We have always known that mental and physical illnesses are closely related and inextricably linked. As more research is done on depression, researchers are discovering that it can alter our brain structure. It is hoped that research in this area can lead to better treatment and less stigma.
Brain structure might sound like science fiction
The thought of depression changing our brain structure might feel scary or anxious.
While it may seem scary, these changes rarely occur with milder or more short-term forms of depression. For people with Major Depressive Disorder (MDD), the good news is that with the right treatment, some effects on the brain are reversible and new treatments are constantly being developed.
The better we understand how depression interacts with our brain, the more we can learn how it affects the way we function. This means that not only can we examine possible medical treatments, but we can also examine non-medical interventions to help us cope with living with our deficits.
Research on the brain is ongoing and new discoveries are made. Some of the discoveries related to depression and the brain are very preliminary, so we’ve covered the ones that are best understood and accepted.
Parts of the brain
Before we look at brain structure, it can be helpful to have definitions for some parts of the brain
- Amygdala: The amygdala sits on our hippocampus in the temporal lobe. It is responsible for pleasure and fear, responsible for aggression, and helps store memories of events and emotions.
- Frontal lobes: The front part of our brain. It controls many things including problem solving, inhibitions, expression of emotions, personality, focus, mental flexibility, and organization.
- Hippocampus: Our hippocampus is located at the bottom of our temporal lobe. It stores memories and regulates how much cortisol is released.
- Hypothalamus: The hypothalamus lives in our temporal lobe, but sits on the top left of it. It creates and controls hormones, helps us regulate our temperature, controls our appetite, tells us when we are thirsty, is responsible for our sleep cycles, is involved in sex drive and childbirth, and plays a role in our blood pressure and pulse rate. It is very busy!
- Prefrontal Cortex: Our prefrontal cortex lives on the front of our frontal lobe. It helps us with many executive functions including focusing, managing our emotions, impulse control, coordination, and planning. It also has a large part in our personal development.
- Temporal lobe: This is a part of our brain that sits under our frontal lobes and on top of our brain stem. It contains our amygdala, hypothalamus, and hippocampus. It helps us understand language, organization and sequencing, retrieve information, music, memory, hearing, learning and our feelings.
Key Terms Involved in Brain Structure
It’s also helpful to understand some terms related to brain structure, including:
- Brain Derived Neurotrophic Factor (BDNF): For a simple protein, BDNF has a very long name! It is a protein that regulates the growth of our nerve cells.
- Cortisol: A hormone that is released when we are stressed. It is also involved in our parasympathetic nervous system.
- C-reactive protein (CRP): CRP is a protein that the liver produces. It hangs around in our blood and occurs after injury, infection, or inflammation.
- Neurodegenerative: “Neuro” means nerve and “degeneration” describes the deterioration over time. Neurodegenerative describes the loss of nerve cells over time.
- Neuron: A neuron is another word for a nerve cell. It sends and receives nerve impulses.
- Neuroplasticity: Neuroplasticity describes how our brain changes as we age. It’s about our brains responding to things we’ve learned and making and reorganizing various connections. Problems with this can lead to changes in our prefrontal cortex and hippocampus.
- Neurotransmitter: Neurotransmitters are chemicals that carry nerve impulses across a synapse (the gap between two nerve cells or a nerve cell and an organ).
When we suffer from depression, parts of our brain can shrink.
Brain shrinkage is exactly what it sounds like; Parts of our brain decrease in size. The amount of shrinkage usually depends on how severe our depression is and how long we’ve lived with it.
When a section is shrunk, the functions of that section are also shrunk. This explains why some things that we previously did almost without thinking can become so difficult when we are living with depression. Shrinkage of the brain can affect our hippocampus, thalamus, amygdala, frontal lobes, and prefrontal cortex.
Some shrinkage can be reversed with proper treatment. Studies have shown that people in remission from depression have a larger hippocampus than those who are not in remission.
C-reactive protein (CRP) is an indication of inflammation, infection, or injury. Those of us who live with depression might have up to 30% more CRP in our blood than those who don’t.
Inflammation of the brain can lead to the death of our brain cells. This means that contrary to intuition, inflammation can cause parts of our brain to shrink and change our brain structure.
Inflammation can cause our neurotransmitters to stop working as well as they should. This means that messages aren’t getting through our bodies as effectively as they could be if we weren’t for inflammation. It also causes problems with neuroplasticity, so our brains don’t change as well as we age. This can mean that we have difficulty learning or adapting to changes.
Cortisol: a hormone with a big difference
One of the functions of our hippocampus is to regulate the amount of cortisol in our body. Cortisol is a hormone that is released when we are stressed. It is usually helpful in the short term. However, when we live with long-term stress, such as when we live with depression, our cortisol levels stay high, which can cause problems.
Our hippocampus is full of a protein called brain-derived neurotrophic factor (BDNF). It is really important for neurons to grow and survive. High levels of cortisol can directly affect BDNF and interfere with proper function.
High levels of cortisol also affect our neurons in other ways. It lets more calcium into our active neurons, which damages them, makes the neurons in our hippocampus shrink, and slows the production of new neurons.
And that’s not all. Cortisol also affects our amygdala, making it enlarged and more active. An enlarged, overactive amygdala then releases irregular amounts of hormones, which later causes further problems.
Prefrontal cortex and brain structure
Our prefrontal cortex is critical to a wide variety of functions, including emotion regulation, language processing, impulse control, assessment, planning, and decision-making. Teens are often classified as stereotypical because they make seemingly bizarre decisions, lack impulse control, and have difficulty dealing with their emotions. One of the reasons for this is that a teenager’s prefrontal cortex is still developing, so the skills associated with our prefrontal cortex are often still developing.
When too much cortisol is released, our prefrontal cortex shrinks. A smaller prefrontal cortex can mean we have difficulty making decisions, have poor impulse control and, among other things, find it difficult to regulate our emotions.
What does it all mean?
It can take at least eight months for structural changes to occur in the brain. Therefore, they are far more common in patients with persistent depression. We cannot see into our brain (unless we are in a scanner) so we cannot visibly see structural changes. However, we will likely see the effects of these changes.
Each part of our brain has a different function. Our frontal lobe takes care of things like problem solving, inhibitions, judgments, planning, learning, expressing emotions and concentration. The prefrontal cortex specifically cares for language processing, decision making, impulse control, planning, and emotional regulation. Feelings of pleasure and fear are controlled by our amygdala. It’s also involved in regulating things like our sleep patterns. Our hippocampus affects our memory, including our verbal memory.
With a changing brain structure affecting all of these things and more, it’s no wonder depression can cause so many problems with function and mood.
The effects of medical treatment
Medications can help balance our hormones and other chemicals in our brain. This could reverse some of the structural changes that occur in our brain when we suffer from depression and improve some of our symptoms. Antidepressants can also help get our ad activity for neural growth going again.
In addition to medication, there are some medical procedures that can help relieve the symptoms of major depression by targeting our brains. For example, electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) can improve communication between our nerve cells and help regulate our mood.
Other things that can help
There are things we can do to prevent some of these changes and to reverse or improve them as they occur.
Stress can make depression worse and have a major impact on our cortisol levels. We know that this can change our brain structure. Unfortunately, reducing our stress levels is usually not as easy as making a decision not to get stressed. It often requires conscious effort over time. We need to notice the things that increase our stress levels and then work to do something about it one by one.
Some life changes can alter our brain structure. A balanced diet and staying active (within the limits of reason) stimulate our brain cells and strengthen communication between them. Sleeping allows our brain cells to grow and repair. Alcohol and drugs can destroy our brain cells, so avoiding them can be a good idea.
Talk therapy, especially psychotherapy, could also alter the structure of the brain. The researchers believe that psychotherapy can help strengthen our prefrontal cortex and help us with decision making, memory formation, and emotion regulation.
Improving our understanding of brain structure
All of these brain changes can be very important, especially if they involve some long, scientific words that are completely new to us. It can sound really scary and overwhelming.
The good news is, the more we understand what’s going on, the more we can do about it. A better understanding of the specific chains of events and mechanisms involved in depression allows researchers to design more specific treatments with better results.
Researchers are also confident that learning about how depression can alter our brain structure will help reduce the stigma some people have about depression as they can see how it physically affects our bodies.
Much hope can be placed in the knowledge that science is constantly advancing.
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