Mechanisms associated with maternal adverse childhood experiences on offspring’s mental health in Nairobi informal settlements: a mediational model testing approach

This study was guided by the integration of the Family Stress Model [9‐12] and the adverse childhood experiences (ACE) framework, proposed by the Centre for Disease Control/World Health Organization [13, 14] which posits that the level of parental and environmental-related stress influences family functioning and child outcomes. The Family Stress model specifically focuses on the current experience of severe economic pressures and other stressors that tend to undermine parents’ mental health, family functioning and subsequent child adjustment [15]. The ACE framework focuses on how early experience of neglect, psychological distress and violence related stressors impacts on an individual’s health-risk behaviors and adulthood chronic disease development. This framework focuses more on the impact on the individual’s long-term outcomes, and less on their impact on the offspring. There are a couple of empirical findings about ACE which are worth noting here. ACEs are common across cultures and social class contexts with higher vulnerability to some groups such as those in economic hardships or refugee contexts. ACEs form into clusters therefore when analyzing their impact and addressing these it is important to see their cumulative impact than individual impact. What is of most relevance is that ACEs have strongly demonstrated a dose-response relationship with adult psychopathology as well as with other health conditions [16]. Some studies have argued that whilst ACEs were significantly predictive of all adult mental health outcomes beyond demographic and socioeconomic characteristics; social disadvantage continues to be identified as being a unique contributing factor and therefore merits continued examination of ACEs integrated within a social disadvantage framework [17, 18]. This study utilizes an integrated ACEs and family stress model, that allows us to examine impact of ACEs on adolescent health-risky behaviors (i.e., adolescent pregnancy) and adulthood health (i.e., physical and mental health), and influence of these current family contexts on offspring’s health and development.

The original sample included 431 parents (415 mothers and 16 fathers). Parents/primary caregivers who had 2–16 years old children and seeking maternal and child health services at Kariobangi and Kangemi public health centers were eligible to the study. Parents in this study were defined as biological birth parents. Parents who were psychologically unstable were ineligible for the study. For the purpose of this study, we further limited our participants to mothers (n = 415) and focused on the psychopathology mechanism testing in the family context where mothers are the primary caregivers. We excluded fathers given the small sample size (n = 16). Among the eligible mothers, 394 (95%) had data for all study variables. They were considered as the final analytical sample for this study.

The original study sample size was estimated based on the anticipated small to moderate effect f² = .04 to .10 (or R² = 4–16%), 10 observed variables (8 independent variables, 2 dependent variables), with power level .80, and probability level .05 of a SEM model. We anticipate a minimum sample size of 160–380 would be required [19].

Participants were recruited between Oct 2015 to April 2016 from two maternal and child health (MCH) centers from two underserved informal settlement communities of Nairobi. We chose these health service settings because families of young children tend to utilize preventive or treatment services from these providers. Eligible parents (describe above) were approached to obtain oral or written informed consent. For parents who were literate, the consent information was shared verbally, and a written consent form (with written information about the study) was given at the time of obtaining consent. A signed consent form was documented for parents who agreed to participate. For parents who were illiterate, an oral consent was obtained, and a literate witness (e.g., an adult who parents trusted) signed the consent form on their behalf, which was then documented. Consent and interviews were conducted in Kiswahili (99%; as it is the most common local language in Kenya) or English (1%, the official language in Kenya education system) based on parents’ preference.

After consent, parents were scheduled for an interview at the MCH center by a trained bachelor or masters-level social science researcher. Participating parents were asked questions related to their childhood experience, their current health and wellbeing, and their child’s health. For families with more than one child (age range 2–16 years), only one child was targeted. Children did not directly participate in the study activities, and they were not the subjects of this study. The study procedures and method of consent was approved by the Institutional Review Board of the Kenyatta National Hospital/University of Nairobi (IRB number: KNH/UoN-ERC Ref. P520/08/2015). To comply with ethical guidelines, participants who identified with a high depression score (cut-off of 10 or more based on our interview questionnaire Kessler Psychological Distress Scale; described below) or requested for other mental health services (due to stress or anxiety) during the data collection interview were referred to the Mental Health Clinic or provided with some onsite psychosocial support.

All study measures, except CBCL and parental health, have been used in Kenyan context, and are available in Kiswahili. To validate CBCL and parental health, a formal translation process was undertaken with permission from the test-developer Achenbach. The Kiswahili version of questionnaires was translated and back-translated, and a team review approach was used to resolve any discrepancies between the versions. Scale reliability (assessed using internal consistency Cronbach’s Alpha/α) and validity for all study measures based on current study sample are reported below, which demonstrated all study measures to be reliable and valid with our study Kenya sample.

Our sample comprises of 394 biological mothers with mean age of 31.56 years (SD = 7.06 years, 52% were < 30 years). About one half of the mothers (52%) in our sample were employed or categorized themselves as self-employed, 70% had educational attainment of primary school or less, 66% were married or living with partner, 32% had her 1st child at or before age 18 (or 60% at or before age 20). Most families (98%) were Christian, 63% experiencing food insecurity, and on average, had 2.84 children (SD = 1.33) and 4.82 (SD = 1.56) household members at home. Target children were on average 6.78 years old (SD = 3.04 years, 41% 1.5–5 years, 53% 6–11 years, and 6% 12–18 years), and 45% were boys.

Table 1 shows prevalence of adverse childhood experiences in 13 areas, and total numbers of ACE by domains and in all 13 areas. The average number of ACEs experienced by mothers was 4.93 (SD = 2.52). Among the 13 ACE areas, the categories of household member treated violently (75%), presence of one or no parents, parental separation or divorce or living with one or no parents (54%), community violence (45%) living with alcohol/drug abuser (44%), and emotion neglect (43%), and collective violence experience (40%) were the most common childhood adversity experiences.

We first examined patterns of mental health of our study caregivers and their children. For maternal health, 33% of mothers had moderate to severe mental disorder indication based on K10 (using the clinical cut-off 25). Another striking finding was that 32% had their first child at the age of 18 years or before, and 42% reported being in poor or fair health. With regards to the offspring, 15.6 and 10.2% were at-risk for internalizing and externalizing problems (T score ≥ 60), respectively. For the purpose of the analysis, we also used T-score cutoff of 50 (above norm mean) (24), which resulted in 44% of children with the internalizing score above mean standardized T score, and 31% with the externalizing score above mean standardized T score.

Next, we examined the associations between ACEs and maternal and offspring’s health using logistic regression analyses. Univariate un-adjusted associations are reported in Table 2.

To examine whether the influence of ACEs on offspring’s mental health is mediated by caregivers’ health, adjusted SEM was carried out. Four demographic covariates (i.e., maternal age, education status, marital and employed status) were considered to adjust for potential confounders The overall χ² statistics based on the original theoretical model showed a reasonable fit in the SEM, χ² (10) = 59.69, p = <.001, RMSEA = .113 and CFI = .95. To improve the model fit, we add additional three paths (i.e., psychological distress of family member ➔ internalizing problem; violence at home ➔ externalizing and internalizing problems) guided by modification indexes suggested in the MPLUS. After including additional three paths, the overall χ² statistics showed a better fit of the model, χ² (7) = 24.16, p = <.001, RMSEA = .077 and CFI = .98. Figure 1 presents findings from this modified model. The standardized path coefficients for the significant paths and the R² values for each endogenous variable (maternal health and child mental health variables) from the SEM are presented in the Figure.

After adjusting for demographic confounders, all 5 domains of ACEs were associated with some aspects of maternal health, and all maternal mental health and physical health were significantly associated development of child mental health problems. Specifically, we found expected mediation links that higher ACEs (i.e., neglect, psychological distress of family members, violence at home, violence in community) were associated with higher adulthood mental disorders, which further associated with higher offspring’s internalizing problem. In addition, exposure to violence at home and sexual abuse during childhood were associated with poor adulthood physical health, which further associated with more offspring internalizing and externalizing problems. Furthermore, higher level of neglect during childhood was associated with increase likely to have underage pregnancy, which further associated with higher offspring’s internalizing problem.

There were also two unexpected findings that we found childhood sexual abuse experience was associated with lower adulthood mental disorder, and experience with psychological distress of family members was associated with fewer offspring’s internalizing problem.

A number of ACE factors such as physical and emotional abuse and neglect, sexual abuse and parental separation or divorce or orphan-hood have been associated with pregnancy and motherhood experience in adolescence. These factors have been well-articulated in the literature on risk factors leading towards adolescent motherhood [31]. In our study we also found that in addition to ACEs predicting poor maternal mental health, other experiences such as physical neglect, emotional abuse and bullying were contributory factors. A number of studies have shown that children exposed to maternal depression are at risk for a wide range of negative cognitive, emotional and behavioral outcomes [32, 33]. Internalizing and externalizing problems are both implicated when caregivers have been through adversities and currently experience mental health problems. Overall all four ACE domains were significantly implicated with development of problem behaviors in the children as found in our analyses. While by and large a number of overlapping ACE domains were common to development of internalizing and externalizing problems, studies have shown that the level of caregiver depressive symptoms may also change over time and result in different trajectories of parenting behaviors [32, 34]. We did not assess changes longitudinally but perhaps a future study would take this into account. This may explain that some may lead to internalizing and others to externalizing problems. We also found that current mental health problems mediated the relationship between maternal ACEs and development of child mental health problems.

Exposure to violence and interpersonal trauma in childhood is a precursor for depression and mental health problems in adulthood [35]. Given that our female participants experienced variable and protracted adversities, such as high stress, anxiety and food insecurity, the K10 scores indicate that there may be other comorbidities impacting their functioning. In another study where such relationship was explored the chronic life events course, implies more severe depression symptoms, and that would mean less recovery as compared to when there is depression only [36].

There are several limitations of the study. The ACE data were collected using retrospective data collection method, we relied on caregivers’ memory, which may not fully exclude recall bias. In addition, the assessment for maternal health and child mental health were concurrent assessments. Future research needs to include longitudinal data to better understand the causal mechanisms. This study was also limited to a maternal sample. Future studies should include fathers to better understand overall familial adversity experience on family functioning and offspring’s health and development. In such studies, ways of engaging fathers would need to be identified as caregiving is largely left to mothers in the Kenyan context. Finally, our sample was drawn from a peri-urban informal settlement and there may be variable patterns in rural poor or more geographically diverse pockets in Kenya. To have broader generalizability, further studies would need to include diverse populations.

Our study findings have several implications for clinical service development and intervention adaptation or engagement strategies development for women in Kenya. Women with high adversities and stress need greater support to prevent intergenerational transmission of mental illness. The adversity and stress experience of Kenyan women living in informal settlements has been well-documented. Interventions such as Problem Management Plus have been developed and championed by WHO to address adversity experiences and to bolster social support and treat depression in vulnerable women [37]. Low dose interventions delivered by community health workers or trained parent peer who may be able to factor in experience of adversities and ongoing depression and psychosocial functioning would be promising for women represented in our sample.

Similarly, a number of interventions focusing on maternal functioning have found positive impact on offspring well-being in recent times [38]. Parent peers can be a potential resource to deliver evidence-based psychosocial interventions [39]. Recent literature shows that ACEs could feed into more trauma-and-stress-mitigation informed practices and when this is combined with intergenerational approaches a number of interventions in clinical, early care, educational, and community contexts could be developed [40]. The especial focus on resilience and coping has been championed with ACE framework [41]. Parenting interventions targeting prosocial parenting and behavior development in families living in resource constraint and multiple adversity context would be helpful [42].