OCD: Pharmacotherapy

Text adapted from "The patient with obsessive compulsive disorder" in Psychiatry in primary care by Peggy A. Richter and Steven Selchen (CAMH, 2019).

Cognitive-Behavioural Therapy (CBT) is the most effective treatment in OCD, typically resulting in better outcomes than pharmacotherapy. CBT integrates behavioural therapy with cognitive approaches. Behavioural therapy was the original gold standard treatment, and is based on the principles of exposure to anxiety-provoking triggers without performance of rituals. This approach is often called “exposure and response prevention.” It is now generally combined with cognitive strategies in which the patient identifies and learns to modify exaggerated or maladaptive thoughts and beliefs.

Various factors determine whether CBT is the best option for a given patient. Insight—recognizing that the OCD is excessive or unreasonable—is important because patients with poor insight may be unwilling to challenge their rituals. Comorbid conditions and their severity also need to be considered; for example, mild depression may not be a barrier to treatment with CBT, but more severe depression or active suicidal ideation generally would be. Similarly, significant personality disorders may complicate CBT.

In many ways, motivation is the single biggest factor to consider because patients need to be committed and actively engaged in therapy for it to succeed. Regular homework is a key requirement for success.

For patients with insight and motivation, CBT is the best first-line option. If you do not have access to a CBT therapist (and do not have the skills yourself), consider regularly scheduled appointments with the patient to supervise them in bibliotherapy. The resources section lists self-help OCD workbooks that take people through the basics of CBT. Patients are far more likely to follow through on reading and homework if they are reporting to someone regularly. The resources section also lists good online CBT programs and apps.

Monitoring Treatment

Treatment response can be assessed relatively objectively at regular intervals to monitor progress. Self-report measures such as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Florida Obsessive-Compulsive Inventory (FOCI) and the Obsessive-Compulsive Inventory–Revised (OCI-R) track changes over time (these tools are free online). An even easier approach is to identify a few key symptoms to track, such as number of handwashes per day, duration of showers or length of time spent performing checking rituals when leaving the house. Some patients initially underestimate the impact of their OCD, so as they become more aware of their symptoms, their estimates may increase.

Psychoeducation

Psychoeducation is vital because patients often believe that they are alone in having “ridiculous” or “horrible” thoughts. Normalize and destigmatize these thoughts from the beginning by explaining that we all have bizarre or inappropriate thoughts and that we cannot prevent them. Explain that CBT and medications are the first-line therapeutic options and discuss the pros and cons of each (see Table 3).

Table 3 Pros and Cons of Medication versus CBT

	Medication	CBT
Pros	Easy to take Safe Helps OCD and common comorbid conditions Readily available	Very effective Safe Long-acting
Cons	Limited benefits Side-effects Significant relapse risk after discontinuation	Requires motivation and hard work Difficult if dealing with many problems Can be difficult to access

Family-based psychoeducation is an important part of treatment because the well-intended responses of family members can maintain or worsen OCD symptoms and undermine treatment. Attempts to help can include providing regular reassurance or making accommodations, for example, doing decontamination rituals to satisfy the family member with OCD. These responses maintain the obsessional fears. Family-based psychoeducation and interventions to reduce accommodation are an effective treatment component.

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To access treatment at CAMH: Access CAMH Anyone can visit the RBC Patient and Family Learning Space (PFLS) for resources and help connecting to services.

Medications for treating OCD

Medication (Brand Name)	Recommended Daily Dose (mg)
First-line antidepressant
Fluoxetine (Prozac)	20 - 80
Fluvoxamine (Luvox)	150 - 300
Sertraline (Zoloft)	100 - 200
Paroxetine (Paxil)	20 - 60
Citalopram (Celexa)	20 - 80 ^a
Escitalopram (Cipralex)	10 - 40 ^b
Second-line antidepressant
Clomipramine (Anafranil)	150 - 250
Venlafaxine (Effexor)	225 - 375
Desvenlafaxine (Pristiq)	100 - 200
Mirtazapine (Remeron)	30 - 45

a Health Canada advises 40 mg or less per day.

b Health Canada advises 20 mg or less per day.

Although the recommended dose range for citalopram and escitalopram exceeds the Health Canada warnings due to risk of QTc prolongation on ECG, this effect usually is modest and can be managed easily with serial ECG monitoring, ensuring that patients do not exceed the recommended safety thresholds.

Keep in mind that response to pharmacological treatments can differ significantly between OCD and the obsessive-compulsive–related disorders.

Only 40 to 60 percent of patients respond to the first SSRI, so many patients need to try at least a second one. There is clear evidence that clonazepam and bupropion (Wellbutrin) do not work in OCD, so avoid them for this indication. If a second SSRI fails, most guidelines recommend moving to a second-line option, such as clomipramine or venlafaxine.

Another frequent recommendation is to augment with atypical antipsychotics. Although there is Level 1 evidence for this strategy, a randomized controlled trial of SSRI partial-responders found CBT to be far more effective than an atypical antipsychotic, raising uncertainty about this augmentation approach (Simpson et al., 2013).

Typically, treatment continues for at least one year because there is a high risk of relapse if medication is discontinued early. Most experts recommend referral for CBT to reduce relapse risk. For patients with very severe illness or if a number of medications have been ineffective, long-term continuation of an effective medication is often recommended to maintain stability.

Starting pharmacotherapy for OCD

Clarify expectations at the start:
- High doses work best.
- Increase regularly to the highest dose comfortably tolerated or to the target dose.
- It takes six to eight weeks to see benefits. Allow 12 weeks for each medication to accurately assess response.
Start at the usual dose, then increase every five to seven days:
- escitalopram: 10 mg → 20 mg
- sertraline: 50 mg → 100 mg → 150 mg → 200 mg
- paroxetine/fluoxetine/citalopram: 20 mg → 40 mg → 60/80/80 mg
Allow 10 weeks at the maximum dosage, for a 12-week total on the medication.
Monitor for change:
- Use the self-report Yale-Brown Obsessive-Compulsive Scale and monitor two or three behavioural targets.

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Table 3 Pros and Cons of Medication versus CBT

Starting pharmacotherapy for OCD