Kindling in bipolar disorders: a longitudinal follow-up study

Relationships between recurrence and polarity in major depressive disorders: Pooled analysis of the BRIDGE and BRIDGE-II-MIX cohorts

BACKGROUND

current classifications of mood disorders focus on polarity rather than recurrence, separating bipolar disorder from major depressive disorder (MDD). The aim of the present study is to explore the possible relationships between number and frequency of depressive episodes and clinical variables associated to bipolarity, in a large sample of MDD patients.

METHODS

the clinical characteristics of 7055 patients with MDD were analyzed and compared according to the number and frequency of depressive episodes. Two stepwise backward logistic regression model were used to identify the predictive value of clinical features based on the presence of high number (≥3 episodes) and high frequency (≥3 episodes/year) of depressive episodes.

RESULTS

high-recurrence and high-frequency MDD patients showed greater family history for bipolar disorder, higher prevalence of psychotic features, more suicide attempts, higher rates of treatment resistance and mood switches with antidepressants (ADs) and higher rates of bipolarity diagnosis according to Angst criteria, compared to low-recurrence and low-frequency patients. Logistic regressions showed that a brief current depressive episode, a previous history of treatment resistance and AD-induced mood switches, a diagnosis of bipolarity and comorbid borderline personality disorder were the variables associated with both high-recurrence and high-frequency depression.

LIMITATIONS

the study participating centers were not randomly selected and several variables were retrospectively assessed.

CONCLUSIONS

even in the absence of hypomanic/manic episodes, high-recurrence and high-frequency MDD seem to be in continuity with the bipolar spectrum disorders in terms of clinical features and, perhaps, treatment response.

Kindling of life stress in bipolar disorder: comparison of sensitization and autonomy models

Research on life stress in bipolar disorder largely fails to account for the possibility of a dynamic relationship between psychosocial stress and episode initiation. The kindling hypothesis (Post, 1992) states that over the course of recurrent affective disorders, there is a weakening temporal relationship between major life stress and episode initiation that could reflect either a progressive sensitization or progressive autonomy to life stress. The present study involved a comprehensive and precise examination of the kindling hypothesis in 102 participants with bipolar II disorder that allowed for a direct comparison of sensitization and autonomy models. Polarity-specific tests were conducted across the continuum of event severity with respect to impact and frequency of life events. Hypotheses were polarity- and event-valence specific and were based on the stress sensitization model. Results were only partially consistent with the sensitization model: Individuals with more prior mood episodes had an increased frequency of minor negative events before depression and of minor positive events before hypomania. However, the number of past episodes did not moderate relationships between life events and time until prospective onset of mood episodes. These results are more consistent with a sensitization than an autonomy model, but several predictions of the sensitization model were not supported. Methodological strengths, limitations, and implications are discussed regarding putative changes in stress reactivity that may occur with repeated exposure to mood episodes in bipolar II disorder.

Anticonvulsant drugs in bipolar disorder

Although much progress has been made in successfully treating bipolar disorder, there is increasing awareness of the limitations of traditional treatment regimens such as lithium and neuroleptics. The large family of anticonvulsant drugs, however, appears to be capable of providing new treatment options, not only as medication of second choice in patients refractory to treatment, but often as a treatment standard with high efficacy and low incidence of side effects. Besides established mood stabilizers such as carbamazepine and valproate, new antiepileptic drugs are entering the field with promising initial results in the treatment of bipolar patients. Furthermore, bringing to light the mechanisms of action of anticonvulsants and the similarities between anticonvulsants effective in bipolar disorder may also deepen our understanding of the pathophysiological basis of the disorder.

US psychiatric residents' treatment of patients with bipolar disorder

We aimed to evaluate the practice patterns of US postgraduate year (PGY) levels 3 and 4 psychiatric residents in the treatment of patients with bipolar disorder (BD) types I and II. We also aimed to determine whether confidence in prescribing mood stabilizers is associated with residents' practice patterns. The residency training directors of 182 Accreditation Council for Graduate Medical Education-accredited US psychiatric residencies were solicited for study participation via e-mail. Their chief residents were asked to forward an online survey Web link to all PGY-3 and PGY-4 residents in their program. The survey was a cross-sectional, online questionnaire, evaluating residents' treatment choices for their BD patients in their psychopharmacology clinics during the last academic year (July 1, 2009, to May 1, 2010), along with resident confidence level in using mood stabilizers. The survey Web link was distributed to 769 residents, and 177 (23.0%) responded to the survey. The percentage of residents who did not initiate treatment in the past year with mood stabilizers was 24.5% for lithium, 26.9% for lamotrigine, 36.7% for valproate, and 73.6% for carbamazepine. Confidence in initiating treatment with each of the 4 mood stabilizers was significantly associated with the number of patients treated with each mood stabilizer in the past year. Residents reported having the lowest confidence with carbamazepine followed by lamotrigine, lithium, and valproate. Experience prescribing first-line treatments for BD, such as lithium and valproate, is inadequate for many US psychiatric residents. Psychiatry residency directors should ensure that their residents have sufficient opportunity to pharmacologically treat BD patients so that these young physicians may develop confidence using an array of evidence-based treatments.

Bipolar disorder

Bipolar disorder is a serious disorder of mood that is associated with considerable psychosocial and economic morbidity. Even though it is more common than previously thought, it has until relatively recently been somewhat neglected in terms of research when compared to disorders such as schizophrenia and major depression. Recent advances in the fields of nosology, epidemiology, and molecular genetics in particular have begun to unravel some of the complexity of this disorder and the next few years are likely to witness substantial changes to the ways in which the broad spectrum of bipolar disorders is diagnosed and managed.

Episode cycles with increasing recurrences in first-episode bipolar-I disorder patients

BACKGROUND

Preliminary review of a century of studies of the course of manic-depressive syndromes produced 40 reports, of which approximately one-third report evidence of shortening wellness intervals or cycle-lengths with more recurrences, and two-thirds did not.

METHODS

We evaluated inter-episode intervals (cycle-length) in 128 clinically-treated, DSM-IV bipolar-I disorder patients followed prospectively and systematically over 5.7 years, with 6.5 episodes/person.

RESULTS

As expected, cycle-length varied inversely with total cycle-count/person; however, multivariate linear regression found only longer initial hospitalization and fewer total cycles to be associated with cycle-length, whereas cycle-number (1, 2, 3, etc.), sex, intake-age, and first-episode polarity were not. Regression of within-subject cycle-length versus cycle-number yielded individual slope-functions with pseudo-random distribution (28% fell within ±1 month/cycle of the null [zero-slope]). Mean duration of early and late euthymic intervals (cycles 2 vs. 5) in patients with matched recurrence-counts was nearly identical.

CONCLUSIONS

The course of bipolar-I disorder from onset was largely random or chaotic over nearly 6 years from onset. Only a minority of patients showed either cycle-acceleration or slowing, without changes in wellness intervals. The findings may be influenced by treatment-effects, but seem to indicate that most current bipolar-I disorder patients are unlikely to show progressive shortening of recurrence-cycles.

Life stress and kindling in bipolar disorder: review of the evidence and integration with emerging biopsychosocial theories

Most life stress literature in bipolar disorder (BD) fails to account for the possibility of a changing relationship between psychosocial context and episode initiation across the course of the disorder. According to Post's (1992) influential kindling hypothesis, major life stress is required to trigger initial onsets and recurrences of affective episodes, but successive episodes become progressively less tied to stressors and may eventually occur autonomously. Subsequent research on kindling has largely focused on unipolar depression (UD), and the model has been tested in imprecise and inconsistent ways. The aim of the present paper is to evaluate evidence for the kindling model as it applies to BD. We first outline the origins of the hypothesis, the evidence for the model in UD, and the issues needing further clarification. Next, we review the extant literature on the changing relationship between life stress and bipolar illness over time, and find that evidence from the methodologically strongest studies is inconsistent with the kindling hypothesis. We then integrate this existing body of research with two emerging biopsychosocial models of BD: the Behavioral Approach System dysregulation model, and the circadian and social rhythm theory. Finally, we present therapeutic implications and suggestions for future research.

Do we need to flick the switch? The need for a broader conceptualization of iatrogenic course aggravation in clinical trials of bipolar disorder

The term 'switching' is often used in bipolar disorder when describing polarity changes in bipolar disorder, but this term is ambiguous and imprecise, and is sometimes used interchangeably with the term 'cycling'. Furthermore, polarity changes in bipolar disorder can be understood in different ways, because their clinical manifestations range from the emergence of subthreshold symptoms to a full episode of the opposite pole. Besides the need to tighten the meaning of the term 'switching', this paper also argues that switching does not adequately describe the complex phenomena that occur with course aggravation of bipolar disorder, such as alteration in episode frequency or amplitude. A more-fine grained approach to course aggravation in bipolar disorder is proposed, which incorporates trans-polar switching, index polarity aggravation, as well as alterations in episodic amplitude, episodic duration, and inter-episode length. This approach has the potential to capture a broader, more fine-grained and clinically relevant picture of the process of aggravation of the bipolar cycle.

Anticonvulsants in bipolar disorder

Anticonvulsant drugs are widely used in psychiatric indications. This includes alcohol and benzodiazepine withdrawal symptoms, panic and anxiety disorders, dementia, schizophrenia, and to some extent personality disorders. Besides pain syndromes, their main domain outside epilepsy, however, is bipolar disorder. Carbamazepine, valproate, and lamotrigine are meanwhile recognized mood stabilizers, but several other antiepileptic drugs have also been tried out with diverging or inconclusive results. Understanding the mechanisms of action and identifying similarities between anticonvulsants effective in bipolar disorder may also enhance our understanding of the underlying pathophysiology of the disorder.

In vivo pharmacological effects of JZP-4, a novel anticonvulsant, in models for anticonvulsant, antimania and antidepressant activity

JZP-4 is a potent calcium and sodium channel blocker, which is currently being evaluated in patients as an anticonvulsant and mood stabilizer. In the current studies, JZP-4 was evaluated in a variety of animal models for anticonvulsant, antimania and antidepressant activity. In the mouse and rat maximal electroshock models, JZP-4 was slightly more potent than LTG. In the mouse pentylenetetrazole induced seizures model, JZP-4 was approximately twice as potent as lamotrigine in prolonging the time to clonus. In the mouse 6-Hz model for drug resistant or refractory epilepsy, JZP-4 had potent anticonvulsant activity at all current intensities, whereas LTG was active at only the lowest current intensity. In the mouse amphetamine-chlordiazepoxide model for antimanic effects, JZP-4, but not LTG, produced dose-related and significant effects at 3 and 10 mg/kg i.p. In the rat forced swim model of antidepressant activity, JZP-4 (30 mg/kg i.p.) produced a significant reduction in immobility and an increase in climbing behavior. LTG (30 mg/kg i.p.) produced similar effects but these effects did not achieve statistical significance. The specificity of this antidepressant response was confirmed in the rat locomotor test. In this test, JZP-4 produced dose-related and significant reductions in locomotor activity, indicating that it was not a CNS stimulant. LTG produced no significant effects in the rat locomotor test. The studies have demonstrated that JZP-4 has greater potency and efficacy than LTG in models of refractory epilepsy, antidepressant activity and antimania activity. The variance between the effects of LTG and JZP-4 may be related to the greater potency at sodium channels or the additional pharmacological actions of JZP-4 on calcium channels.

Bipolar disorder and epilepsy: a bidirectional relation? Neurobiological underpinnings, current hypotheses, and future research directions

A number of studies have demonstrated that affective disorders in epilepsy represent a common psychiatric comorbidity; however, most of the classic neuropsychiatric literature focuses on depression, which is actually prominent, but little is known about bipolar depression, and very little about mania, in epilepsy. Biochemical, structural, and functional abnormalities in primary bipolar disorder could also occur secondary to seizure disorders. The kindling paradigm, invoked as a model for understanding seizure disorders, has also been applied to the episodic nature of bipolar disorder. In bipolar patients, changes in second-messenger systems, such as G-proteins, phosphatidylinositol, protein kinase C, myristoylated alanine-rich C kinase substrate, or calcium activity have been described, along with changes in c-fos expression. Common mechanisms at the level of ion channels might include the antikindling and the calcium-antagonistic and potassium outward current-modulating properties of antiepileptic drugs. All these lines of research appear to be converging on a richer understanding of neurobiological underpinnings between bipolar disorder and epilepsy. Mania, which is the other side of the coin in affective disorders, may represent a privileged window into the neurobiology of mood regulation and the neurobiology of epilepsy itself. Future research on intracellular mechanisms might become decisive for a better understanding of the similarities between these two disorders.

Predictors of relapse in bipolar disorder: A review

INTRODUCTION

Bipolar disorder is the sixth leading cause of disability in the United States. Moreover, repeated episodes and non-responsiveness to treatment continue to present a significant problem, and little is known about the factors that may precipitate relapse. This article reviews the available literature on predictors of bipolar relapse.

METHODS

We conducted a literature search on Medline from 1996 to March 2006, using the keywords "relapse," "recurrence," "compliance," "adherence," "life events," "kindling," and "predictors" combined with the term "bipolar disorder(s)." References from the resulting articles also supplemented the initial search. Thirty-eight articles were included in the analysis.

RESULTS

Predictors of episodes include stressful life events, increased number of previous episodes, decreased interval between episodes, and persistence of affective symptoms and episodes. Factors associated with longer survival times include psychotherapy, social support, and medication adherence.

CONCLUSIONS

Our review suggests several reliable predictors of bipolar episodes. Knowledge of these factors has significant clinical implications and could aid in treatment and prevention strategies. However, further research is clearly needed to address the limitations of the existing research and to increase our understanding of predictors of relapse, with the intent of improving quality of life and preventing episodes in patients with bipolar disorder.

Long-term remission and recovery in bipolar disorder: a review

Longitudinal outcome studies of bipolar disorder show that most patients encounter affective recurrences, interepisode symptoms, and residual functional impairment. The kindling model suggests that the timing and periodicity of recurrent episodes may help to predict future illness course. This article examines contemporary data regarding patterns of affective recurrence, and the extent to which variable versus consistent or sustained remissions influence long-term illness course. Consequences of affective recurrence are examined from psychosocial, pharmacologic, and neurobiological perspectives. Multiple affective recurrences may be linked with subsequent treatment resistance, psychosocial disability, and possible functional neuroanatomic changes. Existing data support the prognostic importance of effective treatment early in the course of illness, with a goal to achieve and maintain clinical homeostasis.

Protective effects of atypical antipsychotic drugs on PC12 cells after serum withdrawal

Atypical antipsychotic drugs are widely used in the treatment of schizophrenia, and clinical evidence has shown that early and prolonged intervention with these drugs will improve the long-term outcome. It is still unclear, however, whether the atypical antipsychotic drugs are also neuroprotective. To clarify this matter, we used PC12 cell cultures and the MTT assay for cell viability to determine whether various concentrations of the atypical antipsychotics clozapine, quetiapine, and risperidone are neuroprotective after serum withdrawal. In addition, to explore the drugs' actions, Northern blot was used to examine the gene expression of SOD1 (Cu/Zn superoxide dismutase) and p75NTR (p75 neurotrophin receptor). The results demonstrated that 1) the antipsychotic drugs can protect PC12 cells from death after serum withdrawal; cell viability in these drug treatment groups is significantly different from that in the groups without serum in the medium (P < 0.01); and 2) these drugs up-regulated the SOD1 gene expression to more than 120% (P < 0.05) and also down-regulated p75NTR mRNA levels to less than 65% of their respective control values (P < 0.05). These findings suggest that the atypical antipsychotics clozapine, quetiapine, and risperidone may exert a neuroprotective function through the modulation of SOD1 and p75NTR expression.

Impact of substance abuse on the course and treatment of bipolar disorder

OBJECTIVES

The objectives of this article are to review the prevalence, natural history, pathophysiology, and treatment of comorbid bipolar disorder with alcoholism and other psychoactive substance use disorders (PSUDs).

METHODS

All identified bibliographies through a literature search of all Medline files and bibliographies of selected articles focusing on the prevalence, natural history, course, prognosis, inter-relationship, and treatment of bipolar disorder with comorbid alcoholism and other PSUDs were reviewed.

RESULTS AND CONCLUSIONS

Comorbidity of bipolar disorder and alcoholism and other PSUDs is highly prevalent. The presence of this so called 'dual diagnoses' creates a serious challenge in terms of establishing an accurate diagnosis and providing appropriate treatment interventions. The inter-relationship between these disorders appears to be mutually detrimental. The course, manifestation, and treatment of each condition are significantly compounded by the presence of the other condition. Substance abuse and alcoholism appear to significantly complicate the course and prognosis of bipolar disorder resulting in increased suffering, disability, and costs. On the other hand, bipolar disorder may be a risk factor for developing PSUDs. Although, there are a number of hypotheses explaining the pathophysiological mechanism involved in such comorbidities, our understanding of the exact nature of such neurobiological mechanisms is still limited. While the antikindling agents and targeted psychotherapeutic techniques may be useful intervention strategies, there is still a significant lack of empirically based treatment options for these patients.

Kindling and second messengers: an approach to the neurobiology of recurrence in bipolar disorder

Since bipolar disorder is inherently a longitudinal illness characterized by recurrence and cycling of mood episodes, neurobiological theories involving kindlinglike phenomena appear to possess a certain explanatory power. An approach to understanding kindlinglike phenomena at the molecular level has been made possible by advances in research on second-messenger systems in the brain. The time frame of interest has shifted from the microseconds of presynaptic events to hours, days, months, and even years in the longer duration of events beyond the synapse--through second messengers, gene regulation, and synthesis of long-acting trophic factors. These complex interlocking systems may explain how environmental stress could interact over time with genetic vulnerability to produce illness. In its two sections, this paper will review an approach to understanding two major aspects of the neurobiology of bipolar disorder: kindling phenomena and second-messenger mechanisms. We will suggest that these two fields of research together help explain the biology of recurrence.

Clinical definitions of sensitisation in affective disorder: a case register study of prevalence and prediction

The observation of a progressive recurrence in affective disorder has been interpreted as a process of sensitisation. The clinical applicability of such a theoretical model was investigated using the Danish case register, which includes all hospital admissions with primary affective disorder in Denmark from 1971 to 1993. A total of 8,737 patients admitted to a psychiatric hospital at least twice constituted the study sample. Information on treatment intervention was not available. Measures describing the initial course of admission episodes were defined in three different ways: 1) a short period between initial episodes 2) decreasing intervals between initial episodes or 3) a combination of 1) and 2). Socio-demographic variables such as gender, age at onset and marital status differentiated between the three types of measures and the measures also demonstrated different effects in predicting the risk of further recurrence. In unipolar disorder, patients with a decreasing interval between episodes had the greatest risk of further recurrence, whereas for bipolar patients, a short period between episodes played a more important role than the sequence of episodes in itself.

Recurrent affective syndromes in bipolar and unipolar mood disorders at follow-up

BACKGROUND

It is in dispute whether affective relapse disrupts psychosocial functioning to the same extent in depressed and manic patients.

METHOD

A prospective, naturalistic, longitudinal follow-up of 84 unipolar and bipolar affectively disordered in-patients was conducted to examine the extent of recurrent affective syndromes and their relationship to overall outcome. Global adjustment relative to relapse was assessed at 2- and 4.5-year follow-ups.

RESULTS

Nearly half of the bipolar patients had subsequent syndromes, which were often associated with uniformly poor psychosocial functioning. Fewer than one-quarter of those with recurrences had steady work performance. Bipolar patients taking lithium alone had fewer recurrences than those taking lithium as well as neuroleptics (P < 0.05). Bipolar and unipolar patients relapsed with equal frequency, but unipolar relapse was less often associated with readmission to hospital, work impairment, or uniformly poor functioning.

CONCLUSION

Affective relapse in bipolar disorders was more detrimental to overall functioning than was recurrence in unipolar depression.