Affective disorders in the first-degree relatives of bipolar probands: results from the South Island Bipolar Study

Common or distinct pathways to psychosis? A systematic review of evidence from prospective studies for developmental risk factors and antecedents of the schizophrenia spectrum disorders and affective psychoses

BACKGROUND

Identifying the unique and shared premorbid indicators of risk for the schizophrenia spectrum disorders (SSD) and affective psychoses (AP) may refine aetiological hypotheses and inform the delivery of universal versus targeted preventive interventions. This systematic review synthesises the available evidence concerning developmental risk factors and antecedents of SSD and AP to identify those with the most robust support, and to highlight remaining evidence gaps.

METHODS

A systematic search of prospective birth, population, high-risk, and case-control cohorts was conducted in Medline and supplemented by hand searching, incorporating published studies in English with full text available. Inclusion/exclusion decisions and data extraction were completed in duplicate. Exposures included three categories of risk factors and four categories of antecedents, with case and comparison groups defined by adult psychiatric diagnosis. Effect sizes and prevalence rates were extracted, where available, and the strength of evidence synthesised and evaluated qualitatively across the study designs.

RESULTS

Of 1775 studies identified by the search, 127 provided data to the review. Individuals who develop SSD experience a diversity of subtle premorbid developmental deficits and risk exposures, spanning the prenatal period through early adolescence. Those of greatest magnitude (or observed most consistently) included obstetric complications, maternal illness during pregnancy (especially infections), other maternal physical factors, negative family emotional environment, psychopathology and psychotic symptoms, and cognitive and motor dysfunctions. Relatively less evidence has accumulated to implicate this diversity of exposures in AP, and many yet remain unexamined, with the most consistent or strongest evidence to date being for obstetric complications, psychopathology, cognitive indicators and motor dysfunction. Among the few investigations affording direct comparison between SSD and AP, larger effect sizes and a greater number of significant associations are commonly reported for SSD relative to AP.

CONCLUSIONS

Shared risk factors for SSD and AP may include obstetric complications, childhood psychopathology, cognitive markers and motor dysfunction, but the capacity to distinguish common versus distinct risk factors/antecedents for SSD and AP is limited by the scant availability of prospective data for AP, and inconsistency in replication. Further studies considering both diagnoses concurrently are needed. Nonetheless, the prevalence of the risk factors/antecedents observed in cases and controls helps demarcate potential targets for preventative interventions for these disorders.

Investigating the role of BDNF and CCK system genes in suicidality in a familial bipolar cohort

BACKGROUND

Suicidal behaviour is a phenotype widely associated with psychiatric disorders such as major depressive disorder and bipolar disorder. However, recent evidence indicates that part of the heritability of suicidal behaviour is independent of the heritability of individual psychiatric disorders. This allows investigation into genetic risk factors for suicidal behaviour within a disorder using a candidate gene association approach.

METHODS

We used family-based association testing in a cohort of 130 multiplex bipolar pedigrees, comprising 795 individuals, to look for associations between suicidal behaviour and 32 single nucleotide polymorphisms (SNPs) from across the genes brain-derived neurotrophic factor (BDNF), cholecystokinin (CCK) and the cholecystokinin beta-receptor (CCKBR).

RESULTS

We found associations (p≤0.05) between suicide attempt and 12 SNPs of CCKBR and five SNPs of BDNF. After correction for multiple testing, seven SNPs of CCKBR remained significantly associated. No association was found between CCK and suicidal behaviour.

LIMITATIONS

The study relied on retrospective self-reporting by individuals to determine phenotype, and the sample size was relatively small.

CONCLUSIONS

The results of the study support the hypothesis that some CCKBR polymorphisms may contribute to an underlying predisposition towards suicidal behaviour in bipolar disorder.

Cholecystokinin system genes: associations with panic and other psychiatric disorders

BACKGROUND

The cholecystokinin (CCK) system has long been hypothesised to have a role in the pathogenesis of panic attacks. Previous research into genetic variation within the CCK gene and the genes for its two receptors, CCKAR and CCKBR, has produced mixed results. We aimed to clarify this association by investigating multiple variants within each gene and multiple phenotypes associated with panic that may have confounded the previous studies' findings.

METHODS

Variants were selected for the three genes based on HapMap CEU data. Individuals from a family based cohort (n=563) were genotyped for these variations and this data was analysed in FBAT.

RESULTS

CCKBR showed the strongest association with panic, having multiple variants with p<0.05 (lowest: p=0.007). In CCKAR, some evidence was found for an association with panic, though further analysis suggested that the co-morbid bipolar-panic phenotype was most strongly associated. No variants in CCK were associated with panic but broader anxiety phenotypes did show associations.

LIMITATIONS

Small sample size prevented thorough investigation of phenotypes, particularly pure disorders, and no correction was made for the multiple phenotypes analysed.

CONCLUSIONS

Our findings support the involvement of variation in the CCK system, particularly CCKBR, in the pathogenesis of panic. Our data suggest that variation in CCK may be involved in several anxiety phenotypes and CCKAR may be involved in the development of panic co-morbid with bipolar disorder. These latter findings require further investigation and highlight the importance of clearly defined phenotypes when investigating psychiatric genetics.

Affective spectrum disorders in an urban Swedish adult psychiatric unit: a descriptive study

Background. Several studies have found that patients with affective-/anxiety-/stress-related syndromes present overlapping features such as cooccurrence within families and individuals and response to the same type of pharmacological treatment, suggesting that these syndromes share pathogenetic mechanisms. The term affective spectrum disorder (AfSD) has been suggested, emphasizing these commonalities. The expectancy rate, sociodemographic characteristics, and global level of functioning in AfSD has hitherto not been studied neglected. Material and Method. Out of 180 consecutive patients 94 were included after clinical investigations and ICD-10 diagnostics. Further investigations included well-known self-evaluation instruments assessing psychiatric symptoms, personality disorders, psychosocial stress, adaptation, quality of life, and global level of functioning. A neuropsychological screening was also included. Results. The patients were young, had many young children, were well educated, and had about expected (normal distribution of) intelligence. Sixty-one percent were identified as belonging to the group of AfSD. Conclusion. The study identifies a large group of patients that presents much suffering and failure of functioning. This group is shared between the levels of medical care, between primary care and psychiatry. The term AfSD facilitates identification of patient groups that share common traits and identifies individuals clinically, besides the referred patients, in need of psychiatric interventions.

Evidence of associations between bipolar disorder and the brain-derived neurotrophic factor (BDNF) gene

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) has important roles in neural cell growth and differentiation. Despite multiple lines of evidence suggesting BDNF as a possible contributor to the pathogenesis of bipolar disorder (BD), the results of genetic association studies have been mixed. We hypothesize that BDNF gene polymorphisms may confer increased susceptibility to BD.

METHODS

Using a cohort of multiplex bipolar families, we performed family-based association testing to look for associations between BD and eight single nucleotide polymorphisms (SNPs) from BDNF.

RESULTS

We found associations (p < 0.05) between BD and six of the eight SNPs analysed, including two SNPs not previously investigated in association studies. We were able to replicate associations previously found between BD and the Val66Met polymorphism of BDNF (rs6265) and the SNPs rs1519480 and rs12273363. We also found evidence of an association between rs11030107 and BD that was not found in a previous study.

CONCLUSIONS

Our results support the hypothesis that some BDNF gene polymorphisms may be contributing factors in the pathogenesis of BD. Our study also adds to the body of evidence associating the functional Val66Met polymorphism of BDNF with BD.

Bipolar Disorder and the TCI: Higher Self-Transcendence in Bipolar Disorder Compared to Major Depression

Personality traits are potential endophenotypes for genetic studies of psychiatric disorders. One personality theory which demonstrates strong heritability is Cloninger's psychobiological model measured using the temperament and character inventory (TCI). 277 individuals who completed the TCI questionnaire as part of the South Island Bipolar Study were also interviewed to assess for lifetime psychiatric diagnoses. Four groups were compared, bipolar disorder (BP), type 1 and 2, MDD (major depressive disorder), and nonaffected relatives of a proband with BP. With correction for mood state, total harm avoidance (HA) was higher than unaffected in both MDD and BP groups, but the mood disorder groups did not differ from each other. However, BP1 individuals had higher self-transcendence (ST) than those with MDD and unaffected relatives. HA may reflect a trait marker of mood disorders whereas high ST may be specific to BP. As ST is heritable, genes that affect ST may be of relevance for vulnerability to BP.

Self-mutilation and suicide attempts: relationships to bipolar disorder, borderline personality disorder, temperament and character

OBJECTIVE

Self-mutilation has traditionally been associated with borderline personality disorder, and seldom examined separately from suicide attempts. Clinical experience suggests that self-mutilation is common in bipolar disorder.

METHODS

A family study was conducted on the molecular genetics of depression and personality, in which the proband had been treated for depression. All probands and parents or siblings were interviewed with a structured interview and completed the Temperament and Character Inventory.

RESULTS

Fourteen per cent of subjects interviewed reported a history of self-mutilation, mostly by wrist cutting. Self-mutilation was more common in bipolar I disorder subjects then in any other diagnostic groups. In multiple logistic regression self-mutilation was predicted by mood disorder diagnosis and harm avoidance, but not by borderline personality disorder. Furthermore, the relatives of non-bipolar depressed probands with self-mutilation had higher rates of bipolar I or II disorder and higher rates of self-mutilation. Sixteen per cent of subjects reported suicide attempts and these were most common in those with bipolar I disorder and in those with borderline personality disorder. On multiple logistic regression, however, only mood disorder diagnosis and harm avoidance predicted suicide attempts. Suicide attempts, unlike self-mutilation, were not familial.

CONCLUSIONS

Self-mutilation and suicide attempts are only partially overlapping behaviours, although both are predicted by mood disorder diagnosis and harm avoidance. Self-mutilation has a particularly strong association with bipolar disorder. Clinicians need to think of bipolar disorder, not borderline personality disorder, when assessing an individual who has a history of self-mutilation.

Parenting an adult child with bipolar disorder in later life

This study extends prior research on family caregiving in mental illness by investigating late-life parenting of adult children with bipolar disorder using a randomly selected community-based sample. The health and mental health, psychological well-being, marriage, work-life, and social resources of 145 parents of adult children with bipolar disorder were examined when parents were in their mid-60s. Stratified random sampling procedures were used to select a comparison group whose children did not have disabilities. Results indicate that parents of adult children with bipolar disorder had a more compromised profile of health and mental health, and experienced more difficulties in marriage and work-life than comparison parents. Furthermore, parents of adult children with bipolar disorder who were diagnosed with mental illness before the onset of their child's symptoms were more vulnerable on multiple dimensions of mental health, psychological well-being, and work-life than parents without a preexisting mental illness.

Disruptive behavior disorders in offspring of parents with major depression: associations with parental behavior disorders

OBJECTIVE

Although the offspring of parents with major depressive disorder (MDD) are at increased risk to develop disruptive behavior disorders (DBD) in addition to MDD, it remains unclear whether this heightened risk is due to MDD or to comorbid DBD in the parents.

METHOD

In a secondary analysis of longitudinal data from offspring at risk for MDD and panic disorder and comparison children, we stratified 169 children of parents who had been treated for MDD based upon presence (n=50) or absence (n=119) of parental history of DBD (ADHD, oppositional disorder, and conduct disorder) and contrasted them with children of parents with DBD but without MDD (n=19) and children whose parents had neither MDD nor DBD (n=106). The children had been assessed in middle childhood using structured diagnostic interviews.

RESULTS

Offspring of parents with MDD + DBD had significantly higher rates of MDD, DBD in general, and ADHD in particular, compared with offspring of parents with MDD alone. Offspring of parents with MDD + DBD also had higher rates of mania than controls. Both parental MDD and DBD conferred independent risk for MDD and DBD in the offspring. However, only parental DBD conferred independent risk for conduct disorder and ADHD and only parental MDD conferred independent risk for oppositional defiant disorder.

CONCLUSION

Elevated rates of DBD in the offspring of parents with MDD appear to be due in part to the presence of DBD in the parents. Further studies of samples not selected on the basis of parental panic disorder are needed to confirm these results.

Heritability of bipolar spectrum disorders. Unity or heterogeneity?

BACKGROUND

The purpose of this study was to investigate whether the three disorders in the bipolar spectrum, Bipolar I disorder, Bipolar II disorder and Cyclothymia, are various expressions of an underlying genetic commonality.

METHOD

A sample consisting of same-sexed mono (MZ)- and dizygotic (DZ) twins were identified using hospital and outpatient registers (N=303). DSM-III-R criteria were assessed by personal interviews. Cross tabulations were used to compare concordance rates for different definitions of the bipolar spectrum. Correlations in liability and estimation of the heritability (h) with biometrical model fitting were performed.

RESULTS

Concordance rates were higher among MZ- than DZ pairs for all the single diagnoses and main combinations of diagnoses. Cross-concordance between different diagnoses was observed. The heritability of Bipolar I was .73, of Bipolar I+II .77 and of Bipolar I+II+Cyclothymia .71.

LIMITATION

Probands were not sampled from the general population. Most often the same person interviewed both twins in a pair. The statistical power was restricted in some sub-analyses.

CONCLUSION

The 'Bipolar Spectrum' category consisting of Bipolar I disorder, Bipolar II disorder and Cyclothymia constitute one entity with high heritability without detectable shared family environmental effects. Future genetic and clinical work might consider that all variants of the bipolar spectrum are an expression of one underlying genetic liability.

Bipolar spectrum disorder: differential diagnosis and treatment

Bipolar disorder commonly presents as a recurrent mood disorder characterized by frequent depressive episodes. Although manic or hypomanic phases are required for the diagnosis to be made based on current diagnostic criteria, a wider expression of mood instability and other historical features or family history may suggest the presence of a bipolar spectrum illness. This article covers the diagnostic issues related to bipolar disorder and the spectrum concept of the illness. A new definition of bipolar spectrum disorder is suggested, and treatment principles and options are discussed. Primary care providers often encounter patients who have depression and mood problems, placing them in a key position for the diagnosis and treatment of this psychiatric illness.

Prevalence and correlates of bipolar I disorder among adults with primary youth-onset anxiety disorders

OBJECTIVES

It is of potentially great public health importance to determine whether youth-onset anxiety disorders are associated with the increased prevalence of subsequent bipolar I disorder (BD) among adults, and to identify risk factors for BD in this population.

METHODS

The 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions was used to identify respondents with social phobia, panic disorder, or generalized anxiety disorder that onset in youth (<19 years) and was not preceded by a major depressive, manic, or mixed episode (N=1571; 572 males, 999 females). The prevalence of BD among subjects with, versus without, these youth-onset anxiety disorders was examined. Variables that could be associated with the increased risk of BD among subjects with youth-onset anxiety disorders were examined, including conduct disorder, youth-onset substance use disorders (SUD), and family history of depression and/or alcoholism. Analyses were computed separately for males and females.

RESULTS

The prevalence of BD was significantly greater among adults with, versus without, primary youth-onset anxiety disorders for both males (15.9% vs 2.7%; chi2=318.4, df=1, p<0.001) and females (13.8% vs 2.9%; chi2=346.2, df=1, p<0.001). Youth-onset anxiety disorders remained significantly associated with BD after controlling for interceding major depression, and this was true for each of the specific anxiety disorders examined. Among males with youth-onset primary anxiety disorders, conduct disorder and loaded family history of depression were associated with significantly increased risk of BD. Among females, conduct disorder and loaded family history of alcoholism were associated with significantly increased risk of BD.

CONCLUSIONS

The prevalence of BD was elevated among subjects with youth-onset primary anxiety disorders, particularly if comorbid conduct disorder was present. Future studies are needed to confirm these findings prospectively, and to develop preventive strategies for populations at risk.

Bipolar II disorder : epidemiology, diagnosis and management

Bipolar II disorder (BP-II) is defined, by DSM-IV, as recurrent episodes of depression and hypomania. Hypomania, according to DSM-IV, requires elevated (euphoric) and/or irritable mood, plus at least three of the following symptoms (four if mood is only irritable): grandiosity, decreased need for sleep, increased talking, racing thoughts, distractibility, overactivity (an increase in goal-directed activity), psychomotor agitation and excessive involvement in risky activities. This observable change in functioning should not be severe enough to cause marked impairment of social or occupational functioning, or to require hospitalisation. The distinction between BP-II and bipolar I disorder (BP-I) is not clearcut. The symptoms of mania (defining BP-I) and hypomania (defining BP-II) are the same, apart from the presence of psychosis in mania, and the distinction is based on the presence of marked impairment associated with mania, i.e. mania is more severe and may require hospitalisation. This is an unclear boundary that can lead to misclassification; however, the fact that hypomania often increases functioning makes the distinction between mania and hypomania clearer. BP-II depression can be syndromal and subsyndromal, and it is the prominent feature of BP-II. It is often a mixed depression, i.e. it has concurrent, usually subsyndromal, hypomanic symptoms. It is the depression that usually leads the patient to seek treatment.DSM-IV bipolar disorders (BP-I, BP-II, cyclothymic disorder and bipolar disorder not otherwise classified, which includes very rapid cycling and recurrent hypomania) are now considered to be part of the 'bipolar spectrum'. This is not included in DSM-IV, but is thought to also include antidepressant/substance-associated hypomania, cyclothymic temperament (a trait of highly unstable mood, thinking and behaviour), unipolar mixed depression and highly recurrent unipolar depression.BP-II is underdiagnosed in clinical practice, and its pharmacological treatment is understudied. Underdiagnosis is demonstrated by recent epidemiological studies. While, in DSM-IV, BP-II is reported to have a lifetime community prevalence of 0.5%, epidemiological studies have instead found that it has a lifetime community prevalence (including the bipolar spectrum) of around 5%. In depressed outpatients, one in two may have BP-II. The recent increased diagnosing of BP-II in research settings is related to several factors, including the introduction of the use of semi-structured interviews by trained research clinicians, a relaxation of diagnostic criteria such that the minimum duration of hypomania is now less than the 4 days stipulated by DSM-IV, and a probing for a history of hypomania focused more on overactivity (increased goal-directed activity) than on mood change (although this is still required for a diagnosis of hypomania). Guidelines on the treatment of BP-II are mainly consensus based and tend to follow those for the treatment of BP-I, because there have been few controlled studies of the treatment of BP-II. The current, limited evidence supports the following lines of treatment for BP-II. Hypomania is likely to respond to the same agents useful for mania, i.e. mood-stabilising agents such as lithium and valproate, and the second-generation antipsychotics (i.e. olanzapine, quetiapine, risperidone, ziprasidone, aripiprazole). Hypomania should be treated even if associated with overfunctioning, because a depression often soon follows hypomania (the hypomania-depression cycle). For the treatment of acute BP-II depression, two controlled studies of quetiapine have not found clearcut positive effects. Naturalistic studies, although open to several biases, have found antidepressants in acute BP-II depression to be as effective as in unipolar depression; however, one recent large controlled study (mainly in patients with BP-I) has found antidepressants to be no more effective than placebo. Results from naturalistic studies and clinical observations on mixed depression, while in need of replication in controlled studies, indicate that antidepressants may worsen the concurrent intradepression hypomanic symptoms. The only preventive treatment for both depression and hypomania that is supported by several, albeit older, controlled studies is lithium. Lamotrigine has shown some efficacy in delaying depression recurrences, but there have also been several negative unpublished studies of the drug in this indication.

Is there a continuity between bipolar and depressive disorders?

BACKGROUND

Recent studies questioned the current categorical split of mood disorders into bipolar disorders (BP) and depressive disorders (MDD).

METHODS

Medline database search of papers from the last 10 years on the categorical-dimensional classification of mood disorders. Various combinations of the following key words were used: mood disorders, bipolar, unipolar, major depressive disorder, spectrum, category/categorical, classification, continuity. Only English language clinical papers were included, review papers were excluded, similar papers selected by quality. The number of papers found was 1,141. The number of papers selected was 109.

RESULTS

The continuity/spectrum between BP (mainly BP-II) and MDD was supported by the following findings:(1) high frequency of mixed states (mixed mania, mixed hypomania, mixed depression, i.e. co-occurring depression and noneuphoric manic/hypomanic symptoms) because opposite polarity symptoms in the same episode do not support a hypomania/mania-depression splitting; (2) MDD was the most common mood disorder in BP probands' relatives; (3) no bimodal distribution of distinguishing symptoms between BP and MDD; (4) bipolar signs not uncommon in MDD; (5) many MDD shifting to BP; (6) many lifetime manic/hypomanic symptoms in MDD; (7) correlation between lifetime manic/hypomanic symptoms and MDD symptoms; (8) hypomania factors in MDD; (9) MDD often recurrent; (10) similar cognitive style. The categorical distinction between BP (mainly BP-I) and MDD was supported by the following findings: (1) BP more common in BP probands' relatives; (2) lower age at BP onset; (3) females as common as males in BP-I, more common than males in MDD; (4) BP-I depression more atypical and retarded, MDD depression more sleepless and agitated; (5) BP more recurrent.

CONCLUSIONS

Focusing on mood spectrum's extremes (BP-I vs. MDD), a categorical distinction seems supported. Focusing on midway disorders (BP-II and MDD plus bipolar signs), a continuity/spectrum seems supported. Results seem to support both a categorical and a dimensional view of mood disorders.

Bipolar disorder--focus on bipolar II disorder and mixed depression

Bipolar II disorder (recurrent depressive and hypomanic episodes) and related disorders (united in the bipolar spectrum) are understudied, despite a prevalence of about 5% in the community and about 50% in depressed outpatients. The apparent increase in prevalence of the bipolar spectrum is related to several changes in diagnostic criteria, including improved probing for history of hypomania (focused more on overactivity than on mood change), lower minimum duration of hypomania, and inclusion of unipolar depressions with bipolar signs (eg, family history of bipolar disorder, mixed depression). Prevalence of mixed depression, a combination of depression and manic or hypomanic symptoms, is high in patients with bipolar disorders. Controlled studies are needed to investigate treatment of mixed depression; antidepressants can worsen manic and hypomanic symptoms, and mood stabilising agents might be necessary.

The phenotypes of bipolar disorder: relevance for genetic investigations

The search for susceptibility genes for bipolar disorder (BD) depends on appropriate definitions of the phenotype. In this paper, we review data on diagnosis and clinical features of BD that could be used in genetic studies to better characterize patients or to define homogeneous subgroups. Clinical symptoms, long-term course, comorbid conditions, and response to prophylactic treatment may define groups associated with more or less specific loci. One such group is characterized by symptoms of psychosis and linkage to 13q and 22q. A second group includes mainly bipolar II patients with comorbid panic disorder, rapid mood switching, and evidence of chromosome 18 linkage. A third group comprises typical BD with an episodic course and favourable response to lithium prophylaxis. Reproducibility of cognitive deficits across studies raises the possibility of using cognitive profiles as endophenotypes of BD, with deficits in verbal explicit memory and executive function commonly reported. Brain imaging provides a more ambiguous data set consistent with heterogeneity of the illness.

Gender differences in bipolar disorder: age of onset, course, comorbidity, and symptom presentation

OBJECTIVE

To determine whether men and women with bipolar disorder differ in age of onset, course of illness, number of suicide attempts, comorbidity rates and symptom presentation.

METHOD

Data were collected from 211 (121 women; 90 men) adults using the Diagnostic Interview for Genetic Studies, medical records, and additional information gathered from relatives.

RESULTS

Most gender comparisons showed no evidence of differences. Nonetheless, more men than women reported mania at the onset of bipolar I disorder. Men also had higher rates of comorbid alcohol abuse/dependence, cannabis abuse/dependence, pathological gambling and conduct disorder. Men were more likely to report 'behavioural problems' and 'being unable to hold a conversation' during mania. Women reported higher rates of comorbid eating disorders, and weight change, appetite change and middle insomnia during depression.

CONCLUSIONS

Men and women were generally similar in their symptom presentation, age of onset of bipolar disorder, and in the total number of mood episodes. However, they differed in the type of episode at onset and comorbidity patterns.