Early intervention for bipolar disorder: current imperatives, future directions

ARTICLES

Early intervention for bipolar disorder: current imperatives, future directions

Intervenção precoce no transtorno bipolar: necessidades atuais, rumos futuros

Matthew Taylor^I; Rodrigo Affonseca Bressan^II; Pedro Mario Pan^II; Elisa Brietzke^{II, III}

^IDepartment of Psychosis Studies, Institute of Psychiatry, King's College London

^IIProgram of Recognition and Intervention in Individuals at Risk Mental States, Department of Psychiatry, Universidade Federal de São Paulo, São Paulo, Brazil

^IIIInterdisciplinary Laboratory of Clinical Neurosciences, Department of Psychiatry, Universidade Federal de São Paulo, São Paulo, Brazil

^{Correspondence}

ABSTRACT

OBJECTIVES: The objective of this article is to discuss the rationale/background for early intervention in bipolar disorder.

METHOD: Narrative review.

RESULTS: There are often significant delays before the diagnosis of bipolar disorder is made and effective management initiated. Growing evidence from both preclinical and clinical literature points to a clear need for improved early identification and early intervention in bipolar disorder. Increasing efforts are being applied to the identification of those at high risk of onset of bipolar disorder. It is hoped that identification of an early prodrome of illness will allow preventative measures to be taken.

CONCLUSIONS: There is a clear rationale for improved early identification and early intervention in bipolar disorder.

Descriptors: Bipolar disorder; Early intervention; Review; Determination; Treatment outcome

RESUMO

OBJETIVOS: O objetivo do artigo é discutir os fundamentos para a intervenção precoce no transtorno bipolar.

MÉTODO: Revisão narrativa.

RESULTADOS: Frequentemente existe um atraso significativo com relação ao momento em que o transtorno bipolar é detectado e o início do tratamento. Evidências crescentes oriundas de estudos pré-clínicos e clínicos apontam para a clara necessidade de melhorar a detecção e o tratamento precoces no transtorno bipolar. Esforços também tem sido direcionados para a identificação de indivíduos em alto risco. Espera-se que a identificação do pródromo do transtorno bipolar permita a instauração de medidas preventivas.

CONCLUSÕES: Existem bases claras para o investimento na melhora da detecção e tratamento precoces do transtorno bipolar.

Descritores: Transtorno bipolar; Intervenção precoce; Revisão; Determinação; Resultado de tratamento

Introduction

Bipolar disorder (BD) is a major global health problem that leads to significant lifetime morbidity and mortality. While the onset of illness is typically in youth, there are often significant delays before the diagnosis is made and effective management initiated. Growing evidence from both preclinical and clinical literature points to the clear imperative for improved early identification and early intervention in BD. In addition to this evidence in established BD, increasing efforts are being applied to the identification of those at high risk of onset of BD. Drawing from the success of such an approach in non-affective psychosis, it is hoped that identification of an early prodrome of illness will allow preventative measures to be taken. Here we draw together the current evidence in these areas.

BD remains a clinical diagnosis. The two major diagnostic classification systems worldwide are the International Classification of Diseases, 10th edition (ICD-10) and the Diagnostic and Statistical Manual of the American Psychiatric Association, 4th edition (DSM-IV). In both systems, BD is characterized by episodes of mood disorder. The key feature differentiating BD from recurrent depressive disorders (major or unipolar depression) is the lifetime presence of mania or hypomania or mixed episodes. DSM-IV further distinguishes between bipolar I disorder, where mania is observed, and bipolar II disorder, where hypomania is observed alongside one or more episodes of major depression. The classification is expected to undergo at least some changes with the forthcoming fifth edition of DSM.

Global impact

BD has a worldwide distribution. Clinical samples are likely to underestimate prevalence; the most accurate available estimates come from painstaking epidemiological household surveys. The recent National Comorbidity Survey - Replication (NCS-R)¹ obtained data from 9282 English-speaking adults across the continental USA, finding lifetime prevalence estimates of 1% for bipolar I and 1.1% for bipolar II, with a further 2.4% having subthreshold BD. Similar estimates were obtained by the World Mental Health Survey Initiative², in which face-to-face interviews of 61392 adults across 11 countries in the Americas, Europe, and Asia were performed. Lifetime prevalences were 0.6% for bipolar I, 0.4% for bipolar II, 1.4% for subthreshold BD, and 2.4% for the bipolar spectrum. A large proportion of those surveyed had severe symptoms and role impairment confirming the serious impact of the disorder.

BD is associated with increased mortality. A number of large studies of people admitted to hospitals with BD have found elevated mortality. In a study of over 15000 patients in Sweden, standardized mortality ratios (SMR) in BD for death by suicide were 15.0 for males and 22.4 for females, and for natural causes of death SMRs were also significantly elevated, with most excess deaths from natural causes³. Similar findings were observed in Denmark⁴. Interestingly, in a community sample, identifying all patients with a first presentation of bipolar I, not restricted to those admitted to hospital, an elevated risk of suicide was also described (SMR 9·77, 95% confidence interval [CI] 4·22-19·24), but no significant increase in deaths by other causes was observed⁵. An elevated risk of suicidality is not restricted to those with bipolar I disorder. In a meta-analysis of 15 studies, rates of attempted suicide did not differ between bipolar I and bipolar II disorder⁶.

Early Onset

The onset of illness in BD is often in young adulthood. In an international study of 1566 patients across six sites using modern diagnostic criteria, the median age of onset for bipolar I was 24.3 years, and for bipolar II 30.1⁷. There is some evidence that age of onset characterizes different subgroups of BD patients. In a recent UK study of more than 1000 participants with bipolar I disorder, three distributions were observed; one group with mean onset age of 18.9, another with mean onset age of 28.3, and a third group with mean onset age of 43.3 years⁸. The group with the earliest onset was found to have a stronger family history of mood disorders, and also some markers of greater clinical severity such as greater suicidality, more rapid-cycling, more episodes of mania and depression, and greater scores on lifetime measures of depressive symptoms.

BD can be rapidly recurrent even after a first episode. In a US study of 166 people followed up for two years after their first episode of mania, 40% went on to experience a new episode of mania or depression, and 19% switched phases of illness without recovery⁹. Similarly, in a Canadian study of 53 participants with first episode mania, more than half experienced a new mood episode within the first year of follow-up¹⁰, and earlier age of onset significantly predicted increased recurrence.

Polarity of initial episode appears to play a role in predicting future illness course. In a follow-up of 303 first episode patients from Europe and the US over two years¹¹, first episode polarity strongly predicted the preponderance of future illness. Similarly, a UK study of 553 participants with well characterized bipolar I disorder found that an initial depressive episode at onset was associated with a predominantly depressive polarity and more frequent and more severe depressive episodes¹².

Delayed diagnosis

Diagnosis of BD appears to be commonly delayed in routine practice. An average delay of 10 years between first symptoms and first treatment was reported in a well-characterized international outpatient sample¹³. Similar delays were described by support group participants in the US diagnosed with BD, of whom one third reported having waited 10 years or more before accurate diagnosis¹⁴. In a retrospective study of over 200 people in Australia, while their symptoms on average had initially started by the age of 18, and medical treatment been sought at 24 years old, the median age at diagnosis was 30 years¹⁵. The most common previous diagnosis in both these samples was of unipolar depression.

A delayed diagnosis may have a range of adverse effects. In studies of outpatients with BD, increased delay in diagnosis and initiation of appropriate treatment has been associated with increased severity of depression^16,17, decreased quality of life¹⁶ and greater likelihood of attempted suicide¹⁸. Unsurprisingly, given these clinical adverse effects, healthcare costs have also been found to increase with each month of delayed diagnosis of BD¹⁹.

Diagnostic error

In the early stages of BD, two key causes of diagnostic error can be differentiation from major depressive disorder or other psychotic illness. The differentiation of BD from unipolar depression represents a common clinical challenge. As it becomes clearer that the optimal management of bipolar and unipolar depression differs, with conventional antidepressants showing disappointing efficacy in recent studies and carrying risks of increased mood instability, the importance of making this distinction becomes greater. Inevitably, some people who experience only depressive episodes early in the course of their illness will 'convert' to bipolar on experiencing their first episode of hypomania or mania. A number of attempts have been made to differentiate episodes of bipolar and unipolar depression on the basis of observed symptoms.

A recent synthesis noted that 'atypical' features such as hypersomnia, hyperphagia, and leaden paralysis, psychomotor retardation, psychotic features, pathological guilt, and lability of mood were more common in bipolar depression²⁰. Bipolar depression was also associated with an earlier age of onset of first depressive episode, more prior episodes of depression, shorter depressive episodes, and a family history of BD. A prospective validation of this 'probabilistic' approach has yielded promising results²¹. Another recent comparison of symptom features between large numbers of people with unipolar and bipolar illness similarly linked the presence of psychosis, diurnal mood variation and hypersomnia during depressive episodes, and a greater number of shorter depressive episodes, with bipolar diagnosis²². There are thus emerging pointers towards the possibility of identifying those with a higher risk of a bipolar illness even before mood elevation is experienced.

Some people who have already experienced hypomania or mania are mistakenly diagnosed with recurrent depressive disorder. This may be made more likely since hypomanic symptoms may not necessarily be identified as pathological by the patient, and may thus not be spontaneously reported. Screening tools such as the Hypomania Checklist (HCL-32)²³ and Bipolar Spectrum Diagnostic Scale (BSDS)²⁴ may be of benefit, although symptoms identified may not reach current diagnostic thresholds for BD²⁵.

Increasing interest is attached to the presence of 'subthreshold' bipolarity in people currently diagnosed with major depression, such as might be identified by these screening instruments. This has the potential to greatly expand the boundaries of BD. In a 20-year prospective community cohort study of young adults, it was found that a broad definition of bipolar II disorder gives a cumulative prevalence rate of 10.9%, compared to 11.4% for broadly defined major depression²⁶. Using current classifications, the prevalence of BD is lower than that of unipolar depression; for example, in the NCS-R study the lifetime prevalence of major depressive disorder was 16.6%, whereas for bipolar I and II it was 3.9%²⁷. However, nearly 40% of study participants with a history of major depressive disorder had a history of subthreshold hypomania²⁸. This more bipolar' subgroup had a younger age at onset, more episodes of depression, and higher rates of comorbidity than those without a history of hypomania, which suggests that the difference may come to be of clinical significance.

A proportion of people presenting with a first episode of apparently non-affective psychosis will go on to be ultimately diagnosed with BD. Psychotic features are not uncommon during mania. In the McLean-Harvard First-Episode Mania Study, studying people during a first manic/mixed episode of bipolar I disorder, most subjects (88.6%) had some initial psychotic features⁹. In the McLean-Harvard International First Episode Project, patients hospitalized in a first psychotic episode were assessed by standard criteria at baseline and at 24 months²⁹. Of 500 participants completing the study, the authors found that initial diagnoses of bipolar I disorder remained stable in 96.5% of cases. However, over one quarter of changes in diagnosis were from another psychotic illness at baseline to bipolar I disorder after two years. It is therefore important to be alert for the development of BD in people with early psychosis.

Comorbidity

Comorbidity is common in BD. In the World Mental Health Survey Initiative, three quarters of patients had at least one comorbidity, commonly anxiety disorders and substance/alcohol abuse². Follow-up of a cohort of 591 individuals (292 men and 299 women) in Zurich, Switzerland, who received six waves of diagnostic interviews over a 20-year period³⁰, allowed for clarification of the chronology of that comorbidity. Participants with manic symptoms were found to be at elevated risk for the later onset of problems with alcohol, cannabis and benzodiazepines. Bipolar II disorder predicted problems with alcohol and benzodiazepines. By contrast, there is some evidence that anxiety disorders tend to precede the onset of BD³¹.

Personality disorder can also pose an important comorbidity³². The emotional instability of borderline personality disorder can lead to its being viewed as a differential diagnosis of BD, or delay recognition of bipolar comorbidity. In clinical practice many patients with borderline personality disorder also meet diagnostic criteria for BD³³.

Illness progression

There is increasing evidence pointing to disease progression over time. Almost one century ago, Kraepelin noted that people with BD presented a progressively worse clinical course over time, with a shortening of inter-episodic periods³⁴. Strong evidence now confirms that recurrence rates increase with further episodes of illness^35-37. This effect persists even when adjustments are made for individual differences in frailty toward recurrence.

There is evidence from cross-sectional studies that a worse prior course of illness is associated with greater neuropsychological dysfunction³⁸. Even early in illness, impaired cognitive functioning has a major impact in functional outcome³⁹. Consistent with this, with a greater number of episodes of illness requiring hospital admission comes a greater degree of sustained functional impairment, even in euthymic patients⁴⁰.

There is evidence that progression may increase the risk of treatment resistance. In an analysis of multiple trials of olanzapine in the treatment of BD, it was found that those in the earlier stages of illness had a more favorable response to treatment⁴¹. A similar effect has also been reported for response to lithium, although this is not consistent across all studies⁴². A potential increase in treatment non-response is not restricted to pharmacological management. In a meta-analysis of psychological interventions to prevent relapse in BD, it appeared that the psychological therapies were less effective in those with a high number of previous episodes⁴³.

A substantial body of neuroimaging evidence now demonstrates abnormalities in brain structure in BD. For example, a major meta-analysis demonstrated enlargement of the lateral ventricles and increased rates of deep white matter hyper intensities in BD⁴⁴. More recently, an analysis of individual patient data combined across eleven research groups demonstrated a reduction in overall cerebral volume with increased illness duration⁴⁵. This reduction in cerebral volume with longer duration of illness is consistent with a neurodegenerative process in the pathophysiology of BD.

How can this disease progression be understood? Post and collaborators proposed the 'kindling model', in which parallels were drawn between observations in the experimental induction of seizures, illness progression, and drug tolerance in affective disorders such as BD^46,47. These clinical observations could be understood as reflecting long-term changes in gene expression and downstream consequences altering a balance between pathological and compensatory systems. More recently, Kapczinski and collaborators developed the idea of 'allostatic load', where the genetic background interacts with an accumulating burden of biological 'wear and tear' due to different environmental stressors and the effects of illness episodes themselves⁴⁸. It appears that disease progression may reflect an interaction of multiple processes⁴⁹. These may not be restricted to changes in neurotransmitter systems, but may include changes in inflammatory cytokines and neurotrophins, such as BDNF⁵⁰, and mitochondrial dysfunction⁵¹ with increased oxidative stress⁵². Importantly, the convergence of preclinical and clinical data point to a key role for early and sustained preventative measures, not only to avoid episodes of illness itself, but also potentially to prevent the associated accumulation of neurobiological vulnerability factors.

Management

Comprehensive guidance on the management of BD is beyond the scope of this article and can be found elsewhere⁵³. The major clinical problems can be considered the treatment of acute episodes of bipolar depression, manic or mixed episodes, and the prevention of relapse. Appropriate pharmacological management is a mainstay of effective treatment, although it is important to recognize that pharmacological agents need to be delivered as part of a coherent package of care that may also involve specific psychological therapies⁵⁴ and other psychological and social support. For example, there is evidence that effective treatment of substance misuse comorbidity can improve both adherence and outcomes. In the STEP-BD study, patients with BD who experience sustained remission from substance use disorders fared better than patients with ongoing substance use disorders, but not as well as subjects with no history of substance-related problems⁵⁵.

Recent years have yielded a much improved evidence base to guide general management. On the one hand, the increasing availability of systematic reviews and meta-analyses allows the existing literature to be better understood. Furthermore, independent, high quality, randomized controlled trials have begun to provide answers to some of the important clinical questions in the management of acute episodes of illness^56,57 and prevention of relapse⁵⁸. Key recent findings include increasing evidence that bipolar depression may require rather different management than unipolar depression⁵⁹. Future studies could investigate whether the presence of predictors of bipolarity in unipolar depression warrants differential management, even if full diagnostic criteria for BD are not met. Remission from depressive symptoms is an important treatment aim, since even subsyndromal depressive symptoms are associated with functional impairment and disability⁶⁰.

Preventative treatment is recognized as increasingly important. Traditionally, particularly in European guidelines, prophylactic medication has often been reserved for cases where multiple episodes of illness occur in rapid succession⁶¹, however, a case can be made for considering preventative medication after a single severe manic episode⁵³.

As noted above, there is a growing theoretical rationale for early prevention. Some initial data suggest that lithium may play a neuroprotective role, preventing structural changes in hippocampus and amygdala⁴⁵. There is also concrete clinical evidence of substantial benefits on major outcomes. Data from controlled trials indicate that people with BD randomized to receive lithium treatment have both decreased suicide rates and all-cause mortality⁶². Psychological interventions have an important role as an adjunct to pharmacological management⁶³, with effects that appear to be sustained well after the course of therapy.

Specialized early intervention services

There remains uncertainty around whether there are specific differences in appropriate treatment models for the earliest stages of BD. The lesson of early intervention services for psychosis has been that they can offer substantial benefits including significant positive effects on psychotic and negative symptoms, secondary substance abuse, treatment adherence, and a higher satisfaction with treatment⁶⁴. It appears that early treatment of psychosis allows for the use of lower doses of antipsychotic medication⁶⁵. Multicenter randomized trials are underway to investigate whether similar specialized care in the early stages of severe affective disorders proves superior to treatment as usual⁶⁶.

Identifying at-risk individuals

Building on the clinical and neurobiological evidence of disease progression outlined above, staging models are beginning to be developed⁶⁷. Similarly to the approach taken for some general medical conditions, an effective staging model could provide a structure for assessment and most appropriately direct therapeutic efforts. These might include people in a prodrome to the onset of BD proper to whom preventative measures could be offered.

Can a prodromal period be clinically defined? A number of studies, both retrospective and prospective, have aimed to identify features of this period⁶⁸. Taken together, these studies indicate that symptoms can predate the onset of BD proper by months to years and can be attenuated forms of bipolar symptoms, general symptoms common to a range of mental disorders, and personality traits, such as cyclothymia. However, none of these features show high sensitivity for progression to BD. Another recent review concluded that the specificity of prodromal symptoms and signs appears to be low⁶⁹. It has been noted that a bipolar prodrome may in some cases be indistinguishable from the schizophrenia prodrome based on clinical and neurocognitive measures currently used in high-risk schizophrenia programs⁷⁰. Thus, clinical features alone may not prove sufficient for all cases.

Genetics play a major role in BD⁷¹. Estimates of heritability from twin studies place it at over 80%^72,73, and there is also a gradation of risk of mood disorder according to the degree of genetic relatedness⁷⁴. Family history is thus a strong putative method for identifying people at elevated risk of developing BD. Observational studies found that the offspring of bipolar parents shows a high risk for psychiatric disorders, and specifically for early-onset bipolar spectrum disorders^75-77.

A number of ongoing studies aiming to prevent conversion to BD combine family history with the presence of (non-specific) symptoms to identify a high risk group for intervention. A recent Melbourne study identified at-risk groups by the presence of subthreshold mania, depression with cyclothymia, or depression together with having a first degree relative with BD⁷⁸. These criteria showed some initial success in identifying people who would progress to a BD diagnosis. Specific intervention may prove valid for such groups. High rates of response have been reported in uncontrolled studies of young people with symptoms and a positive family history of BD for both valproate⁷⁹ and quetiapine⁸⁰. A version of family-focused treatment adapted for youth at high risk for BD (FFT-HR) has also been developed, with promising initial results in a similar group with active mood symptoms and a positive parental history⁸¹.

Conclusions

Growing evidence points to the clear clinical imperative for improved early identification and early intervention in BD. In particular, preclinical and clinical evidence points to the importance of early and sustained treatment for relapse prevention. In addition to this evidence in established BD, increasing efforts are being applied to the identification of those at high risk of onset of BD. Drawing from the success of such an approach in non-affective psychosis, it is hoped that the identification of an early prodrome of illness will allow preventative measures to be taken.

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Publication Dates

• Publication in this collection
  26 Jan 2012
• Date of issue
  Oct 2011