How much of our childhood experiences affect our long-term health? That’s a question a group of Northwestern University researchers, led by Thom McDade, PhD., attempted to answer recently.
Turns out, certain negative experiences can permanently alter your DNA. These results of this study were published recently in the Proceedings of the National Academy of Sciences (PNAS).
Scientists gathered genetic and epigenetic information from around 500 people in the Philippines. McDade and colleagues say they collected a “lifetime of information,” according to the report. Previous research found that mistreatment during childhood might lead to chronic inflammation in adulthood. But this study went one step farther, identifying actual epigenetic mechanisms behind it.
What they found is, growing up in highly stressful situations can lead to low-level, chronic inflammation inside the body, which has been implicated in a number of diseases associated with aging, including cardiovascular disease, diabetes, and cancer, among the topmost killers worldwide. Negative experiences in childhood makes chronic inflammation far more likely in adulthood.
Negative childhood experiences make chronic inflammation in adulthood more likely. Syrian refugee children. Getty Images.
Our DNA is a set of instructions for how to put us together. But it isn’t set in stone. In fact, it changes often, through a process known as epigenetics. This is the system “above” genetics, which bookmark genes for either expression or suppression, depending on environmental circumstances.
Methylation is the process by which methyl tags or bookmarks are placed on genes, activating them. What researchers found is that epigenetic mechanisms can cause long-term inflammation which could lead to a higher risk of age-related conditions later in life. McDade and colleagues wrote, “We provide evidence that nutritional, microbial, and psychosocial exposures in infancy and childhood predict adult levels of DNA methylation…in genes that regulate inflammation.”
The overarching study began with 3,000 pregnant Filipinas from Cebu province in the Philippines in 1983. They came from all different socioeconomic backgrounds. Some lived in urban areas, while others were from rural ones. From there, researchers took data periodically from about 500 of these women’s children over the course of their lifetime, to see if the environment each child grew up in led to epigenetic changes in their DNA. Researchers also looked at their environment and what exposures they had as they grew up.
Certain nutritional, microbial, and psychosocial exposures increase the risk of the methylation of negative genes. Syrian refugee camp. Getty Images.
McDade and his team identified 114 target genes across 10 different sites. In nine of these genes, epigenetic methylation “was significantly predicted by the following variables: household socioeconomic status in childhood, extended absence of a parent in childhood, exposure to animal feces in infancy, birth in the dry season, or duration of exclusive breastfeeding.”
They obtained blood samples from the children when they were ages 20-22 and studied them for inflammatory proteins, as well as patterns of DNA methylation. Three of the identified target sites came up as biomarkers for inflammation. Each one increased the inflammatory response, while one site predicted lower inflammation.
So the takeaway, having certain genes with negative traits isn’t a death sentence. But negative childhood experiences like poverty, the absence of a parent, and others could increase one’s risk to disease. McDade wrote in the study, “We could have genes in our bodies that might lead to some bad outcomes or adverse health outcomes, but if those genes are silent, if they’re turned off due to epigenetic processes, that can be a good thing.” The bad news is that once a gene is methylated, it stays that way, permanently.
McDade said, “If we conceptualize the human genome as a dynamic substrate that embodies information from the environment to alter its structure and function, we can move beyond simplistic ‘nature vs. nurture’ and ‘DNA as destiny’ metaphors that don’t do justice to the complexity of human development.”
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