We are all familiar with stress. This stress happens each and every day and comes in a wide variety of forms. It might be the stress of trying to juggle family, work, and school commitments. It might involve issues like health, money, and relationships. In each instance where we face a potential threat, our minds and bodies go into action, mobilizing to either deal with the issues (fight) or avoid the problem (flight).
You have probably heard all about how bad stress is for your mind and body. It can lead to physical symptoms such as headaches and chest pain. It can produce mood problems such as anxiety or sadness. It can even lead to behavioral problems such as outbursts of anger or overeating.
What you might not know is that stress can also have a serious impact on your brain. In the face of stress, your brain goes through a series of reactions – some good and some bad—designed to mobilize and protect itself from potential threats.
Researchers have found that sometimes stress can help sharpen the mind and improve the ability to remember details about what is happening. In other cases, stress can produce a wide range of negative effects on the brain ranging from contributing to mental illness to actually shrinking the volume of the brain.
Let’s take a closer look at five of the most surprising ways that stress affects your brain.
1. Chronic Stress Increases the Risk of Mental Illness
In a study published in Molecular Psychiatry, researchers found that chronic stress results in long-term changes in the brain. These changes, they suggest, might help explain why those who experience chronic stress are also more prone to mood and anxiety disorders later on in life.
Researchers from the University of California—Berkeley performed a series of experiments looking at the impact of chronic stress on the brain. They discovered that such stress creates more myelin-producing cells, but fewer neurons than normal. The result of this disruption is an excess of myelin in certain areas of the brain, which interferes with the timing and balance of communication.
In particular, the researchers looked at how stress impacted the brain’s hippocampus. They suggest that stress might play a role in the development of mental disorders such as depression and various emotional disorders.
2. Stress Changes the Brain’s Structure
The results of experiments by researchers from the University of California—Berkeley revealed that chronic stress can lead to long-term changes in the structure and function of the brain.
The brain is made up of neurons and support cells, known as “gray matter” responsible for higher-order thinking such as decision-making and problem-solving. But the brain also contains what is known as “white matter,” which is made up of all the axons that connect with other regions of the brain to communicate information. White matter is so named due to the fatty, white sheath known as myelin that surrounds the axons that speed up the electrical signals used to communicate information throughout the brain.
The overproduction of myelin that the researchers observed due to the presence of chronic stress doesn’t just result in a short-term change in the balance between white and gray matter—it can also lead to lasting changes in the brain’s structure.
Doctors and researchers have previously observed that people suffering from post-traumatic stress disorder also have brain abnormalities including imbalances in gray and white matter.
Psychologist Daniela Kaufer, the researcher behind these ground-breaking experiments, suggests that not all stress impacts the brain and neural networks in the same way. Good stress, or the type of stress that helps you perform well in the face of a challenge, helps wire the brain in a positive way, leading to stronger networks and greater resilience.
Chronic stress, on the other hand, can lead to an array of problems. “You’re creating a brain that’s either resilient or very vulnerable to mental disease, based on the patterning of white matter you get early in life,” explained Kaufer.
3. Stress Kills Brain Cells
In a study conducted by researchers from the Rosalind Franklin University of Medicine and Science, researchers discovered that a single socially-stress event could kill new neurons in the brain’s hippocampus.
The hippocampus is one of the regions of the brain heavily associated with memory, emotion, and learning. It is also one of the two areas of the brain where neurogenesis, or the formation of new brain cells, occurs throughout life.
In experiments, the research team placed young rats in a cage with two older rats for a period of 20 minutes. The young rat was then subjected to aggression from the more mature residents of the cage. Later examination of the young rats found that they had cortisol levels up to six times higher than that of rats who had not experienced a stressful social encounter.
Further examination revealed that while the young rats placed under stress had generated the same number of new neurons as those who had not experienced the stress, there was a marked reduction in the number of nerve cells a week later. In other words, while stress did not seem to influence the formation of new neurons, it did impact whether or not those cells survived.
So stress can kill brain cells, but is there anything that can be done to minimize the damaging impact of stress?
“The next step is to understand how stress reduced this survival,” explained lead author Daniel Peterson, Ph.D. “We want to determine if anti-depressant medications might be able to keep these vulnerable new neurons alive.”
4. Stress Shrinks the Brain
Even among otherwise healthy people, stress can lead to shrinkage in areas of the brain associated with the regulation of emotions, metabolism, and memory.
While people often associate negative outcomes to sudden, intense stress created by life-altering events (such as a natural disaster, car accident, death of a loved one), researchers actually suggest that it is the everyday stress that we all seem to face that, over time, can contribute to a wide range of mental disorders.
In one study, researchers from Yale University looked at 100 healthy participants who provided information about the stressful events in their lives. The researchers observed that exposure to stress, even very recent stress, led smaller gray matter in the prefrontal cortex, a region of the brain linked to such things as self-control and emotions.
Chronic, everyday stress appeared to have little impact on brain volume on its own but may make people more vulnerable to brain shrinkage when they are faced with intense, traumatic stressors.
“The accumulation of stressful life events may make it more challenging for these individuals to deal with future stress, particularly if the next demanding event requires effortful control, emotion regulation, or integrated social processing to overcome it,” explained the study’s lead author, Emily Ansell.
Interestingly, the research team also discovered that different kinds of stress had varying effects on the brain. More recent stressful events, like losing a job or being in a car accident, tended to mostly influence emotional awareness. Traumatic events, like the death of a loved one or facing a serious illness, had a greater impact on mood centers.
5. Stress Hurts Your Memory
If you’ve ever tried to remember the details of a stressful event, you are probably aware that sometimes stress can make events can be difficult to remember. Even relatively minor stress can have an immediate impact on your memory, such as struggling to remember where your car keys are or where you left your briefcase when you are late for work.
One 2012 study found that chronic stress has a negative impact on what is known as spatial memory, or the ability to recall information the location of objects in the environment as well as spatial orientation. A 2014 study revealed that high levels of the stress hormone cortisol were connected to short-term memory declines in older rats.
The overall impact of stress on memory hinges on a number of variables, one of which is timing. Numerous studies have demonstrated that when stress occurs immediately before learning, memory can actually be enhanced by aiding in memory consolidation.
On the other hand, stress has been shown to impede memory retrieval. For example, researchers have repeatedly shown that exposure to stress right before a memory retention test leads to decreased performance in both human and animal subjects.
While stress is certainly a part of life that cannot be avoided in many cases, researchers do believe that by understanding exactly how and why stress impacts the brain, they can gain insight into preventing or even undoing some of the damage stress brings. For example, some experts suggest that such research might play a role in the development of drugs designed to prevent the detrimental effects of stress on the brain.