Schizophrenia vs bipolar disorder: how they differ and overlap

Schizophrenia and bipolar disorder are both serious, long-term mental health conditions that can involve psychosis, which is why they are often grouped together or mistaken for each other. They are separate diagnoses with different central features, different patterns over time and, in part, different treatments.

The NHS describes schizophrenia as a long-term condition causing a range of psychological symptoms, and describes bipolar disorder as a mental health condition in which you have extreme mood changes. The key conceptual difference is that in schizophrenia the defining problem is disturbed perception, thinking and motivation, and in bipolar disorder it is disturbed mood with episodes in between of stable mood.

The table is drawn from the NHS overview pages for each condition and the Rethink Mental Illness pages.

The NHS lists symptoms of schizophrenia as hallucinations (hearing or seeing things that do not exist outside the mind), delusions (unusual beliefs not based on reality), muddled thoughts and speech based on hallucinations or delusions, losing interest in everyday activities, not wanting to look after yourself, wanting to avoid people including friends, and feeling disconnected from feelings or emotions. Rethink Mental Illness adds that the symptoms include disorganised thinking, lack of motivation, slow movement and changes in sleep, and that not everyone will experience all of them.

Rethink, citing the Royal College of Psychiatrists, says schizophrenia affects around 1 in 100 people and may develop in early adulthood. The exact cause is unknown, but the NHS says most experts believe a combination of genetic and environmental factors is responsible, with stressful life events or drug misuse acting as possible triggers.

The NHS says schizophrenia is usually treated with a combination of medicine and therapy, most often antipsychotic medicines and CBT, with help from a community mental health team. Many people recover, although they may have periods when symptoms return, and recognising the signs of an acute episode and taking medicine as prescribed can reduce the chance of severe relapses.

The NHS says high moods can be severe (mania) or mild (hypomania), with symptoms such as feeling very happy and excited, irritable or aggressive, restless with a lot of energy or little need for sleep, racing thoughts, talking fast, feeling overly confident, being impulsive, and, sometimes, hearing things that are not real, believing things that are not true or feeling paranoid. Low moods include feeling sad, losing interest, low energy, poor sleep or sleeping a lot, feeling worthless or hopeless, and having suicidal thoughts.

Rethink Mental Illness explains that there are different types: bipolar I disorder, which means at least one episode of mania lasting longer than a week, bipolar II disorder, where depression is common, and cyclothymia, with similar but milder symptoms. It says that in bipolar disorder, psychotic symptoms can occur during a severe episode of mania or depression and can reflect your mood.

The NHS says bipolar disorder cannot be cured but treatments can help manage it, including medicines to stabilise mood and talking therapy. Rethink says antipsychotic medicines are commonly offered first for mania, and lithium or other mood stabilisers may be added. The NHS warns not to stop taking bipolar medicine unless told to by a doctor, even if you feel better, and that some medicines are not safe in pregnancy.

There is no blood test or scan that separates the two. The NHS says there is no single test for schizophrenia and it is usually diagnosed after an assessment by a mental health professional such as a psychiatrist. Rethink Mental Illness says doctors cannot usually use blood tests and scans to diagnose bipolar disorder, that diagnosing mental illnesses can sometimes be difficult, and that your GP cannot diagnose bipolar disorder, only a psychiatrist can make a formal diagnosis.

The NHS says a psychiatrist will ask about moods, behaviour, health and family history, and that bipolar disorder can take time to diagnose because it affects everyone differently and symptoms are similar to other conditions. Rethink notes that a person might be told they have something else, such as depression, before the bipolar diagnosis is made.

There are also related diagnoses where features of both are present. The schizoaffective disorder page on this site covers one of them.

The NHS says that if you are experiencing symptoms of schizophrenia you should see a GP as soon as possible, because the earlier it is treated the better. For bipolar disorder it says to see a GP if you have extreme mood changes that last a long time or affect your everyday life, and to encourage someone you are worried about to speak to their GP.

If there is a mental health crisis or emergency, the NHS pages say support is available no matter what you are going through, and that doctors may arrange hospital stays or crisis team support if someone is at risk of self-harm, suicide or harming someone else. Anyone in immediate danger should call 999.