Dr Paul McLaren gives an overview of this complex condition and the treatments available
Bipolar disorder is characterised by episodes of depression, mania or mixed states that usually recur and become more frequent as the patient ages.
A diagnosis of bipolar I is made when a person has experienced at least one episode of severe mania; a diagnosis of bipolar II is made when a person has experienced at least one hypomanic episode, but has not met the criteria for a full manic episode.
Clinical presentation is often complex and up to 50 per cent of cases may be misdiagnosed, delaying effective treatment. Rapid cycling and mixed affective states can be particularly difficult to recognise and rapid changes in mood and behaviour may be misinterpreted as evidence of personality disorder or attention deficit hyperactivity disorder. Speaking to a relative is often required to establish a diagnosis.
The lifetime prevalence is 1.6 per cent for mania, but may increase to 2-5 per cent if bipolar II and cyclothymic cases are included, representing about 30 per cent of all major mood disorders. The wide range reflects the difficulty in diagnosing non-classical bipolar disorder in research studies, let alone clinical practice.
Untreated bipolar disorder leads to suicide in nearly 20 per cent of cases.
The main clinical burden in both bipolar I and bipolar II is protracted, disabling depression. It has been estimated that sufferers are in depression 32 per cent of the time. The World Health Organisation estimates that bipolar disorder is the sixth leading cause of disability in the world.
When depressive symptoms are present during a manic phase, risks to the patient are increased if the diagnosis and treatment is that for depression. Some 30 per cent of suicides in bipolar disorder take place during mixed manic episodes.
Similar diagnostic difficulties are present in mixed depressive states, for example when a major depressive episode is associated with intra-episode hypomanic signs or symptoms. Early diagnosis matters as treatment with antidepressants alone may trigger mania or lead to rapid cycling.
About 90 per cent of patients who suffer a single manic episode have future recurrences. For 15 per cent the course becomes chronic and for those with a relapsing and remitting course the average time between episodes is two to three years early on and
intervals shorten to eight to nine months
after six-to-eight recurrences.
Patients should be told they have a recurrent illness, but that, through learning about their illness and effective early management, the impact can be significantly reduced. The total time spent in illness has been estimated at between 20-47 per cent.
Data from family, twin and adoption
studies shows genetic factors are involved in the transmission of bipolar disorder. In most cases, the aetiology is complex, with vulnerability produced by the interaction of multiple genes and non-genetic factors.
Some 85 per cent of treatment for bipolar disorder currently rests in primary care.
As mentioned previously, treatment with antidepressants alone may trigger mania or lead to rapid cycling, so bipolar disorder remains a significant treatment challenge because the aim is to relieve distress from a life-threatening and often severely disabling state without precipitating mania.
A significant proportion of patients will require antidepressants, but these should only be given with a mood stabiliser (valproic acid or lithium) or antipsychotic.
Lithium is a weak antidepressant alone, but evidence is encouraging for the soon-to-be-licensed Class B antidepressant mood stabiliser lamotrigine. Some recent studies have shown it is more effective than lithium.
It could be that a combination of anti-manic mood stabiliser and antidepressant mood stabiliser (lamotrigine) is the optimum treatment for some bipolar patients. ECT is indicated, as with unipolar depression, and does not appear to lead to rapid cycling. Patients who fail to respond to treatment in primary care should be referred.
Treating acute mania
Acute mania requires urgent intervention, as episodes can be highly destructive. Loss of insight and poor adherence demand early assessment, with a view to obtaining compulsory treatment. The treatment may include neuroleptics, atypical antispychotics and ECT, as well as mood stabilisers.
Where urgent behavioural control is required or psychotic symptoms are prominent, an antipsychotic such as olanzapine is an appropriate first-line. Benzodiazepines may facilitate early stabilisation. Lithium is an effective anti-manic agent.
One review suggested 60 to 70 per cent of patients responded within 10 days. Valpro-ate has been shown to be as effective as lithium. There is also evidence for the efficacy of carbamazepine in acute mania, although this is less popular.
Rapid cycling disorder
Rapid cycling disorder is the most destructive and difficult to treat form of the illness. It is not fully understood why some patients experience it or why they need two or even three mood stabilisers. But there is clinical consensus that antidepressants should be discontinued as the first step.
Long-term maintenance treatment should be considered where relapse is frequent and disabling. Most evidence is for bipolar I disorder, but even in trials, early discontinuation is frequent. The only drugs licensed in the UK for long-term treatment are lithium, carbamazepine (for lithium non-responders) and olanzapine.
Others such as valproate, lamotrigine, risperidone and quetiapine are also commonly given long-term. All require monitoring. Lithium should be maintained in the range of 0.4-1.0mmol/l and patients should be warned of the risks of rebound mania with abrupt discontinuation. Research has shown lithium maintenance can reduce the time spent in illness by half. It is more effective at reducing manic than depressive relapse.
New psychological interventions are starting to have an impact as an adjunct to pharmacological treatments.
Psycho-education for patients and their families can make a significant impact and CBT techniques tailored to individuals can improve self-monitoring and enhance adherence. While well-stabilised, well-educated patients can lead normal lives, the general outcomes for bipolar disorder remain far from satisfactory.
Paul McLaren is honorary consultant psychiatrist at South London and Maudsley NHS Trust and medical director at the Priory Ticehurst House, Wadhurst, East Sussex
Competing interests None declared