Biological indicators of suicide risk in youth with mood disorders: what do we know so far?

Suicidal behaviour in youth is a major public health concern worldwide, and youth in the early stages of a primary mood disorder are an identifiable high-risk population. Neurobiological research in youth at risk for suicidality has sought to investigate the most promising parameters from research in adults. The present paper provides an overview of the current findings of neurobiological research in children and adolescents with mood disorders and suicidality including genetic/epigenetic findings, neuro-hormonal and immunological investigations. Longitudinal research in high-risk youth is a powerful way to investigate the influences and their pathways in determining suicidal risk in the context of a developing mood disorder. In the meantime, there are clear clinical indicators of risk to help identify youth who would benefit from close surveillance and early intervention.

Commentary on a recent review of lithium toxicity: what are its implications for clinical practice?

A recent paper by McKnight et al. in The Lancet has provided the first formal meta-analysis of the more common adverse reactions to lithium. The authors analyzed 385 studies and focused mainly on the harmful effects of lithium on the kidney, the thyroid and parathyroid glands, body weight, skin and congenital malformations. Their contribution is important and welcome, but as a guide for practice, it needs to be complemented by other relevant observations and individual patient-focused perspectives.The findings from that meta-analysis somewhat underestimate the renal side-effects, and distort to some degree or exclude other adverse effects. The glomerular filtration rate is reduced but not more than 0 to 5 ml/min/year of observation; this may not fully reflect the present state of knowledge. A quarter of patients in the study had abnormalities of the thyroid and/or parathyroid gland, and lithium was found to increase body weight significantly less than did olanzapine. Unfortunately, the authors did not consider the observations from spontaneous reporting systems, which may have changed the picture.We feel that some specific limitations of the study were related to the inclusion of patients regardless of adequacy of treatment, quality of monitoring, drug combinations, age and sex, and stabilization response.

Brief depressive symptoms in patients with bipolar disorder: analysis of long-term self-reported data

OBJECTIVE

Most patients with bipolar disorder experience depressive symptoms outside of an episode of depression as defined by DSM-IV criteria. This study explores the frequency of brief depressive episodes, lasting 1 to 4 days, using daily self-reported mood ratings.

METHOD

Mood ratings were obtained from 448 patients (281 bipolar I, 167 bipolar II) using ChronoRecord software (91,786 total days). Episodes of depression and days of depression outside of episodes were determined. The intensity of depressive symptoms (mild versus moderate to severe) was compared.

RESULTS

Using the DSM-IV length criteria, 61% of all depressive days occurred outside of a depressed episode. Decreasing the minimum length criterion to 2 days, both the number of patients experiencing a depressed episode (128 to 317) and the mean percent of days spent in a depressed episode by each patient (7.9% to 17.8.%) increased by about 2½ times, and 34.3% of depressed days remained outside of an episode. Depending on the episode length, the proportion of days within an episode with severe symptoms varied from 1/3 to 1/4 for episodes lasting from 14 to 2 days, and 1/4 for single-day episodes. There was no significant difference in the frequency of brief depressive episodes between bipolar I and II disorders. For all episode lengths, patients taking antidepressants spent 4% more days within an episode and 6% more days with depressive symptoms outside of an episode than those not taking antidepressants.

CONCLUSION

Brief depressive episodes lasting 1 to 4 days occur frequently in bipolar disorder and do not distinguish between bipolar I and II disorders. Symptoms of moderate to severe intensity occur on 1/4 to 1/3 of the days in brief depressive episodes. This study did not address brief depression in those without bipolar disorder. Patients taking antidepressants experienced more brief depressive episodes. Controlled trials are needed to assess the impact of antidepressants on subsyndromal depressive symptoms.

Biological indicators of illness risk in offspring of bipolar parents: targeting the hypothalamic-pituitary-adrenal axis and immune system

AIM

The study aims to provide a selective review of the literature pertaining to the hypothalamic-pituitary-adrenal (HPA) axis and immune abnormalities as informative biological indicators of vulnerability in bipolar disorder (BD).

METHOD

We summarize key findings relating to HPA axis and immunological abnormalities in bipolar patients and their high-risk offspring. Findings derive from a review of selected original papers published in the literature, and supplemented by papers identified through bibliography review. Neurobiological findings are discussed in the context of emergent BD in those at genetic risk and synthesized into a neurodevelopmental model of illness onset and progression.

RESULTS

BD is associated with a number of genetic and possibly epigenetic abnormalities associated with neurotransmitter, hormonal and immunologically mediated neurobiological pathways. Data from clinical and high-risk studies implicate HPA axis and immune system abnormalities, which may represent inherited vulnerabilities important for the transition to illness onset. Post-mortem and clinical studies implicate intracellular signal transduction processes and disturbance in energy metabolism associated with established BD. Specifically, long-standing maladaptive alterations such as changes in neuronal systems may be mediated through changes in intracellular signalling pathways, oxidative stress, cellular energy metabolism and apoptosis associated with substantial burden of illness.

CONCLUSIONS

Prospective longitudinal studies of endophenotypes and biomarkers such as HPA axis and immune abnormalities in high-risk offspring will be helpful to understand genetically mediated biological pathways associated with illness onset and progression. A clinical staging model describing emergent illness in those at genetic risk should facilitate this line of investigation.

Synapsin II is involved in the molecular pathway of lithium treatment in bipolar disorder

Bipolar disorder (BD) is a debilitating psychiatric condition with a prevalence of 1–2% in the general population that is characterized by severe episodic shifts in mood ranging from depressive to manic episodes. One of the most common treatments is lithium (Li), with successful response in 30–60% of patients. Synapsin II (SYN2) is a neuronal phosphoprotein that we have previously identified as a possible candidate gene for the etiology of BD and/or response to Li treatment in a genome-wide linkage study focusing on BD patients characterized for excellent response to Li prophylaxis. In the present study we investigated the role of this gene in BD, particularly as it pertains to Li treatment. We investigated the effect of lithium treatment on the expression of SYN2 in lymphoblastoid cell lines from patients characterized as excellent Li-responders, non-responders, as well as non-psychiatric controls. Finally, we sought to determine if Li has a cell-type-specific effect on gene expression in neuronal-derived cell lines. In both in vitro models, we found SYN2 to be modulated by the presence of Li. By focusing on Li-responsive BD we have identified a potential mechanism for Li response in some patients.

Findings from bipolar offspring studies: methodology matters

AIM

High-risk studies provide the opportunity to describe the early natural history of bipolar disorder (BD); however, findings have varied substantially. In this review, we compare different methods of ascertainment and assessment, and their impact on study findings.

METHODS

Through a literature search, we identified 11 high-risk studies meeting inclusion criteria for this review. Studies included were those that focused on lifetime psychopathology in the offspring as the main outcome and provided adequate information on the methods of family ascertainment, as well as on parent and offspring assessment. We compared and contrasted psychopathological outcomes in the offspring among the studies using different methods.

RESULTS

High-risk studies that identified affected parents through their involvement in neurobiological research and confirmed diagnosis in the parent and offspring through best estimate procedures tended to report lower rates of co-morbidity in the proband parent, lower rates of psychopathology in the non-proband parent, lower rates of attention deficit hyperactivity disorder and externalizing disorders, and older ages of onset of major mood disorders in the offspring compared with studies that identified affected parents through self-referral and confirmed diagnosis in the parent and offspring through structured research interviews. Studies that identified severely ill parents and used semi-structured assessments tended to have an intermediate position in terms of outcomes.

CONCLUSIONS

This review indicates that different methods of family ascertainment and of assessment of parent and offspring impact the findings pertaining to lifetime psychopathology and clinical course of BD in high-risk studies. The implications of this finding for mapping the natural history of BD are discussed.

Implication of synapse-related genes in bipolar disorder by linkage and gene expression analyses

Several chromosomal regions have been linked to bipolar disorder (BD). However, the search for specific genes has been hampered by inconsistent findings, partly due to genetic and phenotypic heterogeneity. We focused on lithium-responsive bipolar patients, a subgroup thought to be more homogeneous and conducted a multistage study including an initial linkage study followed up by fine mapping and gene expression. Our sample consisted of 36 families (275 genotyped individuals, 132 affected) recruited through probands who were responders to long-term lithium treatment. We conducted a genome-wide scan with 811 microsatellite markers followed by fine mapping. Gene expression studies of candidate regions were conducted on six post-mortem prefrontal brain regions of 20 individuals (8 BD and 12 controls). We identified regions 3p25, 3p14 and 14q11 as showing the highest genome-wide linkage signal (LOD 2.53, 2.04 and 3.19, respectively). Fine mapping provided further support for 3p25, while only modest support was found in the other two regions. We identified a group of synaptic, mitochondrial and apoptotic genes with altered expression patterns in BD. Analysis of an independent microarray dataset supported the implication of synapse-related and mitochondrial genes in BD. In conclusion, using two complementary strategies, we found evidence of linkage to lithium-responsive BD on 3p25, 3p14 and 14q11 as well as significantly dysregulated genes on these regions suggesting altered synaptic and mitochondrial function in BD. Further studies are warranted to demonstrate the functional role of these genes in BD.

Sixty years of lithium responders

It has been 60 years since Cade first described patients who responded to antimanic lithium treatment. Two decades later, responders to lithium stabilization emerged in larger numbers. The responses of many severely ill bipolar patients to lithium were striking and called for an explanation. Remarkable reactions to a simple ion generated hope for an uncomplicated laboratory test of response and an extensive search for suitable biological markers ensued. But despite promising reports, particularly from molecular genetics, we are still waiting for a biological elucidation of the stabilizing effects of lithium. The most useful predictor of lithium stabilization has to date been the patient's clinical profile, based on a comprehensive clinical assessment: complete remissions and other characteristics of episodic clinical course, bipolar family history, low psychiatric comorbidity and a characteristic presenting psychopathology. In brief, the responders approximate the classical Kraepelinian description of a manic-depressive patient. But the most intriguing findings have recently emerged from prospective observations of the next generation: the children of lithium responders, their counterparts coming from parents who did not respond to lithium and controls. Overall, they indicate that parents and offspring suffer from a comparable brain dysfunction that manifests clinically in distinct stages. If the child's predicament starts early in childhood, it presents with varied, nonaffective or subclinical manifestations that are usually nonresponsive to standard treatments prescribed according to the symptoms. The next stage then unfolds in adolescence, first with depressive and later with activated episodes. The observations have a potential to markedly enrich the prevailing understanding and management of mood disorders.

Influence of atypical features on the quality of prophylactic effectiveness of long-term lithium treatment in bipolar disorders

OBJECTIVES

There is still debate about whether the quality of long-term efficacy of lithium in patients with bipolar disorders is influenced by atypical features. Extended Cox regression models allow for the use of all follow-up data on diseases with multiple episodes. The aim of the present analysis was to apply the best suited of these models to analyze the influence of atypical features on the widely used outcome measure of time to recurrence in a large multicenter cohort of lithium responders established by the International Group for the Study of Lithium Treated Patients.

METHODS

A conditional extended Cox model with a random frailty term was applied to the data of 336 bipolar I and II disorder patients, all of whom were responders to lithium with treatment for up to 30 years.

RESULTS

Differences were found in the long-term outcome, even in patients who have demonstrated a relatively good response to lithium treatment. The hazard for recurrence was negatively influenced by the presence of atypical features, mainly mood-incongruent psychotic symptoms, interepisodic residual symptomatology, and rapid cycling.

CONCLUSIONS

As a result of the findings, physicians should regularly reassess the quality of response in bipolar disorder patients with atypical features and, if necessary, modify treatment. Extended Cox regression models are well suited for evaluating long-term outcome and should be used more extensively to analyze treatment outcome in psychiatric and somatic disorders.

The International Consortium on Lithium Genetics (ConLiGen): an initiative by the NIMH and IGSLI to study the genetic basis of response to lithium treatment

For more than half a decade, lithium has been successfully used to treat bipolar disorder. Worldwide, it is considered the first-line mood stabilizer. Apart from its proven antimanic and prophylactic effects, considerable evidence also suggests an antisuicidal effect in affective disorders. Lithium is also effectively used to augment antidepressant drugs in the treatment of refractory major depressive episodes and prevent relapses in recurrent unipolar depression. In contrast to many psychiatric drugs, lithium has outlasted various pharmacotherapeutic 'fashions', and remains an indispensable element in contemporary psychopharmacology. Nevertheless, data from pharmacogenetic studies of lithium are comparatively sparse, and these studies are generally characterized by small sample sizes and varying definitions of response. Here, we present an international effort to elucidate the genetic underpinnings of lithium response in bipolar disorder. Following an initiative by the International Group for the Study of Lithium-Treated Patients (www.IGSLI.org) and the Unit on the Genetic Basis of Mood and Anxiety Disorders at the National Institute of Mental Health,lithium researchers from around the world have formed the Consortium on Lithium Genetics (www.ConLiGen.org) to establish the largest sample to date for genome-wide studies of lithium response in bipolar disorder, currently comprising more than 1,200 patients characterized for response to lithium treatment. A stringent phenotype definition of response is one of the hallmarks of this collaboration. ConLiGen invites all lithium researchers to join its efforts.

Early stages in the development of bipolar disorder

BACKGROUND

Numerous studies have observed that offspring of bipolar parents manifest a broad spectrum of psychiatric disorders. We tested the hypothesis that in high risk offspring, bipolar disorder evolves in a predictable clinical sequence from non-specific (non-mood) to specific (mood) psychopathology.

METHODS

Offspring from well-characterized families with one bipolar parent (high risk) or two well parents (controls) were assessed annually or at anytime symptoms developed using KSADS-PL interviews for up to 15 years. DSM-IV diagnoses were made on blind consensus review using all available clinical material. We compared the age-adjusted risks of lifetime psychopathology between high risk and control subjects and assessed the conditional probability of developing a mood disorder given a history of non-mood disorders. In subjects meeting full DSM-IV criteria for bipolar disorder, we assessed the sequence of psychopathology against a clinical staging model.

RESULTS

High risk offspring manifest higher rates of anxiety and sleep disorders, as well as major mood and substance use disorders compared to controls. Antecedent anxiety increased the age-adjusted risk of mood disorder from 40 to 85% (hazard ratio of 2.6). High risk subjects who developed a mood disorder had an increased risk of a substance use disorder (hazard ratio of 2.4), typically meeting diagnostic criteria during or after the first major mood episode. The evolution of psychopathology leading to bipolar disorder generally followed the proposed sequence, although not all subjects manifest all stages.

LIMITATIONS

Larger numbers of high risk offspring prospectively assessed over the risk period would allow confirmation of these preliminary findings.

CONCLUSIONS

Clinical staging may be a useful approach to refine the early diagnosis and facilitate research into the evolution of bipolar disorder in those at familial risk.

The association between concurrent psychotropic medications and self-reported adherence with taking a mood stabilizer in bipolar disorder

OBJECTIVE

Multiple psychotropic medications are routinely prescribed to treat bipolar disorder, creating complex medication regimens. This study investigated whether the daily number of psychotropic medications or the daily number of pills were associated with self-reported adherence with taking a mood stabilizer.

METHODS

Patients self-reported their mood and medications taken daily for about 6 months. Adherence was defined as taking at least one pill of any mood stabilizer daily. Univariate general linear models (GLMs) were used to estimate if adherence was associated with the number of daily medications and the number of pills, controlling for age. The association between mean daily dosage of mood stabilizer and adherence was also estimated using a GLM.

RESULTS

Three hundred and twelve patients (mean age 38.4 +/- 10.9 years) returned 58,106 days of data and took a mean of 3.1 +/- 1.6 psychotropic medications daily (7.0 +/- 4.2 pills). No significant association was found between either the daily number of medications or the daily number of pills and adherence. For most mood stabilizers, patients with lower adherence took a significantly smaller mean daily dosage.

CONCLUSIONS

The number of concurrent psychotropic medications may not be associated with adherence in bipolar disorder. Patients with lower adherence may be taking smaller dosages of mood stabilizers.

Subsyndromal mood symptoms: a useful concept for maintenance studies of bipolar disorder?

OBJECTIVE

To explore the measurement of subsyndromal mood symptoms in relation to studies of maintenance therapy for bipolar disorder.

METHODS

Literature review of the Medline database using the following selection criteria: (1) 'bipolar disorder' plus 'inter-episode or interepisode or subsyndromal or subclinical or residual or subthreshold' and (2) 'bipolar disorder' plus 'maintenance or prophylaxis or longitudinal'. Studies of children or adolescents and non-English-language reports were excluded.

RESULTS

Of the studies published between 1987 and October 2007, 77 articles about subsyndromal mood symptoms and 257 studies of maintenance therapy agents were found. Only 11 of the 257 studies of maintenance therapy agents discussed subsyndromal mood symptoms. Of the 77 articles, two thirds were published after 2000. Inconsistent definitions of subsyndromal mood symptoms and different evaluation tools and methodologies were used in the studies.

CONCLUSIONS

There is a need to standardize definitions and validate measuring approaches for subsyndromal mood symptoms. However, when measured in both naturalistic studies and clinical trials, subsyndromal mood symptoms were frequently reported by patients receiving maintenance therapy and were associated with poor functioning. As with other chronic illnesses, knowledge of the patient's perspective of daily morbidity is important for improving the clinical outcome. Studies of maintenance therapy for bipolar disorder, regardless of the approach, should measure subsyndromal mood symptoms as an additional outcome.

Lithium response across generations

OBJECTIVE

To describe and integrate observations from bipolar patients responsive to lithium stabilization and their children.

METHOD

Selected findings are described from the clinical and biological investigations of adults meeting research criteria for bipolar disorder and for responsiveness to lithium stabilization; and from prospective studies of the children of lithium responders and non-responders.

RESULTS

Response to prophylactic lithium identifies a valid subtype of bipolar disorder, however the search for biological markers of lithium response, while promising, has so far remained inconclusive. Adult responders to lithium stabilization exhibit definable clinical features which are also observable in their affected children. In prospective studies the children of bipolar parents develop symptoms earlier than reported previously, with marked differences between the offspring of lithium responders and non-responders. The illness evolves in predictable clinical stages, first from non-specific sleep and anxiety disorders to mood symptoms and then, often starting in adolescence, major depressive and later activated episodes.

CONCLUSION

Investigating and comparing unequivocal responders and non-responders to long-term lithium treatment and their offspring is a fertile research strategy for addressing a multitude of clinical and research questions.

Early course of bipolar disorder in high-risk offspring: prospective study

We studied the course of major mood disorders in the offspring of parents with well-characterised bipolar disorder prospectively for up to 15 years. All consenting offspring were assessed annually or anytime symptomatic. The participants began to develop major mood episodes in adolescence and not before. The index major mood episode was almost always depressive, as were the first few recurrences. Onsets and recurrences continued throughout the observation period into adulthood. We did not find evidence of pre-pubertal mania. In summary, adolescence marks the beginning of the high-risk period for major mood episodes related to bipolar disorder.

Comparison of sleep/wake parameters for self-monitoring bipolar disorder

BACKGROUND

Psychosocial interventions may teach patients with bipolar disorder to successfully detect warning signs of relapse. These interventions often include ongoing self-monitoring of sleep. We previously reported that a change in sleep duration (sleep plus bedrest) of >3 h may indicate that a mood change is imminent. This analysis further investigated whether sleep duration, sleep onset or sleep offset was the most useful sleep/wake parameter to monitor for an oncoming mood change.

METHODS

101 adult outpatients receiving treatment as usual recorded mood, sleep and medications every day on a home computer for a mean of 265+/-103 days. A daily time series of mood, sleep duration (sleep plus bedrest), sleep onset and sleep offset was constructed for each patient. After applying an ARIMA (0,1,1) filter, a cross correlation function was used to analyze the temporal relationship between the residuals for lags of +/-7 days.

RESULTS

Less frequent significant correlations were found between a change in either sleep onset or sleep offset and mood, than between sleep duration and mood. Patients with a significant correlation between sleep duration and mood included 86% of those with a significant correlation between sleep onset or sleep offset and mood. Mean sleep duration when euthymic was long (> or =8 h in 89% of patients, > or =9 h in 51% of patients).

LIMITATIONS

Self-reported data, naturalistic study, and computer access required.

CONCLUSIONS

Self-monitoring of sleep duration is recommended for patients with bipolar disorder. Better understanding of the long sleep duration of euthymic patients is required.

Neurocognitive functioning in the early stages of bipolar disorder: visual backward masking performance in high risk subjects

INTRODUCTION

Cognitive deficits, including deficits in early information processing, are associated with remitted bipolar disorder. The temporal relationship between these deficits and the clinical course is not known. The current study investigated whether or not deficits in early information processing were present before the onset and/or during the early stages of bipolar disorder.

METHODS

Unaffected and remitted high risk offspring of well-characterized bipolar parents completed a visual backward masking task. For comparison we included a cohort of unaffected offspring of well parents and a clinically referred group of remitted bipolar patients.

RESULTS

There was no evidence of a deficit in early information processing in well high risk subjects. As expected, the referred patient group had the highest error rates. After excluding the patients, interaction effect showed that the affected remitted high risk subjects performed differently in terms of error rates than unaffected high risk and control subjects. There were no significant differences in response times across study groups. Exploratory analyses revealed an association between a lifetime history of psychosis and increased errors on the task.

CONCLUSIONS

There was no evidence of a vulnerability in early information processing in offspring at risk for bipolar disorder. However, there were emergent changes in performance in the affected remitted high risk group. Psychosis appears to be an important clinical correlate associated with cognitive deficits. Mapping of the early course of bipolar disorder and associated changes in cognition has important implications for establishing critical periods for intervention.

Relationship among latitude, climate, season and self-reported mood in bipolar disorder

OBJECTIVE

Many researchers have analyzed seasonal variation in hospital admissions for bipolar disorder with inconsistent results. We investigated if a seasonal pattern was present in daily self-reported daily mood ratings from patients living in five climate zones in the northern and southern hemispheres. We also investigated the influence of latitude and seasonal climate variables on mood.

METHOD

360 patients who were receiving treatment as usual recorded mood daily (59,422 total days of data). Both the percentage of days depressed and hypomanic/manic, and the episodes of depression and mania were determined. The observations were provided by patients from different geographic locations in North and South America, Europe and Australia. These data were analyzed for seasonality by climate zone using both a sinusoidal regression and the Gini index. Additionally, the influence of latitude and climate variables on mood was estimated using generalized linear models for each season and month.

RESULTS

No seasonality was found in any climate zone by either method. In spite of vastly different weather, neither latitude nor climate variables were associated with mood by season or month.

CONCLUSION

Daily self-reported mood ratings of most patients with bipolar disorder did not show a seasonal pattern. Neither climate nor latitude has a primary influence on the daily mood changes of most patients receiving medication for bipolar disorder.

A critical appraisal of lithium's efficacy and effectiveness: the last 60 years

The history that depicts the evaluation of lithium's efficacy presents an interesting contrast: on the one hand, conviction that, of all psychotropic drugs, lithium has the best demonstrated efficacy; on the other hand, repeated attempts to question it. Those contesting lithium's stabilizing abilities have argued from several angles, for example that the proof was methodologically incorrect or insufficient, that the number of responders is small, or that the response is poor in practice and does not last. But there is a good explanation for this paradox. While the early challenges to lithium's value in recurrent mood disorders reflected mainly that psychiatry had not yet developed a methodology suitable for testing long-term efficacy, more recent questioning has resulted mostly from retesting its efficacy and effectiveness in a substantially broadened bipolar spectrum, outside the classical diagnosis. Lithium, however, continues to stabilize very well the patients suffering from typical bipolar disorder--the condition for which its efficacy was originally demonstrated. More recently, lithium has also proven to dramatically reduce suicidal behavior and mortality and to augment markedly the efficacy of antidepressants in unresponsive patients.