- The immune system does far more than fight off microbes. It defends against everything from cancer to aging.
- The immune system plays a key role in mental health conditions and cognitive ability.
- Psychological resilience has been increasingly tethered to immune function through largely preclinical research.
- Immune-active drugs and lifestyle modification may represent tools for increased psychological resilience, but human research is limited.
When it comes to developing a healthy psychological state, we often hear about the benefits of things like mindfulness techniques, removing negative influences, building a growth mindset, and generally caring for our physical health. But research has increasingly demonstrated that when it comes to promoting mental resilience, we may also want to turn to our immune system.
To be sure, the immune system does a whole lot more than what is commonly described. Immune cells are definitely vital in fending off microbes, but they also play a key role in protecting our cells from aging and our bodies from cancers. Perhaps most surprisingly, the immune system is now known to significantly influence our cognitive and mental states. In fact, elevated levels of inflammation (an imbalanced immune state) have been associated with mental health conditions ranging from PTSD to bipolar disorder and depression.
Stress and immune function
Psychological resilience is commonly defined as the ability to navigate and adapt to the many stressors of life. Stress itself has long been tethered to immune function. Generally, we think about immune dysfunction as a result of excessive stress. For example, both acute and chronic psychosocial stress are associated with elevated inflammation. Changes in immune function as a result of stress might also make us more susceptible to infections. However, we now appreciate that these pathways are bidirectional. In fact, the immune system may affect the way we process psychologically stressful events.
In the last several decades, it’s become clear that our immune function changes our behavior by influencing the brain. This helps explain “sickness behavior;” symptoms like the lethargy, social withdrawal, and memory difficulties that we may experience when we have an infection. Excessive inflammation may bias us towards negative mood, which could make it harder for us to deal with added stressors. Additionally, some research suggests that inflammation could increase brain responses to social feedback, including negative feedback.
Areas of scientific exploration
As it relates to the specific connections between psychological stress, resilience, and immune function, much of the lab work has been performed on animal models. In one 2006 mouse study , researchers showed that mice without a certain type of immune cell (in this case, T cells) had more trouble dealing with psychological stress, but when they were given T cells, this finding was reversed. An additional study in rats showed that resilience to social stress was driven in part by an immune protein.
Another active area of scientific exploration in this area seeks to reframe the effects of well-known molecules. We now know that several commonly prescribed drugs, dietary molecules, and hormones may affect psychological resilience by influencing the immune system. For example, antidepressants like fluoxetine and desipramine may increase resilience to stress by way of T cell immune effects. Naturally occurring plant molecules like polyphenols (found in fruits and vegetables) may help buffer stress and thereby increase resilience, potentially by way of immune effects. Even the so-called “love hormone” oxytocin has been studied for its resilience-enhancing and immune effects including the potential to mitigate an excessive inflammatory response.
In sum, the aforementioned research indicates several important points. First, there are no solid boundaries between our psychological state and our biology. Second, as we better understand how our immunity relates to our psychology, we may start to consider immune-related interventions including prescriptions and lifestyle interventions like dietary modification as therapeutics for mental health conditions, including building mental resilience. Lastly, in realizing the key role of biological systems like immunity on our mental health, we can start to approach conversations on this subject with more empathy and understanding.