We’ve always known that mental illness and physical illness are intrinsically interlinked and inseparable. As more research is done into depression, researchers are discovering that it can alter our brain structure. It’s hoped that research in this area could lead to better treatment and less stigma.
Brain Structure Might Sound Like Science Fiction
The thought of depression changing our brain structure could feel scary or anxiety-provoking.
Though it might seem scary, these changes rarely occur in milder or shorter-term forms of depression. For those 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 being developed all the time.
The more we understand how depression interacts with our brain, the more we can learn about how it affects our functioning. This means that as well as investigating possible medical treatments, we can also look at non-medical interventions to help us manage life with any deficits we have.
Research on the brain is being done all the time and new discoveries are being made. Some of the discoveries around depression and the brain are very tentative, so we’ve covered those that are most understood and accepted.
Bits 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 perches on top of our hippocampus, inside the temporal lobe. It’s responsible for pleasure and fear, in charge of aggression, and helps to store memories of events and emotions.
- Frontal Lobe: The front section of our brain. It controls lots of things including problem-solving, inhibitions, expressing emotions, personality, concentration, mental flexibility, and organisation.
- Hippocampus: Our hippocampus sits at the bottom of our temporal lobe. It stores memories and regulates how much cortisol gets released.
- Hypothalamus: The hypothalamus lives in our temporal lobe, but sits in the top left of it. It creates and controls hormones, helps us to regulate our temperature, controls our appetite, tells us when we’re thirsty, is in charge of our sleep cycles, is involved in sex drive and childbirth, and plays a part in our blood pressure and heart rate. It’s very busy!
- Pre-Frontal Cortex: Our pre-frontal cortex lives at the front of our frontal lobe. It helps us out with lots of executive functions including focus, managing our emotions, impulse control, coordinating, and planning. It’s also got a big part in our personality development.
- Temporal Lobe: This is a part of our brain that sits under our frontal lobe and on top of our brain stem. It holds our amygdala, hypothalamus, and hippocampus. It helps us with understanding language, organisation and sequencing, retrieving information, being aware of music, memory, hearing, learning, and our feelings.
Key Terms Involved In Brain Structure
It’s also helpful to have an understanding of some terms that relate to brain structure including:
- Brain-Derived Neurotrophic Factor (BDNF): For a simple protein, BDNF has a very long name! It’s a protein that regulates the growth of our nerve cells.
- Cortisol: A hormone that’s released when we’re stressed. It’s also involved in our parasympathetic nervous system.
- C-reactive protein (CRP): CRP is a protein that the liver makes. It hangs around in our blood and appears after injury, infection, or inflammation.
- Neurodegenerative: ‘neuro’ means nerve and ‘degeneration’ describes 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 brain responding to things we’ve learned and forming and reorganising different connections. Problems with it can cause changes in our pre-frontal 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 have depression, parts of our brain can shrink.
Brain shrinkage is just as it sounds; parts of our brain reduce 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 shrinks, the functions of that section ‘shrink’ too. This explains why some things we’ve previously done almost without thinking can become so difficult when we live with depression. Brain shrinkage can affect our hippocampus, thalamus, amygdala, frontal lobe, and prefrontal cortex.
Some shrinkage can be reversed with the right treatment. Studies have shown that people in remission from depression have bigger a hippocampus than those who aren’t in remission, for example.
C-reactive protein (CRP) is an indication of inflammation, infection, or injury. Those of us who live with depression could have up to 30% more CRP in our blood than those who don’t.
Brain inflammation can cause our brain cells to die. This means that, counter-intuitively, inflammation can cause parts of our brain to shrink, changing our brain structure.
Inflammation can stop our neurotransmitters from working as well as they should do. This means that messages aren’t passed through our body as effectively as they might be if we didn’t have any inflammation. It also creates problems with neuroplasticity, so our brain isn’t as able to change as we age. This can mean that we struggle to learn or adapt to any changes going on around us.
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’s released when we’re stressed. In the short-term, it’s usually helpful. But when we live with long-term stress, for example when living with depression, our cortisol levels remain high which can start to cause problems.
Our hippocampus is full of a protein called ‘brain-derived neurotrophic factor’ (BDNF). It’s really important for neuron growth and survival. High levels of cortisol can directly affect BDNF, stopping it from working properly.
High cortisol levels affect our neurons in other ways, too. It allows more calcium into our active neurons which damages them, causes the neurons in our hippocampus to shrink, and slows down the production of new neurons.
And that’s not all it does. Cortisol also impacts our amygdala, causing it to become enlarged and more active. An enlarged, over-active amygdala then releases irregular amounts of hormones, causing more problems further down the line.
Prefrontal Cortex And Brain Structure
Our pre-frontal cortex is vital for a variety of functions including emotion regulation, language processing, impulse control, judgement, planning, and decision making. Teenagers are often stereotyped as making seemingly bizarre decisions, lacking impulse control and struggling to manage their emotions. One of the reasons for this is because a teenager’s prefrontal cortex is still developing so skills associated with our pre-frontal cortex are often still developing, too.
When too much cortisol is released, it causes our prefrontal cortex to shrink. Having a smaller prefrontal cortex can mean that we struggle to make decisions, have poor impulse control, and find it hard to regulate our emotions, among other things.
What Does All Of This Mean?
Any structural brain changes can take a minimum of eight months to appear so are far more common in those with persistent depression. We can’t see inside our brain (unless we’re in a scanner) so we can’t visibly see any structural changes. However, we are likely to notice 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, judgements, planning, learning, expressing emotions and concentration. The prefrontal cortex, specifically, takes care of 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 the regulation of 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 that depression can cause so many problems with functioning and mood.
The Effects Of Medical Treatment
Medication can help to balance our hormones and other chemicals in our brain. This could reverse some of the structural changes that occur in our brain when we have depression, improving some of our symptoms. Antidepressants can also help to get our neural growth ad activity going again.
As well as medication, there are some medical procedures which can help to reduce symptoms of major depression by targeting our brain. For example, Electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) can boost communication between our nerve cells and help to regulate our mood.
Other Things That Can Help
There are things that we can do both to prevent some of these changes and to reverse or improve them once they occur.
Stress can exacerbate depression and have a big impact on our cortisol levels. We know that this can alter our brain structure. Unfortunately, reducing our stress levels isn’t usually as simple as just deciding not to be stressed. It often takes conscious effort over time. We have to notice the things that elevate our stress levels and then work to do something about them one at a time.
Some life changes can alter our brain structure. Eating a balanced diet and staying active (within reason) stimulate our brain cells and strengthen the communication between them. Sleeping gives our brain cells the chance to grow and repair. Alcohol and drugs can destroy our brain cells, so avoiding them can be a good idea.
Talking therapies, specifically psychotherapy, could alter the brain structure, too. Researchers think that psychotherapy can help to strengthen our prefrontal cortex, helping us with decision-making, memory-formation, and emotion-regulation.
Increasing Our Understanding Of Brain Structure
All of these brain changes can be a lot to take in, especially when they involve some long, scientific, words that are totally new to us. It can sound really scary and overwhelming.
The good news is, that the more we understand what’s going on, the more we can do about it. An increased understanding of the specific chains of events and mechanisms involved in depression allows researchers to create more specific treatments with better outcomes.
Researchers are also hopeful that learning about how depression can alter our brain structure will help to reduce the amount of stigma that some people hold when it comes to depression because they’ll be able to see how it physically affects our body.
A lot of hope can be placed in the knowledge that science is advancing all of the time.
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