A new study by Israeli researchers has found that positive emotions may help limit cancer growth.
The study, published Friday in science journal Nature Communications, was conducted on mice by a research team at Haifa’s Technion — Israel Institute of Technology, and focused on the role of the brain’s reward system in fighting tumors.
Researchers said that while previous studies have found a connection between one’s emotional state and the body’s ability to combat cancer, they mainly focused on negative emotions and not on “the impact of positive mental attributes on cancer biology.”
The mechanism by which emotions affect the immune system and its response to tumors was also not well understood until now, they said.
One regulator of the immune system’s activity in the body is Myeloid-derived suppressor cells (MDSCs). These suppress the immune response to certain threats, a critical function in preventing the body from overreacting.
But MDSC activity is also believed to suppress the body’s ability to fight tumors.
In their new study, the researchers artificially stimulated the reward system in the brains of tumor-bearing mice, raising their levels of dopamine — a neurotransmitter that helps regulate pleasurable feelings.
They then identified a response by the mice’s immune system, with a reduction in the activity of MDSCs.
After 14 days of continuous treatment, the researchers identified a 50 percent reduction in the size of the tumors.
“Given the central role of the reward system in positive emotions, these findings introduce a physiological mechanism whereby the patient’s psychological state can impact anti-tumor immunity and cancer progression,” the study said.