What is the recommended treatment approach for an adult patient with Avoidant/Restrictive Food Intake Disorder (ARFID) experiencing anxiety, considering the use of Prozac (fluoxetine)?

Treatment of Anxiety in Adult ARFID Patients

Cognitive-behavioral therapy (CBT) specifically designed for ARFID, delivered through graded exposure in a CBT setting, is the primary treatment approach for adult ARFID patients with anxiety, not Prozac (fluoxetine) or other SSRIs as first-line monotherapy. 1

Primary Treatment Approach

The optimal psychological and nutritional rehabilitation approach in ARFID is graded exposure in a cognitive behavioral therapy (CBT) setting rather than pharmacological intervention alone. 1 This represents the evidence-based standard endorsed by the European Society of Clinical Nutrition & Metabolism, European Society of Neurogastroenterology and Motility, and Rome Foundation 1.

CBT-AR (Cognitive-Behavioral Therapy for ARFID)

• CBT-AR is appropriate for adults ages 10 years and older, proceeds through four stages across 20-30 sessions, and is available in both individual and family-supported versions. 2
• Virtual delivery of CBT-AR has demonstrated preliminary efficacy in adults with ARFID, including those with elevated autistic traits, showing improvements in nutritional intake, general well-being, and reductions in eating-related psychosocial impairment and general anxiety. 3
• Individual CBT is prioritized over group therapy due to superior clinical and cost-effectiveness. 4

Role of SSRIs (Including Prozac/Fluoxetine)

While Prozac is not specifically contraindicated, the evidence for SSRIs in adult ARFID is limited:

Evidence in Pediatric Populations

• SSRIs (including fluoxetine, sertraline, escitalopram) may be helpful as adjunctive treatment in children and adolescents with ARFID, particularly when anxiety is prominent, but this evidence comes primarily from pediatric partial hospitalization programs, not adult outpatient settings. 5
• Patients receiving SSRIs in combination with hydroxyzine (for high pre- and postmeal anxiety) experienced similar improvements in weight, eating behaviors, mood, anxiety, and fears of food compared to SSRI-only groups, though the hydroxyzine group had more severe baseline anxiety. 5

Considerations for Adults

• There is no evidence-based psychological treatment suitable for all forms of ARFID at this time, and studies in adults are lacking. 2
• For anxiety disorders in general (not ARFID-specific), SSRIs like escitalopram and sertraline are recommended as first-line agents for social anxiety disorder and generalized anxiety disorder. 4

When to Consider Pharmacotherapy

All patients with ARFID should ideally be screened for comorbid anxiety disorders, as there is significant overlap/comorbidity between disorders of gut-brain interaction and ARFID. 1

Adjunctive Medication Options

If pharmacotherapy is considered alongside CBT:

• SSRIs (escitalopram 10-20mg or sertraline 50-200mg) are suggested for comorbid social anxiety disorder or generalized anxiety disorder. 1, 4
• Mirtazapine can be helpful in increasing food tolerance and body weight in patients with significant weight loss, and it promotes appetite, decreases nausea, and improves gastric emptying. 1, 6
• Low-dose olanzapine (mean final dose 2.8mg/day) as adjunctive treatment may facilitate eating, weight gain, and reduction of anxious, depressive, and cognitive symptoms in ARFID patients, though evidence is limited to case series. 7

Treatment Algorithm for Adult ARFID with Anxiety

1. Initiate CBT-AR as primary treatment (20-30 sessions of graded exposure therapy). 1, 2
2. Screen for and diagnose specific comorbid anxiety disorders (social anxiety disorder, generalized anxiety disorder, panic disorder). 1
3. If comorbid anxiety disorder is present and severe, consider adding an SSRI (escitalopram 10-20mg or sertraline 50-200mg) to CBT-AR. 1, 4
4. If significant weight loss or malnutrition is present, consider mirtazapine (starting 7.5-15mg at bedtime) as it addresses both anxiety and promotes weight gain. 1, 6
5. Involve a multidisciplinary team including dietitian, psychological specialists, and eating disorder specialists for severe or refractory cases. 1

Critical Pitfalls to Avoid

• Never prescribe parenteral nutrition for ARFID except in life-threatening malnutrition extremis as a temporary bridge to appropriate therapies, as it reinforces restriction rather than addressing the underlying disorder. 1
• Avoid overly restrictive diets (gluten-free, low-FODMAP) as elimination diets can increase the risk of developing or worsening ARFID. 1
• Do not use medication as monotherapy without addressing the behavioral and psychological components through CBT-AR, as the optimal approach is graded exposure in a CBT setting. 1
• If prescribing SSRIs, taper gradually over 10-14 days when discontinuing to avoid withdrawal syndrome (dizziness, paresthesias, anxiety, irritability). 4
• Monitor for treatment-emergent suicidal ideation, particularly during the first months of SSRI therapy and following dose adjustments. 4

Monitoring and Follow-Up

• Assess treatment response at 4 weeks and 8 weeks using standardized anxiety rating scales and measures of eating-related psychosocial impairment. 4, 3
• SSRI response follows a logarithmic pattern: statistically significant improvement by week 2, clinically significant improvement by week 6, maximal benefit by week 12. 4
• Monitor weight, nutritional intake, and functional outcomes throughout CBT-AR treatment. 3