Psychosis

What is psychosis?

If you have 'psychosis' this means that what is 'real' to you differs in important ways from what is 'real' to other people. 

This usually means having hallucinations (hearing or seeing things that seem completely real but that no-one else perceives) or unusual beliefs (for example, that other people are trying to harm you or spy on you, or that things in the world have special meanings or messages for you, or that you are special in some way or have a personal mission to fulfil, etc). Sometimes these beliefs are so powerful that they cannot be changed by any evidence or argument - these are called delusions. 

Sometimes people with psychosis have unusual experiences, such as feeling that their actions or thoughts are being controlled by someone or something else (this is called 'passivity'), or that they control events in the world using their minds, or that thoughts are either inserted into or broadcast out of their minds. 

What's the difference between psychosis and schizophrenia?

Schizophrenia is a diagnosis given to some people who have psychosis. It can happen just once, or come back several/multiple times, or be present to some degree almost all the time - it's hard to predict what will happen. 

You can have psychosis for other reasons though, e.g. disorders like bipolar disorder and schizoaffective disorder, in which people also have strong mood symptoms (feeling very high and/or very low) alongside the psychosis symptoms. 

Psychosis can also be drug-induced, especially by taking a lot of high-potency cannabis, or hallucinogenic drugs like LSD, or chronic use of amphetamines or cocaine. 

Some people have psychotic symptoms (such as hearing voices) but not so severely that we would call it schizophrenia - this is also common in people with a so-called 'borderline' (i.e., emotionally unstable) personality. 

More rarely, psychosis can be a symptom of a neurological disorder like autoimmune encephalitis; it is also more common in epilepsy, dementias, and numerous other conditions.

What causes schizophrenia?

This is a complex question - we don't know the full answer. 

We do know there is a big genetic element - if you have an identical twin with schizophrenia, you have a 50% chance of having it too (much higher than the 0.5-1% population risk of having it). A small proportion of people with schizophrenia diagnoses have a single genetic mutation that is likely responsible. But the vast majority of people with schizophrenia don't: instead, they likely have hundreds of minor genetic variants that, combined together, increase the chance of having the diagnosis. 

Equally, there are also strong psychological and environmental risk factors, such as childhood trauma, being an immigrant, experiencing racism, smoking high-potency cannabis, and others. 

Schizophrenia is believed to be a 'neurodevelopmental' disorder. This might sound strange given it usually starts at the end of adolescence - or even in later life. But the brain changes a lot right up to adulthood, both according to genetically preprogrammed instructions, and also according to environmental factors. At the end of adolesence, the balance between excitatory and inhibitory neurons changes a lot, and it is thought that in schizophrenia, this change results in an imbalance between excitation and inhibition that stops some neural circuits from working properly.

What causes psychotic symptoms?

We know even less about this!