Phobias
Conditions
Keywords
anesthetic drugs, associative memory, fear
Brief summary
People often develop fearful responses to things, but have no conscious control over the fear. This is a basic form of unconscious memory, called fear conditioning. Intravenous anesthetic drugs have remarkable effects on conscious memory, but it is unknown whether they have similar effects on these unconscious fear memories. To address this question, the investigators will study 114 healthy adult volunteer subjects. The subject is given a very low dose of an anesthetic drug intravenously (i.e. through the bloodstream). The dose is so low that the subject might not even be able tell if they are getting the drug. While they are receiving the drug, the subject will perform a series of memory tests and a fear conditioning experiment, which are set up like a very simple computer game. To create the fear response, subjects will occasionally receive a mildly uncomfortable shock to their arm. The subject is able to determine the highest level of shock that they will receive. The investigators are doing this study because the investigators wish to know exactly how the drugs affect the way people process fear and emotion. This knowledge might one day be used in the treatment of some psychiatric disorders.
Detailed description
People often develop fearful responses to things, but have no conscious control over the fear (e.g. phobias). This is a basic form of unconscious memory, called fear conditioning. Intravenous anesthetic drugs have remarkable effects on conscious memory, but it is unknown whether they have similar effects on these unconscious fear memories. To address this question, the investigators will study 114 healthy adult volunteer subjects. The subject is given a very low dose of an anesthetic drug intravenously (i.e. through the bloodstream). The dose is so low that the subject might not even be able tell if they are getting the drug. While they are receiving the drug, the subject will perform a series of memory tests and a fear conditioning experiment, which are set up like a very simple computer game. To create the fear response, subjects will occasionally receive a mildly uncomfortable shock to their arm. The subject is able to determine the highest level of shock that they will receive. The investigators are doing this study because the investigators wish to know exactly how the drugs affect the way people process fear and emotion. This knowledge might one day be used in the treatment of some psychiatric disorders.
Interventions
DRUGPlacebos
IV Saline infusion for 2 hours.
DRUGPropofol 0.45mcg/mL
IV Propofol infusion for 2 hours.
DRUGPropofol 0.90mcg/mL
IV Propofol infusion for 2 hours.
DRUGThiopental 1.5mcg/mL
IV Thiopental 1.5mcg/mL infusion for 2 hours
DRUGThiopental 3mcg/mL
IV Thiopental 3mcg/mL infusion for 2 hours
Sponsors
National Institutes of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Weill Medical College of Cornell University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* age between 18 and 50 * minimum of high school education * fluent in English * normal vocabulary
Exclusion criteria
* any significant medical or psychiatric comorbidity (e.g. asthma, diabetes, hypertension, depression, high anxiety)--subjects must be in excellent health such that they would be classified as American Society of Anesthesiologists Physical Status Class I * deficit in vision or hearing that would impede the study * allergies to any of the study drugs, to soybeans, or to eggs * a history of head trauma * a family history of major psychiatric illness * body mass index \> 30 kg/m2 * a recent history of recreational drug use * prior exposure to the study materials * pregnancy * a personal or family history of any porphyria * failure to exhibit a skin conductance response to deep inspiration * the ability to read Chinese characters * assessment by the investigators that the subject may be unable to cooperate or comply with the study requirements.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| GSR Trial 1 | First Trial, for up to 1 day | Galvanic skin repose (GSR) to the first habituation trial (yes/no). Coding: Yes (0) and No (1) |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Placebos Saline Infusion
Placebos: IV Saline infusion for 2 hours. | 21 |
| Propofol 0.45mcg/mL Anesthetic Drug Infusion
Propofol 0.45mcg/mL: IV Propofol infusion for 2 hours. | 20 |
| Propofol 0.9mcg/mL Anesthetic Drug Infusion
Propofol 0.9mcg/mL: IV Propfol infusion for 2 hours. | 20 |
| Thiopental 1.5mcg/mL Anesthetic Drug Infusion
Thiopental 1.5mcg/mL: IV Thiopental infusion for 2 hours. | 3 |
| Thiopental 3mcg/mL Anesthetic Drug Infusion
Thiopental 3mcg/mL: IV Thiopental Infusion for 2 hours. | 3 |
| Total | 67 |
Baseline characteristics
| Characteristic | Placebos | Propofol 0.45mcg/mL | Propofol 0.9mcg/mL | Thiopental 1.5mcg/mL | Thiopental 3mcg/mL | Total |
|---|---|---|---|---|---|---|
| Age, Continuous | 25.1 years STANDARD_DEVIATION 4.4 | 25.4 years STANDARD_DEVIATION 4.1 | 25.6 years STANDARD_DEVIATION 4.5 | 23.7 years STANDARD_DEVIATION 3.4 | 26.3 years STANDARD_DEVIATION 5.8 | 25.2 years STANDARD_DEVIATION 4.4 |
| Sex: Female, Male Female | 14 Participants | 10 Participants | 16 Participants | 2 Participants | 0 Participants | 42 Participants |
| Sex: Female, Male Male | 7 Participants | 10 Participants | 4 Participants | 1 Participants | 3 Participants | 25 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk | EG004 affected / at risk |
|---|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 21 | 0 / 20 | 0 / 20 | 0 / 3 | 0 / 3 |
| other Total, other adverse events | 0 / 21 | 1 / 20 | 0 / 20 | 0 / 3 | 0 / 3 |
| serious Total, serious adverse events | 0 / 21 | 0 / 20 | 0 / 20 | 0 / 3 | 0 / 3 |
Outcome results
Primary
GSR Trial 1
Galvanic skin repose (GSR) to the first habituation trial (yes/no). Coding: Yes (0) and No (1)
Time frame: First Trial, for up to 1 day
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Placebos | GSR Trial 1 | .62 units on a scale | Standard Deviation 0.5 |
| Propofol 0.45mcg/mL | GSR Trial 1 | .55 units on a scale | Standard Deviation 0.51 |
| Propofol 0.9mcg/mL | GSR Trial 1 | .55 units on a scale | Standard Deviation 0.51 |
| Thiopental 1.5mcg/mL | GSR Trial 1 | .67 units on a scale | Standard Deviation 0.5 |
| Thiopental 3mcg/mL | GSR Trial 1 | 0 units on a scale | Standard Deviation 0 |