Background
It is well-established that
maternal depression is associated with a broad range of emotional and behavioral disturbances in children, and that this risk is partially explained by the negative impact of depression on parent-child interactions [
1]. Indeed, interventions that improve depressed mother-infant interactions have shown positive effects on the child [
2]. Depression is likely to have the same impact on caregiving, irrespective of who cares for the child. However, the impact of depression on other key care-givers and its impact on child development has received little empirical attention. These insights are important to inform which family members should be included in interventions aimed at improving emotional and behavioral development of children. Evidence suggests that in Western cultures, where fathers may adopt a greater role in child-rearing, paternal depression has adverse impact on child development [
3]. There is also evidence to suggest the importance of grandparents’ mental health for child development, however, the findings are inconsistent, and the effects may vary depending on the cultural context [
4‐
7].
For instance, in many non-Western cultures, such as Latin America, grandmothers are culturally designated advisors on child-rearing as well as active caregivers [
8]. Qualitative evidence suggests that, in these contexts, grandmothers are highly valued with fathers having relatively limited influence during early infancy [
8]. Given the rising number of mothers in full-time work in both non- and Western world [
9], grandmothers are increasingly taking on the role of preschool day-carers. For instance, in the US and Europe over half of working mothers rely on relatives for childcare, most frequently
maternal grandmothers, who also provide emotional and financial support to parents [
10]. Thus, grandmothers’ mental health may impact grandchildren directly, through frequent caregiving, and indirectly, through influencing their parents [
7]. This pathway may be particularly relevant for maternal grandmothers given recent evidence suggesting that maternal depression predicts daughter’s (but not son’s) depression in adulthood [
11].
As well as any effects of the grandmothers’ depression on child rearing and mothers’ mental health, associations across generations could also be explained by genetic inheritance of vulnerability, even if the grandmother had no contact with the parent or the grandchild. The genetic heritability of depression, however, is relatively low (up to 37%) [
12] and this would become further diluted across generations. This means that it will only contribute to some of the association. In addition, if explained by genetic factors alone, intergenerational associations from maternal and paternal lines would be expected to be the same, given that the genetic contribution is equivalent for maternal and paternal grandparents. In contrast, the child-rearing contribution from maternal and paternal grandmothers are likely to differ. Environmental characteristics that are associated with mental health, such as poverty, are often shared across generations. However, this would also be expected to be at least as strong for paternal as for maternal grandmothers, particularly as family income is more often determined by fathers. In summary, there are several reasons to believe that grandmother’s (especially maternal grandmothers) mental health is important to their grandchildren’s development, with environmental contributions playing an important role.
Longitudinal evidence in high-income countries (HIC) suggests that parent-reported history of grandparent depression/anxiety is associated with increased risk of such disorders in grandchildren [
4‐
6,
12]. However, the retrospective nature of parental reports is likely to be biased by parental mental health as parents may not be aware of the emotional state of their own parents, especially if the symptoms are mild. Parents are more likely to be aware of mental health problems in their own parents if they also suffer from mental health problems. Indeed, some studies only find associations with maternal, and not paternal reports of grandparent mental health, highlighting the influence of the reporter [
4]. Thus, studies using prospectively collected measures of symptoms reported directly by the grandparents are important and presently lacking.
To the best of our knowledge, only two studies up-to-date have examined grandparents’ mental health prospectively and found evidence of intergenerational associations between mental health disorders [
7,
13]. One of these studies focused on major depressive disorders with cases being selected from outpatient specialty services, which is a selective group with severe depression presentation [
13]. However, the majority of depression is treated in primary care with mild symptoms being common at a population level and a cause of significant economic and health burden [
14]. Recall of milder symptoms by family members may be particularly affected by recall bias as they are often not expressed by those who are affected. This highlights the need for population-based prospective studies to address this limitation. One population-based study of grandparent reported (grandmothers only) mental health and grandchild emotional and behavioural development using the UK 1970 British Cohort Study data found evidence of an association between grandmother symptoms of depression and anxiety and grandchild emotional and behavioural problems. [
7]. However, the relationship was reported to operate indirectly through parental mental health. Furthemore, there are no investigations spanning three generations using prospective measures of symptoms in population samples in each generation from the Latin America, where grandparents play a substantial role in childcare. We used prospectively collected data from the Pelotas study, a large birth cohort based in the south of Brazil, to address some of these gaps in the literature. Our research questions were:
1.
Are grandmothers’ emotional symptoms associated with behavioral and emotional problems in grandchildren?
2.
Are these association stronger in maternal, compared to paternal grandmothers, reflecting the relatively greater role of maternal grandmothers in childcare?
Discussion
To the best of our knowledge, this study is the first population-based three-generation study using prospectively collected measures of mental health from low- and middle-income country (LMIC) that examined the association between grandmothers’ mental health and grandchildren emotional and behavioural development. We found evidence that grandmothers’ emotional symptoms were associated with emotional and behavioral problems in their grandchildren. The size of these associations was comparable to the associations between maternal symptoms and emotional and behavioural problems in children. The grandmothers’ associations remained after accounting for the indirect pathways through the impact of grandmothers’ symptoms on the grandchild’s parent, suggesting that grandmothers may have a direct impact on their grandchildren development. This is in contrast to studies from the high-income countries (HIC), where the influence of the grandmothers’ mental health was fully explained by maternal mental health [
5,
7]. This finding could suggest a stronger direct contribution of grandmothers in Brazil where the rate of female labor force participation has tripled even in comparison to the most South American countries [
9].
Effects were considerably stronger for (and generally limited to) maternal rather than paternal grandmothers, with statistical evidence for the effect modification. This finding is most consistent with the greater role of maternal grandmothers in child-rearing, whereas genetic inheritance or shared environmental adversity (e.g., poverty) would seem to predict equivalent associations and no effect modification by parental gender. However, we cannot completely rule out the possibility of differential inheritance of genetic vulnerability from maternal versus paternal grandmothers through a more complex genetic mechanism (such as mitochondrial DNA). Currently, there is no evidence that this type of genetic mechanism is important for emotional or behavioural outcomes [
24], however, this may change with further developments in genetic research.
There was no evidence that fathers’ depression had a negative impact on child emotional or behavioral outcomes. The sample size comprising fathers was relatively small, thus, there was limited power to detect small effect sizes. However, it is worth noting that regression coefficients for paternal effects were generally negative or minimal. In addition, this implies that any association would have been smaller than that of grandmothers for which the sample size was equivalent. This finding is consistent with existing evidence suggesting that in Latin America grandmothers play a greater role in early years childcare than fathers [
8]. Grandmothers are perceived as culturally designated advisors on child-rearing practices as well as active caregivers, representing the ‘authority’ figure in families and reflecting cultural hierarchy and respect for age and experience, whilst fathers play a relatively limited role in day-to-day caregiving within the family system [
8].
Strengths and limitations
The strengths of the study include population-based design and the linkage of prospectively collected three-generational data from the same family. The same instrument was used to measure symptoms in both grandmothers and parents allowing direct comparisons of associations. In addition, data was available for both maternal and paternal grandmothers and for fathers and mothers. Importantly, given the linkage between existing cohorts, fathers were members of the 1982 cohort from birth rather than being recruited into the study as fathers. This may explain the differences between the current findings and previous research investigating effects of paternal depression on the child with fathers who took part as fathers of the study index child. Such selection of fathers may have resulted in the recruitment of a more engaged, and, thus, more influential group of fathers who are highly involved in bringing up their children.
The findings need to be interpreted in light of several limitations. Firstly, the sample with three-generational data was naturally selected according to a specific variable, i.e. parents (G-2) having a child in Pelotas during 2004 when they were 22 years old. This parental age is lower than the mean age of parents in the 2004 cohort, which is 26 years old. A Brazil-based study found that grandmothers’ involvement in day-to-day childcare was greatest for younger mothers [
25]. In addition, to be included in the current study
both parents (G-2) and grandchildren (G-3) must have been born in Pelotas. Thus, parents who moved in or out of Pelotas would not have been included. Parents who remained in the city in which they were born may have stronger and wider family support network than those who move away. Nonetheless, findings of the current study demonstrate that, in certain circumstances, grandmothers appear to be as important as mothers when it comes to the next generation’s mental health.
Secondly, the sample size was relatively small comprising those with complete SRQ-20 measures. It is important to note that the relatively small sample size was due to purposeful sampling and not loss to follow-up, suggesting that the sample was not biased. In addition, the power calculation suggested that the study was powered to detect associations of the magnitude previously reported because we were able to use continuous scores for all variables. It should be noted, however, that the path analysis was likely to be underpowered and should be interpreted as exploratory. There were particularly low numbers of paternal grandmothers and fathers, which may reflect higher average age of fathers compared to mothers with fewer males from the 1982 cohort becoming fathers by age 22 years. Thirdly, child emotional and behavioural problems were parent-reported, most commonly by the mother. This may lead to reporting biases, whereby parents with mental health problems tend to overestimate emotional and behavioural symptoms in their children. However, this would influence the associations with mothers’ mental health more so than grandmothers’, reducing the likelihood of biasing the associations between grandmothers’ and grandchildren mental health problems.
We did not have the data on the specific roles that grandmothers play, such as the type and frequency of child care, geographical proximity to their grandchildren, or their ‘authority’ status in the family. In addition, other cultural, social and geographical factors may affect the health and well-being of the family, thus, future research should focus on disentangling the complex mechanisms by which grandmothers’ mental health is related to the child development, particularly in light of these preliminary findings suggesting that grandmothers’ depression and anxiety have an important effect. Thorough examination of the effects of these factors was beyond the scope of this study, as they may be on a causal pathway between grandmothers’ and grandchildren mental health driving changes in the pattern of caregiving practices. Existing research from HIC has found that the frequency of contact with grandparents did not alter the association between grandparents’ and grandchildren mental health [
4]. However, as noted previously, the grandparent to grandchild associations were found to operate mainly indirectly through parental mental health. Thus, the direct contact with grandparents may be less relevant in HIC compared to LMIC context, where maternal grandmothers may have a greater direct influence on their grandchildren through day-to-day involvement in child-rearing practices [
8].
Other putative mechanisms are also possible. For instance, grandmothers often advise mothers on childcare practices, thus, grandmothers’ depression may influence the quality and quantity of such advice, which may, in turn, influence the child. It is also possible that grandmothers’ depression influences maternal reports of child mental health independently of the effects on maternal mental health. For instance, a grandmother who experiences mental health difficulties may be easily frustrated by the child exaggerating child’s emotional and behavioural difficulties, which, in turn, influences parental reports of such problems. In addition, depression in grandmothers, who are involved in day-to-day care of the grandchildren, may interfere with their ability to provide sensitive and consistent responses to the child [
26]. This is consistent with evidence suggesting that depression in parents is associated with increased use of harsh parenting such as hitting and shouting at the child [
26], thus, similar practices are likely in the context of grandparents’ depression. These negative care-giving practices are in turn associated with emotional and behavioral problems in children [
1].
Conclusions and implications
Our study provides support to the importance of grandmothers’ mental health for grandchild emotional and behavioural development; in some contexts, it is as important as maternal mental health and more so than paternal mental health. Thus, interventions to improve the mental health of grandmothers, as well as parents, may be important to child mental health. Current intervention strategies aimed at improving infant emotional and behavioral development often focus on the mother-infant dyad, and, increasingly, on the role of the father [
1]. However, the role of other family members is given little attention, and the key influence of grandparents in non-Western cultures on the children has rarely been utilized in public health interventions [
8]. Further research is needed to understand the circumstances under which the grandmothers’ mental health may be important for the grandchildren development. The current findings suggest that interventions, especially in Brazil, should consider grandmothers’, particularly maternal grandmothers’, mental health as well as that of parents as this may increase the potential to increase the effectiveness of intervention strategies and to improve child emotional and behavioral development.
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