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Anxiety Disorders, PTSD, and OCD for MRCP Part 1

TL;DR:

 Anxiety disorders, PTSD, and OCD are consistently tested in MRCP Part 1, mainly through diagnosis, timelines, and first-line management. Focus on distinguishing anxiety subtypes, recognising PTSD duration criteria, and knowing evidence-based treatments (CBT and SSRIs). Most marks are gained by avoiding common diagnostic and pharmacological traps.


Why this topic matters in MRCP Part 1

Psychiatry contributes a reliable number of single best answer questions in MRCP Part 1. Anxiety disorders, post-traumatic stress disorder (PTSD), and obsessive–compulsive disorder (OCD) are favourites because they test core clinical reasoning rather than specialist psychiatry knowledge. Examiners expect clarity on definitions, symptom duration, and first-line management aligned with UK guidelines.


Scope of what you need to know

For MRCP Part 1, you are expected to:

  • Identify common anxiety disorders using ICD-style clinical criteria

  • Distinguish PTSD from acute stress disorder using timelines

  • Recognise OCD and separate it from psychosis or personality traits

  • Select correct first-line treatments

  • Avoid inappropriate drug choices commonly used as distractors


High-yield facts you should memorise

  1. Generalised anxiety disorder (GAD) requires excessive worry on most days for ≥6 months.

  2. Panic disorder involves recurrent, unexpected panic attacks with fear of recurrence.

  3. Phobias cause anxiety only in response to a specific trigger.

  4. PTSD occurs after exposure to trauma with symptoms lasting >1 month.

  5. Symptoms <1 month after trauma indicate acute stress disorder, not PTSD.

  6. PTSD symptom clusters include re-experiencing, avoidance, hyperarousal, and negative mood/cognition.

  7. OCD obsessions are ego-dystonic (recognised as irrational).

  8. Insight is usually preserved in OCD, helping differentiate it from psychosis.

  9. CBT and SSRIs are first-line for most anxiety disorders and OCD.

  10. Benzodiazepines are not first-line due to dependence and cognitive impairment.

  11. SSRIs may initially worsen anxiety—a classic exam stem detail.

  12. Clomipramine is effective in OCD but limited by anticholinergic side effects.


Five most tested subtopics

1. GAD vs depressive disorder

Both share fatigue and poor concentration, but GAD centres on excessive worry, not persistent low mood or anhedonia.

2. Panic disorder vs cardiac disease

Sudden chest pain, palpitations, and dyspnoea often mimic myocardial infarction. Normal ECGs and recurrent episodes suggest panic disorder.

3. PTSD timelines

  • <1 month: acute stress disorder

  • 1 month: PTSDThis distinction is tested repeatedly.

4. OCD vs psychosis

Obsessions are intrusive and unwanted. Delusions are fixed beliefs held with conviction.

5. Pharmacology basics

SSRIs are first-line. Tricyclics and antipsychotic augmentation are second-line only.


MRCP Part 1 psychiatry study setup with anxiety disorders, PTSD and OCD notes

Exam-friendly comparison table

Condition

Key feature

Minimum duration

First-line treatment

GAD

Excessive worry

≥6 months

CBT / SSRI

Panic disorder

Panic attacks

Variable

CBT / SSRI

PTSD

Trauma-related symptoms

>1 month

Trauma-focused CBT / SSRI

OCD

Obsessions ± compulsions

Chronic

CBT (ERP) / SSRI

Mini-case (typical MRCP style)

Question: A 29-year-old woman has recurrent intrusive thoughts of harming her baby. She finds them distressing and repeatedly checks locks and washes her hands to relieve anxiety. She recognises the thoughts as irrational. What is the most likely diagnosis?

Answer: Obsessive–compulsive disorder.

Explanation: Intrusive, ego-dystonic thoughts with anxiety-reducing compulsions and preserved insight are classic for OCD. Psychosis would involve fixed beliefs without insight.


Five common exam traps

  • Confusing acute stress disorder with PTSD

  • Choosing benzodiazepines as first-line therapy

  • Missing preserved insight in OCD

  • Attributing panic symptoms to cardiac disease without context

  • Forgetting initial SSRI anxiety exacerbation


Practical MRCP Part 1 study checklist

  • Memorise diagnostic durations

  • Learn first-line vs second-line treatments

  • Practise OCD vs psychosis differentiation

  • Revise PTSD symptom clusters

  • Do mixed psychiatry questions under timed conditions


Frequently Asked Questions

How often are anxiety disorders tested in MRCP Part 1?They appear regularly and are considered high-yield due to predictable patterns.

Is PTSD management tested in detail? No. Focus is on diagnosis, timelines, and first-line treatment rather than psychotherapy specifics.

Are benzodiazepines ever the correct answer? Rarely. They are usually included as distractors due to dependence risk.

Should DSM-5 criteria be memorised? No. Broad ICD-style clinical features are sufficient.


Ready to start?

Consolidate this topic with timed practice from our Free MRCP MCQs and reinforce concepts using the psychiatry section in Psychiatry video lectures. Return to the MRCP Part 1 overview hub to integrate this with your wider revision plan.


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