There are many types of mental illness and, depending on how mental illness is described, 10 or 25% of people living in the United Kingdom can be considered to have had a mental illness at some point in their lives. Like many other illnesses it is common and can occur at any time and happen to any one of us.

Severe mental illness is a term used for longstanding conditions and affects only about 1% of the population. There are many types of mental illness but the easiest way of defining them is as either psychotic or neurotic. Most conditions fit into either of these categories.

Neurotic Conditions

Neurotic conditions are related to ‘normal’ emotions and are the most common type of mental illness. Many of us feel depressed for example and whilst it occurs is unpleasant. However if you have clinical depression it is a far deeper experience than ‘feeling depressed’. Having clinical depression is an illness that has a marked effect on one's life, preventing people from being able to work or look after themselves properly and in extreme cases, leads to suicide. Other examples of neurotic illnesses are Phobias, Obsessive Compulsive Disorder and Anxiety.

Psychotic Conditions

These conditions are different from neuroses being unrelated to normal emotions. Psychosis is a word used to describe symptoms or experiences that happen together. These symptoms cause the patient to not experience reality like most people. Someone with psychotic symptoms may:

  • Hear, smell, feel or see things which others do not – hallucinations
  • Have strange thoughts or beliefs that can make the person feel they are being persecuted or controlled – delusions
  • Have muddled or blocked thinking – thought disorder
  • Appear unusually excited or withdrawn and avoid contact with people
  • Not recognise that they are unwell – lack of insight

These symptoms can occur with a number of psychotic illnesses including schizophrenia. People suffering from Bipolar Disorder (also known as Manic–Depression) and psychotic depression, which are mood disorders, can also experience these symptoms.

More information

Useful websites for further information: 

Visit our Choice and Medications website with explanations of common conditions and their treatment

Learn more about psychosis by visiting our Early Intervention in Psychosis website

FAQs and Diagnoses