Two new studies shed light on the link between digestive irritation and anxiety, suggesting that physical digestive problems may cause psychological distress, rather than vice versa as commonly assumed:
Early Gut Problems Linked to Anxiety, Depression
In a study published recently in PLoS ONE, Dr. Pankaj Pasricha of Stanford University School of Medicine and colleagues found that gastric irritation early in life may change the way the brain is wired and raise sensitivity to stress later in life. Their study on newborn rats suggests that some disorders commonly associated with anxiety, such as irritable bowel syndrome, may be the cause rather than the result of conditions like anxiety and depression. According to Dr. Pasricha, “A lot of research has focused on understanding how the mind can influence the body. But this study suggests that it can be the other way around. Gastric irritation during the first few days of life may reset the brain into a permanently depressed state.”
Bacteria in the Gut Influences Brain Chemistry
Researchers at McMaster University have determined that bacteria residing in the gut influence brain chemistry and behaviour in adult mice. When they changed the normal bacterial content of the gut in healthy mice, they found that the mice became less anxious and had an increase in brain derived neurotrophic factor (BDNF), a protein which has been linked to depression and anxiety. To confirm their conclusion that bacteria can influence behavior, the researchers then colonized germ-free mice with a passive genetic background with bacteria from mice with more exploratory behavior. The result? The passive mice became more daring and active. When the process was reversed, normally active mice became more passive.