Thursday July 29 2010
It is not easy to single out the role of maternal affection
“Maternal love helps you deal better with stress and anxiety later in life,” according to the Daily Mail. The newspaper said that a study has found that children whose mothers showed them high levels of affection at eight months of age experienced lower levels of distress as adults.
The study followed 482 individuals from birth until their mid thirties, and this unusually long follow-up time is one of the study’s strengths. The main limitation of this study is that many unmeasured factors may influence a person’s adult wellbeing, for example paternal affection as a child, or health or work status as an adult. It is also important to note that the adults in this study were, on average, in the normal range of emotional functioning.
It is likely that a complex mix of factors influences our adult wellbeing, and it seems plausible that our childhood experiences could be among them. However, the interactions between these numerous factors mean that teasing out the effects of individual factors is likely to be difficult and that maternal affection may not necessarily be the principal factor behind mental resilience.
Where did the story come from?
The study was carried out by researchers from Duke University, Harvard School of Public Health and Brown University in the US. One of its authors received partial funding from the US National Institutes of Mental Health. The study was published in the peer-reviewed Journal of Epidemiology and Community Health.
The Daily Mail and BBC News have reported on this research. The Daily Mail points out a strength of the study, saying that “most previous studies have relied on people's recollections - whereas this research tracked participants from early childhood to adult life”. The BBC also makes the important point that “the influence of other factors, such as personality, upbringing and schooling, could not be ruled out”.
What kind of research was this?
This was a prospective cohort study that looked at the association between maternal affection early in a child’s life and their emotional functioning as an adult.
The researchers looked at children who had originally been part of the National Collaborative Perinatal Project (NCPP), which had enrolled their mothers during pregnancy from 1959 to 1966. At the age of eight months, the interaction of mothers with their children was observed and rated according to how affectionate it was. The emotional functioning of the offspring was assessed when they became adults. The researchers then looked to see whether there were relationships between a mother’s level of affection at eight months and adult emotional functioning.
What did the research involve?
An evaluation of maternal affection was made by a psychologist while the mother and baby attended cognitive and developmental testing as part of the NCPP study. Levels of affection were rated as: “negative” or “occasionally negative” (both indicating a low level of affection), “warm” (indicating normal affection), and “caressing” or “extravagant” (both indicating a high level of affection). For the current analyses the “negative”, “occasionally negative” and “warm” groups were pooled, while “caressing” and “extravagant” were pooled into a high affection group.
A sample of 1,062 NCPP offspring were contacted in 1996, when they were on average 34 years old. Of these individuals, 482 agreed to participate and had complete data available for analyses. Emotional functioning was assessed using a standard symptom checklist (Symptom Checklist-90, SCL-90). This checklist includes an assessment of four common types of distress, including distress due to:
- somatisation: psychological distress manifesting itself through physical symptoms
- interpersonal sensitivity: the extent to which an individual can recognise or understand another’s emotions or feelings
An overall distress score was calculated based on these four types of distress. These scores were calculated in such a way that they ranged from 0 to 100, where the average score in a normal population would be 50, and a normal range considered to be 40 to 60.
The researchers took into account factors that could influence the analysis, including parental socio-economic status and maternal history of mental illness (based on self-report), which were assessed as part of the NCPP. They also took into account age, race, high-school completion and marital status of the adult offspring.
What were the basic results?
Approximately 10% of mothers displayed a low level of affection for their child at the age of eight months, 85% showed a normal level of affection and 6% showed a high level of affection.
Participants whose mothers showed a high level of affection to them at the age of eight months showed lower levels of overall distress as adults than those whose mothers showed normal or low levels of affection. The high-affection group had an overall average distress score of 50.39 and the low/normal affection group an overall average distress score of 55.38. When looking at the specific areas of distress, the relationship was strongest in the area of anxiety, where the high and low/normal groups differed by 7.15 points, and least strong in the area of hostility, where the high and low/normal groups differed by 3.29 points.
How did the researchers interpret the results?
The researchers concluded that “early nurturing and warmth have long-lasting positive effects on mental health well into adulthood”.
This study’s findings suggest that maternal affection early in life may influence adult distress levels. Strengths of this research include assessment of maternal affection by an independent observer and the following-up of participants from childhood into adulthood. However, there are some limitations:
- Only a subset of children from the original study was followed up. Inclusion of all of the children might have influenced the results if the children who did not participate differed from those who did.
- There may be factors other than maternal affection that are influencing results. Although the researchers took some of these into account, there are many others that may be having an effect, including paternal affection or general family affection as a child, or health and work conditions as an adult.
- Although maternal affection was rated by independent observers, the ratings of affection are likely still to be subjective to some extent (for example, what one observer considered negative might be normal to another observer). The researchers attempted to counteract this by providing extensive training for the assessors and carrying out quality control across the study sites.
- Maternal affection was only assessed on one occasion (at the age of eight months), and may not be representative of overall maternal affection throughout childhood.
- It is also important to note that both groups of adults (those receiving low/normal and those receiving high levels of affection as babies) had distress scores within the normal range.
There are likely to be many factors influencing our adult wellbeing, and it seems plausible that this could include our childhood experiences. However, the number of factors and the possible interactions between these factors means that teasing out the effects of individual factors is likely to be difficult.