What is serious mental illness?

Serious mental illness includes diagnoses which typically involve psychosis (losing touch with reality or experiencing delusions) or high levels of care, and which may require hospital treatment. Here we look at two of the most common severe mental illnesses: schizophrenia and bipolar disorder (or manic depression).


Schizophrenia is a serious mental illness that affects a person’s thinking, and that can consequently alter their perception of reality, their emotions and their behaviour. Often the onset of schizophrenia occurs when a person is in their late teens or early twenties, although it can also begin in later years. Approximately 1 in every 100 people will be affected by schizophrenia.


Scientists have identified a number of potential causes or triggers of schizophrenia – from genetic factors to emotional causes such as a traumatic experience, physical injuries to the brain and problems in the brain’s development.


Symptoms of schizophrenia can be put into two categories: positive symptoms and negative symptoms.

Positive symptoms usually occur in the initial phase of the illness. They tend to be the more extreme, and are termed ‘positive’ because they involve an ‘excessive’ experience, such as a psychotic or delusional episode. Positive symptoms can include:

  • Delusions: personal beliefs that are false and based on incorrect inference about external reality; these beliefs are firmly held despite any evidence to the contrary.
  • Hallucinations: when a person experiences or perceives things that don’t exist. This may be via any of the senses: a hallucination might be seen, heard, smelt or felt.
  • Disturbances in the thought process: these can include a chaotic stream of thoughts or a sudden loss of all thoughts.

Negative symptoms tend to be longer-term symptoms. They are termed ‘negative’ because they describe a loss of normal functions – that is, a ‘subduing’ of experience. Negative symptoms include:

  • A lack of emotion and motivation
  • Tiredness or a lack of energy
  • Becoming withdrawn and isolated
  • A loss of concentration
  • A loss of interest in life
  • Sleep deprivation


Schizophrenia is very treatable. People diagnosed with schizophrenia are normally prescribed medication which targets the positive symptoms. There are a number of antipsychotic medications now available, and you can discuss the choice with your doctor, taking into account side-effects and other issues.

However, medication should only be a part of a recovery package for schizophrenia. For more information on taking a more comprehensive, ‘whole person approach’ to recovering from serious mental illness, click here.


Bipolar disorder (or manic depression) is a serious mental illness that causes extreme shifts in a person’s mood. People with bipolar disorder often have recurring episodes of mania and depression throughout their lives, although many are free of symptoms between these episodes.


Bipolar disorder is known to run in families, so genes are believed to be a significant factor. However, as with schizophrenia, stressful life events or physical injuries as well as other factors can lead to the onset of symptoms of the illness.


The main symptoms of bipolar disorder are as follows:

Manic behaviour such as:

  • A continuous elevated or euphoric mood
  • Irritability and restlessness
  • Increased energy
  • Inflated self-esteem
  • Little need for sleep
  • Talkativeness
  • Increased sex drive
  • Racing thoughts
  • Inability to focus or concentrate
  • Risk-taking
  • Increased spending

Depressive behaviour such as:

  • A persistent subdued or sad mood
  • Anxiety
  • Loss of interest or pleasure in life
  • Change in appetite or body weight
  • Insomnia/oversleeping
  • Fatigue
  • Loss of energy
  • Lack of sex drive
  • Self-harm and suicidal thoughts
  • Feelings of guilt and worthlessness
  • Difficulty concentrating

A person can have symptoms of both mania and depression at the same time.

Psychotic behaviour may also be present during severe episodes of either mania or depression. This can include delusions and hallucinations.


As with schizophrenia, there are effective treatments available for manic depression. Often care and treatment will combine medication and psychosocial treatment.

The most common treatment used during the manic phase of bipolar disorder is lithium carbonate, a mood stabilising medication. Depression may be treated with anti-depressants and talking treatments such as cognitive behavioural therapy (CBT).

The most effective care package for serious mental illness takes into account all areas of life. For more information on taking a ‘whole person approach’ to recovering from serious mental illness, click here.

Need to know more?

For more information on schizophrenia or bipolar disorder, the following websites are a useful place to start:

The BBC Website – a useful overview of mental illnesses with a good balance of information and advice.

Mentalhealth.org – a comprehensive overview of mental illnesses from the Mental Health Foundation.

The Royal College of Psychiatrists Website – contains links to information on schizophrenia from the Royal College of Psychiatrists; a similar bipolar disorder links page can be found here.