Postpartum Depression: Are You Listening?

Causal effect of the age at first birth with depression: a mendelian randomization study

BACKGROUND

This study aimed to explore the causal relationship between age at first birth (AFB) and depression.

METHODS

Using the univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) methods to examine the potential correlation between age at first birth (AFB) and major depressive disorder and postpartum depression. A public database was used to obtain the genome-wide association studies (GWAS) summary data. We put inverse-variance-weighted (IVW) as the primary method in Mendelian randomization (MR) analysis and used sensitivity analysis to confirm the robustness of our result.

RESULTS

We found a significant causal association between AFB and major depressive disorder by using the IVW algorithm (odd ratio [OR] 0.826; 95% confidence interval [CI] 0.793 - 0.861; P = 4.51 × 10- 20). MR-Egger, weighted median, simple mode and weighted mode method concluded the same result (P < 0.05). During the sensitivity analysis, the heterogeneity test (Q-value = 55.061, df = 48, P = 2.81 × 10- 01, I2 = 12.82%) and the leave-one-out plot analysis confirmed the stability of the results. The outcomes of the pleiotropy test (MR-Egger intercept = 8.932 × 10- 3. SE = 6.909 × 10- 3. P = 2.02 × 10- 01) and MR_PRESSO global test (P = 2.03 × 10- 01) indicated there is no pleiotropy.

CONCLUSION

There is solid evidence that a higher age at first birth is associated with a lower risk of major depressive disorder.

Association between Vitamin D Levels During Pregnancy and Postpartum Depression: A Narrative Reviews

Background

Postpartum Depression (PPD) is a serious depression that develops in the first year, with unknown explained reasons. Many studies evaluated the impact of Vitamin D (VD) levels on depression during pregnancy and postnatal. This narrative review aims to review any association between serum VD levels during pregnancy and the development of PPD.

Materials and Methods

PPD data from published trials and research articles (period from 2012 to 2022) were assessed through PubMed, Scopus, Science Direct, and Google Scholar using the following terms: Depression, pregnancy, 25-hydroxyvitamin D (25OH VD), vitamin D deficiency (VDD) and postpartum (PP). Articles were selected manually and with careful tracking to avoid duplication. Articles that investigated any association between VD levels during pregnancy and PPD in the time frame were included in the study, while articles investigating VD levels of PP without depression were excluded.

Results

In this narrative review, five out of seven studies showed an association between PPD and VDD during pregnancy. Danish National Birth Cohort (DNBC), Edinburgh Postnatal Depression Scale (EPDS) and Center for Epidemiologic Studies Depression Scale (CES-D) enrolled among different studies from 3 days to 1 year PP to assess PPD.

Conclusions

Pregnant women with VDD are significantly associated with PPD. Longitudinal follow-up studies are needed to evaluate the association between VDD with PPD. Screening VD levels among pre-postnatal mothers may be essential for awareness programs that can be implemented to promote remission of postnatal depression.

Beneficial Effects of Limosilactobacillus reuteri PBS072 and Bifidobacterium breve BB077 on Mood Imbalance, Self-Confidence, and Breastfeeding in Women during the First Trimester Postpartum

Background: The post-delivery period could be characterized by psychological distress (e.g., anxiety, sadness, and irritability), leading to postpartum depression (PPD). Objective: The present clinical study assesses the effect of probiotic supplementation containing Limosilactobacillus reuteri PBS072 and Bifidobacterium breve BB077 (4 × 109 CFU/day) on the mother's mood and breastfeeding quality during the first trimester after delivery. Methods: A Randomized, Double-Blind, Controlled (RDBPC) trial was carried out on 200 healthy new mothers divided into an active group taking a supplement containing Limosilactobacillus reuteri PBS072 and Bifidobacterium breve BB077 (4 × 109 CFU/day) plus multivitamins and a control group (multivitamin complex only) for 90 days. Symptoms related to maternal depression and breastfeeding quality were evaluated at days 45 and 90 using the Edinburgh Postnatal Depression Scale (EPDS) and the Breastfeeding Self-Efficacy Scale-Short Form (BSES-SF). Results: At days 45 and 90, the probiotic treatment significantly ameliorated the mothers' mood compared to the control treatment (p < 0.001). Likewise, the breastfeeding quality and the baby's cries significantly improved in the probiotic group (p < 0.001). Conclusions: Microbiota alterations could influence a post-delivery woman's mental state. According to our results, L. reuteri PBS072 and B. breve BB077 are potential candidates that are able to improve stress resilience in the postpartum period.

Effect of the INTER-ACT lifestyle intervention on maternal mental health during the first year after childbirth: A randomized controlled trial

We assess whether the INTER-ACT postpartum lifestyle intervention influences symptoms of depression and anxiety, sense of coherence and quality of life during the first year after childbirth. A total of 1047 women of the INTER-ACT RCT were randomized into the intervention (n = 542) or control arm (n = 505). The lifestyle intervention consisted of 4 face-to-face coaching sessions, supported by an e-health app. Anthropometric and mental health data were collected at baseline, end of intervention and 6-months follow-up. We applied mixed models to assess whether the evolution over time of depressive symptoms, anxiety, sense of coherence and quality of life differed between the intervention and control arm, taking into account the women's pre-pregnancy BMI. There was no statistical evidence for a difference in evolution in anxiety or quality of life between intervention and control arm. But an improvement in symptoms of depression and sense of coherence was observed in women who received the intervention, depending on the mother's pre-pregnancy BMI. Women with normal/overweight pre-pregnancy BMI, reported a decrease in EPDS between baseline and end of intervention, and the decrease was larger in the intervention arm (control arm: -0.42 (95% CI, -0.76 to -0.08); intervention arm: -0.71 (95% CI, -1.07 to -0.35)). Women with pre-pregnancy obesity showed an increase in EPDS between baseline and end of intervention, but the increase was less pronounced in the intervention arm (control arm: +0.71 (95% CI, -0.12 to 1.54); intervention arm: +0.42 (95% CI -0.42 to 1.25)). Women with a normal or obese pre-pregnancy BMI in the intervention arm showed a decrease in sense of coherence between baseline and end of intervention (-0.36) (95% CI, -1.60 to 0.88), while women with overweight pre-pregnancy showed an increase in sense of coherence (+1.53) (95% CI, -0.08 to 3.15) between baseline and end of intervention. Receiving the INTER-ACT postpartum lifestyle intervention showed improvement in depressive symptoms, in normal weight or overweight women on the short run, as well as improvement in sense of coherence in women with pre-pregnancy overweight only. Trial registration: ClinicalTrials.gov;NCT02989142.

Mental Health during the Interpregnancy Period and the Association with Pre-Pregnancy Body Mass Index and Body Composition: Data from the INTER-ACT Randomized Controlled Trial

Mental health problems and obesity are two common complications during pregnancy and postpartum. The preconception period is considered an appropriate period for prevention. Therefore, insights into interpregnancy mental health and the impact on weight and body composition are of interest to developing effective weight management strategies. The primary aim of this study is to assess the difference in women's mental health during the interpregnancy period and the association with pre-pregnancy body mass index (BMI) and body composition. The secondary aim is to study whether this association is affected by socio-demographic factors, interpregnancy interval and sleep. The study is a secondary analysis of the INTER-ACT e-health-supported lifestyle trial. Women were eligible if they had a subsequent pregnancy and mental health measurements at 6 weeks after childbirth and at the start of the next pregnancy (n = 276). We used univariate analyses to assess differences in mental health and performed regression analysis to assess their association with pre-pregnancy BMI and body composition at the start of the next pregnancy. Our results show a statistically significant increase in anxiety and depressive symptoms between 6 weeks after childbirth and the start of the next pregnancy (sSTAI-6 ≥ 40: +13%, p =≤ 0.001; GMDS ≥ 13: +9%, p = 0.01). Of the women who were not anxious at 6 weeks after childbirth (sSTAI < 40), more than one-third (39%) developed anxiety at the start of the next pregnancy (p =≤ 0.001). Regression analysis showed that sense of coherence (SOC-13) at the start of the next pregnancy was independently associated with women's pre-pregnancy BMI and fat percentage. We believe that the development of preconception lifestyle interventions that focus on both weight reduction and support in understanding, managing and giving meaning to stressful events (sense of coherence) may be of added value in optimizing women's preconception health.

Effect of pre-administration of esketamine intraoperatively on postpartum depression after cesarean section: A randomized, double-blinded controlled trial

BACKGROUND

To evaluate the effect of pre-administration of esketamine intraoperatively on the occurrence of postpartum depression after cesarean section under combined spinal-epidural anesthesia.

METHODS

A total of 120 women aged 24 to 36 years undergoing cesarean section by spinal-epidural anesthesia with American Society of Anesthesiologists physical status II were enrolled. According to the intraoperative use of esketamine, all participants were randomly divided into 2 groups: test group (group E) and control group (group C). Esketamine was administered intravenously at a dose of 0.2 mg/kg after the infant was delivered in group E and equal volume of normal saline was given in group C. The incidence of postpartum depression was recorded at 1 week and 6 weeks after the operation. The occurrence of adverse reactions such as postpartum bleeding, nausea and vomiting, drowsiness, and nightmares were also recorded at 48 hours after surgery.

RESULTS

Compared with group C, the incidence of postpartum depression was significantly lower at 1 week and 6 weeks after surgery in group E (P < .01). There was no significant difference of the adverse effects at 48 hours after the operation between the 2 groups.

CONCLUSION

Intravenous infusion of 0.2 mg/kg esketamine in women during cesarean section can significantly reduce the incidence of postpartum depression at 1 week and 6 weeks after surgery without increasing related adverse effects.

Exploring the Healthcare Services' Contribution to Reducing Postpartum Depression

Introduction

The postpartum period is accompanied by health risks that impact many women. Postpartum depression (PPD) is a mental health problem that has been neglected in maternal healthcare services.

Objective

The purpose of this study was to explore nurses' perceptions towards health services' contribution to lowering the incidence of PPD.

Methods

An interpretive phenomenological approach was adopted in a tertiary hospital in Saudi Arabia. A convenience sample of 10 postpartum nurses was interviewed face-to-face. The analysis followed Colaizzi's data analysis method.

Results

Seven main themes emerged on how to improve maternal health services to contribute to reducing the incidence of PPD among women: (1) maternal mental health, (2) follow-up of mental health status, (3) screening mental health status, (4) enhancing health education, (5) reducing stigma toward mental health, (6) updating resources, and (7) empowering nurses.

Conclusion

The integration of mental health services into maternal services that are provided to women needs to be considered in the context of Saudi Arabia. This integration will result in high-quality holistic maternal care.

Mental health after childbirth and the impact on postpartum weight retention and body composition. Data from the INTER-ACT randomized controlled trial

OBJECTIVE

To study the evolution of maternal mental health during the first year after childbirth in women with previous excessive gestational weight gain, and the relationship with postpartum weight retention and body composition.

METHODS

Anthropometric and mental health data of 505 women of the INTER-ACT RCT control group were collected and assessed using descriptive statistics and mixed model analyses.

RESULTS

At 6 weeks postpartum 28% of women reported depressive symptoms, 46% anxiety, 47% low sense of coherence and 48% low quality of life. From 6 weeks to 12 months postpartum there was a monthly increase (+0.38, p = .003) in anxiety and a monthly decrease (-0.39, p = .008) in quality of life. High levels of depressive symptoms at 6 weeks postpartum predicted higher body fat (+0.9%, p = .01) and higher waist circumference (+1.3 cm, p = .02) in the first year postpartum. High sense of coherence at 6 weeks postpartum predicted lower body fat (-0.8%, p = .01) the first year postpartum.

CONCLUSIONS

In women with a history of excessive gestational weight gain, the first year after childbirth is characterized by a high prevalence of mental health problems in which levels of anxiety and quality of life deteriorate over time. Moreover, high levels of depressive symptoms and low sense of coherence in the first weeks postpartum predict unfavourable body composition outcomes in the year after childbirth.

"It was terrible, I didn't sleep for two years": A mixed methods exploration of sleep and its effects among family caregivers of in-home hospice patients at end-of-life

BACKGROUND

Due to overnight caregiving demands; exacerbation of high rates of anxiety, depression, and distress; and inadequate support, millions of family caregivers of patients receiving in-home hospice are at risk of poor sleep and negative health effects.

AIM

To describe sleep experiences of family caregivers of in-home hospice patients and perceptions of these experiences on caregivers' wellbeing in the context of caregiver health and live-in status.

DESIGN

Developed using the Symptom Management Model, this mixed methods study featured a concurrent nested design prioritizing qualitative reflexive thematic analysis.

SETTING/PARTICIPANTS

About 47 family caregivers of in-home hospice patients from two randomized clinical trials (NCT03712410, NCT02929108) were interviewed (United States, 2021). Anxiety (GAD-7), depression (PHQ-9), quality-of-life (QOL) (CQLI-R), and self-rated health and energy were reported prior to interviews.

RESULTS

Qualitative analysis revealed three themes: compromised sleep quality, factors influencing sleep, effects of sleep. 72.5% of hospice family caregivers described "fair" or "poor" sleep quality, with "interrupted" sleep and frequent night-waking due to "on-call" "vigilance" and anxiety. Negative effects included exhaustion, mental and physical health decline, and reduced caregiver function. Live-in caregivers reported higher mean depression scores (8.4 vs 4.3, p = 0.08), higher mean anxiety scores (7.7 vs 3.3, p = 0.06), and lower mean QOL scores (24.8 vs 33.6, p < 0.001) than live-out caregivers. Anxiety, depression, and QOL worsened as self-reported caregiver sleep quality decreased. Few caregivers had adequate support.

CONCLUSION

End-of-life family caregivers experience disrupted sleep with negative effects and inadequate support. Clinicians must assess sleep, offer sleep interventions, and provide more supports to hospice family caregivers.

Implementation of a Hospital-based Brexanolone Program

Postpartum depression (PPD) is a serious complication of childbearing affecting ∼1 in 7 mothers. Left unrecognized and untreated, it is associated with negative outcomes for mothers and their infants. Building upon research suggesting that, for some women, hormonal fluctuations after childbirth contribute to the onset of depression, clinical trials have found promise in a novel treatment approach, brexanolone infusion. In 2019, the Food and Drug Administration (FDA) approved brexanolone as the first medication with an indication specifically for PPD. Delivering brexanolone treatment to patients in need requires overcoming some logistical and clinical challenges that are unique to this approach. This brief report describes the process by which a university-affiliated obstetric-gynecologic hospital in the northeast United States successfully implemented a program to administer this novel treatment to women with PPD.

Consumer acceptance of using a digital technology to manage postpartum depression

The goal of the study was to evaluate the end user experience using the MamaLift Plus app for 2 weeks to support the treatment of their postpartum depression (PPD). A total of 14 participants completed the study and their experiences are reported in this publication. Participants reported that MamaLift Plus is an acceptable, highly usable, and practical mobile tool to use weekly for the management of their PPD. More research is warranted to evaluate the benefit of digital behavior health interventions, especially in patient populations where mental health care may be limited or harder to access by patients.

Body Image Dissatisfaction as a Risk Factor for Postpartum Depression

Background and Objectives: Pregnancy and postpartum are periods that imply numerous physical and psychological changes that could lead to mental health consequences. The aim of the present study is to identify whether women who had body image dissatisfaction had a higher incidence of postpartum depression 6 months after birth than women who did not have body image dissatisfaction. Materials and Methods: A descriptive cross-sectional study was designed with a sample of 450 women from two hospitals in Andalusia. Quantitative variables were age and scores on the Edinburgh Postnatal Depression Scale (EPDS) and the Body Shape Questionnaire (BSQ) for body image dissatisfaction. The qualitative variables used were marital status, self-perceived health status, diet or physical exercise, type of delivery, and others. Results: Body dissatisfaction was positively correlated with the symptomatology of postpartum depression. Thus, for each point increased in body dissatisfaction, the occurrence of depression also increased. There was a relationship between the study variables, so women who were more dissatisfied with their body image were more frequently depressed. Conclusions: In conclusion, it can be established that postpartum depression seems to be related to the presence of poor body image.

Koronavirüs salgınında yaşanan korku ve postpartum depresyon ilişkisi: kesitsel bir çalışma

Amaç: Bu çalışmada 0-12 aylık bebeği olan kadınların Koronavirüs salgınında yaşadığı korkunun postpartum depresyon (PPD) ile ilişkisini incelemek amaçlandı. Yöntem Kesitsel tanımlayıcı tipteki çalışma verileri 20 Mart-15 Haziran 2021 tarihleri arasında çevrim içi platformlarda toplandı. Çalışmaya 18-45 yaş aralığında, 0-12 aylık bebeği olan 206 kadın dahil edildi. Veriler katılımcı tanıtım formu, Edinburg Postpartum Depresyon Ölçeği (EPDÖ) ve Koronavirüs Korkusu Ölçeği (KKÖ) kullanılarak elde edildi. Bulgular: Katılımcıların %81.1’inin Koronavirüs geçirmemiş olduğu gözlendi. Koronavirüs geçirenlerin %61.5’i bu süreçte bebeklerini emzirdiği tespit edildi. Katılımcıların %65.7’si Koronavirüse yakalandığını düşündüğünde kalp atışının hızlandığını, %70.9’u Koronavirüse yakalanmaktan duyduğu endişeden uykularının kaçtığını ve %75.2’si Koronavirüsü düşündüğünde ellerinin terlediğini bildirdi. Çalışma durumu, doğum sebebiyle çalışmaya ara verme ve salgın sebebiyle çalışmaya ara verme arasında KKÖ puanlarında istatistiksel açıdan anlamlı fark olduğu belirlendi. Katılımcıların %32.6’sı PPD açısından risk grubunda bulunmaktaydı. İşe tekrar başlamayı düşünen katılımcıların düşünmeyenlere göre daha düşük PPD riskinde oldukları belirlendi. Sonuç: Çalışmada postpartum süreçte kadınların orta düzeyde Koronavirüs korkusuna sahip olduğu ve Koronavirüs korkusu ile PPD arasında pozitif bir ilişki olduğu belirlendi. Koronavirüs salgını sırasında anne sağlığı hizmetlerini iyileştirmek için Koronavirüs bilgisi ve doğum sonrası sağlık bilgisinin tanıtımının güçlendirilmesi, doğum sonrası kadınlara profesyonel danışmanlık hizmeti verilmesinin önemli olduğu düşünülmektedir.

Personality traits as a risk factor for postpartum depression: A systematic review and meta-analysis

BACKGROUND

Certain personality traits increase vulnerability to depression, but the evidence linking personality and postpartum depression (PPD) is less robust. This systematic review aimed to identify personality traits that increase the risk of PPD.

METHODS

We systematically reviewed studies retrieved from PubMed/Medline, PsycINFO, Scopus, CINAHL, and Cochrane, following the PRISMA guidelines for reporting. We carried out a meta-analysis on the association between neuroticism and PPD.

RESULTS

A total of 34 studies were analyzed. Of these, 31 considered at least one trait associated with PPD; 10 studies considered at least one trait not associated with PPD. The meta-analysis included 13 studies, concluding that neuroticism was associated with PPD (OR: 1.37; 95%CI: 1.22-1.53; p<0.001).

LIMITATIONS

Study design and approach to personality assessment influence results. Prospective longitudinal studies of persons with no prior history of mood disorder would provide stronger evidence about whether particular personality traits predict PPD. Most studies reviewed used self-report measures to assess personality. Study design and approach to personality assessment influence results, and indications of publication bias were found.

CONCLUSIONS

Neuroticism is the personality trait most widely studied in relation to PPD. Our meta-analysis found this trait is strongly related with PPD. Moreover, vulnerable personality style and trait anxiety are also associated with PPD. Screening for these traits might help identify women at risk, improving prevention, early detection, and possibly treatment.

Increased sugar-sweetened beverage use tendency in pregnancy positively associates with peripartum Edinburgh postpartum depression scores

The association among sugar sweetened beverages (SSB) consumption, addiction and depression in adults, children and adolescents is widely reported. Dieting patterns during pregnancy is complicated by maternal fetal concerns. Specifically, restrained use of SSB might be potentially a source of perinatal distress. The current study modified diagnostic criteria for Substance Use Disorder (SUD) in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), into SSB-specific questions to assess SSB use tendency. Edinburgh Postpartum Depression Scores (EPDS) is used to assess maternal distress during pregnancy. One hundred and ninety-six consecutive pregnant women receiving antenatal care at Kaohsiung Medical University Hospital were invited to participate in this study. In the first trimester, 46.6% of women had none or 1 DSM-5 symptom, 27.0% had 2–3 symptoms, while 26.4% had ≥ 4 symptoms. The mean numbers of DSM-5 symptoms in each trimester were found to be 2.5 ± 2.25, 2.6 ± 2.45, 2.4 ± 2.43 for the first, second and third trimester, respectively, p = 0.750. While EPDS score showed no difference among DSM-5 symptoms 0–1, 2–3 and ≥ 4 groups in the first trimester (8.1 ± 4.59, 8.4 ± 5.00, 8.8 ± 4.82, p = 0.343), women with ≥ 4 DSM-symptoms was found significantly higher EPDS scores than those with < 4 DSM-symptoms in the second (7.2 ± 4.81, 7.7 ± 4.98, 8.8 ± 4.33, p = 0.030) and third trimester (6.8 ± 5.00, 7.2 ± 4.63, 8.7 ± 5.24, p = 0.019). The relationship remained significant after adjusting for covariates including actual SSB amount consumed (adjusted β = 0.25 with 95% confident interval (CI) 0.04–0.45 and 0.21 with 95% CI 0.04–0.38 for the second and third trimesters, respectively). Overall, the study is the first to characterize the positive relationship between SSB use tendency and antenatal distress in pregnancy, independent of actual SSB amount consumed. The observational nature of the study design precludes inferences of its underlying socio-psychomotor mechanisms, although restrained SSB use in pregnancy is suspected to contribute. The novel employment of modified SSB-specific DSM-5 scores and EPDS in this setting is feasible and further validation is promising. With better understanding and awareness, pregnant women with increased SSB use tendency should be properly counseled with special attention to their mental state.

Perinatal Complications as a Mediator of the Association Between Chronic Disease and Postpartum Mental Illness

Background: Chronic disease is associated with increased risk of postpartum mental illness, but the mechanisms underlying this association are unclear. Our aim was to explore the mediating role of perinatal complications in the association between chronic disease and postpartum mental illness. Materials and Methods: This was a population-based retrospective cohort study of all women in Ontario, Canada, from 2005 to 2015 with a singleton live birth and no recent history of mental illness during or 2 years before pregnancy. The outcome was mental illness diagnosis between delivery and 365 days postpartum, with perinatal complications, including pregnancy, delivery, and neonatal complications. Modified Poisson regression models were used to examine the association between chronic disease and perinatal mental illness, with generalized estimating equations for the calculation of total, direct, and indirect effects. All models were adjusted for sociodemographic characteristics and remote history of mental health care. Results: Of the 792,972 women, 21.1% had a chronic disease. Chronic disease was associated with an increased risk of postpartum mental illness (adjusted relative risk [aRR] 1.15 [95% confidence interval, CI 1.14-1.16]). There was no evidence of an indirect effect of chronic disease on postpartum mental illness via perinatal complications (aRR 1.003, 95% CI 1.002-1.003). Perinatal complications explained only 1.5% of the association between chronic disease and postpartum mental illness. Results were consistent by type of perinatal complication and chronic disease diagnosis. Conclusion: We observed no clinically meaningful mediating effect of perinatal complications in the association between chronic disease and postpartum mental illness. Future research should investigate alternative mechanisms explaining this association.

LncRNA Gm14205 induces astrocytic NLRP3 inflammasome activation via inhibiting oxytocin receptor in postpartum depression

Postpartum depression (PPD) is a kind of mental disorder characterized by persistent low emotions in puerperium. The most significant physiological change in postpartum is lactation which is regulated by oxytocin receptor (OXTR). However, whether OXTR is related to pathological process of PPD and the potential mechanism still remain unclear. In the present study, we prepared hormone-simulated pregnancy (HSP)-induced PPD mouse model and found that the protein level of OXTR in hippocampus of PPD model mice was down-regulated and Nod-like receptor protein 3 (NLRP3) inflammasome was activated. We identified five long non-coding RNAs (lncRNAs) related to PPD by transcriptome sequencing, including three up-regulated and two down-regulated. The five lncRNAs were associated with the signaling pathway of OXTR according to the bioinformatics analysis. Furthermore, we focused on one of the five lncRNAs, Gm14205, and found that it targeted OXTR which inhibited astrocytic NLRP3 inflammasome activation in hippocampal primary astrocytes. These findings illustrate that OXTR has protective effects in PPD by inhibiting NLRP3 inflammasome activation and provides a new strategy for targeting lncRNA Gm14205 in the pathogenesis of PPD.