Dopamine dysregulation syndrome : implications for a dopamine hypothesis of bipolar disorder

Objective: Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder.

Method: A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles.

Results: Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper.

Conclusion: Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson’s disease, administration of high-dose dopamine precursors can produce a ‘maniform’ picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

Health-related quality of life and functioning in bipolar disorder : the impact of pharmacotherapy

Bipolar disorder has a major deleterious impact on many aspects of a patient's functioning and health-related quality of life. Although the formal measurement of these deficits has been neglected until recently, many well-designed trials now include an assessment of functioning and health-related quality of life using one or more rating scales. This review describes recent developments in the measurement of functioning and health-related quality of life in bipolar disorder, and discusses the evidence that medications that improve symptoms in bipolar disorder also offer clinically relevant benefits in functioning and health-related quality of life. Direct comparisons of the benefits of medications including atypical antipsychotics are problematic due to differences in trial populations, study durations and rating scales. Data from quetiapine trials indicate that this medication offers prompt and sustained improvement of functioning in patients with mania and enhancement of health-related quality of life in patients with bipolar depression, to accompany the significant improvements in mood episodes.

Evidence and implications for early intervention in bipolar disorder

Aims: To review the evidence that supports early intervention in the treatment of bipolar disorder.

Background: Bipolar disorder is a pleomorphic condition, with varying manifestations that are determined by a number of complex factors including the ‘‘stage’’ of illness. It is consequently a notoriously difficult illness to diagnose and as a corollary is associated with lengthy delays in recognition and the initiation of suitable treatment.

Methods: A literature search was conducted using MEDLINE augmented by a manual search.

Results: Emerging neuroimaging data suggests that, in contrast to schizophrenia, where at the time of a first-episode of illness there is already discernible volume loss, in bipolar disorder, gross brain structure is relatively preserved, and it is only with recurrences that there is a sequential, but marked loss of brain volume. Recent evidence suggests that both pharmacotherapy and psychotherapy are more effective if instituted early in the course of bipolar disorder, and that with multiple episodes and disease progression there is a noticeable decline in treatment response.

Conclusions: Such data supports the notion of clinical staging, and the tailored implementation of treatments according to the stage of illness. The progressive nature of bipolar disorder further supports the concept that the first episode is a period that requires energetic broad-based treatment, with the hope that this could alter the temporal trajectory of the illness. It also raises hope that prompt treatment may be neuroprotective and that this perhaps attenuates or even prevents the neurostructural and neurocognitive changes seen to emerge with chronicity. This highlights the need for early identification at a population level and the necessity of implementing treatments and services at a stage of the illness where prognosis is optimal.

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 interepisode 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.

Effects of N-acetylcysteine on substance use in bipolar disorder : a randomized placebo controlled clinical trial

Objective: To evaluate the effect of N-acetylcysteine (NAC) on substance use in a double-blind, placebo-controlled trial of NAC in bipolar disorder. It is hypothesised that NAC will be superior to placebo for reducing scores on the Clinical Global Impressions scale for Substance Use (CGI-SU).

Methods: Participants were randomised to 6-months of treatment with 2 g/day NAC (n = 38) or placebo (n = 37). Substance use was assessed at baseline using the Habits instrument. Change in substance use was assessed at regular study visits using the CGI-SU.

Results: Amongst the 75 participants 78.7% drank alcohol (any frequency), 45.3% smoked tobacco and 92% consumer caffeine. Other substances were used by fewer than six participants. Caffeine use was significantly lower for NAC-treated participants compared with placebo at week 2 of treatment but not at other study visits.

Conclusion: NAC appeared to have little effect on substance use in this population. A larger study on a substance using population will be necessary to determine if NAC may be a useful treatment for substance use.

The impact of age at onset of bipolar I disorder on functioning and clinical presentation

Objectives: Recent studies have proposed the existence of three distinct subgroups of bipolar 1 disorder based on age at onset (AAO). The present study aims to investigate potential clinical and functional differences between these subgroups in an Australian sample.

Methods: Participants (n = 239) were enrolled in the Bipolar Comprehensive Outcomes Study (BCOS), a 2-year longitudinal, observational, cross-sectional study. Assessment measures included the Young Mania Rating Scale (YMRS), Hamilton Depression Rating Scale (HAMD21), Clinical Global Impressions Scale (CGI-BP), SF-36, SLICE/Life Scale, and the EuroQol (EQ-5D). Participants were also asked about their age at the first major affective episode.

Results: Three AAO groups were compared: early (AAO < 20, mean = 15.5 ± 2.72; 44.4% of the participants); intermediate (AAO 20–39, mean = 26.1 ± 4.8; 48.14% of the participants) and late (AAO > 40, mean = 50.6 ± 9.04; 7.4% of the participants). Higher rates of depression, suicidal ideation and binge drinking were reported by the early AAO group. This group also reported poorer quality of life in a number of areas. The early AAO group had a predominant depressive initial polarity and the intermediate group had a manic predominance.

Conclusion: Early AAO is associated with an adverse outcome.