GPs typically see three cases of bipolar disorder during their career, but 85 per cent of treatment for these conditions is in primary care. Patients should be referred initially to secondary care, but once diagnosed and stabilised are usually managed in primary care.
The age of onset is usually 25–35 years. There tends to be a gap of six to eight years between the first depressive episode and the first episode of mania.
Data from family, twin and adoption studies show that genetic factors are involved in bipolar disorder, but in most cases the aetiology of the disorder is complex, with multiple genes and non-genetic factors combining to make patients vulnerable to the condition.
Bipolar disorder is divided into two main types: bipolar I disorder and bipolar II disorder. In bipolar I disorder there are recurrent episodes of mania and depression.
Severe episodes of mania or depression may include psychosis, which usually takes the form of hallucinations and delusions echoing the patient’s current mood state. Some patients may present with a mixed bipolar state.
When four or more episodes of illness occur within 12 months the patient has rapid-cycling bipolar disorder.
Patients may also experience multiple episodes in a single week or in a day, and in some cases of bipolar disorder the cycles are so rapid that patients can swing high to low minute to minute.
Rapid cycling tends to develop later in the course of the illness and is more common in women than men.
Bipolar II disorder has hypomanic but not manic episodes, and does not include psychotic features. Bipolar II disorder is characterised by one or more major depressive episodes accompanied by at least one hypomanic episode.
The hypomania associated with bipolar II disorder does not cause marked impairment of functioning or require admission. Correct diagnosis is important with bipolar II disorder because of the high rates of alcohol and drug misuse, and the higher frequency and severity of depressive episodes.
If bipolar II disorder is misdiagnosed as simple depression, treatment will cause more rapid cycles in mood.
Patients should be told that they have a chronic, recurring illness and that its impact can be ameliorated by early treatment, sustained pharmacotherapy and psychotherapy.
Mood stabilisation must be started as soon as possible. For some patients, the combination of an anti-manic mood stabiliser and an antidepressant mood stabiliser represents the optimum treatment.
A significant proportion of patients will require antidepressants, which should only be given with a mood stabiliser to reduce the chance of it inducing a switch to either a manic episode or rapid mood cycling.
When depressive symptoms are present during a manic phase the patient is placed at risk if they are diagnosed and treated for depression; 30 per cent of suicides in bipolar patients take place during mixed manic episodes.
Acute mania requires urgent intervention.
When urgent behavioural control is needed or when psychotic symptoms are prominent, an antipsychotic such as olanzapine is an appropriate first-line treatment for stabilisation.
Lithium is an effective anti-manic agent; one review suggested that 60 to 70 per cent of patients responded within seven to 10 days.
It has been the treatment of choice over the last 20 years, but requires monitoring of the thyroid, particularly in females, where 30 per cent can suffer from hypothyroidism, and it is less effective for rapid cycling and mixed states.
Valproate has been shown to be as effective as lithium and there is also evidence for the efficacy of carbamazepine in acute mania.
Although semisodium valproate is extremely effective, it can have serious side-effects.
The medication of choice for bipolar II disorder is lamotrigine, although it is not officially licensed for this purpose. It is the treatment most commonly prescribed by psychiatrists.
Long-term maintenance treatment is essential when relapse is frequent. The only drugs currently licensed in the UK for long-term treatment are lithium, carbamazepine and olanzapine. However, other drugs such as valproate, lamotrigine, risperidone and quetiapine are commonly administered long-term.
Lithium should be maintained in the range of 0.4-1.0mmol/l and patients should be warned of the risk of rebound mania if they discontinue treatment abruptly. Lithium maintenance can achieve a 50 per cent reduction in the time spent in illness.
Compliance is an issue: most patients stop lithium too early. On average the treatment is taken for 76 days, yet the recommended treatment period is at least two years.
Approximately 90 per cent of people who suffer a single manic episode have recurrences, and the course becomes chronic for 15 per cent. For those with a relapsing and remitting course, the average time between episodes is two to three years early in the illness, with intervals shortening to eight to nine months after six to eight episodes.
Dr Soutzos is a consultant psychiatrist at the Priory Hospital, Roehampton