Tuesday September 10 2013
Childhood events affected the risk of death before 50 years of age
“Traumatic childhoods increase the risk of death before the age of 50 by up to 80%,” reports the Mail Online.
The news is based on research that followed children born during one week in 1958 to see whether they died prematurely (before age 50) and to see what adverse events they went through as children.
The researchers looked at childhood adverse experiences as reported by parents and teachers when the children were 7, 11 and 16 years of age. These bad experiences included spending time in care, suffering from neglect, parental separation, or having a family member in prison. The researchers also took into account factors such as socioeconomic status and lifestyle during childhood and when people were young adults.
Overall, adverse childhood experiences were associated with a higher risk of death before 50. For those who had suffered two adverse experiences, this risk was 57% higher for men and 80% higher for women, compared to those with no such experiences.
If there is a true link, we still don’t know the exact reasons. The researchers speculate that adverse events change the way the brain is wired or that people who have experienced adversity develop short-term coping strategies that lead to long-term health damage. However, this can’t be proved by the current study. It may be that as yet unaccounted for factors explain the link between adverse events and premature mortality.
Where did the story come from?
The study was carried out by researchers from INSERM (The French National Institute for health and medical research) and other French and British research organisations and universities. It was funded by the French Institut National du Cancer and the Institut de recherche en santé publique and La Ligue nationale contre le cancer.
The study was published in the peer-reviewed European Journal of Epidemiology.
The Mail Online mostly reported the results of this study accurately. However, it’s headline cherry-picked the highest premature mortality figures (those of women experiencing two or more adverse life variables). The coverage also failed to mention the limitations of the study design (although the study was large and used the most appropriate study design, cohort studies cannot show causation, only association).
What kind of research was this?
This was a cohort study. It examined whether events causing stress responses during childhood are linked to premature mortality – defined in this study as death before 50 years of age.
This is the ideal study design to investigate this issue, although it cannot prove that events causing stress responses during childhood cause premature mortality, as other factors, called confounders, could be responsible for any association seen.
What did the research involve?
The researchers used results from 7,816 men and 7,405 women who were part of a cohort study of people born during one week in 1958 in Great Britain (the 1958 National Child Development Study).
Information was collected when people were 7, 11, 16, 23, 33, 42, 46, and 50 years of age.
Childhood adverse experiences were reported by parents and teachers at 7, 11 and 16 years of age. The following were counted as adverse experiences:
- being put into care by age 7, 11 or 16
- physical neglect, including being undernourished or dirty at ages 7 or 11
- having a family member in prison or on probation (at age 11) or in contact with the probation services (age seven or all) or being imprisoned or on probation at age 16
- being separated from their father or mother due to death, divorce or separation at 7, 11 or 16 years of age
- having a family member with a mental illness at ages 7, 11 or 16 or having someone in the household in contact with the mental health services at ages 7 or 11
- having a family member with an alcohol abuse problem at seven years of age
Deaths were monitored through death certificates. The researchers looked at the relationship between adverse childhood experiences and death before 50 years of age after controlling for “early life variables” and for characteristics at 23 years of age. These early life variables included:
- mother’s age at birth
- the number of people per household
- whether the mother’s partner was employed in manual or non-manual labour
- mother’s educational level
- maternal smoking during pregnancy
- gestational age at birth
- how many pregnancies the mother had previously had
- birth weight
- congenital conditions
- moderate/severe disabilities
- chronic respiratory or circulatory conditions
- sensory impairments
- special schooling
Characteristics at 23 years of age included:
- educational attainment
- occupational social class
- symptoms of depression
- alcohol consumption
- smoking status
- body mass index (BMI)
What were the basic results?
In the cohort, 70% of people had experienced no adverse childhood experiences, 22% had experienced one adverse childhood experience and 8% had experienced two or more adverse childhood experiences. Between the ages of 16 and 50 4.1% of men and 2.4% of women died.
In men, the risk of death was 57% higher among those who had experienced two or more adversities compared to those men who had experienced none (hazard ratio (HR) 1.57, 95% confidence interval (CI) 1.13 to 2.18).
In women, the risk of premature mortality increased with increasing number of adverse experiences. Women with one childhood adverse experience had a 66% increased risk of death (HR 1.66, 95% CI 1.19 to 2.33) and women who had had two or more had an 80% increased risk (HR 1.80, 95% CI 1.10 to 2.95) compared to women who had had none.
How did the researchers interpret the results?
The researchers conclude that the results, “point towards early life stressful events, particularly in a child’s [family] environment, being risk factors for long term health across the lifecourse and premature mortality possibly via the mechanisms of biological embedding which may occur via social, neuro-cognitive or behavioural pathways.”
This large cohort study found that (after taking into account early life and young adult sociological and lifestyles) being exposed to adverse childhood events was associated with an increased risk of premature death.
In men, having two or more adverse childhood experiences was associated with a 57% higher risk of death by age 50, compared to men who had none. In women, one childhood adverse experience was associated with a 66% increased risk of death, two or more was associated with an 80% increased risk of death by age 50, compared to women who'd had none.
Although the study was large, collected data as it went along (prospectively), and used the most appropriate study design, cohort studies cannot show causation, only association. And as this was a long-term cohort study, it had to deal with a significant amount of missing data. It did this by assuming that data was missing at random.
If there is a true link between adverse events in childhood and premature death, the reasons for this remain unknown. The researchers suggest that childhood exposure to adverse experiences could affect brain or other biological system development. Or, they suggest, it could encourage behaviours which reduce stress in the short-term but increase mortality in the long-term. However, this is speculative.
It is possible that the study has not been able to fully account for all health-related or environmental factors that could be associated with both adverse events and premature death, and it could be these that influence the relationship.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.