• INCLUSION CRITERIA:

ANXIETY DISORDERS SAMPLES:

Eighty four subjects (ages 18-50) with anxiety disorders (PD and PTSD) will be selected who additionally meet criteria for one of 4 subgroups:

A) PD, Currently Depressed (n=27):

As defined by DSM-IV criteria for PD, and still symptomatic as defined by at least 1 panic attack/week or a CGI score of at least 4, and current HDRS score in the mild-moderately-to-severely depressed range (greater than 15).

Patients are requested to meet the DSM-IV criteria for a single or recurrent episode of major depressive disorder.

In case of comorbid depression it will be ensured that PD had an earlier onset than the depressive disorder.

B) PD, Currently Not Depressed (n=27):

Defined as having symptomatic PD with at least 1 panic attack/week or a CGI score of at least 4 and never having had experienced a depressive episode meeting DSM-IV criteria for major depressive disorder or dysthymia, OR a period of at least six months with no more than one clinically significant symptom, and during which time subjects were not taking an AD agent, with Hamilton Depression Rating Scale (HDRS; 25 item) scores in the non-depressed range (less than or equal to 7) will be selected.

C) PTSD, Currently Depressed (n=15):

As defined by DSM-IV with a duration of illness at least three months.

Patients must score greater than or equal to 50 on Clinician-Administered PTSD Scale (CAPS-2) as a measure of PTSD symptom severity.

Patients are requested to meet the DSM-IV criteria for a single or recurrent episode of major depressive disorder.

Current HDRS score is in the mild-moderately-to-severely depressed range (greater than or equal to 15).

In case of comorbid depression it will be ensured that PTSD had an earlier onset than the depressive disorder.

D) PTSD, Currently Not Depressed (n=15):

Defined as having PTSD and never having had experienced a depressive episode meeting DSM-IV criteria for major depressive disorder or dysthymia OR a period of at least six months with no more than one clinically significant symptom, and during which time subjects were not taking an AD agent, with Hamilton Depression Rating Scale (HDRS; 25 item) scores in the non-depressed range (less than or equal to 7) will be selected.

HEALTHY CONTROL SAMPLE:

One hundred sixteen subjects (ages 18-50) who have not met criteria for any major psychiatric disorder.

The control subjects will have no known first-degree relatives with PD or PTSD.

PSYCHIATRIC CONTROL SAMPLE (n=30):

Subjects with Major Depressive Disorder (MDD), currently remitted, as defined by a period of at least three months during which the subject has not taken an antidepressant agent, with Hamilton Depression Rating Scales (HDRS; 21-item) scores in the non-depressed range (less than 8), and with no more than one clinically significant depressive symptom.

These subjects must not have a history of PTSD and/or serious trauma.

EXCLUSION CRITERIA:

Subjects will be recruited who are drug-naive or who are not currently receiving psychotropic drugs for at least 3 weeks (8 weeks for fluoxetine). In case a patient is on psychotropic medications and this treatment is not successful (as defined by meeting the inclusion criteria as noted above), the medication will be tapered off to ensure that the subject is drug-free for at least 3 weeks prior to PET scanning.

Subjects will be also be excluded if they have: a) serious suicidal ideation or behavior, b) psychosis to the extent that the ability to provide informed consent is in doubt, c) medical or neurological illnesses likely to affect physiology or anatomy, d) a history of drug (including BZDs) or alcohol abuse within 1 year or a lifetime history of alcohol or drug dependence (DSM IV criteria), e) current pregnancy (as documented by pregnancy testing prior to scanning), f) current breast feeding, g) general MRI exclusion criteria, h) patients who are currently taking fluoxetine.

Patients and controls must exhibit no or only moderate alcohol use.

Subjects with current or previous regular (greater than 4 weeks) of BZDs and excessive use of alcohol (greater than 8 ounce/day for men and greater than six ounces /day for women) in the past or present are ineligible to participate, as they may produce a down-regulation of the BZD receptor that may confound the results.

Postmenopausal female subjects.

Subjects beyond age 50 are excluded to reduce the biological heterogeneity encompassed by the MDD and anxiety disorders criteria.

Subjects whose first anxiety disorder episode arose temporally after other major medical or psychiatric conditions will also be excluded.

In addition to the above criteria, subjects undergoing the serotonin transporter scan will also be excluded if they have taken the recreational drug ecstasy within 3 weeks prior to scan or for regular use in the past.