14.1: Psychosis and Antipsychotic Drugs: Overview

The term "psychosis" refers to a spectrum of mental disorders characterized by abnormal thoughts, perceptions, and behaviors. It can manifest as mood disorders, dementia, delirium with psychotic features, substance-induced psychosis with psychotic features, brief psychotic disorder, delusional disorder, schizoaffective disorder, and schizophrenia. Among all these disorders, schizophrenia is the most common psychotic disorder, affecting 1% of the worldwide population. Psychotic symptoms in all psychotic disorders can include hallucinations, delusions, disorganized speech, and disorganized or agitated behavior.

Antipsychotic drugs manage these symptoms and work by modulating dopaminergic neurotransmission. Typical antipsychotic drugs act specifically at D₂ receptors, while second-generation antipsychotics (also called atypical antipsychotics) antagonize the serotonin (5HT_2A) receptors with less affinity for D₂ receptors. These drugs can have adverse effects, including extrapyramidal symptoms, and their use must be carefully monitored. Antipsychotics are typically administered for transient psychotic symptoms on a short-term basis, while chronic psychotic symptoms may require long-term drug therapy.

Continuous antipsychotic treatment can reduce relapse rates and improve functional recovery in patients. However, treatment adherence is critical as poor adherence often leads to an increased risk of relapse. The choice of antipsychotic medication depends on several factors, including the underlying disease state, clinical insight, potential drug-drug interactions, and patient sensitivity to adverse effects. In the treatment of mania, most atypical antipsychotic medications are effective; however, typical antipsychotics are often avoided due to the risk of extrapyramidal symptoms. Patients with major depressive disorder with psychotic features may require lower doses of antipsychotic drugs in combination with an antidepressant.

In schizophrenia therapy, acute antipsychotic treatment aims to reduce agitated behavior, hallucinations, disorganized thoughts, and social withdrawal. Clozapine (Clozaril) is particularly effective in refractory schizophrenia but is used as a last resort due to its high metabolic risk. Long-term antipsychotic treatment is used for chronic psychotic illnesses such as schizophrenia and schizoaffective disorder.

Psychosis is a mental disorder characterized by abnormal thinking and perceptions.

It can manifest in various forms, such as mood disorders, dementia, delirium with psychotic features, substance-induced psychosis, brief psychotic disorder, delusional disorder, schizoaffective disorder, and schizophrenia.

Schizophrenia, affecting about 1% of the global population, is the most prevalent psychotic disorder.

In schizophrenia, patients display positive symptoms like hallucinations, delusions, incoherent speech, disorganized or agitated behavior, and negative symptoms like anhedonia, apathy, and alogia. Additionally, cognitive defects may also be observed.

Antipsychotic drugs alleviate psychotic symptoms by blocking dopamine receptors in the brain.

First-generation antipsychotics act at D₂ receptors, while second-generation drugs also antagonize the 5HT_2A receptor.

The goal of antipsychotic treatment is to ease positive symptoms while improving negative symptoms and cognitive dysfunction.

Long-term antipsychotic therapy is vital for chronic disorders like delusional or schizoaffective disorders, schizophrenia, and Parkinson's disease psychosis.