🧠 Biological Treatments for Schizophrenia 🧠

1. Overview

• Biological treatments for schizophrenia focus on addressing the underlying neurochemical imbalances and brain dysfunction associated with the disorder.

• Primary biological treatments include:

  • Antipsychotic drugs (typical and atypical)

  • Emerging treatments (e.g., brain stimulation)

2. Antipsychotic Drugs

👉 Main aim: Reduce psychotic symptoms by altering dopamine and other neurotransmitter activity.

🏥 a) Typical Antipsychotics (First-Generation)

• Developed in the 1950s.

• Primarily target the dopamine hypothesis — excessive dopamine activity in the mesolimbic pathway.

• Block dopamine D2 receptors in the brain to reduce dopamine transmission.

Examples:

• Chlorpromazine

• Haloperidol

Effects:
✅ Effective at reducing positive symptoms (hallucinations, delusions).
❌ Less effective for negative symptoms (avolition, social withdrawal).
❌ High risk of side effects:

• Extrapyramidal symptoms (motor control issues, tremors)

• Tardive dyskinesia (involuntary facial and body movements)

• Sedation and weight gain

🏥 b) Atypical Antipsychotics (Second-Generation)

• Developed in the 1990s.

• Target dopamine and serotonin receptors (especially 5-HT2A).

• Weaker dopamine antagonism → fewer motor side effects.

Examples:

• Clozapine – most effective but can cause agranulocytosis (potentially fatal drop in white blood cells).

• Risperidone – more balanced dopamine/serotonin activity; fewer side effects.

• Olanzapine – effective for both positive and negative symptoms.

Effects:
✅ Reduce both positive and negative symptoms.
✅ Lower risk of motor side effects.
❌ Still cause weight gain, sedation, and metabolic issues.
❌ Clozapine requires regular blood monitoring.

3. How Antipsychotics Work

🌟 Dopamine Hypothesis

• Schizophrenia is linked to hyperactivity of dopamine in the mesolimbic pathway → causes positive symptoms.

• Typical antipsychotics reduce dopamine activity by blocking D2 receptors.

🌟 Serotonin-Dopamine Interaction

• Atypical antipsychotics block both dopamine and serotonin receptors.

• Reduces dopamine in some brain regions → treats positive symptoms.

• Increases dopamine in others → reduces negative and cognitive symptoms.

4. Effectiveness of Drug Treatments

✅ Strengths:

✔ Antipsychotics reduce positive symptoms for 70% of patients.
✔ Atypical antipsychotics improve both positive and negative symptoms.
✔ Allow many patients to live independently.

❌ Limitations:

✖ Only effective for positive symptoms — negative and cognitive symptoms often persist.
✖ High relapse rates if medication is stopped (40% within a year).
✖ Side effects can reduce compliance (patients stop taking medication).
✖ Ethical issues – risk of over-sedation and chemical restraint.

5. Emerging Biological Treatments

🔬 a) Brain Stimulation (TMS – Transcranial Magnetic Stimulation)

• Uses magnetic fields to stimulate brain areas linked to schizophrenia.

• Mixed evidence — may help with negative symptoms.

🔬 b) Glutamate-Based Drugs

• Target glutamate activity (linked to cognitive symptoms).

• Still in experimental stages — potential for future use.

6. Research Evidence

🧪 Davis et al. (1980)

• Meta-analysis of 29 studies.

• Relapse rates:

  • Placebo = 55%

  • Antipsychotics = 19%
    👉 Antipsychotics are highly effective in preventing relapse.

🧪 Kahn et al. (2008)

• Examined the effectiveness of treating 1st instance schizophrenia with 1st and 2nd generation medications - 

• Found antipsychotics are effective for at least a year, but that 2nds weren't any more effective than 1sts.

🧪 Leucht et al. (2012)

• Meta-analysis of 65 studies.

• Antipsychotics were significantly more effective than placebo in treating positive symptoms.

• Atypical antipsychotics were slightly more effective than typical antipsychotics for negative symptoms.

🧪 Leucht et al. (2012)

• .Thornley et al carried out a meta-analysis comparing the effects of Chlorpromazine to placebo conditions 

• Found Chlorpromazine to be associated with better overall functioning – Drug therapy is an effective treatment for SZ.

7. Evaluation

✅ Strengths:

✔ Strong empirical support for antipsychotic effectiveness.
✔ Atypical drugs offer broader symptom relief and fewer motor side effects.
✔ Medications reduce relapse rates and improve functioning.

❌ Limitations:

✖ Side effects → reduced compliance.
✖ Not a cure → symptoms may persist.
✖ Treats symptoms, not underlying cause.
✖ Ethical concerns – sedation and long-term dependency.