The biological approach to explaining and treating OCD: genetic and neural explanations; drug therapy.

What is the Basic Assumption of the Biological Approach to OCD?

• OCD caused by biological factors.
• Includes genetic and neural explanations.

What are Candidate Genes in OCD?

• Specific genes increase vulnerability to OCD.
• Genes linked to serotonin and dopamine regulation may affect anxiety and obsessive thoughts.

How do Candidate Genes Explain OCD?

• Mutations in serotonin-related genes may disrupt mood regulation.
• This may increase obsessive thoughts and compulsive behaviours.

What is a Polygenic Explanation of OCD?

• OCD caused by many genes acting together rather than one single gene.

How does the Polygenic Explanation Explain OCD?

• Different combinations of genes increase vulnerability to OCD.
• Explains why OCD is complex and symptoms vary between individuals.

What does Aetiologically Heterogeneous mean in OCD?

• Different people may develop OCD through different genetic combinations and causes.

How does Aetiologically Heterogeneous Explain OCD?

• OCD may have different biological causes in different individuals.
• Explains variation in symptoms and experiences of OCD.

Nestadt et al. — Aim

• Investigated genetic influence on OCD using twins.

Nestadt et al. — Procedure

• Compared concordance rates for OCD in monozygotic and dizygotic twins.

Nestadt et al. — Findings

• Concordance rates higher in monozygotic twins than dizygotic twins.
• Supports genetic explanation of OCD.

What is Serotonin?

• Neurotransmitter involved in mood regulation and emotional control.

How does Serotonin Explain OCD?

• Low serotonin levels linked to OCD.
• Reduced serotonin may impair control of anxiety and obsessive thoughts.

What is the Orbitofrontal Cortex (OFC)?

• Brain area involved in decision making and processing worry signals.

How does the Orbitofrontal Cortex Explain OCD?

• OFC may become overactive in OCD.
• Sends excessive worry signals causing obsessive thoughts.

What are the Basal Ganglia?

• Brain areas involved in movement and routine behaviours.
• Help suppress repetitive actions and thoughts.

How do the Basal Ganglia Explain OCD?

• Malfunctioning basal ganglia fail to suppress worry signals.
• Leads to repetitive compulsions and obsessions.

What is the Worry Circuit in OCD?

• Orbitofrontal cortex sends worry signal to thalamus.
• Thalamus relays signal to basal ganglia.
• Faulty basal ganglia fail to suppress signal.
• Worry circuit becomes hyperactive causing obsessions and compulsions.

What are SSRIs?

• Selective serotonin reuptake inhibitors.
• Antidepressants used to treat OCD.

How do SSRIs Work?

• Block reuptake of serotonin into presynaptic neuron.
• More serotonin remains in synapse.
• Increases serotonin activity and reduces OCD symptoms.

What are Tricyclics?

• Older antidepressants used to treat OCD.
• Example: clomipramine.

How do Tricyclics Work?

• Block reuptake of serotonin and other neurotransmitters.
• Increase neurotransmitter levels to reduce OCD symptoms.

What are SNRIs?

• Serotonin-noradrenaline reuptake inhibitors.
• Used when SSRIs are ineffective.

How do SNRIs Work?

• Increase serotonin and noradrenaline levels in synapse.
• Help regulate mood and anxiety.

Biological Explanation Evaluation — Research Support

• Nestadt et al. found higher concordance rates in identical twins.
• Supports genetic explanation of OCD.

Biological Explanation Evaluation — Brain Scan Evidence

• Brain scans show abnormal activity in OCD patients.
• Supports neural explanation.

Biological Explanation Evaluation — Environmental Factors Ignored

• Life experiences may also contribute to OCD.
• Biological explanation may be reductionist.

Biological Explanation Evaluation — Not Entirely Genetic

• Concordance rates for identical twins not 100%.
• Genes cannot fully explain OCD.

Drug Therapy Evaluation — Effective Treatment

• SSRIs reduce OCD symptoms for many patients.

Drug Therapy Evaluation — Cost Effective

• Drug therapy cheaper and quicker than psychological therapies.

Drug Therapy Evaluation — Side Effects

• Side effects include nausea, insomnia and loss of sex drive.

Drug Therapy Evaluation — Treats Symptoms Not Cause

• Drugs manage symptoms rather than underlying causes of OCD.