Advanced Psychology ESL – Mechanisms, Symptoms, Differential Diagnosis & Treatment

1. Introduction

Obsessive–Compulsive and Related Disorders involve:

• intrusive thoughts

• compulsive or repetitive behaviours

• distress caused by inability to suppress urges or thoughts

• impaired functioning due to rituals or mental compulsions

These disorders share:

• anxiety

• negative reinforcement

• cognitive rigidity

• impaired inhibitory control

—but each presents with distinct patterns.

Scientific Expansion: Why These Disorders Are Linked

All conditions in this category involve:

• habit loop dysfunction

• error detection overactivity (“something is wrong”)

• difficulty stopping behaviours (impaired inhibitory control)

• rigid, repetitive thought patterns

This cluster shares neurobiological roots in the cortico-striato-thalamo-cortical (CSTC) circuits.

2. Obsessive–Compulsive Disorder (OCD)

A disorder involving obsessions, compulsions, or both.

Obsessions

Intrusive, unwanted thoughts, images, or urges causing anxiety.

Examples:

• contamination fears

• intrusive violent or sexual thoughts

• fears of causing harm

• symmetry or “not just right” feelings

Compulsions

Repetitive behaviours or mental acts to reduce anxiety or prevent feared outcomes.

Examples:

• washing or cleaning

• checking

• repeating, counting, ordering

• mental rituals (praying, neutralising, reviewing memories)

Compulsions provide short-term relief → reinforcing the OCD cycle.

Diagnostic structure

• obsessions/compulsions ≥1 hour/day

• distress or impairment

• insight may range from good → poor → delusional

Etiology

• hyperactivity in CSTC circuits

• serotonin dysregulation

• cognitive distortions (inflated responsibility, thought–action fusion)

• high intolerance of uncertainty

• negative reinforcement learning

Treatment

• Exposure and Response Prevention (ERP) → gold standard

• SSRIs (often at higher doses)

• CBT targeting catastrophic beliefs

• ACT (acceptance of intrusive thoughts)

• severe cases → TMS, DBS

Scientific Expansion: OCD Neurobiology

OCD involves:

• Overactive orbitofrontal cortex → constant error detection

• Overactive anterior cingulate cortex → chronic “alarm”

• Underactive inhibitory pathways → difficulty stopping rituals

• Glutamate abnormalities → intrusive thoughts

Brain imaging consistently shows cortico-striatal loop hyperactivity.

3. Body Dysmorphic Disorder (BDD)

BDD involves preoccupation with perceived appearance flaws unnoticeable to others.

Core features

• repetitive checking/grooming

• extreme appearance-related distress

• poor or delusional insight

• avoidance of mirrors or social situations

• focus on skin, nose, hair, symmetry, etc.

BDD reflects distortions in internal body representation, not vanity.

Etiology

• perfectionism

• distorted self-worth

• trauma or bullying

• detail-focused visual processing abnormalities

Treatment

• CBT with perceptual retraining

• ERP for appearance rituals

• SSRIs

• identity restructuring and cognitive reframing

Scientific Expansion: BDD Brain Mechanisms

• Visual processing imbalance → excessive detail focus, poor holistic perception

• Overactivation in amygdala → high emotional distress

• Impaired frontostriatal connections → difficulty shifting attention

BDD overlaps with OCD in cognitive style but has unique perceptual deficits.

4. Hoarding Disorder

Persistent difficulty discarding possessions, leading to clutter and functional impairment.

Core features

• distress when discarding items

• accumulation blocking living spaces

• excessive acquisition

• emotional attachment to objects

Unlike OCD, hoarding behaviour is pleasurable or comforting, not driven by intrusive fears.

Etiology

• decision-making deficits

• perfectionism (“fear of discarding the wrong thing”)

• trauma or loss

• emotional reliance on objects

Treatment

• CBT for hoarding (decision-making + exposure to discarding)

• skills training (organisation, categorisation)

• home-based interventions

• motivational interviewing

Medication: limited evidence.

Scientific Expansion: Hoarding Neurobiology

Research shows:

• Underactivity in anterior cingulate cortex → difficulty deciding

• Overactivity when discarding personal items → emotional distress

• Poor categorisation ability

• Unique neural pattern distinct from OCD

5. Trichotillomania (Hair-Pulling Disorder)

An impulse-control disorder involving recurrent hair pulling.

Core features

• tension or sensory discomfort before pulling

• relief or gratification after pulling

• occurs during stress, boredom, or dissociation

• difficult to stop despite attempts

Etiology

• habit-learning dysfunction

• emotional regulation problems

• sensory reinforcement

• genetic components

Treatment

• Habit Reversal Training (HRT) → gold standard

• stimulus control strategies

• CBT for emotion regulation

• acceptance-based approaches

Medication: inconsistent benefit.

Scientific Expansion: Trichotillomania Mechanisms

• overactive motor habit pathways

• reduced inhibitory control

• sensory reward loop → tactile satisfaction reinforces pulling

This explains why pulling feels relieving.

6. Excoriation (Skin-Picking) Disorder

Recurrent picking resulting in skin lesions.

Core features

• repeated failed attempts to stop

• picking triggered by anxiety, boredom, sensory urges, or noticing imperfections

• risk of infection and scarring

• frequently comorbid with OCD, anxiety, BDD

Treatment

• Habit Reversal Training

• CBT

• sensory substitution (e.g., fidget tools)

• SSRIs may help

Scientific Expansion: Skin-Picking Neurobiology

• habit loop dysfunction

• sensory hypersensitivity

• dopamine reward from tactile stimulation

• difficulty disengaging from urges due to impaired inhibitory control

7. Neurobiological Mechanisms Across OCD-Related Disorders

• Cortico-striatal loop dysfunction → rigid habits, intrusive thoughts

• Hyperactive anterior cingulate cortex → constant “error” signal

• Serotonin and glutamate imbalance → intrusive thoughts, compulsions

• Impaired inhibitory control → difficulty stopping urges

These shared mechanisms explain why these disorders respond to similar treatments.

8. Cognitive–Behavioural Models

Negative reinforcement

Compulsions remove anxiety → behaviour strengthens.

Thought–action fusion

“Thinking it = doing it” or “Thinking it makes it more likely.”

Inflated responsibility

Feeling responsible for preventing harm.

Intolerance of uncertainty

Anxiety about not knowing, leading to checking or rituals.

These beliefs create urgency, making rituals feel necessary.

9. Treatment Approaches Across Disorders

Exposure and Response Prevention (ERP)

Confront feared situation → block compulsive response.

Cognitive restructuring

Challenge irrational beliefs (responsibility, threat perception).

Habit Reversal Training (HRT)

Increase awareness → replace behaviour → build competing habits.

Mindfulness and ACT

Detach from intrusive thoughts rather than fight them.

Medication

• SSRIs → first line

• Clomipramine → for severe OCD

• Higher doses required than for depression/anxiety

Scientific Expansion: Why ERP Works

ERP decreases:

• amygdala activation

• compulsive urge intensity

• catastrophic predictions

ERP creates new learning, not simply “toughness.”

10. Key Academic Vocabulary

• obsession

• compulsion

• thought–action fusion

• negative reinforcement

• perceptual distortion

• rituals

• habit loop

• intolerance of uncertainty

• body-focused repetitive behaviours (BFRBs)

• error detection circuitry

• perfectionism

• insight level

11. Discussion Questions

• What distinguishes an obsession from a compulsion?

• Why is ERP considered the gold standard for OCD?

• How does BDD differ from general body insecurity?

• Why is hoarding no longer classified as an OCD subtype?

• What brain circuits are involved in compulsive behaviours?

• Why do trichotillomania and skin-picking feel relieving?

• What psychological factors maintain the OCD cycle?

12. Case Studies & Clinical Reasoning

Case Study 1: OCD – Contamination subtype

A 22-year-old student washes her hands 40–60 times daily. She fears causing illness to others. She recognises the behaviour is excessive but cannot stop. Skin is cracked and bleeding.

Questions

1. Which obsessions and compulsions are present?

2. What cognitive distortions maintain her behaviour?

3. Why would ERP be effective?

4. What neural circuits are overactive?

Case Study 2: Body Dysmorphic Disorder

A 19-year-old man believes his nose is “deformed.” Others say it looks normal. He checks mirrors repeatedly, avoids photos, and refuses social events.

Questions

1. Why is this BDD, not social anxiety?

2. What perceptual processing differences might be present?

3. How would CBT + perceptual retraining help?

Case Study 3: Trichotillomania

A 26-year-old woman pulls hair during stress. She describes a sense of tension before pulling and relief afterward. Bald patches have formed.

Questions

1. Why is this not OCD?

2. Why is HRT the recommended treatment?

3. What habit-learning pathways reinforce pulling?