Biology
Chemicals in the brain
For some people changes in brain chemicals will be important. But it is hard to know if the changes cause psychosis, or if psychosis causes the changes. Remember, our brains are changing all the time. For example, when we are happy our brain changes. Does this brain change cause you to be happy, or does being happy cause your brain to change? These are not easy questions to answer. It depends on your view in life.
Medication and the brain
Medication works by changing the balance of chemicals in the brain. This helps lots of people get better from upsetting psychosis. It can stop voices and it can calm feelings. But the side-effects can be hard to live with. Not all people get better with medication on its own. The effects are different for everyone.
Finding out how medication works has led to theories about what causes psychosis. But research done since then suggests that things are much more complex. A lot more work remains to be done on this.
Other things have been found out about the brains of people with psychosis. On the whole though, the answers have not been clear. Some changes in the brains of some people have been found. But again it is hard to tell if the changes have caused psychosis. Or whether psychosis caused the changes.
Genetics and the family
Research shows that people who have close family with psychosis have a greater risk of getting psychosis. There are different reasons why. Often it might be genetics. But it could also be the effect of growing up with someone with psychosis. Psychosis can put families under a lot of pressure.
This research showed that genetics is important in psychosis. But it also showed that early experience is just as important. For many with close family with psychosis, it will be both genetics and experience which increases their chances of having it.
Most experts now think that genetics, biology & early experience make some people more prone to psychosis. These people might respond to stress by having an unusual experience like hearing voices. Some people are less prone than others. It would take more stress to make them psychosis. But some people are more prone, and it takes less stress. We need to learn more about how biology, early experience and stress mix to make some people psychosis.
Drugs
People who use street drugs for a long time are also more likely to get psychosis. There are different ideas why this is too. Drugs might increase chances of psychosis. Or people with psychosis might be more likely to use drugs to get relief from their problems. It is hard to tell. Both reasons are probably true for most people.
Clearly drugs on their own do not cause psychosis. Other things will matter too. Such as social factors, or your psychology, or your genetics. Maybe all of these will be important.
