Bipolar disorder



Bipolar disorder is a cyclical mood disorder that fluctuates between episodes of mania and depression.

Bipolar disorder is characterised by a significant disruption in mood and behaviour, which includes both periods of elated and depressed mood. It is a serious long-term condition with a much higher risk of suicide compared to the average population (0.4% annual risk).

Patients with bipolar experience episodes of both mania and depression.

  • Mania: elevated, expansive, or irritable mood. May be features of psychosis. Lack of insight with significant impairment in functioning.
  • Depression: low mood or loss of interest/pleasure in nearly all activities coupled with other depressive symptoms. Causes significant distress and impairs normal function.

Classification systems

There are two major classification systems used in the assessment and diagnosis of mental health disorders: ICD-10 & DSM-V

  • ICD-10: The International Statistical Classification of Diseases and Related Health Problems (ICD) is a classification of human disease created by the World Health Organisation.
  • DSM-V: The Diagnostic and Statistical Manual of Mental Disorders (DSM) now in its fifth edition is a classification of mental health disorders published by the American Psychiatric Association.

While similar, these systems often differ in their interpretation of mental health disorders and how they are diagnosed. Therefore, it is important to state the classification system being used.


Bipolar disorder is recognised as one of the most common and disabling medical conditions worldwide.

The lifetime prevalence of bipolar disorder is estimated between 0.1-2.4% with an overall incidence rate of 0.7 per 100,000 person-years. The condition has an equal sex prevalence and the age of onset is typically before 30 years, although there is an estimated small peak in incidence in the 5th and 6th decades.

There is usually a significant delay (average of eight years in one study) between the first onset of symptoms and presentation to services. This is thought to be due to a long period of ‘subsyndromal’ symptoms that fall short of a ‘full’ episode.


At present, little is known about the exact cause of bipolar disorder although there are several proposed mechanisms.

Bipolar disorder has a strong heritable component. This means a patient's underlying genetic code, and the expression of that code into the phenotype (observable characteristics), influences whether they develop bipolar disorder. The estimated lifetime risk of bipolar is 5-10 times greater than the general public if a first-degree relative (parent, sibling, child) suffers from the condition. Furthermore, monozygotic twin studies show there is a 40-70% risk of developing bipolar if the other sibling suffers from the disorder.

Other factors that impact the development of bipolar disorder include hormonal abnormalities (in particular problems with the hypothalamic-pituitary axis) and psychosocial influences. The latter can include childhood maltreatment, social class, social support and self-esteem.

Clinical features

Bipolar disorder is characterised by symptoms of both mania and depression.


Mania is characterised by an abnormal and persistently elevated, expansive or irritable mood, which leads to impairment in social and/or occupational function. There are numerous features suggestive of mania:

  • Elevated mood
  • Extreme irritability and/or aggression
  • Increased energy
  • Restlessness
  • Decreased need for sleep
  • Flight of ideas
  • Racing thought
  • Pressure of speech
  • Increase libido and disinhibition
  • Distractibility, poor concentration
  • Psychotic features: delusions (fixed belief contradictory to reality or rational argument) or hallucinations


Hypomania is characterised by features of mania, but usually not as severe and does not lead to social and/or occupational impairment in function. In particular, there are no psychotic features.

  • Elevated mood
  • Irritability
  • Increased energy
  • Feeling of physical and/or mental efficiency
  • Increased sociability
  • Talkativeness
  • Over-familiarity


Depression is characterised by a persistently low mood or loss of interest/pleasure in normal activities.

  • Low mood
  • Loss of interest or pleasure
  • Significant weight change
  • Insomnia or hypersomnia (sleep disturbance)
  • Psychomotor agitation or retardation
  • Fatigue
  • Feelings of worthlessness
  • Diminished concentration
  • Suicidal thoughts: recurrent thoughts of death/suicide, or a suicide attempt, or a specific plan for committing suicide


Bipolar disorder can be classified according to different discrete episodes of elated, depressed or mixed disturbances in mood.

These discrete episodes are used to determine the diagnosis of bipolar according to the ICD-10 or DSM-V criteria. It is also important to identify the current episode when assessing a patient with confirmed or suspected bipolar disorder.

  • Manic episode: abnormal and persistently elevated, expansive, or irritable mood. Symptoms last ≥ 1 week. Three additional symptoms are supportive of mania. The presence of impairment in social and/or occupational function, necessitates hospitalisation or psychotic features present.
  • Hypomanic episode: abnormal and persistently elevated, expansive, or irritable mood. Symptoms last ≥ 4 days. Three additional symptoms are supportive of mania. No impairment in social and/or occupational functioning, requirement for hospitalisation or psychotic features.
  • Depressive episode: depressed mood or loss of interest/pleasure in nearly all activities. Symptoms last ≥2 weeks. Four additional symptoms are supportive of depression. Causes distress and impairs function.
  • Mixed episode: rapid alternating between manic and depressive symptoms, or criteria for mania/hypomania and at least three symptoms of depression for ≥1 week, or criteria for a depressive episode and at least three mania/hypomania symptoms for ≥ 2 weeks.


Bipolar disorder is classified based on different ‘episodes’, which are used in the diagnostic criteria.

Both the ICD-10 and DSM-V outline diagnostic criteria for bipolar, which differ on some important concepts (e.g. number of episodes needed, whether bipolar is differentiated into two types). As part of the diagnostic assessment, it is important to comment on both the diagnosis and current episode (i.e. mania, hypomania, depressive, mixed).

ICD-10 diagnostic criteria

Classifies bipolar as a single entity: bipolar affective disorder

  • Bipolar affective disorder: at least two mood episodes, one of which must be mania or hypomania.

DSM-V diagnostic criteria

Classifies bipolar disorder into three major categories: bipolar I disorder, bipolar II disorder and cyclothymia

  • Bipolar I disorder: at least one manic episode. Depression episode not required for diagnosis.
  • Bipolar II disorder: at least one major depressive episode and one major hypomanic episode.
  • Cyclothymia: refers to chronic mood disturbance with depression and hypomania symptoms that do not meet the criteria for a full episode.

Differential diagnosis

Clinical assessment coupled with routine investigations are important to exclude other causes of elevated or depressed mood.

Other mental health disorders, substance misuse and medical conditions manifesting with primary mental health symptoms (often termed ‘organic’ causes) need to be excluded. Routine investigations like blood tests (e.g. TFTs, cortisol, haematinics) or neuroimaging (e.g. MRI brain) can be used to look for an organic cause.


  • Mental health disorders: schizophrenia, unipolar depression, personality disorder or anxiety disorder.
  • Substance misuse: cocaine, ecstasy or amphetamines
  • ‘Organic’ causes: thyroid disorder, multiple sclerosis, Cushing’s, Addison’s, cerebrovascular disease, dementia, epilepsy, systemic lupus erythematosus, encephalitis.
  • Iatrogenic causes: antidepressants, corticosteroids, levodopa or dopamine agonists.


Initially, patients should be referred to mental health services to confirm the diagnosis, treat the initial episode and provide an ongoing care plan.

Pharmacological therapies are the cornerstone of treatment and some patients may require admission to hospital for further assessment and treatment. The urgency of a referral for further assessment depends on the severity of the presentation and whether the person poses a risk to themselves or other people.


If a person with confirmed, or suspected, bipolar requires admission to hospital due to deterioration in their symptoms, every effort should be made for it to be a voluntary admission.

Compulsory admission (i.e. being detained) may be necessary if a patient requires assessment and/or treatment and admission is felt to be in the interests of their own health/safety or for the protection of other people. When arranging compulsory admission utilisation of the Mental Health Act is required.

  • Section 135: power to remove a person from a dwelling if it is considered they have a mental disorder and they may be in need of care and attention for this. Assessment at dwelling or remove to place of safety.
  • Section 5(4): temporary nurse holding power. Use if already in hospital. Ability to detain someone in hospital for up to 6 hours.
  • Section 5(2): temporary doctor holding power. Use if already in hospital. Ability to detain someone in hospital for up to 72 hours.
  • Section 2: detained in hospital for up to 28 days for assessment.
  • Section 3: detained in hospital for up to 6 months for treatment.

Pharmacological management

Pharmacological management is usually required to treat and prevent episodes of mania, hypomania and depression. There are a number of treatment options including antipsychotics, mood stabilisers (e.g. lithium, anti-epileptic medications) and anti-depressants. Treatment can be started acutely and then continued as long-term maintenance therapy.

The choice of treatment depends on the patient's co-morbidity, current episode (i.e. mania or depression) and side effects. The main aim of treatment is to stabilise mood without any relapses into mania or depression.

  • Antipsychotics: used as a therapeutic trial to treat mania. May be switched to mood stabiliser once the acute episode resolved. Options can include haloperidol, olanzapine or quetiapine. Newer antipsychotics associated with fewer side effects.
  • Lithium: used for many years, still unclear mechanism. Often referred to as the ‘gold-standard’. Used in acute mania, recurrent depressive episodes or long-term maintenance. Its narrow therapeutic window increases the risk of toxicity and it is teratogenic. Patients on lithium require close monitoring.
  • Antiepileptics: also used as mood stabilisers in bipolar. Options include sodium valproate, lamotrigine or carbamazepine. May be used alone or in combination. It can help prevent depression relapses.
  • Antidepressants: may be restricted due to the risk of inducing mania or rapid-cycling (frequent, distinct episodes). The selective-serotonin reuptake inhibitor fluoxetine is commonly used.

Psychological therapies

Psychological interventions can provide mood regulation and self-management skills to help cope with bipolar disorder more effectively.

Several psychological interventions can be used in bipolar disorder. The general aim of each therapy is to provide information about the condition, enable identification of warning signs and symptoms, and to develop skills to be able to cope with the challenges of living with bipolar.

  • Individual psychoeducation: trained to identify and cope with early warning signs of mania and/or depression.
  • Cognitive behavioural therapy (CBT): talking therapy. Focuses on the emotional response to thinking and behaviour.
  • Interpersonal and social rhythm therapy: focuses on the role of interpersonal factors (i.e. interpersonal relationships, role conflicts) and circadian rhythm stability (i.e. sleep-wake cycle, work-life balance) in the context of bipolar.
  • Group psychoeducation: high frequency and intensity sessions to help patients become experts in their own condition. Aims to improve mood stability, medication adherence and self-management.
  • Family-focused therapy: psychoeducation for families with one individual suffering from bipolar. Looks at risks, communication and problem-solving within the family to prevent relapses.


Bipolar disorder is associated with a high lifetime risk of suicide and self harm.

It is estimated that up to 59% of patients with bipolar have suicidal ideation and up to 56% will attempt suicide at least once in their lifetime. In addition, there are many issues relating to impaired social functioning and disinhibition including, but not limited to, financial difficulties, sexual issues (unplanned pregnancies, sexually transmitted infections), substance misuse and exploitation.

Bipolar disorder has also been linked to other mental and physical health issues including anxiety, attention-deficit hyperactivity disorder (ADHD), alcohol misuse, cardiovascular disease, chronic lung disease and chronic kidney disease.


There is a 50% risk of a recurrence at one year following an acute episode in bipolar disorder.

Bipolar disorder is characterised by periods of remission and subsequent relapse. Overtime, episodes may become more frequent with shorter intervals between them. As more episodes develop, there may be incomplete recovery leading to greater impairment and worse quality of life. Patients with bipolar have a higher risk death from both suicide and cardiovascular disease.


Updated: May 2020 by Benjamin Norton
Author Dr. Benjamin Norton Ben is Medical Registrar in London. Outside of work he enjoys cricket and rugby.

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