Glossary
The terms used in our articles, and what they mean.
- Acetylcholine
- A chemical messenger that carries signals between nerve cells, in the brain and in the rest of the body.
- Antipsychotic
- A medicine that reduces psychotic symptoms such as hallucinations and delusions. Most act on dopamine receptors in the brain.
- Codon
- A sequence of three chemical bases in DNA that the cell reads as one instruction: either to add a particular amino acid to a protein, or to stop building it.
- Delusion
- A firmly held belief that is not true and does not change in the face of clear evidence.
- Dopamine
- A chemical messenger in the brain involved in motivation, reward and movement. Too much dopamine signalling in certain brain areas is linked to psychotic symptoms.
- Dopamine D2 receptor
- One of the brain's receptors for dopamine. Almost every antipsychotic approved before 2024 works mainly by blocking it.
- Double-blind
- When neither the participants nor the researchers know who is getting the real treatment, so expectations cannot sway the results.
- Ectoderm
- The outer of the three layers of cells in an early embryo. It gives rise to the nervous system and to the epidermis, the outer layer of the skin.
- Epidermis
- The outer layer of the skin. It develops from the ectoderm, the outer layer of cells in an early embryo.
- Glutamate
- The brain's main excitatory chemical messenger. Most nerve cells use it to activate the cells they connect to.
- Hallucination
- Perceiving something that is not there, such as hearing a voice when no one is speaking.
- Locus
- A region of DNA at a particular place on a chromosome. A locus can contain several genes or none. The plural is loci.
- Muscarinic receptors
- Receptors for the chemical messenger acetylcholine. They are found in the brain and throughout the body, where they help control functions such as digestion and heart rate.
- Negative symptoms
- Abilities that the illness reduces, such as motivation, pleasure, speech and emotional expression.
- NMDA receptor
- One of the brain's receptors for glutamate, important for learning and memory. Ketamine and phencyclidine (PCP) block it.
- PANSS (Positive and Negative Syndrome Scale)
- A 30-item interview that trained clinicians use to rate the severity of schizophrenia symptoms. Scores range from 30 to 210; higher means more severe.
- Phase 3 trial
- A large trial that tests whether a treatment works and is safe in the people it is meant for, usually the last step before a medicine is approved.
- Placebo
- A dummy treatment with no active ingredient, given to one group in a trial so the real treatment can be compared against it.
- Positive symptoms
- Experiences the illness adds to a person's life, such as hallucinations and delusions.
- Psychosis
- A state in which a person loses some contact with reality, usually through hallucinations or delusions. Schizophrenia is one of several conditions that can cause it.
- Randomised controlled trial
- A study in which chance decides whether each participant gets the treatment being tested or a comparison, such as a placebo. It is the strongest single test of whether a treatment works.
- Striatum
- A region deep in the brain involved in movement, motivation and reward. It receives signals from many of the brain’s dopamine-releasing nerve cells.
- Strong synapse
- A synapse where a single signal from the sending nerve cell makes the receiving cell respond strongly. The sending cell releases more chemical messenger, or the receiving cell has more receptors for it. Synapses that are used often tend to become stronger.
- Synapse
- The junction where one nerve cell passes a signal to another, usually by releasing a chemical messenger.
- Weak synapse
- A synapse where a signal from the sending nerve cell makes the receiving cell respond only slightly. The receiving cell may need many signals in quick succession before it responds. Synapses that are used rarely tend to become weaker and may be removed.