Obsessive-Compulsive Disorder (OCD)

Obsessive-compulsive disorder (OCD) affects approximately 2.3% of the U.S. population at some point in their lives — about 1 in 40 adults. Characterized by persistent, unwanted thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) performed to reduce anxiety, OCD can be severely disabling, ranking among the top 10 most debilitating conditions worldwide.

First-line treatments include cognitive-behavioral therapy with exposure and response prevention (ERP) and serotonin reuptake inhibitors (SSRIs, particularly at higher doses). However, 40–60% of OCD patients do not achieve adequate remission with these standard approaches, and treatment resistance is common.

Ketamine represents a novel approach to OCD treatment, targeting the glutamate system rather than the serotonin system. While research is still emerging compared to depression and PTSD, early clinical evidence is promising for rapid reduction of obsessive-compulsive symptoms.

The neurobiology of OCD involves dysfunction in cortico-striato-thalamo-cortical (CSTC) circuits, and ketamine may address this through several mechanisms:

• Glutamate system normalization: OCD is associated with elevated glutamate levels in the striatum and anterior cingulate cortex. Ketamine's modulation of glutamate signaling may help normalize activity in these overactive circuits.
• Synaptic plasticity: By promoting synaptogenesis in the prefrontal cortex, ketamine may strengthen the brain's ability to exert cognitive control over obsessive thoughts and compulsive urges.
• Habit circuit disruption: OCD compulsions are driven by dysfunctional habit circuits in the basal ganglia. Ketamine's effects on NMDA receptors may help disrupt the automatic, habitual nature of compulsive behaviors.
• Rapid BDNF release: The neurotrophin BDNF, rapidly released by ketamine, plays a role in cognitive flexibility — the ability to shift thoughts and behaviors that is impaired in OCD.

OCD treatment protocols with ketamine are still being refined but generally include:

• Induction series: 6 IV infusions over 2–3 weeks at the standard dose of 0.5 mg/kg over 40 minutes.
• Combination with ERP: Ketamine may be most effective for OCD when combined with exposure and response prevention (ERP) therapy, leveraging the enhanced cognitive flexibility during the post-infusion neuroplasticity window.
• Maintenance: Ongoing infusions at individualized intervals based on symptom response. The optimal maintenance schedule for OCD is still being studied but typically follows a similar pattern to depression protocols.
• Monitoring: Response is tracked using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at each visit to quantify improvement and guide treatment decisions.

OCD-specific safety considerations:

• Dissociation and control: Some OCD patients may find the loss of control during dissociation particularly anxiety-provoking. Thorough preparation and a supportive environment are essential.
• Temporary symptom flux: Some patients may notice temporary changes in obsessive content or intensity in the first 24–48 hours after infusion before improvement stabilizes.
• Standard monitoring: All standard ketamine safety protocols apply, including cardiovascular monitoring and post-infusion supervision.
• Medication interactions: Patients on SRI medications (which are often used at high doses for OCD) can generally continue these alongside ketamine, though the treating clinician should review all medications.