Effects of Arousal and Stress in Anxiety

Not Applicable

Completed

Conditions: Healthy Volunteers

Interventions: Device: Shock Device
Device: Auditory Startle Device

Registration Number: NCT00026559

Lead Sponsor: National Institute of Mental Health (NIMH)

Brief Summary: This study has several parts. One part will examine the influence of factors such as personality and past experience on reactions to unpleasant stimuli. Others will examine the effect of personality and emotional and attentional states on learning and memory.

When confronted with fearful or unpleasant events, people can develop fear of specific cues that were associated with these events as well as to the environmental context in which the events occurred via a process called classical conditioning. Classical conditioning has been used to model anxiety disorders, but the relationship between stress and anxiety and conditioned responses remains unclear. This study will examine the relationship between cued conditioning and context conditioning . This study will also explore the acquisition and retention of different types of motor, emotional, and cognitive associative processes during various tasks that range from mildly arousing to stressful.

Detailed Description: Objective: Fear and anxiety are adaptive responses to different types of threats. Fear is a short-duration response evoked by explicit threat cues and anxiety a more sustained state of apprehension evoked by unpredictable threat. This protocol studied fear using Pavlovian fear conditioning in two studies. Studies 1 and 3. Study 2 focused on anxiety. Studies 1 and 3 will be discontinued to focus uniquely on the study of anxiety. Specifically, we will examine the interactions between anxiety induced experimentally using verbal threat and cognitive processes. We will seek to 1) characterize the effect of anxiety on key cognitive processes including working memory and attention control and 2) examine the extent to which performance of cognitive tasks distract from anxiety.

Study population: This more-than-minimal-risk protocol will test medically and psychiatrically healthy volunteers aged 18-50. Pregnant or nursing women will be excluded.

Method: Fear and anxiety will be measured using the startle reflex to brief and loud sounds. Fear conditioning will be assessed using shock as unconditioned stimulus. Cognitive performance will be examined during periods of unpredictable shock anticipation.

Outcome measures: The study will include cognitive performance and measure of aversive states, primarily the startle reflex.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 1418

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Healthy volunteers	Auditory Startle Device	Sub-study A: Working memory task / Participant performed a working memory task in two conditions, under threat of shock and in safety and asked to remember verbal and nonverbal stimuli from the current stimulus on the screen (N-back task) Sub-study C: Sustained attention to response task (SART) / participant was presented with stimuli and either initiated a response (i.e. "go") or inhibited their response (i.e. "stop") based on what stimuli were presented Sub-study D: Stroop task/ In the classic Stroop test, the name of a color is printed in a color that conflicts or does not conflict with the word. In the emotional Stroop, the words emotional words. The participant's task was to name the color of the word Pilot studies / (1) Shocks were delivered via electrodes located on the forearm or fingers while participant performed a working memory or vigilance task or (2) Subject performed cognitive tasks during alternating safe and threat periods
Healthy volunteers	Shock Device	Sub-study A: Working memory task / Participant performed a working memory task in two conditions, under threat of shock and in safety and asked to remember verbal and nonverbal stimuli from the current stimulus on the screen (N-back task) Sub-study C: Sustained attention to response task (SART) / participant was presented with stimuli and either initiated a response (i.e. "go") or inhibited their response (i.e. "stop") based on what stimuli were presented Sub-study D: Stroop task/ In the classic Stroop test, the name of a color is printed in a color that conflicts or does not conflict with the word. In the emotional Stroop, the words emotional words. The participant's task was to name the color of the word Pilot studies / (1) Shocks were delivered via electrodes located on the forearm or fingers while participant performed a working memory or vigilance task or (2) Subject performed cognitive tasks during alternating safe and threat periods

Primary Outcome Measures

Name	Time	Method
Correct-go Reaction Time (RT)	2000 ms during trial	Correct go responses were go trials followed by button press. Mean reaction time (RT) was calculated for correct-go to evaluate speed-accuracy trade-off.
Nogo Trials Followed by no Button Press	250 ms at a rate of one every 2000 ms	Subjects participated in go/no go (GNG) task condition during periods of threat of shocks and periods of safety when no shock could be administered. During the GNG stimuli were presented on a monitor. In the GNG task, participants were asked to respond to frequent 'go' stimuli ('=') by pressing the '2' on the keypad of a computer keyboard and to withhold their response to infrequent 'nogo' stimuli ('O'). Stimuli were randomly distributed. A correct go hit was a response recorded during these 2000 millisecond (ms) to a go trial. Similarly, a correct nogo omission was a no response during the same period to a nogo trial. Performance was determined for each condition (threat, safe) and trial type (go, nogo) by dividing the number of correct response by the total number of each trial type.
Response to Startle Reflex	20-100 ms window following the onset of the startle stimulus	The startle reflex was elicited with a 103-decibel (dB) white noise (40-ms duration) delivered via headphone. The eyeblink component of the startle reflex was recorded binaurally with two AgCl electrodes placed under the left eye. The peak startle/eyeblink reflex magnitude was determined in the 20-100 ms timeframe. The shock was administered either on the left wrist or on the left middle and ring fingers, depending on where the desired intensity was reached. Startle stimuli were delivered between two go trials and go trials that followed a startle stimulus were not included in the analysis. A shock was delivered in two of the four threat blocks in each sequence, just prior to the last go trial, which was not included in the analysis (for a total of 4 shocks). Shock could be administered only in the threat condition and never in the safe condition. The results were analyzed using a Condition (safe, threat) x Task (task, no task) repeated ANOVA.
Go Correct Hits Followed by Button Press	250 ms at a rate of one every 2000 ms	Subjects participated in go/no go (GNG) task condition during periods of threat of shocks and periods of safety when no shock could be administered. During the GNG stimuli were presented on a monitor. In the GNG task, participants were asked to respond to frequent 'go' stimuli ('=') by pressing the '2' on the keypad of a computer keyboard and to withhold their response to infrequent 'nogo' stimuli ('O'). Stimuli were randomly distributed. A correct go hit was a response recorded during these 2000 millisecond (ms) to a go trial. Similarly, a correct nogo omission was a no response during the same period to a nogo trial. Performance was determined for each condition (threat, safe) and trial type (go, nogo) by dividing the number of correct response by the total number of each trial type.
Subjective Measures of Level of Anxiety	Every 100 sec repeated 8 times	Subjects retrospectively rated their level of anxiety using a scale of 1-10 where 1 = "not at all anxious" and 10 = "extremely anxious" at the end of each block of a sequence for a total of eight blocks. A block was defined as a combination of a condition (safe or threat) and a task (task or no task). The results were analyzed using a Condition (safe, threat) x Task (task, no task) repeated ANOVA.

Secondary Outcome Measures

Name	Time	Method
Measure of Level of Anxiety	1-3 weeks before start of study	The level of anxiety was assessed using the Trait Anxiety Inventory questionnaire. The Trait Anxiety Scale (T-Anxiety) evaluates relatively stable aspects of "anxiety proneness", including general states of calmness, confidence, and security. The Trait Anxiety Scale has 20 items. All items are rated on a 4-point scale: 1 = almost never, 2 = sometimes, 3 = often, and 4 = almost always.. The scale has a minimum score of 20 and a maximum score of 80. Higher score indicates greater anxiety. Trait Anxiety score was measured prior to start of the study.
Measure of Attention Control	1-3 weeks before start of study	Subjects completed the Attention Control Scale (ACS) prior to start of the study. The ACS is a 20-item self-report scale that measures attentional focusing (9 items) and attentional shifting (11 items) rated on a four-point likert scale from "1 - almost never" to "4 - always" with total score range of 20 to 80. Higher score on ACS reflect better ability to direct and maintain attention.