Retrospective studies show that compromised human development during the in utero period and infancy can increase risks for adult diseases and behaviour problems.
The Adverse Childhood Experiences Study examined biological and psychosocial survey data from over 17,000 adults in San Diego, California who were part of a private insurer called Kaiser Permanente.53 It is one of the largest studies ever conducted on the links between childhood maltreatment and health in later life. The study revealed that negative early childhood experiences, including child abuse and household dysfunction, are statistically associated with higher incidence of mental health problems, addiction, obesity, type 2 diabetes, high blood pressure and coronary heart disease in adolescence and adulthood.
Under Nicolai Ceausescu, both abortion and contraception were forbidden in Romania. Many children were abandoned to institutions where they were subjected to neglect and abuse. After the fall of the regime, middle class North American and European families adopted some of the abandoned children. Follow-up studies show that children left in orphanages for less than six months fared better at age 11 than those who were adopted later.54 Children who were in the orphanages for more than six months were likely to have abnormal brain development (small brain), abnormal EEGs and low metabolic activity. They were also more likely to display autistic behaviours, ADHD, aggression, antisocial behaviour and poor cognitive development at age 11.
The Bucharest Early Intervention Project is tracking two groups of institutionalized children—those who remained in the orphanages and those who were placed in high-quality foster care at varying ages. In addition to findings that the length of time spent in the orphanages is associated with lower IQ and behaviour problems, researchers report that the early adversity affected children’s chromosomes and hastened how quickly their cells age and potentially increased their risk for cancer and heart disease as adults.55
Other studies corroborate the findings from Romanian orphanage studies. Early interventions can ameliorate the impact of adverse experiences. Between 1987 and 1989, a landmark study of growth-retarded 9- to 24-month-old Jamaican children found that two years of nutritional supplements and/or cognitive stimulation improved children’s development56 and continued to show benefits to cognition at age 7.57 The group who received stimulation continued to sustain cognitive benefits at ages 11, 17 and 22 years, while those who received nutrition supplements only did not.58 Also at age 22, the stimulated group was less likely to be involved in serious violence.59
The Dunedin Longitudinal Study is following 1,000 people born in 1972 in Dunedin, New Zealand. The study highlights the interaction of adverse experiences and gene regulation.60 Combining detailed histories and psychological testing with genetic analysis, scientists Moffitt and Caspi have followed the cohort every two years up to age 15, then at ages 18, 21, 26, 32 and 38. The longitudinal data create a scientific tool with genetic and environmental markers that predict long-term mood disorders, antisocial and criminal behaviour, psychosis and addiction.
Moffitt, Caspi and their colleagues studied the interaction of environments and the MAOA gene to explain why some children who are abused develop antisocial behaviour and others do not. MAOA is an enzyme that acts to maintain the healthy balance of several different neurotransmitters, including serotonin and dopamine. MAOA also breaks down and recycles excess neurotransmitters. Findings show that how the gene encoding MAOA is expressed affects the levels of the enzyme in the brain and has an impact on its biological processes. Males who were maltreated as children are more likely to engage in antisocial behaviour if the MAOA activity is low. However, males with low MAOA activity who were not maltreated and those with high MAOA activity who were maltreated did not develop higher levels of antisocial behaviour.
The Dunedin study also revealed that individuals with a short form or allele for a gene involved in the production of seratonin were more likely to develop depression and suicidal tendencies if they were exposed to adversity early in life. Others exposed to the same types of adversity but who had two long alleles or forms of the gene were resilient and less prone to depression.
Next: 9. Consilience: A new framework of understanding
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