The possibility that climate change might have a substantial impact not only on the body but also on the mind has emerged from approaches adopted in an academic discipline called economic statistics. Scientists suggest that global warming and natural disasters may cause mental health to deteriorate, resulting in an increase in psychiatric disorders such as depression. There is also data indicating that crime rates increase as temperatures rise. The WHO has pointed out that climate change poses a serious risk to mental health. In addition to measures to curb temperature rises, we need a health care system that supports both mental and physical health.

When it comes to the gut–brain axis —— the connections via which the brain and the intestines influence each other —— it is not all that easy to create a good intestinal environment. However, the existence of factors controlling the intestinal microbiota and keeping them in an appropriate state has been revealed, and scientists have discovered that Paneth cells in the small intestine are related to those factors. Shedding light on the mechanisms will enable a completely new approach to be taken to mental and physical health.

It was long believed that neurons were not produced in the brain past the early developmental stages. However, the 2000s saw the discovery that neurons are generated even in adults. Since then, the increasing number of researchers have been investigating links to PTSD and other mental illnesses, gradually shedding light on adult neurogenesis and its close relationship to the body and mind. One could even say that physical health significantly affects neurogenesis, which might offer a ray of hope for combating dementia. Moderate exercise, diet, sleep, and relaxation are crucial.