The structure of the hippocampus is known to be highly sensitive to stress, and the volume of the hippocampus decreases in people who have experienced trauma or PTSD from major events such as earthquakes or terrorist attacks.

　So, what kind of impact did the first state of emergency declaration regarding the COVID-19 pandemic have on people's hippocampal structure? In particular, did the unprecedented restrictions on social activities, such as the closure of schools and the ``stay-at-home'' policy, affect the brain development of adolescents?

　Using a large-scale longitudinal brain imaging dataset from the Tokyo Teen Cohort Subsample Study (pn-TTC) project, this research team investigated Macro and micro brain structural changes in the hippocampus were investigated.

　As a result, independent of hippocampal development during adolescence, the first state of emergency declaration was associated with a transient increase in total hippocampal volume, an increase in the volumes of three hippocampal subregions, and enhanced microstructural integration of the hippocampus. I discovered that.

　Adolescents in the pn-TTC research project did show a trend toward less depressive symptoms during this period. These results suggest that stress reduction in adolescents may be related to a temporary increase in hippocampal volume and enhanced integration after the first state of emergency was declared.

　It can be said that significant life events may have a temporary effect on the development of hippocampal structure during adolescence. The results of this research are expected to be useful in understanding how the plasticity and vulnerability of the hippocampus are affected by life events during adolescence, and in preparing for future large-scale natural disasters.

Paper information:[JAMA Network Open] Hippocampal Structures Among Japanese Adolescents Before and After the COVID-19 Pandemic