I could have sworn I’d written about the Barbados long-term malnutrition follow-up study before, but I could not for the life of me remember the context or the name of the article. That’s the problem with having over 350 articles since 2010…I tried looking for the similarly-designed Mauritius study and found it at the bottom of this breezy post from last summer, Mainstreaming. In that study, poor nutrition in early childhood correlated with low IQ at age 12 and schizotypal personality traits at age 23. (Schizotypal traits in the Five Factor model include low self-directedness, introversion, and some distorted perceptions of reality, though an increased openness to new ideas). It was felt the malnutrition resulted in poor development and functioning of the frontal lobes.
This week a new study came out from Barbados (1). 77 children who were admitted to the hospital at age 7 months for malnutrition were matched with 57 controls. All the malnourished children were subsequently enrolled in an interventional program from infancy until age 12. All 77 malnourished infants were otherwise healthy and achieved complete catch-up of growth by the end of puberty. The children and their matched classmates with no hospital admissions have been followed pretty much ever since. What is interesting about the original cohort is that malnutrition was a “reportable” disease in Barbados, so every child on the island who presented with malnutrition was subsequently enrolled in the same program. That means there is not extra "selection bias" in the malnourished cohort, besides the obvious that they were malnourished in the first place. In addition, on Barbados, education is compulsory until age 16, and 99% of the population is literate.
As children, the malnourished cohort had impaired IQ and poorer grades than their peers. They also had poorer attention and behavior, even after controlling for socioeconomics and family background. These problems persisted through adolescence, along with a greater tendency to be depressed. At age 40 years, both groups were given personality testing, measuring the tendency of the person to be open or withdrawn, altruistic or suspicious, angry, depressed, hopeful, and other measures such as whether the person tends to have irrational ideas, poor planning abilities, or brittle coping skills. All adults with IQ less than or equal to 70 were taken out of the sample, and a number of other measures that had been taken over the years, including questionnaires completed by their parents, were used to sort out other factors that might cause certain personality traits in mid-adulthood.
After all the data-crunching, the personality testing showed some significant differences between the previously malnourished cohort and their classmates. The malnourished cohort was more likely to have more negative feelings such as anxiety, anger and depression, seemed more vulnerable to stress, were less warm and gregarious, less trusting and less altruistic. They were less likely to consider new ideas and try to experience new things, and they also reported being less able to carry out plans, less punctuality and reliability. These significant differences remained after controlling for IQ and socioeconomic status in adulthood and childhood.
The malnourishment itself could have affected the brain, of course, particularly the frontal lobe and hippocampus, where it is known that early protein malnutrition can cause changes. In addition, maternal depression is associated with malnourishment in children, and maternal depression is known to affect childhood behavior and coping. Also, it is clear the early malnutrition was associated with other problems in childhood (behavioral issues, less ability to achieve in school) and these childhood experiences could have contributed to the adult personality differences as well.
Children born during the Dutch Famine in WWII were found to have an increased prevalence of antisocial and schizoid personality traits (which would include some of the traits studied here, such as decreased trust of others). In a Finnish study, children with slow growth in the first 6 months of life were more likely to be hospitalized later for personality disorders, particularly borderline and antisocial personality (2). No study had examined the personality particular traits in a Five Factor Personality questionnaire after 40 years of follow-up as was done in the Barbados cohort.
These are interesting studies and fascinating cohorts, and I think it is very plausible that early malnutrition would affect personality development and coping skills. It is also plausible that other kinds of maltreatment in early infancy could be factors as well.