By Courtney Adams
The brain is organized as circuits responsible for complex behavior, which are affected by early life adversity. Credit: Pixabay
“The most potent and relevant human early life signals are the signals coming from the parent,” said Tallie Baram, a University of California, Irvine developmental neuroscientist, during a Feb. 15 talk at the 2019 American Association for the Advancement of Science (AAAS) annual meeting.
A caregiver’s influence and a child’s environment determine much of the brain’s wiring in the first two years of life, Baram said. During this period of rapid development, these circuits are vulnerable to adversity, and the connections made last well into adolescence and even adulthood.
For example, growing up in poverty makes for an unpredictable and chaotic environment for a child. It is not the poverty itself that is responsible, however, but rather, how poverty alters the signals received from the caregiver, Baram said.
In laboratory studies investigating the relationship between poverty and mental health, her team provided less nesting material to one group of test rats than to another. Mother rats with access to plentiful nesting material displayed consistent, active care of their pups, rarely leaving their sides. Impoverished rats, on the other hand, tended to their pups in a series of short time periods. The researchers determined that the inability to build a proper nest for their little ones leads to significant chronic stress and mild anxiety in the mother rats, and that, in turn, leads to the erratic nurturing behaviors.
This uneven parenting approach ultimately resulted in cognitive and emotional problems in the rat pups: they had issues with memory and a reduced ability to experience pleasure, indicated by lack of interest in sugary M&Ms.
Similarly in humans, inconsistent caregiving in childhood can have adverse effects on brain development. To investigate, Columbia University neuropsychologist Nim Tottenham collected data from children in institutional care, where youngsters awaiting adoption often live in substandard conditions despite the best intentions. Often, the children are cared for intermittently by several different adults who are responsible for several children at once.
Under such subpar care, the children were found to have accelerated development of their amygdala, an area of the brain associated with fear. The quick development poses a concern, because those brain changes may be irreversible and can cause an increased level of anxiety later in life, Tottenham said.
The relationship between early life adversity and later mental illness can be seen across populations, too. Rural residents, for example, experience a higher and more persistent level of childhood poverty than their urban counterparts, according to research by Elizabeth Crouch, deputy director of the Rural and Minority Health Research Center in Columbia, South Carolina. The center found that people who experienced poverty as children are more likely than others to develop substance use disorders and mental health issues as adults. That risk increases with each additional childhood adverse event experienced, Crouch said, as she called for investment in education to tackle mental illness.
“Helping people improve their life circumstances, their education, and their parenting skills is a great first place to start.”
Courtney Adams is a science and technology journalism student at Texas A&M University. She is a blog ambassador for her school’s office of graduate and professional studies, and a teaching assistant for a biomedical writing course. Connect with her on Twitter @ctayadams and via email at ctayadams@gmail.com.
