Mood disorders and parity - a clue to the aetiology of the postpartum trigger.

BACKGROUND: Episodes of postpartum psychosis have been associated with first pregnancies in women with bipolar I disorder. It is unclear, however, if the effect extends to episodes at other times in relation to childbirth and to women with other mood disorders such as major depression and bipolar II disorder. This primiparity effect, which is also seen in other pregnancy related conditions such as pre-eclampsia, is a potentially important clue to the aetiology of childbirth related mood episodes. METHODS: Participants were interviewed and case notes reviewed. Best-estimate diagnoses were made according to DSM-IV criteria. Data on the occurrence of episodes in pregnancy and the postpartum were available on 3345 full term deliveries from 1667 participants, 934 with bipolar I disorder (BD-I), 278 with bipolar II disorder (BD-II) and 455 with recurrent major depression (RMD). RESULTS: Onsets of psychosis/mania within 6 weeks of childbirth were overrepresented in primiparae (p=0.007) with BD-I. Although primiparity was not associated with perinatal bipolar depression, there was an association with the onset of depression within 6 weeks in women with RMD (p=0.035). Whilst women experiencing a postpartum episode were less likely to go on to have further children, this did not account for the association with primiparity. LIMITATIONS: Data were collected retrospectively. Information on pharmacological treatment was not available. CONCLUSIONS: Primiparity is associated not only with postpartum psychosis/mania in BD-I, but also with postpartum depression in RMD. Psychosocial factors and biological differences between first and subsequent pregnancies may play a role and are candidates for examination in further studies.

Perinatal episodes across the mood disorder spectrum.

CONTEXT Affective disorders are common in women, with many episodes having an onset in pregnancy or during the postpartum period. OBJECTIVE To investigate the occurrence and timing of perinatal mood episodes in women with bipolar I disorder, bipolar II disorder, and recurrent major depression (RMD). SETTING AND PATIENTS Women were recruited in our ongoing research on the genetic and nongenetic determinants of major affective disorders. Participants were interviewed and case notes were reviewed. Best-estimate diagnoses were made according to DSM-IV criteria. The 1785 parous women identified included 1212 women with bipolar disorder (980 with type I and 232 with type II) and 573 with RMD. Data were available on 3017 live births. MAIN OUTCOME MEASURES We report the lifetime occurrence of perinatal mood episodes, the rates of perinatal episodes per pregnancy/postpartum period, and the timing of the onset of episodes in relation to delivery. RESULTS More than two-thirds of all diagnostic groups reported at least 1 lifetime episode of illness during pregnancy or the postpartum period. Women with bipolar I disorder reported an approximately 50% risk of a perinatal major affective episode per pregnancy/postpartum period. Risks were lower in women with RMD or bipolar II disorder, at approximately 40% per pregnancy/postpartum period. Mood episodes were significantly more common in the postpartum period in bipolar I disorder and RMD. Most perinatal episodes occurred within the first postpartum month, with mania or psychosis having an earlier onset than depression. CONCLUSIONS Although episodes of postpartum mood disorder are more common in bipolar I disorder and manic and psychotic presentations occur earlier in the postpartum period, perinatal episodes are highly prevalent across the mood disorder spectrum.

Bipolar affective puerperal psychosis: genome-wide significant evidence for linkage to chromosome 16.

OBJECTIVE: Vulnerability to the triggering of bipolar episodes by childbirth aggregates in families and may define a genetically relevant subtype of bipolar disorder. The authors conducted a search by systematic whole genome linkage scan for loci influencing vulnerability to bipolar affective puerperal psychosis. METHOD: The authors selected families with bipolar disorder from their previous bipolar disorder genome scan, in which there was at least one family member with a manic or psychotic episode with an onset within 6 weeks of delivery. Individuals were coded as affected if they had been diagnosed with bipolar I disorder; bipolar II disorder; or schizoaffective disorder, bipolar type, according to DSM-IV. A total of 36 pedigrees contributed 54 affected sibling pairs to the cohort. A genome scan with 494 microsatellite markers was analyzed using GENEHUNTER and MAPMAKER/SIBS. RESULTS: A genome-wide significant linkage signal was observed on chromosome 16p13, and a genome-wide suggestive linkage was observed on chromosome 8q24. No significant or suggestive linkage was observed in these regions in our original bipolar scan. CONCLUSIONS: This study identifies chromosomal regions that are likely to harbor genes that predispose individuals to bipolar affective puerperal psychosis. The identification of susceptibility genes would enhance understanding of pathogenesis and offer the possibility of improvements in treatment and risk prediction.

Operation of the schizophrenia susceptibility gene, neuregulin 1, across traditional diagnostic boundaries to increase risk for bipolar disorder.

CONTEXT: Family and twin data suggest that, in addition to susceptibility genes specific for bipolar disorder or schizophrenia, genes exist that contribute to susceptibility across the traditional kraepelinian divide. Several studies have provided evidence that variation at the neuregulin 1 (NRG1) gene on chromosome 8p12 influences susceptibility to schizophrenia. The most consistent finding has been that one particular haplotype (the "core" haplotype) is overrepresented in cases compared with control subjects. OBJECTIVE: To investigate the possible role of NRG1 in bipolar disorder. DESIGN: Genetic case-control association analysis. SETTING: Subjects were unrelated and ascertained from general psychiatric inpatient and outpatient services. PARTICIPANTS: Five hundred twenty-nine patients with DSM-IV bipolar I disorder and 1011 controls from the United Kingdom (100% white). METHODS: We genotyped the markers constituting the NRG1 core haplotype in cases and controls and reanalyzed our existing data from 573 DSM-IV schizophrenia cases with this larger set of controls. RESULTS: We found a significant difference in haplotype distribution between bipolar cases and controls globally (P = .003) and specifically for the core haplotype. Frequencies were 10.2% for bipolar cases and 7.8% for controls (effect size, as measured by odds ratio [OR], 1.37; 95% confidence interval [CI], 1.03-1.80; P = .04). The effect size in our bipolar sample was similar to that in our schizophrenia sample (OR, 1.22; 95% CI, 0.92-1.61). In the bipolar cases with predominantly mood-incongruent psychotic features (n = 193), the effect was greater (OR, 1.71; 95% CI, 1.29-2.59; P = .009), as was the case in the subset of schizophrenia cases (n = 27) who had experienced mania (OR, 1.64; 95% CI, 0.54-5.01). CONCLUSIONS: Our findings suggest that neuregulin 1 plays a role in influencing susceptibility to bipolar disorder and schizophrenia and that it may exert a specific effect in the subset of functional psychosis that has manic and mood-incongruent psychotic features.

Bipolar disorder and polymorphisms in the dysbindin gene (DTNBP1).

BACKGROUND: Several studies support the dysbindin (dystrobrevin binding protein 1) gene (DTNBP1) as a susceptibility gene for schizophrenia. We previously reported that variation at a specific 3-locus haplotype influences susceptibility to schizophrenia in a large United Kingdom (UK) Caucasian case-control sample. METHODS: Using similar methodology to our schizophrenia study, we have investigated this same 3-locus haplotype in a large, well-characterized bipolar sample (726 Caucasian UK DSM-IV bipolar I patients; 1407 ethnically matched controls). RESULTS: No significant differences were found in the distribution of the 3-locus haplotype in the full sample. Within the subset of bipolar I cases with predominantly psychotic episodes of mood disturbance (n = 133) we found nominally significant support for association at this haploptype (p < .042) and at SNP rs2619538 (p = .003), with a pattern of findings similar to that in our schizophrenia sample. This finding was not significant after correction for multiple testing. CONCLUSIONS: Our data suggest that variation at the polymorphisms examined does not make a major contribution to susceptibility to bipolar disorder in general. They are consistent with the possibility that DTNBP1 influences susceptibility to a subset of bipolar disorder cases with psychosis. However, our subset sample is small and the hypothesis requires testing in independent, adequately powered samples.