Social isolation during adolescence causes brain damage: study

A study conducted by Korean medical researchers has revealed that social interactions experienced during adolescence have a significant impact on brain development, drawing considerable attention.

A research team led by Professor Lee Jung-hee of the Department of Radiology at Samsung Medical Center, Professor Chung Sung-kwon and Researcher Yoo Tae-yi of the Department of Physiology at Sungkyunkwan University School of Medicine, Principal Researcher Lee Tae-kwan of the Korea Brain Research Institute, and Professor Kim Kil-soo of the Daegu-Gyeongbuk Medical Cluster announced Monday that they had confirmed damage to the brain's sensory processing network caused by social isolation using animal models.

The research team divided male mice aged four to 11 weeks into two groups and raised them in two different environments: an environment rich in physical stimuli and social interaction (Environmental Enrichment), which included tunnels, spinning wheels, and nests, and a socially isolated environment with no external stimuli (Social Isolation).

The researchers sequentially applied various sensory stimuli, including front paws, whiskers, vision, and olfaction, while capturing functional magnetic resonance imaging (fMRI) to analyze the effects of each stimulus on the entire brain (activation map) and cross-modal responses in terms of time and space.

The analysis revealed that mice raised in an enriched environment exhibited improved higher-order visual and tactile processing abilities, maintained functional network segregation in the brain, and enhanced sensorimotor integration functions.

In contrast, mice raised in a socially isolated environment showed reduced functional connectivity and network co-occurrence across the entire brain, as well as decreased network segregation. In the olfactory area, abnormal hyperactivity was accompanied by a decline in olfactory recognition function.

In addition, a comprehensive analysis of resting-state brain connectivity (resting-state fMRI), behavioral experiments, and c-Fos protein expression analysis revealed the effects of sensory stimulation on local and whole-brain neural networks, as well as the process of brain development reorganization in response to environmental changes.

“This is the first case in the world to analyze the brain’s sensory integration response to multisensory stimuli using fMRI, and it is expected to provide new directions for the treatment of various mental health disorders such as depression, anxiety, and autism spectrum disorders,” Professor Lee said.

She continued, “By presenting the risks of social isolation during adolescence to the brain and the potential of sensory-based intervention methods and olfactory systems as new biomarkers, we hope to provide important clues for mental illness prevention and treatment strategies.”

Their study was published in the latest issue of “Nature Communications.” It was supported by the National Research Foundation of Korea's Mid-Career Researcher Program.