Protocol Number: 02-M-0263

Title:

Psychopharmacology of Fear-Potentiated Startle in Humans

Number:

02-M-0263

Summary:

The purpose of this study is to understand the effects of the drug alprazolam (Xanax ) on anxiety.

To understand the effect of anxiety-relieving drugs on fear and anxiety, researchers often have participants anticipate unpleasant stimuli. Anticipating unpleasant stimuli increases or potentiates a simple reflex called the startle reflex. The so-called fear-potentiated startle reflex (FPS) effect may be blocked or reduced by anxiety-relieving drugs. Evidence suggests that the FPS can be mediated by two mechanisms that regulate the phasic- and sustained enhancement of startle. This study will elicit phasic and sustained FPS in participants by having them anticipate moderately painful stimuli that are administered predictably and unpredictably. The main goal of this study is to assess the affect of alprazolam on the phasic and sustained enhancement of startle.

This study comprises two pilot experiments and a main study. Participants in the study will be screened with a psychiatric history, physical examination, electrocardiogram (EKG), and blood and urine tests. Participants will four testing sessions separated by 5 to 10 days. At each session, participants will be given one of two doses of alprazolam, diphenhydramine, or placebo (an inactive pill). Questionnaires and other tests will be performed.

Sponsoring Institute:

National Institute of Mental Health (NIMH)

Recruitment Detail

Type: Participants currently recruited/enrolled

Gender: Male & Female

Referral Letter Required: Yes

Population Exclusion(s): Children

Eligibility Criteria:

INCLUSION CRITERIA:

Subjects will be healthy volunteers between 18-45 years old and free of current psychopathology and organic central nervous system disorders.

EXCLUSION CRITERIA:

- Any significant medical or neurological problems (e.g. cardiovascular illness, respiratory illness, neurologic illness, seizure, etc.)

- Adverse reactions to ACE inhibitors and ACE receptor antagonists (candesartan study only)

- Adverse reactions to cortisol (cortisol study only)

- History of angioedema

- Osteoporosis (Hydrocortisone study only)

- Blood pressure below 100 (candesartan study only)

- Use of potassium supplements (candesartan study only)

- A family history of mania, schizophrenia, or other psychoses

- A history of mania, schizophrenia, or other psychoses

- Current migraine

- Use of herbal medicines or dietary supplements with psychoactive properties (citalopram study only)

- Any current psychiatric disorders

- Past alcohol/drug dependence and alcohol/drug abuse in past one year

- Current use of psychotropic medication

- Use of diuretics or laxatives (candesartan study only)

- Impaired hearing

- Reduced startle reactivity

- Pregnancy

- Positive results of beta-human chorionic gonadotropin testing (females only)

- Neurological syndrome of the wrist (e.g., carpal tunnel syndrome)

- Adverse reaction to candesartan or other blood pressure lowering medications

Special Instructions:

Currently Not Provided

Keywords:

SSRI

Anxiety

Stress

Citalopram

Benadryl

Diphenhydramine

Startle

Fear-Potentiated Startle

Fear

Normal Volunteers

Recruitment Keyword(s):

Healthy Volunteers

HV

Condition(s):

Healthy

Investigational Drug(s):

None

Investigational Device(s):

None

Intervention(s):

None

Supporting Site:

National Institute of Mental Health

Contact(s):

Patient Recruitment and Public Liaison Office
Building 61
10 Cloister Court
Bethesda, Maryland 20892-4754
Toll Free: 1-800-411-1222
TTY: 301-594-9774 (local),1-866-411-1010 (toll free)
Fax: 301-480-9793

Electronic Mail:prpl@mail.cc.nih.gov

Citation(s):

Bitsios P, Philpott A, Langley RW, Bradshaw CM, Szabadi E. Comparison of the effects of diazepam on the fear-potentiated startle reflex and the fear-inhibited light reflex in man. J Psychopharmacol. 1999;13(3):226-34.

Riba J, Rodriguez-Fornells A, Urbano G, Morte A, Antonijoan R, Barbanoj MJ. Differential effects of alprazolam on the baseline and fear-potentiated startle reflex in humans: a dose-response study. Psychopharmacology (Berl). 2001 Oct;157(4):358-67.

Davis M, Falls WA, Campeau S, Kim M. Fear-potentiated startle: a neural and pharmacological analysis. Behav Brain Res. 1993 Dec 20;58(1-2):175-98. Review.

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