Psychosis and Schizophrenia

• Symptom dimensions in schizophrenia
• Clinical description of psychosis
• Schizophrenia is more than a psychosis
• Beyond positive and negative symptoms of schizophrenia
• Symptoms of schizophrenia are not necessarily unique to schizophrenia
• Brain circuits and symptom dimensions in schizophrenia
• Neurotransmitters and circuits in schizophrenia
• Dopamine
• Dopaminergic neurons
• Key dopamine pathways in the brain
• The integrated dopamine hypothesis of schizophrenia
• Glutamate
• Glutamate synthesis
• Synthesis of glutamate cotransmitters glycine and d-serine
• Glutamate receptors
• Key glutamate pathways in the brain and the NMDA receptor hypofunction hypothesis of schizophrenia
• Neurodegenerative hypothesis of schizophrenia
• Excitotoxicity and the glutamate system in neurodegenerative disorders such as schizophrenia
• Neurodevelopmental hypothesis and genetics of schizophrenia
• Is schizophrenia acquired or inherited?
• Genes that affect connectivity, synaptogenesis and NMDA receptors
• Dysconnectivity
• Abnormal synaptogenesis
• NMDA receptors, AMPA receptors, and synaptogenesis
• Convergence of susceptibility genes for schizophrenia upon glutamate synapses
• The bottom line
• Neuroimaging circuits in schizophrenia
• Summary

Psychosis and Schizophrenia

Psychosis is a difficult term to define and is frequently misused, not only in the newspapers, in movies, and on television but unfortunately among mental health professionals as well. Stigma and fear surround the concept of psychosis, and the average citizen worries about long-standing myths of “mental illness,” including “psychotic killers,” “psychotic rage,” and the equivalence of “psychosis” with the pejorative term “crazy.”

There is perhaps no area of psychiatry where misconceptions are greater than in that of psychotic illnesses. The reader is well served to develop an expertise on the facts about the diagnosis and treatment of psychotic illnesses in order to dispel unwarranted beliefs and to help destigmatize this devastating group of illnesses. This chapter is not intended to list the diagnostic criteria for all the different mental disorders of which psychosis is either a defining or associated feature. The reader is referred to standard reference sources (DSM-IV and ICD-10) for that information. Although schizophrenia is emphasized here, we will approach psychosis as a syndrome associated with a variety of illnesses that are all targets for antipsychotic drug treatment.