“Thinking positively” actually helps your immune system, for real
If you have been growing up surrounded by more mature people, you will often get the same advice:
“Think positiv! The glass can be seen as either half full or half empty”,
and if you have been anything like me, you rolled your eyes and moved on with your day. We are all aware about things like the placebo-effect, a measureable therapeutic response of people who believe that they will cured even if the pills they were transcibed are only sugar.
However, we still have a hard time believing that just positive expectations does anything else for us in “real life”, except maybe changing our mood or letting us down harder.
We, the smart people, do not subscribe to these petty self-manipulations, we know full well that the bacteria infecting us do not give a f’#% about our expectations. Might aswell enjoy being miserable!
Right? right?
Well, not really. Ben-Shaanan and collegues tried to put some data behind this common wisdom, and what they found backed not only 50 years of clinical experience, but also gave for the first time a mechanistic insight into how positive expectation can cause physiologic effects.
What they did was to stimulate dopaminergic neurons in ventral tegmental area (VTA), a brain region involved in reward-related stimuli. The details of this artificial system are quite technical and laborious, but also quite powerful to recapitulate “reward system” stimulation. After the mice were injected with a drug to “brainwash” them to be “positive”, they were infected with a common bacteria and their immune response was measured and compaired to mice that were not “brainwashed”.
To cut a long experiment short, they found that “positive thinking” mice had an improved immune response compaired to their “non-positive control” peers as measured by probing their immune system, namely cells involved in phagocytosis. Furthermore, “positive thinking” mice showed behavioral changes, they were more likely to particibate in social interactions with cage mates, a finding that has been reported before.
For a conclusive experiment, the scientist tried to narrow down how dopaminergic neuron stimulation in the VTA region signals to the body to 1-up it’s immune response; so they chemically induced nerve damage to the sympathic nervous system and found that these mice, although still “thinking positively”, are unable to tell their body to improve the immune response. As always, further research will be needed to narrow it down to the molecular level and to gain even more insights.
In conclusion, this paper is the first to establish a causal relationship between “positive thinking”, the reward system and the immune response to bacterial infection.
Finally, the authors offer one evolutionary explanation why this behavior could have evolved:
“we speculate this reward-system driven enhancement of antibacterial immunity might be beneficial in natural contexts that are known to activate the VTA but which might also increase the exposure to pathogens (such as feeding or mating behaviors)”
TL;DR: Eating and having sex makes us happy via the reward system, but these activities also expose us to more pathogens than usual. Thus everytime we are happy, our body enhances our immune response because it expects higher risk if infection.
This story is part of advances in biological sciences, a science communication plattform that aims to explain ground-breaking science in the field of biology, medicine, biotechnology, neuroscience and genetics to literally everyone. Scientific understanding has too much barriers, let’s break them down!
