Meta-Analyses of Genome-Wide Association Studies for Postpartum Depression.

OBJECTIVE: Postpartum depression (PPD) is a common subtype of major depressive disorder (MDD) that is more heritable, yet is understudied in psychiatric genetics. The authors conducted meta-analyses of genome-wide association studies (GWASs) to investigate the genetic architecture of PPD. METHOD: Meta-analyses were conducted on 18 cohorts of European ancestry (17,339 PPD cases and 53,426 controls), one cohort of East Asian ancestry (975 cases and 3,780 controls), and one cohort of African ancestry (456 cases and 1,255 controls), totaling 18,770 PPD cases and 58,461 controls. Post-GWAS analyses included 1) single-nucleotide polymorphism (SNP)-based heritability ([Formula: see text]), 2) genetic correlations between PPD and other phenotypes, and 3) enrichment of the PPD GWAS findings in 27 human tissues and 265 cell types from the mouse central and peripheral nervous system. RESULTS: No SNP achieved genome-wide significance in the European or the trans-ancestry meta-analyses. The [Formula: see text] of PPD was 0.14 (SE=0.02). Significant genetic correlations were estimated for PPD with MDD, bipolar disorder, anxiety disorders, posttraumatic stress disorder, insomnia, age at menarche, and polycystic ovary syndrome. Cell-type enrichment analyses implicate inhibitory neurons in the thalamus and cholinergic neurons within septal nuclei of the hypothalamus, a pattern that differs from MDD. CONCLUSIONS: While more samples are needed to reach genome-wide levels of significance, the results presented confirm PPD as a polygenic and heritable phenotype. There is also evidence that despite a high correlation with MDD, PPD may have unique genetic components. Cell enrichment results suggest GABAergic neurons, which converge on a common mechanism with the only medication approved by the U.S. Food and Drug Administration for PPD (brexanolone).

Borderline personality traits are differently associated with postpartum psychosis and postpartum depression episodes in women with bipolar disorder.

BACKGROUND: Women with bipolar disorder have approximately 40 %-50 % chance of having a perinatal bipolar recurrence. Knowing the factors associated will be beneficial for the prediction and prevention of episodes. We aim to establish if borderline personality disorder traits, as measured by the BEST (Borderline Evaluation of Severity over Time) scale, are associated with perinatal psychiatric outcomes. METHODS: We recruited women with bipolar disorder as part of the BDRN (Bipolar Disorder Research Network) study. Women were interviewed and we collected their demographic and clinical information. Participants subsequently completed the BEST questionnaire. We analysed the association of BEST scores with lifetime presence/absence of perinatal bipolar relapse and, employing multinomial logistic regression, with different subtypes of perinatal outcomes: postpartum psychosis; postpartum depression, and other episodes. RESULTS: In our sample of 807, although there was no significant association between the BEST total score and perinatal episodes as a whole (adjustedOR 1.01 CI95% [0.99, 1.03], p = 0.204), we found significant differing associations with different subtypes of episodes. Women scoring highly on BEST were less likely to experience a postpartum psychotic episode (RRR 0.96 CI95% [0.94, 0.99], p = 0.005) but more likely to experience a non-psychotic depressive episode (RRR 1.03 CI95% [1.01, 1.05], p = 0.007) than no relapse. LIMITATIONS: This study is limited by its cross-sectional design and self-report nature of BEST. CONCLUSIONS: In women with bipolar disorder, borderline traits differentiate the risk of postpartum depression and postpartum psychosis, emphasise the importance of considering risk factors for these perinatal episodes separately, and may help individualise the risk for women in the perinatal period.

Mood episodes in pregnancy and risk of postpartum recurrence in bipolar disorder: The Bipolar Disorder Research Network Pregnancy Study.

BACKGROUND: Women with bipolar disorder (BD) are at high risk of mania/psychosis following childbirth. The risk factors for these episodes remain poorly understood and prospective studies are rare. Here, we examine whether mood episodes occurring within pregnancy predict postpartum recurrence in women with BD using a prospective design. METHOD: 128 women with DSM-5 BD were followed from week 12 of pregnancy (baseline) to 12-weeks postpartum. Semi-structured interviews, supplemented by clinician questionnaires and case-note review, assessed lifetime psychiatric history at baseline, and perinatal psychopathology at two follow-up assessments: third-trimester of pregnancy and 12-weeks postpartum. RESULTS: Postpartum follow-up data were obtained for 124/128 (97%) women [98 bipolar I disorder/schizoaffective-BD (BD-I/SA-BD group) and 26 bipolar II disorder/other specified BD and related disorder (BD-II/BD-OS group)]. Perinatal recurrence was high in both diagnostic groups (57% and 62% respectively). Women with BD-I/SA-BD were significantly more likely to experience mania/psychosis within 6 weeks postpartum (23%, n=22/96) compared to those with BD-II/BD-NOS (4%, n=1/25; p=0.042). In BD-I/SA-BD, mania/psychosis in pregnancy significantly elevated risk of mania/psychosis postpartum compared to remaining well (RR 7.0, p<0.001) and experiencing non-psychotic depression in pregnancy (RR 3.18, p=0.023) Limitations: Predominantly United Kingdom White sample and limited BD-II/BD-OS sample size. CONCLUSIONS: Women with BD are at high risk of recurrence during pregnancy and the postpartum. Over and above risk conferred by a history of BD-I/SA-BD, mania/psychosis during pregnancy further increased risk of postpartum mania/psychosis in this high-risk group. These data may have important implications for prediction and management of severe postpartum recurrence of BD.

Cardiac Fibroblasts Mediate a Sexually Dimorphic Fibrotic Response to ß-Adrenergic Stimulation.

Background Biological sex is an important modifier of cardiovascular disease and women generally have better outcomes compared with men. However, the contribution of cardiac fibroblasts (CFs) to this sexual dimorphism is relatively unexplored. Methods and Results Isoproterenol (ISO) was administered to rats as a model for chronic ß-adrenergic receptor (ß-AR)-mediated cardiovascular disease. ISO-treated males had higher mortality than females and also developed fibrosis whereas females did not. Gonadectomy did not abrogate this sex difference. To determine the cellular contribution to this phenotype, CFs were studied. CFs from both sexes had increased proliferation in vivo in response to ISO, but CFs from female hearts proliferated more than male cells. In addition, male CFs were significantly more activated to myofibroblasts by ISO. To investigate potential regulatory mechanisms for the sexually dimorphic fibrotic response, ß-AR mRNA and PKA (protein kinase A) activity were measured. In response to ISO treatment, male CFs increased expression of ß1- and ß2-ARs, whereas expression of both receptors decreased in female CFs. Moreover, ISO-treated male CFs had higher PKA activity relative to vehicle controls, whereas ISO did not activate PKA in female CFs. Conclusions Chronic in vivo ß-AR stimulation causes fibrosis in male but not female rat hearts. Male CFs are more activated than female CFs, consistent with elevated fibrosis in male rat hearts and may be caused by higher ß-AR expression and PKA activation in male CFs. Taken together, our data suggest that CFs play a substantial role in mediating sex differences observed after cardiac injury.

Migraine associated with early onset postpartum depression in women with major depressive disorder.

Major depressive disorder (MDD) and migraine are both more common among women than men. Women's reproductive years are associated with increased susceptibility to recurrence of both conditions, suggesting a potential role of sex hormones in aetiology. We examined associations between comorbid migraine and clinical features of MDD in women, including relationships with lifetime reproductive events such as childbirth. Lifetime clinical characteristics and reproductive events in a well-characterised sample of 222 UK women with recurrent MDD, with (n = 98) and without (n = 124) migraine were compared. Women had all been recruited as part of a UK-based ongoing programme of research into the genetic and non-genetic determinants of mood disorders. Multivariate analysis showed a specific association between the lifetime presence of migraine and postpartum depression (PPD) within 6 weeks of delivery (OR = 2.555; 95% CI: 1.037-6.295, p = 0.041). This association did not extend to a broader definition of PPD with onset up to 6 months postpartum. All other factors included in the analysis were not significantly associated with the presence of migraine: family history of depression, younger age at depression onset, history of suicide attempt and severe premenstrual syndrome symptoms. The finding that women with MDD and comorbid migraine may be particularly sensitive to hormonal changes early in the postpartum period leads to aetiological hypotheses and suggests this group may be useful for future studies attempting to characterise PPD and MDD phenotypes. The refinement of such phenotypes has implications for individualising risk and treatment and for future biological and genetic studies.

Phenomenology, Epidemiology and Aetiology of Postpartum Psychosis: A Review.

Postpartum psychoses are a severe form of postnatal mood disorders, affecting 1-2 in every 1000 deliveries. These episodes typically present as acute mania or depression with psychosis within the first few weeks of childbirth, which, as life-threatening psychiatric emergencies, can have a significant adverse impact on the mother, baby and wider family. The nosological status of postpartum psychosis remains contentious; however, evidence indicates most episodes to be manifestations of bipolar disorder and a vulnerability to a puerperal trigger. While childbirth appears to be a potent trigger of severe mood disorders, the precise mechanisms by which postpartum psychosis occurs are poorly understood. This review examines the current evidence with respect to potential aetiology and childbirth-related triggers of postpartum psychosis. Findings to date have implicated neurobiological factors, such as hormones, immunological dysregulation, circadian rhythm disruption and genetics, to be important in the pathogenesis of this disorder. Prediction models, informed by prospective cohort studies of high-risk women, are required to identify those at greatest risk of postpartum psychosis.

The influence of borderline personality traits on clinical outcomes in bipolar disorder.

OBJECTIVES: Systematic reviews suggest comorbid borderline personality disorder is present in approximately 20% of individuals who have bipolar disorder, but current diagnostic systems demonstrate a move towards dimensional rather than categorical approaches to classifying personality pathology. We aimed to examine the presence and severity of borderline personality traits in bipolar I and bipolar II disorder, and to explore associations between the presence/severity of borderline personality traits and clinical outcomes in bipolar disorder. METHODS: Borderline personality traits were measured in 1447 individuals with DSM-IV bipolar disorder (1008 bipolar I disorder and 439 bipolar II disorder) using the Borderline Evaluation of Severity over Time (BEST) questionnaire. Lifetime clinical outcomes were assessed via Schedules for Clinical Assessment in Neuropsychiatry (SCAN) semi-structured interview and clinical case notes. RESULTS: Borderline personality traits were common in both bipolar disorder groups, with 86.2% participants reporting at least one trait. These included traits that overlap with (eg mood instability) and those that are distinct from the symptoms of bipolar disorder (eg fear of abandonment). Borderline personality traits were significantly more frequent and more severe in bipolar II disorder compared to bipolar I disorder. More severe borderline traits, and even the presence of a single borderline personality trait, were significantly associated with younger age of bipolar disorder onset and higher prevalence of lifetime alcohol misuse in both bipolar disorder groups. CONCLUSIONS: The presence of comorbid borderline personality traits should be considered in the management of all patients with bipolar disorder irrespective of whether criteria for a categorical borderline personality disorder diagnosis are met.

Patterns and clinical correlates of lifetime alcohol consumption in women and men with bipolar disorder: Findings from the UK Bipolar Disorder Research Network.

OBJECTIVES: Despite previous literature on comorbid alcohol use disorders (AUDs) in bipolar disorder (BD), little is known about patterns of alcohol use more widely in this population. We have examined lifetime heaviest average weekly alcohol consumption levels in a large well-characterised UK sample including lifetime clinical correlates of increasing levels of alcohol use. METHODS: Participants were 1203 women and 673 men with bipolar I disorder interviewed by semi-structured interview who had consumed alcohol regularly at any point in their life. RESULTS: Over half of both women (52.3%) and men (73.6%) had regularly consumed over double the current UK recommended guideline for alcohol consumption. In women and men increasing levels of lifetime alcohol consumption were significantly associated with the presence of suicide attempts (women: OR 1.82, P < .001; men: OR 1.48, P = .005) and rapid cycling (women: OR 1.89, P < .001; men: OR 1.88, P < .001). In women only, increasing levels of alcohol consumption were significantly associated with more episodes of depression (OR 1.35, P < .001) and mania (OR 1.30, P < .004) per illness year, less impairment in functioning during the worst episode of mania (OR 1.02, P < .001), fewer psychiatric admissions (OR 0.51, P < .001), comorbid panic disorder (OR 2.16, P < .001) and eating disorder (OR 2.37, P < .001). CONCLUSIONS: Our results highlight the clinical importance of obtaining detailed information on levels of alcohol consumption among patients with BD. Increased levels of alcohol use, not necessarily reaching criteria for AUD, may be helpful in predicting BD illness course, in particular eating disorders comorbidity in women.

Symptom profile of postpartum and non-postpartum manic episodes in bipolar I disorder: a within-subjects study.

The relationship of postpartum mania to episodes of mania occurring outside the perinatal period among women with bipolar disorder remains controversial. Previous studies have used between-subjects designs to compare the clinical presentations of these episodes meaning the differences, in part, may reflect between-group differences. To overcome this we have undertaken within-subject comparisons of the symptom profile of postpartum and non-postpartum manic episodes in 50 women with DSM-IV bipolar I disorder. For each woman detailed symptom information on a postpartum episode of mania and a comparison non-postpartum manic episode was collected. The occurrence of manic, psychotic and depressive symptoms in these episodes were compared. Postpartum manic episodes had a significantly higher incidence of perplexity and excessive self-reproach. Classic manic symptoms, specifically pressured speech and increased sociability, were significantly less frequent in postpartum manic episodes. Overall there were significantly fewer manic symptoms and significantly more depressive symptoms in the postpartum episodes than in the non-postpartum episodes. The mixed presentation of postpartum manic episodes suggests childbirth may act as a pathoplastic trigger in women with bipolar disorder. The differences in symptom profiles suggests further research is warranted into whether differences in treatment response exist among women experiencing postpartum and non-postpartum manic episodes.

Explaining why childhood abuse is a risk factor for poorer clinical course in bipolar disorder: a path analysis of 923 people with bipolar I disorder.

BACKGROUND: Childhood abuse is a risk factor for poorer illness course in bipolar disorder, but the reasons why are unclear. Trait-like features such as affective instability and impulsivity could be part of the explanation. We aimed to examine whether childhood abuse was associated with clinical features of bipolar disorder, and whether associations were mediated by affective instability or impulsivity. METHODS: We analysed data from 923 people with bipolar I disorder recruited by the Bipolar Disorder Research Network. Adjusted associations between childhood abuse, affective instability and impulsivity and eight clinical variables were analysed. A path analysis examined the direct and indirect links between childhood abuse and clinical features with affective instability and impulsivity as mediators. RESULTS: Affective instability significantly mediated the association between childhood abuse and earlier age of onset [effect estimate (θ)/standard error (SE): 2.49], number of depressive (θ/SE: 2.08) and manic episodes/illness year (θ/SE: 1.32), anxiety disorders (θ/SE: 1.98) and rapid cycling (θ/SE: 2.25). Impulsivity significantly mediated the association between childhood abuse and manic episodes/illness year (θ/SE: 1.79), anxiety disorders (θ/SE: 1.59), rapid cycling (θ/SE: 1.809), suicidal behaviour (θ/SE: 2.12) and substance misuse (θ/SE: 3.09). Measures of path analysis fit indicated an excellent fit to the data. CONCLUSIONS: Affective instability and impulsivity are likely part of the mechanism of why childhood abuse increases risk of poorer clinical course in bipolar disorder, with each showing some selectivity in pathways. They are potential novel targets for intervention to improve outcome in bipolar disorder.

Adverse childhood experiences and postpartum depression in bipolar disorder.

BACKGROUND: Women are particularly vulnerable to recurrence of bipolar disorder (BD) following childbirth. Risk of postpartum psychosis (PP) is especially high, but postpartum depression (PPD) is also common. Adverse childhood experiences (ACEs) have not been associated with PP, but have been associated with PPD in non-bipolar samples. The relationship between ACEs and PPD within BD remains to be investigated. Here, we examined this association in a large, well-defined sample of women with BD. METHODS: Participants were 575 parous women with DSM-IV BD. Lifetime psychopathology, including perinatal, was assessed via semi-structured interview and case-notes. ACEs, assessed via self-report and case-notes, were compared between women with lifetime PPD (n = 368) and those without a lifetime history of perinatal mood episodes (n = 207). RESULTS: In univariate analysis exposure to 3 or more ACEs, and to childhood abuse specifically, was significantly associated with PPD (p = 0.026 and 0.041 respectively), but this did not remain significant after adjusting for lifetime number of episodes of depression and parity. Post-hoc analysis revealed more frequent episodes of depression to be associated with both a history of 3 or more ACEs and of childhood abuse. LIMITATIONS: Limited range of ACEs assessed and potential recall bias. CONCLUSIONS: Increased frequency of ACEs and particularly childhood abuse was associated with more frequent lifetime episodes of depression, but not specifically episodes with postpartum onset. Understanding factors that mediate the pathway between ACEs and PPD in BD has implications for risk prediction of PPD.

Expression of Normally Repressed Myosin Heavy Chain 7b in the Mammalian Heart Induces Dilated Cardiomyopathy.

Background In mammals, muscle contraction is controlled by a family of 10 sarcomeric myosin motors. The expression of one of its members, MYH7b, is regulated by alternative splicing, and while the protein is restricted to specialized muscles such as extraocular muscles or muscle spindles, RNA that cannot encode protein is expressed in most skeletal muscles and in the heart. Remarkably, birds and snakes express MYH7b protein in both heart and skeletal muscles. This observation suggests that in the mammalian heart, the motor activity of MYH7b may only be needed during development since its expression is prevented in adult tissue, possibly because it could promote disease by unbalancing myocardial contractility. Methods and Results We have analyzed MYH7b null mice to determine the potential role of MYH7b during cardiac development and also generated transgenic mice with cardiac myocyte expression of MYH7b protein to measure its impact on cardiomyocyte function and contractility. We found that MYH7b null mice are born at expected Mendelian ratios and do not have a baseline cardiac phenotype as adults. In contrast, transgenic cardiac MYH7b protein expression induced early cardiac dilation in males with significantly increased left ventricular mass in both sexes. Cardiac dilation is progressive, leading to early cardiac dysfunction in males, but later dysfunction in females. Conclusions The data presented show that the expression of MYH7b protein in the mammalian heart has been inhibited during the evolution of mammals most likely to prevent the development of a severe cardiomyopathy that is sexually dimorphic.

Agitated depression in bipolar disorder.

OBJECTIVES: It has been suggested that agitated depression (AD) is a common, severe feature in bipolar disorder. We aimed to estimate the prevalence of AD and investigate whether presence of AD was associated with episodic and lifetime clinical features in a large well-characterized bipolar disorder sample. METHOD: The prevalence of agitation, based on semi-structured interview and medical case-notes, in the most severe depressive episode was estimated in 2925 individuals with DSM-IV bipolar disorder recruited into the UK Bipolar Disorder Research Network. Predictors of agitation were ascertained using symptoms within the same episode and lifetime clinical features using multivariate models. RESULTS: 32.3% (n = 946) experienced agitation during the worst depressive episode. Within the same episode, significant predictors of presence of agitation were: insomnia (OR 2.119, P < 0.001), poor concentration (OR 1.966, P = 0.027), decreased libido (OR 1.960, P < 0.001), suicidal ideation (OR 1.861, P < 0.001), slowed activity (OR 1.504, P = 0.001), and poor appetite (OR 1.297, P = 0.029). Over the lifetime illness course, co-morbid panic disorder (OR 2.000, P < 0.001), suicide attempt (OR 1.399, P = 0.007), and dysphoric mania (OR 1.354, P = 0.017) were significantly associated with AD. CONCLUSIONS: Agitation accompanied bipolar depression in at least one-third of cases in our sample and was associated with concurrent somatic depressive symptoms, which are also common features of mixed manic states. Furthermore, AD in our sample was associated with lifetime experience of mixed mania, in addition to severe lifetime illness course including comorbid panic disorder and suicidal behavior. Our results have implications for the diagnosis and treatment of agitated features in bipolar depression.

Stratification of the risk of bipolar disorder recurrences in pregnancy and postpartum.

BACKGROUND: Pregnancy and childbirth are a period of high risk for women with bipolar disorder and involve difficult decisions particularly about continuing or stopping medications.AimsTo explore what clinical predictors may help to individualise the risk of perinatal recurrence in women with bipolar disorder. METHOD: Information was gathered retrospectively by semi-structured interview, questionnaires and case-note review from 887 women with bipolar disorder who have had children. Clinical predictors were selected using backwards stepwise logistic regression, conditional permutation random forests and reinforcement learning trees. RESULTS: Previous perinatal history of affective psychosis or depression was the most significant predictor of a perinatal recurrence (odds ratio (OR) = 8.5, 95% CI 5.04-14.82 and OR = 3.6, 95% CI 2.55-5.07 respectively) but even parous women with bipolar disorder without a previous perinatal mood episode were at risk following a subsequent pregnancy, with 7% developing postpartum psychosis. CONCLUSIONS: Previous perinatal history of affective psychosis or depression is the most important predictor of perinatal recurrence in women with bipolar disorder and can be used to individualise risk assessments.Declaration of interestNone.

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.

Autistic and schizotypal traits and global functioning in bipolar I disorder.

OBJECTIVE: To determine the expression of autistic and positive schizotypal traits in a large sample of adults with bipolar I disorder (BD I), and the effect of co-occurring autistic and positive schizotypal traits on global functioning in BD I. METHOD: Autistic and positive schizotypal traits were self-assessed in 797 individuals with BD-I recruited by the Bipolar Disorder Research Network. Differences in global functioning (rated using the Global Assessment Scale) during lifetime worst depressive and manic episodes (GASD and GASM respectively) were calculated in groups with high/low autistic and positive schizotypal traits. Regression analyses assessed the interactive effect of autistic and positive schizotypal traits on global functioning. RESULTS: 47.2% (CI=43.7-50.7%) showed clinically significant levels of autistic traits, and 23.22% (95% CI=20.29-26.14) showed clinically significant levels of positive schizotypal traits. In the worst episode of mania, the high autistic, high positive schizotypal group had better global functioning compared to the other groups. Individual differences analyses showed that high levels of both traits were associated with better global functioning in both mood states. LIMITATIONS: Autistic and schizotypal traits were assessed using self-rated questionnaires. CONCLUSIONS: Expression of autistic and schizotypal traits in adults with BD I is prevalent, and may be important to predict illness aetiology, prognosis, and diagnostic practices in this population. Future work should focus on replicating these findings in independent samples, and on the biological and/or psychosocial mechanisms underlying better global functioning in those who have high levels of both autistic and positive schizotypal traits.

Gambling problems in bipolar disorder in the UK: prevalence and distribution.

BACKGROUND: North American studies show bipolar disorder is associated with elevated rates of problem gambling; however, little is known about rates in the different presentations of bipolar illness. AIMS: To determine the prevalence and distribution of problem gambling in people with bipolar disorder in the UK. METHOD: The Problem Gambling Severity Index was used to measure gambling problems in 635 participants with bipolar disorder. RESULTS: Moderate to severe gambling problems were four times higher in people with bipolar disorder than in the general population, and were associated with type 2 disorder (OR = 1.74, P = 0.036), history of suicidal ideation or attempt (OR = 3.44, P = 0.02) and rapid cycling (OR = 2.63, P = 0.008). CONCLUSIONS: Approximately 1 in 10 patients with bipolar disorder may be at moderate to severe risk of problem gambling, possibly associated with suicidal behaviour and a rapid cycling course. Elevated rates of gambling problems in type 2 disorder highlight the probable significance of modest but unstable mood disturbance in the development and maintenance of such problems.