Understanding How Ketamine Brings About Rapid Improvement in OCD

Inclusion Criteria for participants with OCD:

* age 18-65
* Primary diagnosis of OCD
* Sufficient severity of OCD symptoms
* ability to tolerate a treatment-free period
* capacity to provide informed consent

Inclusion criteria for healthy controls:

* ages 18-65
* capacity to provide informed consent

Exclusion criteria for participants with OCD:

* Psychiatric or medical conditions that make participation unsafe
* pregnant or nursing females
* concurrent use of any medications that might increase the risk of participation (e.g. drug interactions)
* presence of metallic device or dental braces

Exclusion criteria for healthy controls:

* any current or lifetime psychiatric diagnosis
* pregnant or nursing females
* major medical or neurological problem
* presence of metallic device or dental braces