Molecular genetic approaches to puerperal psychosis

Puerperal psychosis: identifying and caring for women at risk

Puerperal (postpartum) psychosis – the acute onset of a manic or psychotic episode shortly after childbirth – most commonly occurs in women with a bipolar disorder diathesis who have a vulnerability to a specific childbirth-related trigger. Women with bipolar disorder are at particularly high risk of puerperal psychosis, with a severe affective episode following between 25 and 50% of deliveries. Suicide is a leading cause of maternal death in the UK and it is clear that we must do more to identify and better manage women at high risk of illness related to childbirth. The clinical picture of puerperal psychosis can vary dramatically from hour to hour and can escalate quickly to a true psychiatric emergency. It is vital that clinical services identify women who are unwell and can respond quickly to the severity of illness, delivering treatment in the most appropriate setting for the mother and her baby.

Mania triggered by sleep loss and risk of postpartum psychosis in women with bipolar disorder

BACKGROUND

Women with bipolar disorder are at high risk of affective psychoses following childbirth (i.e. "postpartum psychosis", PP) and there is a need to identify which factors underlie this increased risk. Vulnerability to mood dysregulation following sleep loss may influence risk of PP, as childbirth is typified by sleep disruption. We investigated whether a history of mood episodes triggered by sleep loss was associated with PP in women with bipolar disorder (BD).

METHODS

Participants were 870 parous women with BD recruited to the Bipolar Disorder Research Network. Lifetime diagnoses of BD and perinatal episodes were identified via interview and case notes. Information on whether mood episodes had been triggered by sleep loss was derived at interview. Rates of PP were compared between women who did and did not report mood episodes following sleep loss.

RESULTS

Women who reported sleep loss triggering episodes of mania were twice as likely to have experienced an episode of PP (OR = 2.09, 95% CI = 1.47-2.97, p < 0.001) compared to women who did not report this. There was no significant association between depression triggered by sleep loss and PP (p = 0.526).

LIMITATIONS

Data were cross-sectional therefore may be subject to recall bias. We also did not have objective data on sleep disruption that had occurred during the postpartum period or prior to mood episodes.

CONCLUSIONS

In clinical practice, a history of mania following sleep loss could be a marker of increased vulnerability to PP, and should be discussed with BD women who are pregnant or planning to conceive.

Perinatal psychiatric disorders: an overview

Perinatal mental illness has a significant implication on maternal health, birth outcomes, and the offspring's development. Prevalence estimates of perinatal psychiatric illnesses range widely, with substantial heterogeneity in different population studies, with a lower prevalence rate in high- rather than low- or middle-income countries. Because of the potential negative impact on maternal and child outcomes and the potential lability of these disorders, the perinatal period is a critical time to identify psychiatric illnesses. Thus, obstetricians and midwives play a crucial role in assessing women's mental health needs and to refer identified women promptly for multidisciplinary specialist assessment. However, there is still limited evidence on best practice assessment and management policies during pregnancy and postpartum. This review focuses on the prevalence of common perinatal mental disorders and antenatal screening policies to identify women at risk. The effect of these conditions and their management on pregnancy, fetal outcomes, and child development are discussed.

Post-partum transverse sinus thrombosis presenting as acute psychosis

Whilst cerebral vascular disease and mental illness in the post-partum period are well recognised, their co-existence and the concept of organic psychoses in pregnancy, parturition and the puerperium remains poorly appreciated (Brockington 2006; Brockington Arch Women's Ment Health 10: 177-178, 2007a; Brockington Arch Women's Ment Health 10: 305-306, b). We report a woman who was referred to the Medical team on-call with a mixed presentation of euphoria, mutism and aggressive behaviour but ultimately demonstrated to have a transverse sinus thrombosis and recovered well with anti-coagulation. This serves an important reminder of the implications of a missed medical diagnosis in this high-risk and vulnerable group of patients.

Gene expression profiling in porcine maternal infanticide: a model for puerperal psychosis

The etiology of mental disorders remains largely unclear. Complex interactions between genetic and environmental factors are key to the development of such disorders. Puerperal psychosis is the most extreme form of postnatal mood disorder in women. Similarly, parturition in the pig can trigger extreme behavioral disturbances, including maternal infanticide. In this study, we have used a targeted cDNA microarray approach using the pig as a model to understand the genes and genetic pathways that are involved in these processes. Two subtracted cDNA libraries from porcine hypothalamus were constructed, which were enriched for genes that were over-expressed and under-expressed in the aberrant behavioral phenotype, compared to the matched control. In addition to this, a normalized library was constructed from hypothalamus and pituitary samples taken from pigs in a variety of reproductive states. The libraries were partially sequenced and combined represented approximately 5,159 different genes. Microarray analysis determined differences in gene expression between hypothalamus samples from nine matched pairs of infanticidal versus control animals, using a common reference design. Microarray analysis of variance (MAANOVA) identified 52 clones as being differentially expressed (P <or= 0.002) in the infanticide phenotype, a second analysis with friendly statistics package for microarray analysis (FSPMA) identified 9 genes in common to MAANOVA, and a further 16 genes. A rapid cross-species screen onto a human oligonucleotide array confirmed 3 genes and highlighted 61 more potential candidates. Some of these genes and the pathways in which they are involved were also implicated in a parallel QTL study on maternal infanticide.

Is the perimenopause a time of increased risk of recurrence in women with a history of bipolar affective postpartum psychosis? A case series

There is increasing awareness of the influence of female reproductive life events on the course of bipolar disorder. Here, we describe the case histories of 5 women diagnosed with postpartum psychosis who subsequently experienced major mood disorders in relation to the perimenopause. This case series suggests that (a) the perimenopause may be a time of increased risk for women who experienced postpartum bipolar episodes and (b) periods of hormonal change represent a major trigger for bipolar episodes in some women.

Porcine maternal infanticide as a model for puerperal psychosis

Childbirth is a period of substantial rapid biological and psychological change and a wide range of psychotic disorders can occur ranging from mild 'baby blues' to severe episodes of psychotic illnesses. Puerperal psychosis is the most extreme form of postnatal psychosis, occurring in 1 in 1,000 births. In this study, we have used the pig as an animal model for human postnatal psychiatric illness. Our aim was to identify quantitative trait loci (QTL) associated with maternal (infanticide) sow aggression. This is defined by sows attacking and killing their own newborn offspring, within 24 hr of birth. An affected sib pair whole genome linkage analysis was carried out with 80 microsatellite markers covering the 18 porcine autosomes and the X chromosome, with the aim of identifying chromosomal regions responsible for this abnormal behavior. Analysis was carried out using the non-parametric linkage test of Whittemore and Halpern, as implemented in the Merlin software. The results identified 4 QTL mapping on Sus scrofa chromosomes 2 (SSC2), 10 (SSC10), and X (SSCX). The peak regions of these QTL are syntenic to HSA 5q14.3-15, 1q32, Xpter-Xp2.1, and Xq2.4-Xqter, respectively. Several potential candidate genes lie in these regions in addition to relevant abnormal behavioral QTL, found in humans and rodents.

Serotonergic candidate genes and puerperal psychosis: an association study

BACKGROUND

Altered serotonergic function is implicated in the aetiology and pathogenesis of a host of psychiatric disorders, and structural variations/polymorphisms in genes encoding the serotonin transporter and various serotonin receptor subtypes are attractive candidates to investigate the biological component underlying these disorders. Specific phenotypic subtypes, that perhaps represent homogeneous forms of the disorder, may increase the power to detect genes in complex diseases.

OBJECTIVE

We investigated regulatory and functional polymorphic DNA markers of serotonergic candidate genes using a case-control approach in puerperal psychosis and bipolar affective disorder probands.

METHODS

We genotyped 320 female participants (104 puerperal psychosis probands, 102 bipolar disorder participants and 114 controls) at the serotonin transporter SERT (5-HTT) 5-HTTVNTR and 5-HTTLPR locus; serotonin receptor 2A (5-HT2A)-T102C and His452Tyr loci, the serotonin receptor 2C (5-HT2C)-Cys23Ser locus, and seven unrelated Alu polymorphic markers.

RESULTS

We observed an association of the puerperal psychosis phenotype with the allele 10 of 5-HTTVNTR of SERT (P=0.004) and a modest association with the genotypic frequencies of the 5-HTTLPR (P=0.036). A nominal P value of 0.006 was observed with the S-10 haplotype in the PP group as compared with bipolar affective disorder probands. Significant association was observed with bipolar affective disorder phenotype with Tyr allele of the 5-HT2A His452Tyr gene polymorphism (P=0.00043) even after a conservative multiple test correction. No association was observed, however, with the 5-HT2A T102C locus, and the distribution of the other seven Alu markers did not differ between the groups.

CONCLUSION

The association between polymorphisms in serotonergic genes (SERT and 5-HT2A, 5-HT2C) suggests that these genetic factors can modulate vulnerability to puerperal psychosis in female bipolar participants.

No 'latent period' in the onset of bipolar affective puerperal psychosis

The weeks following childbirth are a period of high risk in bipolar women with manic or mixed affective episodes following 20-30% of deliveries. Although the vast majority of episodes have their onset within 2 weeks of delivery it is commonly believed that there is a "latent" or symptom-free period in the first few days after delivery. We examine the day of onset of clinically significant symptoms in 101 bipolar women who have experienced an episode of puerperal (postpartum) psychosis. We find no evidence of a latent period. Over 50% of symptom onsets occur on days 1-3, with over 22% occurring on the first postpartum day.

Obstetric variables associated with bipolar affective puerperal psychosis

BACKGROUND

Previous cross-sectional studies have highlighted a number of obstetric variables that may be associated with the development of broadly defined puerperal (post-partum) psychosis. These include: (a) primiparity, (b) pregnancy complications, (c) delivery complications, (d) Caesarean section, (e) female baby and (f) shorter gestation period.

AIMS

To examine these risk factors in women with well-characterised bipolar affective puerperal psychosis.

METHOD

A sample of 129 women with bipolar affective puerperal psychosis were investigated using a design that takes advantage of within-subject comparisons of affected and unaffected deliveries.

RESULTS

Two of the variables studied were independently associated with an episode of puerperal psychosis: primiparity (odds ratio=3.76, P < 0.001) and delivery complications (odds ratio=2.68, P=0.022).

CONCLUSIONS

This study provides further evidence of the association between primiparity and puerperal psychosis and suggests that complications during delivery may be associated with a severe post-partum episode.

Variation in the coding sequence and flanking splice junctions of the estrogen receptor alpha (ERalpha) gene does not play an important role in genetic susceptibility to bipolar disorder or bipolar affective puerperal psychosis

Genes involved in estrogen pathways have been proposed as possible candidates influencing susceptibility to bipolar disorder and the affective symptoms suffered by many women during the puerperal period. The estrogen receptor alpha (ERalpha) gene in particular has been a subject of interest and has recently been intensively screened for variations of potential relevance to psychiatric disorders, resulting in the identification of four mutations in individuals with bipolar disorder or puerperal psychosis. We have examined the frequency of these four ERalpha variations in a case control study using a group of mixed gender bipolar individuals (N = 231), further classified into subsets of parous bipolar females with (N = 112) and without (N = 50) puerperal psychosis, and a non-psychiatric comparison group (N = 110). We have also investigated the families in which the variations were initially detected, for evidence of co-segregation of the variants with mood disorder. We found no evidence in our case control sample to support the involvement of any of the ERalpha variations in either the aetiology of bipolar disorder or puerperal triggering of bipolar episodes. Nor did we find co-segregation of ERalpha variants and disease in any of the four families examined. We conclude that variation in the coding sequence and flanking splice junctions of the ERalpha gene does not play an important pathogenic role in the majority of cases of Bipolar Disorder or Bipolar Affective Puerperal Psychosis.

Do puerperal psychotic episodes identify a more familial subtype of bipolar disorder? Results of a family history study

Bipolar women have a marked vulnerability to puerperal psychosis, an episode of mania or psychosis following childbirth. We have conducted a family history study to examine the question of whether a vulnerability to puerperal episodes of illness is a marker for a more familial form of bipolar disorder. A consecutive series of 103 bipolar disorder probands were recruited in a lithium clinic and given a semi-structured interview, including a detailed family history. For the 52 female probands, information was also obtained about the relationship of episodes to childbirth. The morbid risk of affective disorder in first-degree relatives of bipolar women who had suffered an episode of mania, hypomania or schizoaffective mania with onset within 6 weeks of childbirth was significantly higher than that in relatives of parous bipolar women with no episodes in relation to childbirth (P = 0.0077). Despite relatively small numbers, this study provides evidence to support the hypothesis that puerperal episodes identify a more familial subtype of bipolar disorder.

Association studies of bipolar disorder

Association studies in outbred populations represent an important paradigm for investigation of complex traits, such as bipolar disorder, both to follow-up regions of interest from linkage studies (by systematic linkage disequilibrium mapping and positional candidate studies) and for pure functional studies. The advantages of the association method include its relative robustness to genetic heterogeneity and the ability to detect much smaller effect sizes than are detectable using feasible sample sizes in linkage studies. The candidate gene approach is potentially very powerful, particularly when used within the context of a VAPSE (variation affecting protein structure or expression) paradigm, but a major problem is that the efficiency in the choice of candidates is inevitably a function of the level of previous understanding of disease pathophysiology. To date, most candidate gene studies in bipolar disorder have focussed on the major neurotransmitter systems that are influenced by medication used in clinical management of the disorder. Early studies often used anonymous markers in the hope of detecting linkage disequilibrium but recently direct examination of polymorphisms of known or presumed functional relevance has become more usual. Most studies in the literature have been of the unrelated case-control design with samples rarely exceeding 200-300 subjects. No definitive findings have yet emerged although there have been some interesting preliminary findings including those with polymorphisms within the genes encoding catechol-o-methyl transferase (COMT), monoamine oxidase A (MAOA) and the serotonin transporter (hSERT; 5-HTT). In this article we critically review the current status of the literature within the context of the important methodological issues and limitations inherent in the use of association studies for genetic dissection of bipolar disorder. We conclude by examining likely future directions and developments in the field.