Early childhood experience has profound impact on structural and dynamical features of the brain and may shed light on precursors of brain dysfunction.
The Bucharest Early Intervention Project
In the year 2000, 136 abandoned children in Bucharest were enrolled in a now famous study. The Bucharest Early Intervention Project (BEIP) was a longitudinal study examining the impact of institutionalization on young children. After completing a variety of bench-line assessments, half the participants were moved from the institutions to high-quality, study-organized foster homes.
Children were moved from the institutions between 6-months and 31-months of age, with 22-months being the average. All of the children – those raised in institutions and those raised in foster care – were assessed at regular intervals to evaluate how their home environments might be influencing their development. The results were sobering. All of the children exhibited “profound deficits in many domains examined.” Lower IQ, changes in how they experienced and processed rewards, and a tendency towards behavioral and psychological disorders were observed at alarming rates. Though placing children in high-quality foster care did improve their development outcomes, the earlier they were removed from institutional care the more recovery could be expected. Removal before the age of two was paramount to success.
Charles Nelson and his colleagues at Harvard University have studied the effects of deprivation in depth. In one study they looked at Magnetic resonance imaging (MRI) data from children from the Bucharest Early Intervention Project and compared them to age-matched community controls. They also assessed ADHD symptoms. This study found significant structural differences such as reduced cortical volume and grey matter as measured with MRI (McGlaughlin et al 2014) in the institutionalized children. In a subsequent study (Stamoulis et al, 2015) they looked for functional correlates of the brain activity of BEIP children compared to those of children who had never been institutionalized. They compared EEG activity of three different groups: children that had never been institutionalized, children that never left the institutions, and those that were placed in foster homes. What were these children’s brains actually doing and how might that have resulted in their cognitive deficits? How might it trigger a higher propensity for psychosocial disorders?
A primer on EEG spectral properties
EEG has typically been studied in terms of its spectral properties – converting the time series of the signal into its frequency components and dividing up the spectrum of frequencies into groupings called delta, theta, alpha, beta and gamma (listed from low to high frequency bands; for more understanding of the power spectrum read The Blue Frog in the EEG). When there is a larger high frequency component in the EEG, this signals a potentially greater complexity of underlying activity (you can create more patterns within a period of time with higher frequencies), and the brain is usually doing something more complex. And indeed, greater the higher frequency beta and gamma bands have been associated with problem solving and high level thinking, learning and memory. On the other hand, a dominance of lower frequencies in the signal (the delta band), is associated with dreamless sleep. There can also be embedded oscillations or periodic components. These embedded oscillations have been associated with enabling selective attention or binding activities from different regions together into a composite whole and may emerge out of changes in the wiring of the brain that typically occur during development.
Differences in oscillations and synchronization
Just as the cognitive, behavioral, and psychosocial ramifications of institutionalization were reduced for children who were placed in foster care, so too were aspects of their EEG. Stamoulis et al reported numerous differences between never institutionalized children compared to those in foster care and those who remain institutionalized. These included reduced oscillation amplitudes as well as reduced coherence of these oscillations across brain regions. Earlier studies have found greater asymmetries across hemispheres in the frontal regions of the brain. Altogether this points to large scale differences arising from early psychosocial deprivation that are apparent in the functional physiology of the brain.
A wider view of deprivation
These results have relevance beyond those abandoned at birth and raised in institutions. Poverty, for example, is a more widely suffered form of deprivation. Though the impact of poverty on bodily health and nutrition is well documented, its impact on the human brain is not as well understood.
Recently researchers have started to piece together the impact that poverty might have on the developing brain. Children born and raised in poverty have higher levels of behavioral and psychological disorders and may not reach their cognitive potential. They also exhibit electrophysiological differences from children raised outside of deprivation.
In 2016 the same group published a study assessing resting EEG activity and cognitive function in 105 impoverished, 48-month-old children in Pakistan. The study found that looking at children’s gamma oscillations was indicative of executive function. For girls, gamma oscillations also predicted IQ test performance.
Such early effects may persist and grow into dramatic differences in adulthood. Evidence for wide differences in adulthood were as found in Sapien Labs’ studies of 402 adults across a wide range of economic circumstances. Here features of the EEG scaled systematically with income and other aspects of life experience.
Development as a window to dysfunction
The brain is a window into the how and why of human cognition, social integration, and behavior. Increasingly studies point to an immense role of experience in the development of brain function. Perhaps more importantly, as we continue to learn about brain development in the context of deprivation, we will be better able to address the physical precursors of brain dysfunction around the world.