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How are mental health issues diagnosed?

Whenever a person is diagnosed with a mental health issue, a detailed assessment is conducted to build up a picture of the person’s needs
© Coventry University. CC BY-NC 4.0

Whenever a person is diagnosed with a mental health issue, a detailed assessment is conducted to build up an accurate picture of the person’s needs (NHS 2016). The word diagnosis is defined in two different ways.

It does not only refer to:

  • ‘The act of identifying a disease, illness, or problem by examining someone.’

But also to:

  • ‘A statement or conclusion that describes a disease or illness’ (Susman 2018).

Likewise, the process for diagnosing a mental health issue reflects both of these definitions and can be explained in three major steps:

1 Gathering information

A mental health professional will first gather information from a person via a detailed interview which comprises finding out the person’s foremost concerns, their symptoms, and their life history.

Additional information is at times obtained from the person’s family or caregivers and from previous treatment records. A physical examination, lab tests, and psychological questionnaires may be included, often to rule out other conditions (Susman 2018).

2 Narrowing down the options

As all of this information is obtained and synthesised, the professional will start to determine if the person’s symptoms match up with one or more official diagnoses.

Each diagnosis is made up of a list of common signs or symptoms. The professional will compare the symptoms the person is experiencing with the list of symptoms that involves a specific diagnosis.

If the person’s symptoms closely match the ones on the official list for a particular disorder, the diagnosis can then be made.

3 Forming a diagnostic impression

Subsequently when all the information has been reviewed, the professional will form an initial or tentative impression, using established diagnostic terms.

There are well over 200 different diagnoses for mental disorders within the DSM-5. For example, schizophrenia, bipolar disorder, agoraphobia and alcohol use disorder are examples of diagnoses.

It’s not unusual for someone to have more than one diagnosis, particularly if they are dealing with multiple problems at the same time (Susman 2018).


American Psychiatric Association (2013) Diagnostic and Statistical Manual of Mental Disorders DSM-5®. 5th edn. Arlignton, Va: APA

NHS (2016) ‘Mental Health Assessments’ [Online]. available from [16th November 2018]

Susman, D. (2018) ‘How do you Diagnose a Mental Illness?’ Psychology Today [Online]. available from [16th November 2018]

© Coventry University. CC BY-NC 4.0
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Defining Mental Health: A Short Introduction

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