The purpose of this study is to determine the effects of the drug dextroamphetamine on the
brain function and mood of healthy volunteers.
Monoaminergic drugs are substances that affect the nervous system; these drugs can raise,
hamper, or have no effect on brain function when given to healthy individuals. Different
responses to a drug may be the result of genetic variations. This study will examine the
effects of the monoaminergic drug dextroamphetamine on thought and sensorimotor processes
while participants perform a variety of tasks.
Participants in this study will undergo a medical history, physical examination, blood
tests, and an electrocardiogram (EKG). Women of reproductive potential will undergo a
pregnancy test. Participants will be given either dextroamphetamine or placebo (an inactive
solution) on two occasions separated by at least 3 to 7 days. Participants will then perform
neuropsychological tests that will measure attention, problem solving, memory, and ability
to complete simple motor tasks.
Neuropharmacological intervention with monoaminergic drugs in healthy subjects can either
augment, have no effect, or hamper brain function. We hypothesize that these population
differences might be related to differences (high vs. low) in monoaminergic synaptic
function which may be due to specific allelic variations in monoamine system genes (e.g.,
various synaptic proteins, synthetic enzymes, etc.). We wish to examine the effect of
dextroamphetamine, a non-specific monoaminergic drug, on cognitive efficiency while subjects
perform a variety of tasks including memory challenges with increasing cognitive load and
varying rewards, selective attention and emotional processing. Further, in collaboration
with other NIMH neuroimaging protocols, we wish to examine the neurophysiological correlates
of these effects. We believe this protocol will provide a matrix for many investigations to
elucidate important neurophysiological mechanisms that underlie normal cognition and
cognitive efficiency. It is anticipated that these studies would be of potential
'pharmacogenetic' importance with regard to individual differences in the metabolism of
monoaminergic drugs in normal health, aging and in disease.
- INCLUSION CRITERIA:
Normal volunteers will be recruited exclusively from among individuals who have
volunteered for studies under protocol 95-M-0150 as normal control subjects and for whom
genetic data is already available. Subjects will satisfy the inclusion/exclusion criteria
for that protocol before being given an opportunity to volunteer under this protocol. Here
we detail criteria that are specific to this protocol, per se.
1. Prior participation as a normal volunteer under NIH protocol # 95-M-0150.
2. No Axis I or Axis II diagnosis.
3. Age range: 18-45 years.
1. Subjects with an Axis I or II disorder will be excluded.
2. Subjects with a history of cardiovascular disease and other medical illnesses,
substance abuse or recreational drug use, and hypertension will be excluded. An
electrocardiogram, blood pressure and pulse rate will be checked on all subjects
prior to participation in the study.
3. Pregnant women. Women of childbearing potential will undergo a urine pregnancy test
the day of the study and screened by history for the possibility of pregnancy.