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bipolar_disorder

bipolar disorder

Introduction

  • bipolar disorder is characterised by episodic depressions and elevations of mood
    • bipolar I involves manic symptoms which last for at least a week and are severe enough to markedly impair functioning or require hospitalisation
    • bipolar II involves hypomania in which elevated symptoms are less severe but still clearly different from usual mood and last for at least four days
      • Importantly, patients with only hypomanic but no manic episodes (bipolar II pattern) do not tend to progress to bipolar I manic states
    • In both forms of the illness, depressive episodes tend to be more frequent and disabling than mania.
  • lifetime prevalence of bipolar disorders is estimated at 1-4% of the general population.
  • suicide is attempted by 25-50% of sufferers.
  • overall 15% of people with bipolar disorders die by suicide.
  • accurate diagnosis depends on recognising often under-reported symptoms of elevated mood.

Mania episodes

  • episodes of mania typically require inpatient management and require sedation to reduce psychomotor acceleration.
  • resolution of the acute mania episode takes weeks to months. Approximately 50% of patients with mania will respond to monotherapy with any antimanic drug, and around 70-75% will respond to combination therapy.

Hypomanic episodes

  • Due to the shorter duration of hypomanic episodes, and the lack of marked impairment, hypomania is less frequently the presenting symptom of the illness. Patients with hypomania may feel energetic and creative, and may not need much sleep.
    • Nonetheless, hypomanic episodes are a core precipitant of downward mood destabilisations into major depressive episodes, and thus warrant active treatment, even though depression is invariably the reason patients present for treatment in bipolar II disorder.

Mixed episodes

  • “Mixed states are characterised by elevated and depressed mood mixed together and are among the most difficult mood conditions to identify. Elevated symptoms can be brief, and include racing and 'crowded' thoughts, lability of affect, insomnia and restlessness. Specific pharmacotherapy for mixed states is extrapolated from treatments for mania. One crucial factor is to avoid antidepressants during such mixed states, as they will exacerbate and sometimes trigger the episodes. This can be counterintuitive, when patients present with a dysphoric affect. Mixed states are the most under-recognised of the bipolar specific states, and it is likely that many mixed states are triggered by antidepressants. If a patient's agitated depressive symptoms seem to worsen with antidepressants, consider the possibility of a mixed state and bipolar diagnosis.”

Pharmacologic Mx of elevated mood component

  • mood stabilisers such as lithium, some anticonvulsants Rx and prevent mood elevations, and to a lesser extent help control depressive episodes.
  • the basic principle of maintenenance Rx is that most patients with recurrent, severe or disabling illness are highly likely to benefit from prophylactic treatment. Usually (but not always) the maintenance treatment will be a continuation of the drug that was effective for acute treatment.

1st line

    • although lithium was first discovered to be effective in mania in 1949, by the Melbourne psychiatrist John Cade, it is still the 'gold standard' therapy.
    • many patients are unable to tolerate lithium and it has limited effectiveness for the depressive phase of bipolar disorders.
    • many patients on lithium suffer from frequent and prolonged depressive episodes, despite dramatic suppression of the periods of elevated mood.
    • non-compliance is common (20-50% of patients) and if lithium is abruptly discontinued, the chance of sudden relapse into mania is considerable.
    • the main drawbacks of lithium are the need for serum concentration monitoring, the possibility of serious toxicity, and the risk of thyroid (and less commonly renal) impairment.
    • tremors, increased muscle tone, hyperreflexia and disorientation are signs of severe toxicity.
  • 2nd generation anti-psychotic medications - olanzapine, risperidone, quetiapine, aripiprazole, ziprasidone

2nd line

3rd line

  • electroconvulsive therapy (ECT)
  • clozapine (but efficiency decreased with smoking)

Pharmacologic Mx of depressed mood component

  • The best current evidence for efficacy in bipolar depression exists for lithium, quetiapine and lamotrigine.
  • antidepressants place patients at risk of switching to elevated phases of the disorder and rapid cycling patterns.
  • if an antidepressant is used, it should be concurrent with a mood stabiliser and with frequent review to watch for destabilisation.
    • usually an SSRI is best but as fluoxetine has a five-week washout period it is best avoided in bipolar conditions in case mood destabilisation necessitates cessation.

Other references

bipolar_disorder.txt · Last modified: 2009/05/01 00:05 (external edit)