Women to experience twice amount of early-life stress than men
Early-life stress hinders development of neurons in mice, causing attention disorders. Researchers at Brown University found that stress early in the life of female mice leads to fewer “tuning” neurons in the part of the brain responsible for making sense of emotions and following rules.
Women are roughly twice as likely as men to develop depression, anxiety and other stress-related problems, including difficulty with attention, and new research from Brown University neuroscientists sheds light on the biological reasons why.
Studying mice whose mothers had inadequate supplies to make nests — a model for early-life stress in humans — the researchers found that only female mice developed problems with attention, in part because they had fewer “tuning” neurons in the part of the brain that makes sense of rules and regulating emotions.
“The million-dollar questions are: What’s driving the development of depression and anxiety symptoms, and co-occurring attentional problems, and why is stress a predisposing factor?” said Kevin Bath, an assistant professor of cognitive, linguistic and psychological sciences at Brown.
“If we can understand the neurobiological mechanisms of how the brain is developing differently as a consequence of early-life stress, using our animal model, then we can better understand what types of things we need to do to get children back on the right course for healthy brain development.”
To conduct the study, the researchers moved four-day-old mice and their mothers from standard cages to ones where nest-building materials were inadequate. Food and water remained plentiful, but the mothers frequently departed their pups to search for anything that might work as nesting material. Pups therefore received less consistent and more hypervigilant care from their stressed mothers compared to control pups that were never moved from standard cages. After seven days, the mice returned to cages with everything they needed.
Bath, who is affiliated with Brown’s Carney Institute for Brain Science, said the condition was designed to reflect common early-life stresses faced by children — growing up in a home with a single parent who works multiple jobs, for example. Previous work has shown that nearly 60 percent of individuals will experience at least one significant stress in childhood, he added.
The team found that when the mouse pups reared by stressed mothers reached adulthood at two months old, the female mice found it difficult to adapt their behavior to changing circumstances. The researchers taught the mice to find a treat in a small container with a specific odor and texture. Once they learned to find a treat in containers that smelled one way, the researchers would change the setup and hide the food in containers with a different odor, Bath said.