Randomized Trial of Adult Participants With Generalized Anxiety Disorder

Inclusion Criteria: * Primary diagnosis of generalized anxiety disorder (GAD) either moderate or severe as per Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) as confirmed by the MINI at Screening, in addition to a psychiatric evaluation by a board- certified or Biohaven-approved board-eligible psychiatrist; The duration of illness must be ≥ 1 year * Hamilton Anxiety Rating Scale (HAM-A) Total Score of ≥ 18 at both Screening and Baseline * Clinical Global Impression of Severity Scale (CGI-S) score of ≥ 4 at both Screening and Baseline * Determined by the investigator to be medically stable at baseline/randomization as assessed by medical history, physical examination, laboratory test results, and electrocardiogram testing. Participants must be physically able and expected to complete the trial as designed * Minimum of 6 years of education or equivalent to complete necessary scales and understand consent forms * Participants must be able to understand and agree to comply with the prescribed dosage regimens and procedures; report for regularly scheduled office visits; and reliably communicate with study personnel about adverse events and concomitant medications * Women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test prior to dosing at Baseline Exclusion Criteria: * Participants with a primary DSM-V psychiatric disorder diagnosis other than GAD within the past 6-months. Note: Participants with a secondary diagnosis of comorbid social anxiety disorder or specific phobia are allowed, if in the investigator's judgement, the diagnosis is not sufficiently prominent and active so as to be confound the assessment of GAD symptoms * Participants should be excluded at screening or baseline if any medical or psychiatric condition other than GAD, as specified in the inclusion criteria, could predominantly explain or contribute significantly to the subjects' symptoms or that could confound assessment of GAD symptoms * Participants who report a history of inadequate response (per investigator judgement) to 3 or more adequate trials (including current trial) of any SSRI or SNRI, at an adequate dose and adequate duration (at least 8 weeks) for the treatment of GAD within the 3 years prior to randomization * Hamilton Depression Rating Scale 17 (HAM-D-17) item 1 of \>1 at Screening or Baseline * HAM-D-17 of \> 19 at Baseline * Any eating disorder within the last 12 months prior to Screening * Acute suicidality in the last 12 months, or suicide attempt or self-injurious behavior in the last 12 months prior to Screening * Score of \>0 on the Sheehan Suicidality Tracking Scale for the period of 12 months prior to screening, and at baseline * History of psychosurgery, deep brain stimulation (DBS) or electroconvulsive therapy (ECT)