Beyond genetics: childhood affective trauma in bipolar disorder

Objectives: Despite the demonstrated high heritability of bipolar disorder, few susceptibility genes have been identified and linkage and/or association studies have produced conflicting results. This search for susceptibility genes is hampered by several methodological limitations, and environmental risk factors for the disease (requiring incorporation into analyses) remain misunderstood. Among them, childhood trauma is probably the most promising environmental factor for further investigation. The objectives are to review the arguments in favor of an association between childhood trauma and bipolar disorder and to discuss the interpretations of such an observation. Methods: We computed a literature search using PubMed to identify relevant publications concerning childhood trauma and bipolar disorder. We also present some personal data in this field. Results: Growing evidence suggests that incidences of childhood trauma are frequent and severe in bipolar disorder, probably affect the clinical expression of the disease in terms of suicidal behavior and age at onset, and also have an insidious influence on the affective functioning of patients between episodes. The relationships between childhood trauma and bipolar disorder suggest several interpretations, mainly a causal link, a neurodevelopmental consequence, or the intergenerational transmission of traumatic experiences. The neurobiological consequences of childhood trauma on a maturing brain remain unclear, although such stressors may alter the organization of brain development, leading to inadequate affective regulation. Conclusions: Childhood trauma is associated with bipolar disorder and its clinical expression and may interact with genetic susceptibility factors. Although not completely understood, the relationships between childhood trauma and bipolar disorder require further attention. Several suggestions for further exploration of this environmental factor and of its interaction with susceptibility genes are proposed.     

Relationship of childhood physical and sexual abuse to adult bipolar disorder

Objectives: To characterize whether adult depressives with either bipolar or unipolar disorder differ in the prevalence of childhood sexual or physical abuse.

Method: The investigators reviewed data from patients who were evaluated over a 2-year period by a semi-structured clinical interview. In total, 333 cases with a bipolar or unipolar diagnosis were included in the present study.

Results: A childhood history of abuse, in particular sexual abuse, was significantly more frequent in bipolar subjects compared with unipolar subjects. Consistent with previous studies, women reported higher rates of sexual abuse than men, although no interaction by diagnosis was shown. Sexual abuse incidence in male samples was markedly dissimilar, with male bipolar subjects demonstrating a significantly increased rate of sexual abuse and combined sexual and physical abuse compared with unipolar male subjects.

Conclusion: The increased incidence of sexual abuse in women supports growing evidence of gender differences in sexual abuse among adult depressives. In contrast to literature reports, the finding that male bipolar patients have significantly increased rates of sexual abuse histories suggests differences in psychiatric depressive subgroups. This result may reflect the particular characteristics of our cohort (treatment resistant, privately insured, and educated). Further work will aid in characterizing sexual abuse prevalence in other male bipolar samples.     

Association of clinical symptoms and neurocognitive performance in bipolar disorder: a longitudinal study

Chaves OC, Lombardo LE, Bearden CE, Woolsey MD, Martinez DM, Barrett JA, Miller AL, Velligan DI, Glahn DC. Association of clinical symptoms and neurocognitive performance in bipolar disorder: a longitudinal study.
Bipolar Disord 2011: 13: 118–123. © 2011 The Authors. Journal compilation © 2011 John Wiley & Sons A/S. Objective: Despite evidence that individuals with bipolar disorder have neurocognitive impairment that persists during euthymia, the impact of changes in affective symptoms on cognitive function has not been well established. Here, we sought to determine whether specific neurocognitive functions are sensitive to mood changes in individuals with bipolar disorder assessed three months apart without changes in treatment regimen. Methods: A total of 29 individuals with DSM‐IV bipolar disorder and 30 healthy controls participated in the study. All participants received a comprehensive neuropsychological assessment and ratings of depressive [Hamilton Depression Rating Scale (HAMD)] and manic [Young Mania Rating Scale (YMRS)] symptoms at baseline and follow‐up. Changes in symptoms over time were calculated and were examined in relation to changes in neurocognitive performance. Results: At baseline, clinically stable but symptomatic patients were impaired on measures of speed of processing and attention. Over the three‐month follow‐up period, HAMD scores changed by 6 points on average [range: ?10 to +18] and YMRS scores changed by 5.31 points on average [range ?11 to +15]. Changes in depressive symptoms were correlated with poorer verbal fluency, while no relationship between manic symptoms and neuropsychological performance was detected. Conclusions: Individuals with bipolar disorder showed consistent impairment on speed of processing and attention over time, despite significant changes in mood.     

Neuropsychological deficits and functional impairment in bipolar depression, hypomania and euthymia

OBJECTIVE: To examine whether patients with bipolar disorder (BD) have subtle neuropsychological deficits that manifest clinically as cognitive and functional compromise, and this study attempted to determine the pattern of such cognitive deficits and their functional impact across all three phases of BD. We hypothesised that euthymia does not equate with normal neuropsychological function and that each phase has a characteristic pattern of deficits, with disturbance in attention and memory being common across all phases of the illness: (i) bipolar depression - psychomotor slowing and impairment of memory; (ii) hypomania by frontal-executive deficits and (iii) euthymia - a mild disturbance of attention, memory and executive function. METHODS: Twenty-five patients with a diagnosis of bipolar I disorder underwent neuropsychological testing over a period of 30 months in the natural course of their illness while hypomanic and/or depressed and/or euthymic. The results from these assessments were compared with findings from neuropsychological tests conducted on 25 healthy controls matched for age, sex, education and handedness. RESULTS: Initial analyses revealed modest impairment in executive functioning, memory and attention in both hypomanic and depressed bipolar patients, with additional fine motor skills impairment in the latter. Memory deficits, also noted in euthymic patients, were non-significant after controlling for confounding variables, although bipolar depressed patients remained significantly impaired on tests of verbal recall. Bipolar depressed and hypomanic patients differed with respect to the nature of their memory impairment. Depressed patients were more impaired as compared with euthymic patients on tests of verbal recall and fine motor skills. Psychosocial functioning was impaired across all three patient groups, but only in depressed and hypomanic patients did this correlate significantly with neuropsychological performance. CONCLUSIONS: The mood-state-related cognitive deficits in both bipolar depression and hypomania compromise psychosocial function when patients are unwell. In euthymic patients, subtle impairments in attention and memory suggest that an absence of symptoms does not necessarily equate to 'recovery'. The possibility of persistent cognitive deficits in BD is an issue of profound clinical and research interest that warrants further investigation; however, future research needs to adopt more sophisticated neuropsychological probes that are able to better define state and trait deficits and determine their functional impact.     

Childhood trauma and depressive symptoms in bipolar disorder: A network analysis

Background

Childhood trauma is related to an increased number of depressive episodes and more severe depressive symptoms in bipolar disorder. The evaluation of the networks of depressive symptoms—or the patterns of relationships between individual symptoms—among people with bipolar disorder with and without a history of childhood trauma may assist in further clarifying this complex relationship.

Methods

Data from over 500 participants from the Heinz C. Prechter Longitudinal Study of Bipolar Disorder were used to construct a series of regularised Gaussian Graphical Models. The networks of individual depressive symptoms—self-reported (Patient Health Questionnaire—9; n = 543) and clinician-rated (Hamilton Depression Rating Scale—17; n = 529)—among participants with bipolar disorder with and without a history of childhood trauma (Childhood Trauma Questionnaire) were characterised and compared.

Results

Across the sets of networks, depressed mood consistently emerged as a central symptom (as indicated by strength centrality and expected influence); regardless of participants' history of childhood trauma. Additionally, feelings of worthlessness emerged as a key symptom in the network of self-reported depressive symptoms among participants with—but not without—a history of childhood trauma.

Conclusion

The present analyses—although exploratory—provide nuanced insights into the impact of childhood trauma on the presentation of depressive symptoms in bipolar disorder, which have the potential to aid detection and inform targeted intervention development.     

Conceptualizing impulsivity and risk taking in bipolar disorder: importance of history of alcohol abuse

Background:  Elevated levels of impulsivity and increased risk taking are thought to be core features of both bipolar disorder (BD) and addictive disorders. Given the high rates of comorbid alcohol abuse in BD, alcohol addiction may exacerbate impulsive behavior and risk-taking propensity in BD. Here we examine multiple dimensions of impulsivity and risk taking, using cognitive tasks and self-report measures, in BD patients with and without a history of alcohol abuse.
Methods:  Thirty-one BD subjects with a prior history of alcohol abuse or dependence (BD-A), 24 BD subjects with no history of alcohol abuse/dependence (BD-N), and 25 healthy control subjects (HC) were assessed with the Barratt Impulsiveness Scale (BIS) and the computerized Balloon Analogue Risk Task (BART).
Results:  Both BD groups scored significantly higher than controls on the BIS. In contrast, only the BD-A group showed impaired performance on the BART. BD-A subjects popped significantly more balloons than the BD-N and HC groups. In addition, subjects in the BD-A group failed to adjust their performance after popping balloons. Severity of mood symptomatology was not associated with performance on either task.
Discussion:  The current study supports a primary role of prior alcohol abuse in risk-taking propensity among patients with bipolar disorder. In addition, findings suggest that impulsivity and risky behavior, as operationalized by self-report and experimental cognitive probes, respectively, are separable constructs that tap distinct aspects of the bipolar phenotype.     

Molecular genetics of bipolar disorder and depression

In this review, all papers relevant to the molecular genetics of bipolar disorder published from 2004 to the present (mid 2006) are reviewed, and major results on depression are summarized. Several candidate genes for schizophrenia may also be associated with bipolar disorder: G72, DISC1, NRG1, RGS4, NCAM1, DAO, GRM3, GRM4, GRIN2B, MLC1, SYNGR1, and SLC12A6. Of these, association with G72 may be most robust. However, G72 haplotypes and polymorphisms associated with bipolar disorder are not consistent with each other. The positional candidate approach showed an association between bipolar disorder and TRPM2 (21q22.3), GPR50 (Xq28), Citron (12q24), CHMP1.5 (18p11.2), GCHI (14q22-24), MLC1 (22q13), GABRA5 (15q11-q13), BCR (22q11), CUX2, FLJ32356 (12q23-q24), and NAPG (18p11). Studies that focused on mood disorder comorbid with somatic symptoms, suggested roles for the mitochondrial DNA (mtDNA) 3644 mutation and the POLG mutation. From gene expression analysis, PDLIM5, somatostatin, and the mtDNA 3243 mutation were found to be related to bipolar disorder. Whereas most previous positive findings were not supported by subsequent studies, DRD1 and IMPA2 have been implicated in follow-up studies. Several candidate genes in the circadian rhythm pathway, BmaL1, TIMELESS, and PERIOD3, are reported to be associated with bipolar disorder. Linkage studies show many new linkage loci. In depression, the previously reported positive finding of a gene-environmental interaction between HTTLPR (insertion/deletion polymorphism in the promoter of a serotonin transporter) and stress was not replicated. Although the role of the TPH2 mutation in depression had drawn attention previously, this has not been replicated either. Pharmacogenetic studies show a relationship between antidepressant response and HTR2A or FKBP5. New technologies for comprehensive genomic analysis have already been applied. HTTLPR and BDNF promoter polymorphisms are now found to be more complex than previously thought, and previous papers on these polymorphisms should be treated with caution. Finally, this report addresses some possible causes for the lack of replication in this field.     

Lifetime prevalence of substance or alcohol abuse and dependence among subjects with bipolar I and II disorders in a voluntary registry

Objective: To evaluate the prevalence of substance abuse dependence and/or alcohol abuse dependence among subjects with bipolar I versus bipolar II disorder in a voluntary registry.

Method: One hundred randomly selected registrants in a voluntary case registry for bipolar disorder were interviewed, using the Structured Clinical Interview for DSM‐IV Axis I Disorders, to validate the diagnosis of this registry. Corroborative information was obtained from medical records, family members and the treating psychiatrist. Eighty‐nine adults (18–65 years) met criteria for bipolar disorder (bipolar I=71, bipolar II=18) and were included in this analysis.

Results: Forty‐one (57.8%) subjects with bipolar I disorder abused, or were dependent on one or more substances or alcohol, 28.2% abused, or were dependent on, two substances or alcohol, and 11.3% abused or were dependent on three or more substances or alcohol. Nearly 39% of bipolar II subjects abused or were dependent on one or more substances, nearly 17% were dependent on two or more substances or alcohol, and 11% were dependent on three or more substances or alcohol. Alcohol was the most commonly abused drug among either bipolar I or II subjects.

Conclusions: Consistent with other epidemiologic and hospital population studies, this voluntary bipolar disorder registry suggests a high prevalence of comorbidity with alcohol and/or substance abuse dependence. Bipolar I subjects appear to have higher rates of these comorbid conditions than bipolar II subjects; however, as the number of bipolar II subjects was rather small, this suggestion needs confirmation.     

Hot and cold cognition in unmedicated depressed subjects with bipolar disorder

Objectives: Neuropsychological studies in subjects with bipolar disorder (BD) have reported deficits on a variety of cognitive measures. However, because the majority of subjects were medicated at the time of testing in previous studies, it is currently unclear whether the pattern of deficits reported is related to BD itself or to psychotropic medication. We addressed this issue by examining cognitive performance in a group of unmedicated, currently depressed subjects with BD. Methods: Forty‐nine unmedicated subjects who met DSM‐IV criteria for BD, depressed phase, and 55 control subjects participated in this study. Most patients were diagnosed with bipolar II disorder. Performance on emotion‐dependent, or ‘hot’, and emotion‐independent, or ‘cold’, cognitive tasks was assessed using tests from the Cambridge Neuropsychological Test Automated Battery. Results: The groups were well matched with respect to general intelligence and demographic variables. Deficits in the unmedicated depressed BD group were apparent on tests tapping ‘hot’ cognitive processing, for example the Cambridge Gamble task and the Probabilistic Reversal Learning task. However, other than a deficit on the Spatial Span test in the depressed BD subjects, the groups performed equivalently on most measures of ‘cold’ cognitive processing, for example visual memory, attention, and working memory. Conclusions: These data suggest that deficits on tests involving reward processing, short‐term spatial memory storage, and sensitivity to negative feedback in depressed BD subjects represent an effect of the illness itself and not mood‐stabilizing medication.     

Aggression and substance abuse in bipolar disorder

Objectives:  The goal of this retrospective study was to examine factors differentiating persons with bipolar disorder who did or did not have comorbid lifetime substance use disorders (SUD) at an index assessment. We also explored the chronology of onset of mood and SUD.
Methods:  We studied 146 subjects with DSM-defined bipolar disorder. Subgroups with and without lifetime SUD were compared on demographic and clinical measures.
Results:  Substance abuse disorders in this bipolar sample were associated with male sex, impulsive-aggressive traits, comorbid conduct and Cluster B personality disorders, number of suicide attempts and earlier age at onset of a first mood episode. In a multivariable logistic regression analysis, male sex and aggression and possibly earlier age at mood disorder onset were associated with SUD. In those with or without SUD, the first mood episode tended to be depressive and to precede the onset of SUD.
Conclusions:  In persons with bipolar disorder, an earlier age of onset and aggressive traits appear to be factors associated with later development of comorbid SUD.     

The relationship between childhood trauma history and the psychotic subtype of major depression

Gaudiano BA, Zimmerman M. The relationship between childhood trauma history and the psychotic subtype of major depression. Objective: Increasing evidence exists linking childhood trauma and primary psychotic disorders, but there is little research on patients with primary affective disorders with psychotic features. Method: The sample consisted of adult out‐patients diagnosed with major depressive disorder (MDD) at clinic intake using a structured clinical interview. Patients with MDD with (n = 32) vs. without psychotic features (n = 591) were compared as to their rates of different types of childhood trauma. Results: Psychotic MDD patients were significantly more likely to report histories of physical (OR = 2.81) or sexual abuse (OR = 2.75) compared with non‐psychotic MDD patients. These relationships remained after controlling for baseline differences. Within the subsample with comorbid post‐traumatic stress disorder, patients with psychotic MDD were significantly more likely to report childhood physical abuse (OR = 3.20). Conclusion: Results support and extend previous research by demonstrating that the relationship between childhood trauma and psychosis is found across diagnostic groups.     

Neuropsychological functioning in adolescent children of mothers with a history of bipolar or major depressive disorders.

BACKGROUND: Growing evidence demonstrates an association of neuropsychological deficits with mood disorders, but it is not yet clear whether these deficits are risk factors or are concomitant with the symptoms. This study examines the neuropsychological functioning of a group of adolescent offspring who are at risk for a mood disorder by virtue of being raised by mothers who have been diagnosed with major depressive disorder (MDD) or bipolar disorder (BPD). METHODS: Adolescent offspring of mothers with BPD (n = 43) or MDD (n = 72) and of psychiatrically well parents (n = 50) completed a battery of neuropsychological tests to assess executive functioning, memory, and attention. RESULTS: Children of mothers with BPD showed deficits in executive functioning and selective deficits in spatial memory and attention, in comparison with children of well mothers. Deficits were not found for children of MDD mothers. CONCLUSIONS: Knowledge of these neurocognitive processes could aid ultimately in determining whether neurocognitive deficits precede BPD, whether unique profiles are associated with various types of mood disorders, and who may benefit from interventions.     

Changes in neuronal activation in patients with bipolar disorder during performance of a working memory task

OBJECTIVES: Several lines of evidence suggest that deficits in cognition persist in bipolar patients during periods of euthymia. Working memory impairment has been observed in euthymic bipolar patients and noted to be a significant source of functional deficits in psychiatric disorders. Functional changes associated with these cognitive deficits however, remain poorly understood. We hypothesized that patients with bipolar disorder would demonstrate changes in neuronal activation in specific regions forming part of the working memory network. METHODS: Fifteen euthymic bipolar patients and fifteen age- and gender-matched healthy controls were recruited. Subjects participated in fMRI scans during which a two-back working memory task alternated with a zero-back control/attention task using a block-design paradigm. Groups were analyzed separately, and intergroup comparisons were made using an exploratory, voxel-by-voxel analysis. RESULTS: Bipolar patients performed more poorly on the cognitive tasks than did healthy controls (F = 3.77, p = 0.04). After covarying for task performance and reaction time, bipolar patients demonstrated significantly greater activation than healthy subjects in several regions including the fronto-polar prefrontal cortex, temporal cortex, basal ganglia, thalamus, and posterior parietal cortex. No areas showed a significant decrease in activation, compared with healthy controls. CONCLUSIONS: Our findings suggest that decreased working memory performance in bipolar patients reflects specific neurofunctional deficits. These deficits may represent primary areas of neuropathology or be secondary to neuropathology elsewhere in the working memory network. Continued research utilizing other imaging modalities may further clarify the underlying neuropathology involved in these cognitive deficits.