleep will bring about an antidepressant
effect by a similar mechanism as sleep deprivation, we will "enrich" our sample with sleep
deprivation responders in this pilot study.
Patients, ages 18 to 65 with a diagnosis of major depressive disorder, currently depressed
without psychotic features will be recruited into this study. This experimental
proof-of-concept study has two Study Phases. Study Phase I consists of total sleep
deprivation. Responders to total sleep deprivation who subsequently relapse will enter Study
Phase II. Study Phase II is a double-blind crossover administration of either intravenous
yohimbine or saline solution during REM sleep.
The specific aim of this study is to assess the efficacy of a single dose of intravenous
yohimbine hydrochloride (0.125 mg/kg given over 3 minutes) compared with placebo in improving
overall depressive symptomatology when administered during REM sleep.
Our primary hypothesis is that the intravenous use of an alpha(2) antagonist in patients with
major depression during REM sleep will activate the LC and thus increase noradrenergic
activity during a time when the LC is normally quiescent- namely REM sleep. If the hypothesis
that it is the timing of the activation of the noradrenergic system that is crucial in the
antidepressant effect of sleep deprivation is correct then an acute antidepressant effect
should be observed in patients despite minimal to no disruption of sleep.
Assuming that 10% will drop out of the study, then a minimum of 25 patients is necessary in
order to obtain a minimum of 8 patients with major depression who will complete the
double-blind crossover phase of the study.
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