Panos Demakakos from UCL explores how childhood upbringing is related to health issues in later life.
A bit of a background
After years of epidemiological and ageing research, I have reached a fundamental conclusion: it is impossible to gain a good understanding of complex phenomena such as the ageing process or the development of chronic disease unless one examines these phenomena within a life course perspective with a particular focus on the formative early life and childhood years.
Currently, there is good evidence on the importance of early life and childhood factors for later life health. Some of these factors, like childhood socioeconomic position, have extensively been studied, while others less so. Surprisingly, one of the most important ones, parenting, has not been studied in relation to health at older ages. By parenting, I refer to everyday parenting practices, and not parental abuse or neglect, which to some extent have been studied in relation to disease development at older ages (see here).
Parenting is a factor that greatly influences human development over the long and sensitive period between birth and adolescence. My hypothesis is that if something goes wrong with the parent-child relationship during this period and the child experiences poor quality parenting then this may have implications for their development, which, in turn, could affect their health and wellbeing in adulthood.
Data – a mixture of prospective, retrospective and linked data from ELSA
For the needs of my research I used data from the English Longitudinal Study of Ageing (ELSA).
ELSA has run since 2002 and over the years has collected a wealth of prospective information on health, behaviours and social circumstances of a national sample of people born before 01 March 1952. The ELSA data are linked with national databases including the ONS mortality registry and constitute an excellent source of information to study (among other things) incidence of chronic disease, ageing outcomes and mortality. What ELSA did not have at baseline is information about what had happened to its participants when they were younger. This gap was covered by the one-off Life History survey, which took place in 2007 and collected retrospective information about the life circumstances and experiences of the ELSA participants before joining ELSA – mostly about “important events in their lives and what their childhood was like”.
Retrospectively collected data are subject to measurement error and bias and for that reason are considered inferior to prospectively collected data. Nevertheless, this does not mean that they have no use; their validity and reliability can be tested and established and ultimately they can be a good alternative to prospective data, if prospective data are not available.
Research on the association between experiences of poor parenting in childhood and cancer risk at older ages
Parenting: measure and concepts
Childhood experiences of parenting were measured using a shortened (7-item) version of the Parental Bonding Instrument (PBI), which has been designed to collect retrospective information about parenting experiences in childhood (when people aged ≤15 years). PBI focuses on two fundamental dimensions of parenting, care and overprotection and has good long-term reliability.
According to the PBI developers (see original publication by Parker et al. 1979), parental care as measured by the PBI refers to parental behaviours reflecting emotional warmth, affection, empathy, closeness and care for one’s child as opposed to emotional coldness and indifference.
Parental overprotection refers to parental behaviours reflecting:
- overprotection,
- intrusion,
- excessive contact
- prevention of independent behaviour as opposed to allowance of independence and autonomy.
The seven-item PBI includes three care and four overprotection items, which we used to derive care and overprotection scores for both natural parents and a parenting summary score.
Prior research
Before examining the association between poor quality parenting and cancer, I examined the association between poor quality parenting and mortality (the paper can be downloaded here).
The main finding of the mortality analyses was that poor quality parenting is associated with an increased risk of all-cause mortality. Interestingly, I also found a strong (but non-significant) association with cancer mortality, which was the initial stimulus to examine whether childhood experiences of poor quality parenting were associated with the development of cancer in adulthood.
Research hypotheses
Our hypothesis was that poor quality parenting is a pluripotent and omnipresent childhood stressor and as such might be associated with cancer risk at older ages. Based on this hypothesis, we examined whether people who had experiences of poorer quality parenting in childhood had an increased risk of incident cancer. We also investigated whether experiences of poorer quality parenting in childhood were associated with lifetime prevalence of cancer.
Methods of analysis
We used logistic and Cox proportional hazards regression to analyse data from 4,471 community-dwelling ELSA participants aged ≥55 years in 2007. Our investigation was sex-stratified and focused on all-site cancer and cancer sites, for which we had data.
Findings (from the fully-adjusted models)
Men
Overall poorer experiences of parenting, decreasing parental care and increasing parental overprotection were associated with increased risk of incident all-site and skin cancer in men, but not in women. Increasing paternal overprotection was also associated with increased risk of incident colorectal cancer in men.
No significant association was observed between parenting experiences and prevalent cancer in men, but we did find a marginally non-significant association between increasing paternal overprotection and the risk of prevalent skin cancer.
Women
Overall poorer experiences of parenting and increasing paternal overprotection were associated with increased risk of prevalent all-site and colorectal cancer in women. There was no significant association between poor quality parenting and incident cancer in women.
It is important to note that adjustment for childhood and adulthood covariates including childhood socioeconomic disadvantage and self-reported experiences of childhood abuse explained a small part of these associations.
Conclusions
- Experiences of poorer quality parenting in childhood are associated with cancer risk in a national sample of community-dwelling men and women aged ≥55 years.
- Men with childhood experiences of poorer quality parenting were at increased risk of incident cancer.
- Women with childhood experiences of poorer quality parenting were at increased risk of prevalent cancer.
- These findings considered together indicate an earlier onset of cancer in women who have experienced poorer quality parenting in childhood compared with men with the same experiences. This can be interpreted as an indication of women’s increased vulnerability to adversity and chronic stress in childhood.
- Common risk factors, such as unhealthy behaviours and affective problems, did not explain the associations. Nevertheless, more research on the role of these factors is needed.
- Our findings presuppose that childhood experiences of poor parenting as a powerful childhood stressor can initiate, modulate or catalyse biological processes, which in the long-term and under the right conditions might lead to the development of cancer in late adulthood.
Impact
Our findings are novel and indicate that poor quality parenting possibly is a childhood risk factor for cancer at older ages. They expand on the current understanding of cancer aetiology and add to the debate about the role of psychosocial factors in cancer causation.
The official stance of Cancer Research UK is that there is no good evidence linking stress with cancer and that stress does not cause (at least directly) cancer. But it is important to distinguish between childhood stressful experiences and stress and stress experienced in adulthood – the former is expected to be more harmful given its impact on the developing brain and body.
The universality and importance of parenting from birth to childhood and early adulthood makes our findings pertinent to the vast majority of the population and not just people who experienced social disadvantage or abuse and neglect in childhood.
On the understanding that suboptimal parenting is a potentially modifiable risk factor, our findings can inform prevention strategies and early life interventions.
The full paper can be downloaded here.
Data from the English Longitudinal Study of Ageing can be accessed from the UK Data Service.
About the author
Panos Demakakos is a senior epidemiologist at UCL and a member of the team that has developed and runs the English Longitudinal Study of Ageing (ELSA). Panos has a great interest in socioeconomic inequalities in health and ageing as dynamic multidimensional phenomena and the life course as the key to explain outcomes at older ages. Currently, he uses the ELSA data to explore the role of childhood adversity and psychosocial childhood experiences in the determination of health at older ages.