This six-arm study is being conducted to measure the effect of a combination of paroxetine and vestipitant on the arousal induced by public speaking in Seasonal Effective Disorder (SAD) patients, using functional brain imaging readouts (i.e., WAT(Wave Analysis Technology) PET(Positron Emission Tomography)), after one or eight weeks of treatment. The effect of paroxetine alone after one or eight weeks of treatment will also be measured.

A double-blind, double dummy, placebo-controlled, randomised, parallel group positron emission tomography study to investigate the effects of a 8 week administration of vestipitant and paroxetine in combination or paroxetine alone on regional cerebral blood flow during a public speaking test in subjects affected by social anxiety disorder.

Inclusion criteria:

• Social phobic ambulatory subjects, defined according to DSM-IV criteria.
• Must be capable of giving informed consent and can comply with the study requirements.
• Women of childbearing potential must agree to acceptable method of birth control.

Exclusion criteria:

• Primary diagnosis within the past 6 months of other psychiatric conditions such as major depression or another anxiety disorder.
• Use of medications for a psychiatric condition including herbals in the past 2-12 weeks according to medication type.
• Subjects who, in the investigator's judgement pose a current, serious suicidal or homicidal risk or have made a suicide attempt within the past 6 months.
• Subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance abuse or subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance dependence (other than nicotine).
• Significantly abnormal blood or urine laboratory tests or electrocardiogram (ECG) findings.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.