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What Is The Process Involved In Diagnosing Mental Disorders?

Definition of mental disorder

Mental disorder is defined as an abnormality of one’s psychological state or behaviour. It includes changes in emotion, thoughts (cognitive), perception or behaviour caused by an imbalance of the neurotransmitters in the brain. Mental disorders may differ in terms of types, severity, duration of illness and the degree of impairment in daily activities.

It is important for health care providers to diagnose mental disorders early and accurately to prevent symptoms prolonged and ensure correct treatment delivered. Early commencement of treatment can prevent progression of illness and improve recovery.

How diagnosis is made?:

The diagnosis process can be done in the Psychiatry clinic or in the ward, depending on the condition of the patient. Patients are normally referred from the health /private clinic, emergency department or other medical discipline after they are suspected of having a mental disorder.

The differences between assessment of mental disorder and physical illness are :

  1. The history taking from patient is more lengthy and comprehensive.
  2. Collaborative history is taken from family members or close friends.
  3. Mental state examination is performed.
  4. There is no specific medical test that can confirm the diagnosis of a mental disorder.
  5. Diagnosis of mental disorder is made using the ‘Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5)

The diagnosis process will include the following steps :

    1. History of presenting illness from patient

This is to obtain the chief complaint and the associated symptoms. The history taking process is lengthy because apart from asking about the symptoms , the patient will also be asked regarding the following matters:

    1. The duration of illness.

      Unlike physical illness, it is very important for psychiatrist to know the exact duration of illness because it will aid in making the diagnosis. For example, to diagnose Schizophrenia, the duration of illness required is 6 months. If the symptoms occurred for less than 6 months but more than a month, the diagnosis made will be Schizophreniform disorder, while if it is less than a month, the diagnosis will be ‘Brief psychotic disorder’. Why is this important? It is very important because even though the symptoms may appear to be the same, the prognosis and the duration patient need to be on treatment will differ. Patients with Schizophrenia, for example, may required to be on long term medication and have a poorer prognosis if compared to those with ‘Brief psychotic disorder’ or ‘Schizophreniform’ disorder.

    2. Stressor.

      This is to identify the reason of patient’s distress. Subsequently, we may help patients to handle their stress through problem solving skills, stress management or individual/group counselling.

    3. Birth history such as born prematurely, history of jaundice or infection during delivery.
    4. Developmental history
    5. Family history of any medical, surgical or psychiatric illnesses
    6. Existing medical illness (For example : Chronic illness, trauma, fits or fever)
    7. Background personal history includes schooling, jobs and marriage.
    8. The personality of patient before they became ill (Pre-morbid personality). This is because changes of behaviour may be a sign of mental disorder.
    9. History of drugs/substance use.
    10. Patient’s ability to function in daily activities.
    11. Risk of harming self or others. This is to decide whether patient requires to be admitted to the ward or can be treated as an out-patient in the clinic.
  1. Collaborative history from family members and close friends.

    Unlike physical illness, history taken from the person who is close to the patient is essential. This is because patient may not be able to describe accurately on the symptoms of the illness or may not be aware of the changes in behaviour. Apart from that, this will also help to verify the history given by the patient.

  2. Mental state examination

    This is done based on observation and questioning made by the doctor. Among the components of a mental state examination are general appearance, ability to cooperate, mood, presence of abnormal thoughts or symptoms (delusion and hallucination), suicidal ideation, cognitive function, the ability to make decision (judgement) and insight.

  3. Physical examination

    A complete physical examination is part of a comprehensive psychiatric assessment. This is because there is several physical illnesses such as neurological and thyroid diseases that may give rise to symptoms similar to a mental disorder. Apart from the usual vital signs such as the blood pressure and heart rate, body weight will also be taken to calculate the Body mass index (BMI).

  4. Blood and radiological investigation if necessary

    Blood investigation is done to rule out physical illness and to identify the patient’s basic health status. The blood investigations done routinely are ‘Full blood count”., kidney / renal function test and liver function test. Thyroid function test may also be done in certain cases. If necessary, a Computed Tomography scan (CT Scan) of the brain may also be requested if neurological problem is suspected.

The diagnosis of mental disorders are made based on the criteria in the “Diagnostic and Statistical Manual of Mental Disorders 5th edition, APA ” (DSM-5) or ICD 10 Classification of Mental and Behavioral Disorders, WHO (ICD10). A patient is required to fulfil the specific criteria before a diagnosis can be made. Apart from a collection of symptoms, there are other criteria that need to be fulfilled in order to diagnose mental disorder. There criteria are as listed:

  1. The disturbance is not directly due to a physical illness
  2. The disturbance is not directly due to substance use
  3. The disturbance causes significant impairment to the person social and occupational functioning.

The manual use to diagnose mental disorders, “Diagnostic and Statistical Manual of Mental Disorders 5th edition ” (DSM-5)

After the diagnosis is established, the patient and family will be given explanation on the illness, type of treatment, side effects of medication and the duration of follow-up. Most of the cases of mental disorders can be treated as an out-patient. However; there are some cases that need to be admitted for observation and intensive treatment, especially if they have a potential risk to harm themselves or others.

References :

  1. American Psychiatric Association (2013) .Diagnostic And Statistical Manual Of Mental disorders Fifth Edition : DSM-5. Washington DC; APA
  2. Bhugra D, Bell S, Burns A,Howes O (2010).The complete psychiatrist. London; The Royal        College of Psychiatrist.
  3. Medical development divison (2011).Psychiatry and mental health services operational policy.  Kuala Lumpur; MOH.
  4. Gelder M, Andereasen N, Lopez-Ibor J, Geddes J (2012). New Oxford textbook of psychiatry. Oxford; Oxford University press.
  5. Sadock BJ, Sadock VA (2003).Kaplan & Sadock’s  Synopsis of Psychiatry Behavioral sciences/ clinical psychiatry 9th edition.Philadephia, Lippincott Williams & Wilkins.
  6. World Health Organization (1996).Diagnostic and management guidelines for mental disorders in primary care :ICD 10 Chapter V Primary care version.Germany ; WHO/Hogrefe & Huber Publishers.
Last Reviewed :  28 August 2020
Translator :  Dr. Firdaus Bt. Datuk Abdul Gani
Accreditor :  Dr. Ramli Mohd Ali 
Reviewer : Dr. Nurulwafa binti Hussain