Hidden Brain Stressors: Oxidative Stress and Inflammation

Anything that has the potential to put strain on normal physiological processes or structures can be viewed as a stressor – from a cold to a bar fight. When it comes to the brain, two common stressors that can impact brain health are oxidative stress and inflammation. Both of these stressors can lead to activation of protective cellular processes as well as activation of the HPA axis.

Oxidation is the process by which electrons are lost during a chemical reaction – when a cut apple browns or metal rusts, oxidation is at work. Oxidation happens constantly throughout our body; oxidative stress occurs when there’s an imbalance of reactive oxygen species (ROS) and antioxidants. (If you’ve ever heard the term “free radical,” a reactive oxygen species is one of those – with oxygen in it.) Injury, inflammation, insufficient diet, disease, and environmental toxins – such as heavy metals and certain drugs – can all result in excessive levels of ROS, oxidative stress, and damage to the body. 

ROS aren’t inherently bad – they’re a natural byproduct of cell metabolism (normal) and exercise (good for you) – however, ROS are unstable particles capable of reacting with and damaging cell structures. In fact, our immune system produces ROS as a strategy to destroy pathogens. Our bodies have natural antioxidants that buffer ROS levels, thereby preventing undesirable ROS damage. Dysfunction can occur when antioxidant levels are not sufficiently balanced out ROS levels. An imbalance can be due to increased ROS production, decreased antioxidant production, or a combination of the two. This imbalance between ROS and antioxidants results in oxidative stress – a condition that can impact brain health, impair cognitive function, and damage structures throughout the body. 

Reactive oxygen species are thought to be especially harmful to the brain, partially because of the distinctive make up of neuronal tissue. One unique aspect of the brain is that  it is very fatty. And this fat actually improves the brain’s functionality. Some specialized cells in the brain called neurons are covered in delicate fatty acids that make up myelin. However, because of their unique structure, myelin can be easily damaged by ROS and trigger cell death mechanisms. Other cellular structures sensitive to ROS damage include proteins and DNA.  

Antioxidants – including many different compounds, such as glutathione, superoxide, and dismutase, as well as vitamins and polyphenols – include some of the body’s defenses against excessive levels of ROS. Maintaining cellular structures is critical to maintain cell survival. Excellive ROS level can damage these cellular structures and compromise the health of a cell. Fortunately,  cells have mechanisms in place to repair damaged proteins, fats, and DNA. These repair mechanisms allow the brain to rebound from oxidative injury. However, chronic oxidative stressors can overwhelm the antioxidant defenses and repair systems. This can be the result of poor diet, brain injury, or exposure to environmental toxins, to name a few. Excessive ROS production (or deficient antioxidant defenses) in the brain ultimately result in damaged neurons that are no longer able to function at their full potential. Furthermore, damaged cell structures are often recognized by the immune system as a problem, and result in production of inflammatory compounds. Normally this would be a signal to the body to initiate repair mechanisms. However, the body’s response to chronic oxidative stress results in chronic inflammation. 

Long-standing research demonstrates that maintaining a healthy, antioxidant-rich diet –keeps ROS levels in check and protects the body against disease.

Short-term or acute inflammatory responses are crucial for our immune response and healing processes. Anytime you have a fever or a cut that becomes red and swollen, that’s inflammation at work. However, when inflammatory processes become low grade and chronic, our health can suffer from the continuously present inflammation.

Different parts of the body experience and react to inflammation in different ways. Systemic inflammation, circulation throughout the body, activates immune cells and increases blood flow. When inflammation reaches the central nervous system, it can change brain chemistry. One example is the feeling of sadness and malaise that come with being sick. These emotions are termed “sickness behavior” and are largely attributed to the presence of inflammation. Other data suggests that system-wide inflammation can cause an increase in the permeability of the blood brain barrier, allowing toxins to pass from the blood and into the brain.

Chronic inflammation has a deleterious impact on the brain. The proinflammatory cytokines released by the neuroinflammatory cascade can lead to decreased cognitive function and contribute to age-related cognitive decline. Research demonstrates that those suffering from neurodegenerative diseases have high levels of inflammatory markers. Aging itself is also often associated with increased levels of inflammation, in what has been coined as “inflammaging” – a term describing the role that inflammation has in age-related disease.

Chronic inflammation resulting from prolonged illness or other environmental factors can damage the brain and impair brain function. Supporting brain health through lifestyle choices - from diet and exercise to sleep and social engagement – can help to alleviate conditions that exacerbate inflammation in the brain and support long term brain health.