Protocol Number: 02-M-0263

Title:

Effect of Alprazolam on 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: Active Accrual Of New Subjects

Gender: Male & Female

Referral Letter Required: Yes

Population Exclusion(s): Children

Eligibility Criteria:

INCLUSION CRITERIA:

Subjects will be healthy volunteers ages 18-45 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 benzodiazepines or antihistamines.

A past history of psychotic disorder, bipolar disorder, PTSD, major depression, social phobia, panic disorder, anorexia.

Any current psychiatric disorders, including alcohol or drug (except nicotine) abuse/dependence and anxiety disorders.

Past history of alcohol or drug abuse/dependence in the last 10 years.

Current use of psychotropic medication or an illicit substance.

Impaired hearing.

Reduced startle reactivity.

Pregnancy.

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

Special Instructions: Currently Not Provided

Keywords:

Benzodiazepine

Anxiety

Stress

Alprazolam

Benadryl

Diphenhydramine

Startle

Fear-Potentiated Startle

Fear

Normal Volunteers

Recruitment Keywords:

Healthy Volunteers

HV

Conditions:

Healthy

Investigational Drug(s):

None

Investigational Device(s):

None

Contacts:

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

Citations:

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. PMID: 10512076

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. PMID: 11605094

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. PMID: 8136044

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