GC171 Stress-related Disorders And Obsessive-compulsive Disorder (post-traumatic Stress Disorder Adjustment Disorder, Acute Stress Disorder): Rev
Stress-related disorders (including PTSD, acute stress disorder, and adjustment disorder) and obsessive-compulsive disorder are conditions characterized by maladaptive psychological and physiological responses to traumatic events, significant life stressors, or intrusive repetitive thoughts and compulsive behaviors that cause marked functional impairment.
Anxiety, Stressor-Related, and Obsessive-Compulsive Disorders
This lecture (GC 171) is a comprehensive survey covering three clusters of disorders that were historically lumped under "neuroses" but are now classified separately in both DSM-5 and ICD-11 [1][2]:
- Anxiety Disorders — Phobic disorders (agoraphobia, social phobia, specific phobia), Panic disorder, GAD, Mixed anxiety-depressive disorder
- Trauma- and Stressor-Related Disorders — Acute stress reaction/disorder, PTSD, Adjustment disorders
- Obsessive-Compulsive and Related Disorders — OCD, Body dysmorphic disorder, Hoarding disorder, Trichotillomania, Excoriation disorder
The lecture covers epidemiology, neural circuitry, diagnostic criteria, screening questions, comorbidity, and general treatment approaches (pharmacotherapy + psychotherapy). This maps directly onto the clinical encounter: recognizing pathological anxiety, differentiating between the disorders, and initiating evidence-based management.
Learning Objectives [1]:
- List prevalence of anxiety and related disorders
- Identify comorbid psychiatric diagnoses
- Perform a quick screen for anxiety and related disorders
- Apply general pharmacologic approaches to treatment
How this fits into exams: HKUMed Fourth Summative exams frequently test the ability to distinguish between these diagnoses (e.g., GAD vs panic disorder vs PTSD vs adjustment disorder vs OCD) via EMQ stems and MCQs. They also test pharmacology (which drug class for which disorder) and screening questions. The 2020, 2022, 2023, and 2024 papers all had questions directly from this lecture cluster.
Core Concepts and Mechanisms
Normal anxiety is adaptive to stress. It is an inborn response to threat that can result in cognitive and somatic symptoms. [1]
Pathologic anxiety is anxiety that is excessive and impairs function. [1]
Why this distinction matters: Every human experiences anxiety — it is evolutionarily advantageous (the "fight-or-flight" response keeps us alive). The line between normal and pathological is crossed when anxiety becomes excessive relative to the stimulus, persistent beyond the situation, and functionally impairing (can't work, can't socialize, can't leave the house). This is the key threshold examiners test: does this patient have a disorder or a normal reaction?
Amygdala — involved with processing of emotionally salient stimuli [1]
Medial prefrontal cortex (includes the anterior cingulate cortex, the subcallosal cortex, and the medial frontal gyrus) — involved in modulation of affect [1]
Hippocampus — involved in memory encoding and retrieval [1]
From first principles:
- The amygdala is the brain's "alarm system." It tags incoming sensory information with emotional significance. In anxiety disorders, the amygdala is hyperactive — it over-fires, tagging benign stimuli as threatening.
- The medial prefrontal cortex (mPFC) normally acts as a "brake" on the amygdala. It modulates and dampens the fear response ("top-down regulation"). In anxiety and PTSD, this region is hypoactive — the brake fails.
- The hippocampus contextualizes memories — it tells you where and when something happened. In PTSD, hippocampal dysfunction means traumatic memories are poorly contextualized, so they intrude into consciousness as if happening now (flashbacks).
This triad explains the core neuroimaging findings in PTSD and anxiety: hyperactive amygdala + hypoactive mPFC + dysfunctional hippocampus = poorly regulated fear response with intrusive, decontextualized memories.
Part 1: Anxiety Disorders
Types of Anxiety Disorders [1]:
- Phobic anxiety disorders: Agoraphobia, Social phobias, Specific phobias
- Other anxiety disorders: Panic disorder, GAD, Mixed anxiety and depressive disorder
DSM-5 vs ICD Classification
In DSM-5, anxiety disorders, OCD-related disorders, and trauma/stressor-related disorders are in separate chapters. In ICD-10, they were grouped under "Neurotic, stress-related and somatoform disorders" (F40-F48). ICD-11 also separates them. Know both frameworks for exams [2].
Anxiety disorders: [1]
- Often have an early onset — teens or early twenties
- Show 2:1 female predominance
- Have a waxing and waning course over lifetime
- Similar to major depression and chronic diseases such as diabetes in functional impairment and decreased quality of life
Why this matters clinically: Anxiety disorders are NOT trivial. Their functional impairment is comparable to diabetes. They start young, meaning decades of disability if untreated. The female predominance (2:1) means you should have a lower threshold for screening in women, though men are by no means immune.
The prevalence data from the lecture's referenced table [1]:
| Disorder | Lifetime Prevalence (approx.) |
|---|---|
| Specific phobia | 7-11% |
| Social phobia | 3-13% |
| Agoraphobia | 1-5% |
| GAD | 4-7% |
| Panic disorder | 1-4% |
| PTSD | 7-9% |
| OCD | 2% |
Marked and consistently manifest fear in or avoidance of at least two of the following situations: crowds; public places; travelling alone; travelling away from home. [1]
Why "at least two": This threshold distinguishes agoraphobia from a specific phobia. A person afraid only of elevators has a specific phobia. Agoraphobia is broader — it's about escape difficulty and helplessness in open/crowded/unfamiliar environments.
Symptom clusters required (at least 2 symptoms present together, at least one from autonomic arousal) [1]:
| Category | Symptoms |
|---|---|
| Autonomic arousal (≥1 required) | Palpitations, sweating, trembling/shaking, dry mouth |
| Chest and abdomen | Difficulty breathing, choking feeling, chest pain, nausea/abdominal distress |
| Brain and mind | Dizziness/faintness, derealization/depersonalization, fear of losing control/going crazy, fear of dying |
| General | Hot flushes/cold chills, numbness/tingling |
Significant emotional distress due to the avoidance or the anxiety symptoms, and a recognition that these are excessive or unreasonable. [1]
Symptoms are restricted to or predominate in the feared situations or when thinking about them. [1]
Key point: The patient must recognize the symptoms are excessive. This preserved insight distinguishes phobic disorders from psychotic disorders where the patient truly believes the feared scenario is real.
Recurrent panic attacks, that are not consistently associated with a specific situation or object, and often occurring spontaneously (i.e. the episodes are unpredictable). [1]
The panic attacks are not associated with marked exertion or with exposure to dangerous or life-threatening situations. [1]
Defining a panic attack [1]:
- Discrete episode of intense fear or discomfort
- Starts abruptly
- Reaches a crescendo within a few minutes and lasts at least some minutes
- At least four symptoms from the same four categories (autonomic, chest/abdomen, brain/mind, general)
Exam Trap: Panic Disorder vs Agoraphobia with Panic
From the 2022 MCQ: "Characteristic features of a certain disorder include unpredictable attacks, signs reminiscent of myocardial infarction, and anticipatory anxiety, in the absence of severe stress." Answer: D. Panic disorder [5]
A period of at least six months with prominent tension, worry, and feelings of apprehension, about every-day events and problems. [1]
At least four symptoms must be present from the four categories. [1]
Why six months? This duration criterion separates GAD from transient worry. Everyone worries sometimes. GAD is the disorder of chronic, pervasive, free-floating worry — the patient worries about everything (health, money, family, work) and cannot control the worry. The "free-floating" nature means it is NOT attached to a specific situation (unlike phobias) or a specific trauma (unlike PTSD).
From the 2024 MCQ [6]: A 27-year-old male with 3 months of constant worry about finances, girlfriend, parents' health, trouble sleeping, restlessness, GAD-7 score of 10 → Moderate Anxiety (GAD-7 scoring: 5-9 mild, 10-14 moderate, ≥15 severe).
Fear of social situations where the person may be scrutinized, judged, or embarrassed. The key differentiator from normal shyness: it must be excessive, severe, and cause significant impairment [4].
Fear restricted to a specific object or situation (animals, heights, blood, etc.). The feared object is circumscribed and avoidable, so these patients often function well unless the phobia impacts daily life (e.g., needle phobia preventing medical care).
Part 2: Trauma- and Stressor-Related Disorders
Trauma- and Stressor-Related Disorders: Acute Stress Reaction, Posttraumatic Stress Disorder, Adjustment Disorders [1]
| Feature | Psychosocial Stress | Traumatic Stress |
|---|---|---|
| Nature | Any life event placing strain on coping | Outside range of normal human experience |
| Severity | Subjective; depends on individual coping | Objectively severe; would be traumatic for most people |
| Physical integrity | Not necessarily threatened | Person/loved one's physical or psychological integrity seriously threatened |
| Associated diagnoses | Normal reaction, Adjustment disorder | Acute stress reaction, Acute stress disorder, PTSD |
[Source: Ryan Ho Psychiatry notes [4]]
Post-Traumatic Stress Disorder (PTSD)
Exposure to actual or threatened death, serious injury, or sexual violence in one or more of the following ways: [1]
- Direct experiencing of traumatic event(s)
- Witnessed in person the events as it occurred to others
- Learning that the traumatic events occurred to person close to them
- Experiencing repeated or extreme exposure to aversive details of trauma (e.g., first responders repeatedly collecting human remains)
Why these specific routes matter: PTSD is NOT limited to direct victims. Witnesses, bereaved relatives, and first responders can all develop PTSD. The "learning" criterion is important — a mother told her child died in an accident can develop PTSD even though she wasn't there. The "repeated exposure" criterion captures occupational trauma (paramedics, police).
Presence of 1 or more after the event: [1]
- Recurrent, involuntary and intrusive memories of event
- Recurrent trauma-related nightmares
- Dissociative reactions (flashbacks — acting/feeling as if the event is recurring)
- Intense psychological distress at cue exposure
- Marked physiological reactivity at cue exposure (e.g., heart racing when hearing a car backfire after a shooting)
From first principles: Intrusion symptoms arise because the traumatic memory was encoded by a hyperactive amygdala but poorly contextualized by a dysfunctional hippocampus. The memory is stored in a "raw," emotionally charged form that intrudes into consciousness triggered by cues (sounds, smells, images). The person literally re-experiences the terror because the brain hasn't properly filed the memory as "past event."
Persistent avoidance by 1 or both: [1]
- Avoidance of distressing memories, thoughts, or feelings of the event(s)
- Avoidance of external reminders (people, places, activities, situations)
Why avoidance develops: This is a learned behavioral response — avoiding triggers prevents the distressing re-experiencing. But avoidance paradoxically maintains the disorder because it prevents extinction of the conditioned fear response. This is why CBT for PTSD involves graded exposure — you have to break the avoidance cycle.
Negative alterations in cognitions and mood associated with the traumatic event(s) as evidenced by 2 or more of the following: [1]
- Inability to remember an important aspect of the traumatic event(s) (dissociative amnesia)
- Persistent distorted cognitions about cause or consequence of event that lead to blame of self or others ("It was my fault")
- Persistent negative emotional state (fear, horror, anger, guilt, shame)
- Marked diminished interest in activities
- Feeling detached from others
- Persistent inability to experience positive emotions (emotional numbing)
Why this cluster is distinct from depression: While diminished interest and emotional numbing overlap with depression, in PTSD these are specifically linked to the trauma and are accompanied by the other PTSD symptom clusters. The self-blame/distorted cognitions are particularly PTSD-specific — the patient may believe they caused the event or that the world is fundamentally unsafe.
Marked alterations in arousal and reactivity with 2 or more of: [1]
- Irritable behavior and angry outbursts
- Reckless or self-destructive behavior
- Hypervigilance
- Exaggerated startle response
- Problems with concentration
- Sleep disturbance
From first principles: The arousal cluster reflects a chronically activated sympathetic nervous system. The brain is stuck in "threat mode." This explains the hypervigilance (constantly scanning for danger), exaggerated startle (primed alarm response), and sleep disturbance (the brain won't let its guard down).
Duration of disturbance is more than one month AND causes significant impairment in function [1]
Specifiers: [1]
- With dissociative symptoms (derealization or depersonalization)
- With delayed expression (don't meet criteria until > 6 months after event)
Critical Time Distinctions
This is one of the most commonly tested differentiators:
- Acute stress reaction (ICD-10): Starts within 1 hour, resolves within 48 hours, gone within days
- Acute stress disorder (DSM-5): 3 days to 1 month after trauma
- PTSD: > 1 month after trauma
- PTSD with delayed expression: Full criteria not met until > 6 months
If the question says symptoms have lasted 2 weeks after a trauma → Acute Stress Disorder (not PTSD yet!). If symptoms persist > 1 month → now it's PTSD [1][4].
7-9% of general population [1] 60-80% of trauma victims [1] 30% of combat veterans [1] 50-80% of sexual assault victims [1] Increased risk in women, younger people [1] Risk increases with "dose" of trauma, lack of social support, pre-existing psychiatric disorder [1]
The "dose-response" relationship is key: more severe, prolonged, and interpersonal trauma (especially sexual assault) carries higher PTSD risk. Social support is protective — isolated individuals are more vulnerable. Pre-existing psychiatric disorder (especially depression, prior anxiety) lowers the threshold.
Depression; Other anxiety disorders; Substance use disorders; Somatization; Dissociative disorders [1]
Why comorbidity is the rule, not the exception: PTSD rarely exists in isolation. Depression develops because of persistent negative mood and anhedonia. Substance use develops as self-medication (alcohol to dampen hyperarousal, opioids for emotional numbing). Somatization occurs because the body is chronically hyperaroused. Always screen for these.
Conditioned fear; Genetic/familial vulnerability; Stress-induced release — Norepinephrine, CRF, Cortisol; Autonomic arousal immediately after trauma predicts PTSD [1]
Breaking this down:
- Conditioned fear: Classical conditioning — the traumatic event (unconditioned stimulus) becomes associated with neutral cues present during the trauma (conditioned stimuli). These cues later trigger the fear response.
- Genetic vulnerability: ~1/3 of variance in PTSD susceptibility is heritable [4]
- Neuroendocrine: Norepinephrine surges strengthen emotional memory encoding (amygdala-mediated). CRF (corticotropin-releasing factor) activates the HPA axis. Interestingly, PTSD patients often have lower cortisol levels (paradoxical — possibly due to HPA axis exhaustion or enhanced negative feedback via upregulated glucocorticoid receptors) [4]
- Autonomic arousal immediately after trauma: This is both a predictor and a treatment target — high HR at the emergency department after trauma predicts later PTSD, which is why beta-blockers have been studied (though evidence is mixed).
Increased amygdala activation is seen in PTSD pts compared to controls [1]
Hypoactivation of the medial prefrontal cortex including the orbitofrontal cortex and anterior cingulate cortex (area implicated in affect regulation) [1]
Summary: Overactive alarm (amygdala) + broken brake (mPFC) = unregulated fear.
Debriefing immediately following trauma is NOT necessarily effective [1]
High Yield — Debriefing Myth
This is a classic exam point. Psychological debriefing (forcing everyone to talk about what happened immediately after a trauma) was once standard practice but evidence shows it does NOT prevent PTSD and may even worsen outcomes. Do NOT recommend routine debriefing [1].
Cognitive-behavioral therapy [1]
Trauma-focused CBT is first-line. It includes:
- Cognitive restructuring: Challenging distorted beliefs about the trauma ("It was all my fault")
- Prolonged exposure: Graded, systematic re-exposure to trauma memories and avoided situations to extinguish the conditioned fear response
- Psychoeducation: Normalizing symptoms, explaining the disorder
Eye Movement Desensitization and Reprocessing (EMDR) [1]
EMDR involves the patient imagining a trauma scene while tracking the therapist's finger movements across their visual field. The bilateral stimulation is thought to facilitate reprocessing of traumatic memories. Evidence supports efficacy comparable to trauma-focused CBT [4].
Medications — antidepressants, beta-blockers, mood stabilizers, clonidine, prazosin, gabapentin [1]
| Medication | Role in PTSD |
|---|---|
| SSRIs/SNRIs | First-line pharmacotherapy; reduce all symptom clusters [1][4] |
| Prazosin (α1-blocker) | Specifically targets PTSD-related nightmares and sleep disturbance [1][4] |
| Clonidine (α2-agonist) | Reduces sympathetic hyperarousal |
| Beta-blockers | May reduce autonomic hyperarousal; studied for prevention (evidence mixed) |
| Mood stabilizers | Adjunctive for irritability/emotional dysregulation |
| Gabapentin | Adjunctive for anxiety and sleep |
| SGAs (antipsychotics) | Augmentation for treatment-resistant cases [4] |
| Benzodiazepines | May help acute anxiety/hyperarousal but risk of dependence; use with caution [4] |
Similar exposure as in PTSD [1]
Presence of > 9 of 5 categories of intrusion, negative mood, dissociation, avoidance, and arousal related to the trauma. [1]
Duration of disturbance is 3 days to 1 month after trauma [1]
Causes significant impairment [1]
Key discriminator from PTSD: Time. Same symptom clusters, but if it's been < 1 month since the trauma, it's Acute Stress Disorder. If symptoms persist beyond 1 month, reclassify as PTSD. Acute stress disorder also places more emphasis on dissociative symptoms (feeling numb, detached, derealized, depersonalized, having dissociative amnesia).
| Feature | Acute Stress Reaction (ICD-10) | Acute Stress Disorder (DSM-5) | PTSD |
|---|---|---|---|
| Onset | Within 1 hour of stressor | During/shortly after stressor | Anytime, usually within 6 months |
| Duration | Hours to ~2-3 days | 3 days to 1 month | > 1 month |
| Key emphasis | Transient, resolves spontaneously | Dissociative symptoms prominent; ≥9 symptoms from 5 categories | 4 symptom clusters (intrusion, avoidance, cognition/mood, arousal) |
| Significance | Normal short-lived response | Predicts later PTSD | Chronic condition needing treatment |
While not given a dedicated slide, adjustment disorder is listed under trauma- and stressor-related disorders [1] and is an important differential:
- Stressor: Any psychosocial stressor (NOT necessarily traumatic) — job loss, divorce, moving, illness
- Symptoms: Anxiety and/or depressive symptoms that are clearly arising from the stressor and out of proportion to the stressor, but do NOT meet criteria for a full mood or anxiety disorder
- Onset: Within 3 months of the stressor (DSM-5) / within 1 month (ICD-10)
- Duration: Resolves within 6 months after the stressor or its consequences have ended
- Subtypes: With depressed mood, with anxiety, with mixed anxiety and depressed mood, with disturbance of conduct, with mixed disturbance of emotions and conduct [4]
Adjustment Disorder = Diagnosis of Exclusion
Adjustment disorder is diagnosed only when symptoms don't meet criteria for any other specific disorder (e.g., MDD, GAD, PTSD). If the stressor was traumatic AND the patient has intrusion/avoidance/arousal symptoms → consider PTSD or acute stress disorder, not adjustment disorder [4].
Part 3: Obsessive-Compulsive and Related Disorders
OCD and Related Disorders: [1]
- Obsessive-Compulsive Disorder
- Body Dysmorphic Disorder
- Hoarding Disorder
- Trichotillomania
- Excoriation Disorder
Why these are grouped together: They all share a core feature of repetitive thoughts and/or behaviors that the person feels driven to perform, causing distress or impairment. They share overlapping neurobiology (frontal-striatal circuitry) and treatment response (serotonergic medications, CBT).
Body Dysmorphic Disorder — 2.4% [1]
- 9-15% of dermatologic patients
- 7% of cosmetic surgery patients
- 10% of patients presenting for oral or maxillofacial surgery
Hoarding Disorder — est. 2-6%, F < M [1]
Trichotillomania — 1-2%, F:M 10:1 [1]
Excoriation Disorder — 1.4%, F > M [1]
Clinical Pearl — BDD in Surgical Settings
Body dysmorphic disorder is massively overrepresented in dermatology and cosmetic surgery clinics. These patients seek procedures for perceived defects that are not observable or appear slight to others. Surgery does NOT relieve their distress and often worsens it. Recognize this pattern to avoid futile procedures [1].
Obsessive-Compulsive Disorder (OCD)
Obsessions defined by: recurrent and persistent thoughts, impulses or images that are intrusive and unwanted that cause marked anxiety or distress. [1]
The person attempts to ignore or suppress such thoughts, urges or images, or to neutralize them with some other thought or action (i.e. compulsion). [1]
Key features: Obsessions are ego-dystonic — the patient recognizes them as their own thoughts but finds them distressing, unwanted, and alien to their personality. A patient with violent obsessional thoughts is horrified by them, not entertained. This distinguishes obsessions from delusions (which are held with conviction) and from normal worries (which are about realistic concerns).
Compulsions defined by: Repetitive behaviors or mental acts that the person feels driven to perform in response to an obsession or according to rigidly applied rules. [1]
The behaviors or acts are aimed at reducing distress or preventing some dreaded situation however these acts or behaviors are not connected in a realistic way with what they are designed to neutralize or prevent. [1]
Why "not connected in a realistic way" matters: Washing hands after touching something dirty is normal. Washing hands 50 times because you fear contaminating your family with an unspecified toxin, knowing this is irrational but being unable to stop, is a compulsion. The disconnect between the feared consequence and the behavior is pathognomonic.
Common obsession-compulsion pairings:
| Obsession Theme | Common Compulsion |
|---|---|
| Contamination | Washing, cleaning |
| Doubt ("Did I lock the door?") | Checking |
| Need for symmetry/order | Arranging, counting |
| Forbidden thoughts (aggression, sexual, religious) | Mental rituals, reassurance seeking |
| Fear of harm to self/others | Checking, avoidance |
The obsessions or compulsions cause marked distress, take > 1 hour/day or cause clinically significant distress or impairment in function [1]
Specify if: [1]
- With good or fair insight — recognizes beliefs are definitely or most likely not true
- With poor insight — thinks are probably true
- With absent insight — is completely convinced the OCD beliefs are true
- Tic-related
Why insight specifiers matter: Most OCD patients have good insight ("I know this is ridiculous, but I can't stop"). However, some patients have poor or absent insight, making them difficult to distinguish from psychotic disorders. Absent insight OCD can be mistaken for delusional disorder. The tic-related specifier is important because OCD with comorbid tics may respond differently to treatment (may need augmentation with antipsychotics).
> 70% have lifetime dx of an anxiety disorder (PD, SAD, GAD, phobia) [1] > 60% have lifetime dx of a mood disorder, MDD being the most common [1] Up to 30% have a lifetime Tic disorder [1] 12% of persons with schizophrenia/schizoaffective disorder [1]
Key clinical implication: Always screen for depression in OCD patients. The relentless nature of obsessions and the time consumed by compulsions makes OCD patients profoundly miserable. Suicide risk exists.
Genetics; Serotonergic dysfunction; Cortico-striato-thalamo-cortical loop; Autoimmune — PANDAS (Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infection) [1]
From first principles:
- Serotonergic dysfunction: OCD responds specifically to serotonergic antidepressants (SSRIs, clomipramine) but NOT to noradrenergic antidepressants, implicating the serotonin system. Higher doses are often needed than for depression.
- Cortico-striato-thalamo-cortical (CSTC) loop: This circuit links the cortex → striatum (caudate) → thalamus → back to cortex. Normally, it helps filter and gate thoughts and behaviors. In OCD, this loop is hyperactive — the "filter" is broken, so intrusive thoughts keep cycling back to consciousness and compulsive behaviors keep being triggered.
- PANDAS: Post-streptococcal autoimmune antibodies cross-react with basal ganglia neurons → sudden-onset OCD/tics in children after strep throat. This is rare but important to recognize because treatment may include immunotherapy.
Increased activity in the right caudate is found in pts with OCD and Cognitive behavior therapy reduces resting state glucose metabolism or blood flow in the right caudate in treatment responders. [1]
Similar results have been obtained with drug treatment. [1]
Why this is remarkable: Both CBT and medication normalize the same brain abnormality (right caudate hyperactivity). This demonstrates that psychotherapy produces measurable biological changes in the brain — a powerful teaching point about the mind-brain relationship.
40-60% treatment response [1] Serotonergic antidepressants [1] Behavior therapy [1] Adjunctive antipsychotics [1] Psychosurgery (rarely) [1]
Treatment details:
| Modality | Details |
|---|---|
| SSRIs | First-line pharmacotherapy. Often need higher doses than for depression (e.g., fluoxetine 40-80mg vs 20mg for depression). May take 8-12 weeks for response (longer than depression). |
| Clomipramine | Tricyclic antidepressant with potent serotonergic action. Effective but more side effects (anticholinergic, cardiac). |
| Exposure and Response Prevention (ERP) | Gold-standard behavioral therapy. Patient is exposed to the feared stimulus (exposure) and prevented from performing the compulsion (response prevention). This breaks the obsession-compulsion cycle and allows extinction of the anxiety response. |
| Adjunct antipsychotics | Low-dose SGAs (risperidone, aripiprazole) added to SSRIs for treatment-resistant cases, especially with comorbid tics. |
| Psychosurgery | Anterior cingulotomy or capsulotomy for extremely refractory cases. Last resort. |
Exam Point — OCD Treatment Specifically Requires Serotonergic Agents
Do NOT choose noradrenergic antidepressants (e.g., desipramine, reboxetine) for OCD. OCD is uniquely responsive to serotonergic drugs. This is different from depression where both serotonergic and noradrenergic agents work. This is a common MCQ discriminator [1].
Screening Questions: [1]
- "When you are in a situation where people can observe you, do you feel nervous and worry that they will judge you?" → Social Anxiety Disorder
- "Do you consider yourself a worrier?" → GAD
- "Have you ever experienced a panic attack?" → Panic Disorder
- "Have you ever had anything happen that still haunts you?" → PTSD
- "Do you get thoughts stuck in your head that really bother you, or need to do things over and over like washing your hands, checking things, or counting?" → OCD
High Yield — Memorize These 5 Screening Questions
These one-liners are extremely practical for clinical exams and OSCEs. Each question targets a specific disorder. They are sensitive screening tools — a "yes" warrants further assessment; a "no" makes the diagnosis much less likely. The lecture specifically highlighted these for quick clinical screening [1].
General Treatment Approaches (All Anxiety and Related Disorders)
General treatment approaches: [1]
- Pharmacotherapy: Antidepressants, Anxiolytics, Antipsychotics, Mood stabilizers
- Psychotherapy: Cognitive Behavior Therapy (CBT), Mindfulness-based Therapy
| Drug Class | Disorders | Key Points |
|---|---|---|
| SSRIs | GAD, Panic, Social phobia, PTSD, OCD | First-line for almost all anxiety/related disorders. Takes 2-4 weeks for anxiolytic effect (8-12 weeks for OCD). |
| SNRIs (venlafaxine, duloxetine) | GAD, Social phobia, PTSD | Alternative first-line, especially if comorbid pain. |
| Clomipramine (TCA) | OCD | Potent serotonergic TCA; more side effects but very effective for OCD. |
| Benzodiazepines | Short-term relief of severe anxiety, Panic | Rapid onset but risk of tolerance, dependence, withdrawal. NOT for long-term use. NOT first-line for PTSD [3]. |
| Buspirone | GAD | 5-HT1A partial agonist; slow onset, no dependence risk. |
| Beta-blockers (propranolol) | Performance anxiety, PTSD hyperarousal | Reduce peripheral autonomic symptoms (tremor, tachycardia). |
| Prazosin | PTSD nightmares | Alpha-1 blocker; reduces trauma-related nightmares. |
| Antipsychotics (SGAs) | Augmentation for OCD, treatment-resistant PTSD | Low-dose adjunctive use. |
| Mood stabilizers | PTSD irritability/dysregulation | Adjunctive. |
| Gabapentin/pregabalin | GAD, PTSD (adjunctive) | May help with anxiety and sleep. |
| Therapy | Mechanism | Best For |
|---|---|---|
| CBT | Identifies and modifies maladaptive thoughts (cognitive) and behaviors (behavioral); includes exposure therapy | All anxiety disorders, PTSD, OCD |
| ERP (Exposure and Response Prevention) | Subset of CBT; exposure to feared stimulus + prevention of compulsive response | OCD specifically |
| Trauma-focused CBT | Prolonged exposure + cognitive restructuring of trauma-related beliefs | PTSD |
| EMDR | Bilateral stimulation during trauma recall; facilitates memory reprocessing | PTSD |
| Mindfulness-based therapy | Teaches present-moment awareness; reduces rumination and anxiety | GAD, as adjunct in many disorders |
| Feature | GAD | Panic Disorder | Agoraphobia | Social Phobia | Specific Phobia | PTSD | OCD | Adjustment Disorder |
|---|---|---|---|---|---|---|---|---|
| Core feature | Chronic free-floating worry | Recurrent unpredictable panic attacks | Fear of crowds/public/travel | Fear of social scrutiny | Fear of specific object/situation | Re-experiencing + avoidance + arousal after trauma | Intrusive thoughts + compulsions | Emotional/behavioral response to identifiable stressor |
| Duration | ≥6 months | Recurrent | Persistent | Persistent | Persistent | > 1 month | Persistent | ≤6 months after stressor ends |
| Trigger | Non-specific ("everything") | Spontaneous, unpredictable | Specific situations | Social situations | Specific stimulus | Trauma cues | Obsessional triggers | Identifiable stressor |
| Insight | Good | Good | Good (recognizes excessive) | Good | Good | Variable | Variable (good to absent) | Good |
| Gender ratio | 2:1 F:M | 2:1 F:M | 2:1 F:M | 2:1 F:M | 2:1 F:M | F > M | 1:1 | — |
| Key treatment | SSRIs, CBT | SSRIs, CBT | SSRIs, CBT with exposure | SSRIs, CBT | Graded exposure | Trauma-focused CBT, EMDR, SSRIs, prazosin | SSRIs (high dose), ERP | Supportive therapy |
From the 2023 MCQ [7]:
"It is not uncommon to have difficulties during interview with patients with anxiety disorder. Which of the following techniques would have a negative impact during interviewing anxious patients?"
A. Address the anxious feeling
B. Ask specific questions
C. Clarification and explanation
D. Give a diagnostic label ✓
Rationale: Giving a premature diagnostic label can increase anxiety, create stigma, and shut down communication. Instead, address the feeling, ask specific questions to understand symptoms, and provide clarification. This is a tested communication skill point [7].
Past Paper Questions
Common stem: For each patient presenting with the respective symptom, select the MOST LIKELY diagnosis.
Options: A. Adjustment disorder, B. Bipolar disorder, C. Eating disorder, D. GAD, E. MDD, F. OCD, G. Panic disorder, H. PTSD, I. Substance use disorder, J. Undifferentiated psychological distress
- Q23: "Constant worrying even when there is no specific threat." → D. GAD (free-floating, persistent worry about everyday things without specific threat = hallmark of GAD)
- Q24: "Difficulty staying asleep, and in particular, waking too early and unable to get back to sleep." → E. MDD (early morning awakening is a biological/endogenous feature of depression)
- Q25: "Recurrent episodes of feeling short of breath as though one cannot get enough air in." → G. Panic disorder (recurrent episodes of dyspnea with fear = panic attacks)
- Q26: "Loss of pleasure in things that are usually enjoyable." → E. MDD (anhedonia is the cardinal feature of depression)
- Q27: "Constant need to check that the stove is switched off and doors are locked." → F. OCD (checking compulsion driven by doubt obsession)
Discriminators: Q23 — GAD vs Adjustment disorder: GAD has no specific identifiable stressor, adjustment disorder does. Q27 — OCD vs GAD: OCD has specific ritualistic behaviors (checking), GAD has generalized worry without rituals.
"Characteristic features of a certain disorder include unpredictable attacks, signs reminiscent of myocardial infarction, and anticipatory anxiety, in the absence of severe stress."
→ D. Panic disorder
Rationale: "Unpredictable attacks" = not situationally bound = panic disorder (not agoraphobia). "Signs reminiscent of MI" = chest pain, palpitations, dyspnea. "Anticipatory anxiety" = fear of next attack. "Absence of severe stress" = not PTSD/acute stress.
Trap: Option A (Agoraphobic disorder) — agoraphobia involves panic IN specific situations (crowds, public places), not unpredictably.
"27-year-old male... worries about finances, girlfriend, parents' health, own health... trouble sleeping, can't control worries... restless... GAD-7 score is 10. What is the severity level?"
→ B. Moderate Anxiety
GAD-7 scoring: 0-4 minimal, 5-9 mild, 10-14 moderate, ≥15 severe.
"Which of the following techniques would have a negative impact during interviewing anxious patients?"
→ D. Give a diagnostic label
"Ms. Cheng, 25-year-old, low mood and anxious for 2 months, poor sleep and poor appetite... no psychosis..."
(a) Name one psychiatric classification system → DSM-5 or ICD-11 (or ICD-10) (b) List two reasons to classify mental disorders → Communication between clinicians; Guide treatment decisions; Research; Prognostication; Medicolegal purposes (c) Name two differential diagnoses → Adjustment disorder (with mixed anxiety and depressed mood), MDD (with anxious features), GAD, Mixed anxiety and depressive disorder
"Which of the following disorders is characterised by a persistent preoccupation of the possibility of having a serious physical disorder and persistent refusal to accept advice of doctors that there is no physical illness?"
→ C. Hypochondriacal disorder
Discriminator: This is NOT Body Dysmorphic Disorder (preoccupied with appearance defect, not illness). Not somatoform disorder (broader category). Not depressive disorder (although hypochondriacal concerns can occur in depression, the persistent refusal to accept reassurance is pathognomonic of hypochondriasis).
| Trap | How to Avoid |
|---|---|
| Confusing acute stress disorder with PTSD | Time: ASD = 3 days to 1 month; PTSD = > 1 month |
| Confusing adjustment disorder with PTSD | Stressor type: Adjustment = any stressor (non-traumatic OK); PTSD = traumatic event. Symptoms: Adjustment = non-specific anxiety/depression; PTSD = specific intrusion/avoidance/arousal |
| Confusing GAD with adjustment disorder | Stressor: Adjustment has identifiable stressor; GAD = free-floating worry without specific trigger |
| Confusing panic disorder with agoraphobia | Setting: Panic = unpredictable, spontaneous; Agoraphobia = situational (crowds, public, travel) |
| Choosing noradrenergic drugs for OCD | Only serotonergic agents work for OCD |
| Recommending debriefing for trauma prevention | Debriefing is NOT effective and may worsen outcomes |
| Forgetting duration criteria | GAD ≥6 months; ASD 3 days–1 month; PTSD > 1 month; Adjustment ≤6 months after stressor resolution |
| Thinking OCD patients enjoy their rituals | Compulsions are ego-dystonic — performed to reduce distress, not for pleasure |
| Assuming OCD always has good insight | OCD insight ranges from good to absent; absent insight mimics psychosis |
- CFB PSY02 [2]: DSM-5 classifies Anxiety disorders, OCD and related disorders, and Trauma/stressor-related disorders as separate chapters — this reclassification from DSM-IV (where they were grouped) is exam-relevant.
- GC 167 (Anxiety Disorders) [11]: Provides the broader anxiety disorders overview including the "Major Anxiety Related Disorders" map showing how panic, GAD, phobias, OCD, and PTSD relate to each other via the common pathway of psychological and somatic anxiety manifestations.
- AOS Psych [3]: Notes that exam MCQs often test medication management — "BZD and sleeping pills will NOT be used in long-term management; long-term management includes antidepressants, antipsychotics, mood stabilizers." Also notes common exam diagnoses include anxiety, PTSD, OCD, adjustment disorder.
- Ryan Ho Psychiatry [4]: Provides the detailed differential diagnosis table (PTSD vs adjustment disorder vs acute stress disorder vs TBI) and treatment algorithms that complement the lecture slides.
High Yield Summary
1. Anxiety vs pathological anxiety: Normal = adaptive; Pathological = excessive + impairs function.
2. Neural triad: Hyperactive amygdala + hypoactive mPFC + dysfunctional hippocampus → unregulated fear + intrusive decontextualized memories.
3. PTSD requires: (A) Traumatic exposure + (B) ≥1 intrusion symptom + (C) ≥1 avoidance symptom + (D) ≥2 negative cognition/mood changes + (E) ≥2 arousal symptoms + duration > 1 month + functional impairment.
4. Time discriminators: Acute stress reaction (hours–days) → Acute stress disorder (3 days–1 month) → PTSD ( > 1 month). Adjustment disorder ≤6 months after stressor resolution.
5. OCD: Ego-dystonic intrusive thoughts + ritualistic behaviors; F:M 1:1; serotonergic drugs ONLY (SSRIs, clomipramine); ERP is gold-standard psychotherapy; CSTC loop hyperactivity (right caudate); insight specifiers range from good to absent.
6. Debriefing after trauma is NOT effective — do not recommend routine psychological debriefing.
7. Prazosin specifically for PTSD nightmares; SSRIs first-line pharmacotherapy for PTSD and most anxiety disorders.
8. Screening questions (5 one-liners for SAD, GAD, Panic, PTSD, OCD) are high-yield for clinical exams.
9. Comorbidity is the rule: PTSD comorbid with depression, substance use, anxiety; OCD comorbid with anxiety ( > 70%), depression ( > 60%), tics (30%).
10. BDD is common in surgical settings (9-15% derm, 7% cosmetic surgery) — surgery does NOT help.
Active Recall - Lecture Notes
[1] Lecture slides: GC 171. Stress-related disorders and obsessive-compulsive disorder (Post-traumatic stress disorder adjustment disorder, acute stress disorder)_rev.pdf (slides 1-44) [2] Lecture slides: CFB (PSY02) Classification and Diagnosis of Psychiatric Illness.pdf (p4, p29, p53) [3] AOS material: AOS - Psych.md [4] Senior notes: Ryan Ho Psychiatry.pdf (p170-171, p191-192, p196-197) [5] Past papers: 2022 Fourth Summative MCQ.pdf (Q24, p9) [6] Past papers: 2024 Fourth Summative MCQ.pdf (Q77, p28) [7] Past papers: 2023 Fourth Summative MCQ.pdf (Q95, p36) [8] Past papers: 2020 Fourth Summative Assessment MCQ paper.pdf (Q23-27, p41) [9] Past papers: 2021 Fourth Summative SAQ.pdf (Q3, p4) [10] Past papers: 2021 Fourth Summative Assessment MCQ.pdf (Q24, p9) [11] Lecture slides: GC 167. I feel very nervous Anxiety disorders.pdf (p12)
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