Difficulty: Intermediate | Prerequisites: Part 1 of these notes (Symptoms, Genetics, and Neurobiology). Familiarity with the dopamine and glutamate hypotheses is assumed here.
Genes load the gun, but environment pulls the trigger. That framing captures a large part of schizophrenia research: even with strong genetic risk, the disorder does not develop in isolation from environmental and developmental context. This second set of notes covers prenatal risk factors, progressive brain changes observed on neuroimaging, and the treatment landscape, from established antipsychotic pharmacotherapy through to emerging interventions. If you have not reviewed the dopamine and glutamate hypotheses from Part 1, go back and do that, because the treatment section assumes you understand why these drugs work at the receptor level.
Prenatal complications (infections, malnutrition, obstetric problems) interact with genetic vulnerability to increase schizophrenia risk. Neuroimaging shows progressive cortical grey matter loss starting in adolescence. Treatment relies primarily on antipsychotic medications that block D2/D3 dopamine receptors for positive symptoms, with atypical antipsychotics offering some benefit for negative symptoms. Emerging treatments include brexanolone and NMDA-targeting agents like ketamine for treatment-resistant cases.
Prenatal risk factors
Environmental exposures during pregnancy that increase the likelihood of schizophrenia in offspring. These include maternal infections, malnutrition, and obstetric complications. Think of it as insults to the developing brain during a critical window.
Obstetric complications
Problems during pregnancy or delivery (e.g., oxygen deprivation, low birth weight, pre-eclampsia) that have been linked to elevated schizophrenia risk in the child.
Grey matter loss
A progressive reduction in the volume of cortical grey matter (the outer layer of the brain containing neuronal cell bodies). In schizophrenia, neuroimaging shows this loss begins in adolescence and continues into adulthood.
Typical antipsychotics (first-generation)
Older antipsychotic medications that primarily block D2 dopamine receptors. Effective for positive symptoms but carry a higher risk of motor side effects (extrapyramidal symptoms).
Atypical antipsychotics (second-generation)
Newer antipsychotic medications that block D2 and D3 dopamine receptors and also act on serotonin receptors. They can address some negative symptoms by modulating dopamine activity in the prefrontal cortex, and tend to carry a lower risk of motor side effects.
Brexanolone
An antidepressant drug initially developed for postpartum depression. Recent research suggests it may have broader applications in affective disorders associated with schizophrenia.
NMDA receptor antagonists
Drugs that block NMDA-type glutamate receptors. PCP and ketamine are the most cited examples. While they can produce schizophrenia-like symptoms in healthy people (supporting the glutamate hypothesis), ketamine at controlled doses has shown rapid antidepressant effects in treatment-resistant cases.
Diathesis-stress model
A framework proposing that disorders arise from the interaction of a pre-existing vulnerability (diathesis, often genetic) with environmental stressors. Schizophrenia is one of the textbook examples.
Disturbances during prenatal brain development are a significant part of schizophrenia's aetiology.
Key prenatal risk factors include:
Maternal infections during pregnancy (e.g., influenza, toxoplasmosis)
Malnutrition during pregnancy, particularly severe caloric restriction
Obstetric complications such as hypoxia (oxygen deprivation) during delivery
These environmental insults do not cause schizophrenia on their own. They interact with genetic predispositions, fitting the diathesis-stress model: a genetically vulnerable foetus exposed to prenatal complications is at considerably higher risk than one without that genetic background.
Neuroimaging studies have tracked structural brain changes in people with schizophrenia over time.
The most consistent finding is progressive loss of cortical grey matter, starting during adolescence and continuing into adulthood.
This grey matter loss is more pronounced in individuals with schizophrenia compared to age-matched controls, suggesting it is not simply normal ageing but a feature of the disorder itself.
These structural changes help explain why schizophrenia often worsens over time in untreated individuals and why early intervention is emphasised in clinical practice.
Antipsychotic medication remains the first-line treatment for schizophrenia.
Mechanism: these drugs primarily block D2 and D3 dopamine receptors, reducing dopamine transmission in the mesolimbic pathway and alleviating positive symptoms.
Typical (first-generation) antipsychotics are effective for positive symptoms but carry a higher burden of extrapyramidal side effects (involuntary movements, rigidity, tremor).
Atypical (second-generation) antipsychotics also target serotonin receptors and can modulate dopamine activity in the prefrontal cortex, offering some benefit for negative symptoms as well.
Limitations: no current antipsychotic fully resolves cognitive symptoms. This remains a major unmet need in schizophrenia treatment.
Brexanolone: originally approved for postpartum depression, it acts on GABA-A receptors. Researchers are exploring whether it could help with the affective (mood-related) symptoms that often accompany schizophrenia.
Ketamine and NMDA receptor agents: at sub-anaesthetic doses, ketamine has shown rapid antidepressant effects, particularly in treatment-resistant cases. This line of research connects back to the glutamate hypothesis and suggests that targeting glutamate pathways could open new treatment avenues beyond traditional dopamine-blocking drugs.
These are still emerging areas. Exams are unlikely to ask you to evaluate the evidence in detail, but knowing that the field is moving beyond dopamine-only approaches is worth a sentence or two in an essay.
The prenatal risk factor research has practical public health implications: adequate prenatal nutrition and infection prevention during pregnancy are, in part, schizophrenia prevention measures. On the treatment side, the distinction between typical and atypical antipsychotics matters in clinical decision-making every day, since choosing between them involves weighing symptom coverage against side-effect profiles for each patient.
"Schizophrenia is caused by bad parenting." This is an outdated idea. The current evidence points to genetic vulnerability interacting with biological and environmental factors (prenatal insults, brain development), not family dynamics.
"Antipsychotics cure schizophrenia." They manage symptoms, particularly positive ones. They do not cure the underlying condition, and most patients require long-term or lifelong treatment.
"If it's genetic, environment doesn't matter." The 50% concordance in identical twins (from Part 1) directly refutes this. Prenatal factors and brain development play a real role.
"Ketamine is only a drug of abuse." In a clinical context, ketamine at controlled doses is a legitimate treatment tool being studied for treatment-resistant depression and potentially for schizophrenia-related mood disturbance.
⚠️ Be able to explain the diathesis-stress model using schizophrenia as your example. This is a favourite essay prompt.
⚠️ Know the difference between typical and atypical antipsychotics: mechanism, symptom targets, and side-effect profiles.
⚠️ Progressive grey matter loss is a neuroimaging finding you should be able to cite when discussing the course of the disorder over time.
⚠️ Prenatal risk factors (infections, malnutrition, obstetric complications) are commonly tested as examples of environmental contributions to schizophrenia.
True or false: Obstetric complications alone are sufficient to cause schizophrenia.
Fill in the blank: Progressive loss of cortical _______ _______ has been documented in schizophrenia, beginning in adolescence.
True or false: Atypical antipsychotics can offer some benefit for negative symptoms.
Fill in the blank: Antipsychotic medications primarily work by blocking _____ and _____ dopamine receptors.
True or false: Brexanolone was originally developed to treat schizophrenia.
Answers: 1. False (they interact with genetic predisposition). 2. Grey matter. 3. True. 4. D2 and D3. 5. False (it was developed for postpartum depression).
Q: How do prenatal environmental factors fit into the diathesis-stress model of schizophrenia?
A: Genetic vulnerability acts as the diathesis (predisposition). Prenatal insults such as maternal infection, malnutrition, or obstetric complications act as stressors that interact with this vulnerability, increasing the likelihood of the disorder developing.
Q: What progressive brain change has neuroimaging identified in schizophrenia, and when does it begin?
A: Progressive loss of cortical grey matter, beginning in adolescence and continuing into adulthood. This loss is more pronounced in affected individuals than in controls.
Q: Compare typical and atypical antipsychotics in terms of mechanism and symptom coverage.
A: Typical antipsychotics primarily block D2 receptors and target positive symptoms, but carry a higher risk of extrapyramidal side effects. Atypical antipsychotics also block D3 and serotonin receptors, can modulate prefrontal dopamine activity, and may improve some negative symptoms with a lower motor side-effect burden.
Q: Why is ketamine relevant to schizophrenia research, given that NMDA antagonists can produce schizophrenia-like symptoms?
A: Ketamine at sub-anaesthetic doses has shown rapid antidepressant effects in treatment-resistant cases. While NMDA antagonists can mimic negative and cognitive symptoms (supporting the glutamate hypothesis), controlled clinical use of ketamine targets a different aspect: the mood and depressive features that often co-occur with schizophrenia.
Q: Why does the fact that antipsychotics do not fully resolve cognitive symptoms matter clinically?
A: Cognitive symptoms (attention deficits, memory impairment, poor problem-solving) are a major source of functional disability. Because current medications leave these largely untreated, patients often struggle with daily tasks, employment, and independence even when positive symptoms are controlled. This is a key unmet need driving research into new treatment targets.
The diathesis-stress model introduced here applies across abnormal psychology, not just to schizophrenia. You will see the same framework in depression, anxiety disorders, and PTSD. The pharmacotherapy section connects to your psychopharmacology material on receptor binding and side-effect profiles. The progressive brain changes link to developmental psychology and the broader question of whether schizophrenia is best understood as a neurodevelopmental disorder, a neurodegenerative one, or both.
schizophrenia treatment, antipsychotics, typical antipsychotics, atypical antipsychotics, first-generation antipsychotics, second-generation antipsychotics, D2 receptor, D3 receptor, dopamine blockade, brexanolone, ketamine, NMDA antagonist, prenatal risk factors, obstetric complications, maternal infection, malnutrition, diathesis-stress model, grey matter loss, cortical thinning, neuroimaging, progressive brain changes, treatment-resistant schizophrenia, extrapyramidal symptoms, abnormal psychology, psychopharmacology