“It’s all in your head”: How physical brain changes affect mental health

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Euan Findlay
Writer

Mental illness has long been subject to misconception. Having experienced struggles with anxiety and depression myself, I am all too aware of the stigmas and misunder that many others have around the conditions. “It’s all just in your head” is a prime example. However, while this statement is largely insensitive and vastly oversimplifying the nature of mental illness, there is a breath of truth to it. Research has long been focused on just what is physically happening inside the brain to someone experiencing a mental illness. So, what’s really going on?

“It’s just a little chemical imbalance” is another statement that is a hugely over-simplified view of mental illness. It certainly isn’t comforting or even useful advice to give someone. However, it’s understandable why so many people resort to telling this to someone struggling with their mental health: varying levels of chemicals in the brain can affect mental health.

Scientists have found that when individuals endure an illness such as depression, there is a decrease in levels of a chemical called serotonin in the brain. Serotonin is what is known as a neurotransmitter. These chemicals are secreted by synapses (the end part of our neurons) and allow for a signal to be transferred from one neuron to the next. Although there is still a lot of ongoing research regarding serotonin, it is thought to be involved in things such as mood regulation, social behaviour and sleep, amongst other things.

The link between serotonin and depression has been observed so much that this neurotransmitter is often the basis for how antidepressants work. Selective Serotonin Reuptake Inhibitors (SSRIs) are a popular type of antidepressant used for symptoms of depression and anxiety. They work by blocking synapses from reabsorbing serotonin after it has been released. This allows for the levels of the chemical to remain at a more stable level for longer, often keeping the low moods of individuals with mental illness at a more stable level.

What many don’t seem to understand about mental illness is that it very rarely just appears out of nowhere. There are often core traumatic events or experiences in a person’s life that explains at least part of their illness. Researchers have already seen that people who have experienced some sort of trauma during childhood tend to develop larger amygdala’s as they go on in life. The amygdala is a structure in the limbic system, made up of many neurons, that is shown to play a large role in emotion processing. Importantly, it is also known as the fear centre of the brain and is the core structure involved in the flight-or-fight response. When a child experiences a traumatic event, this fear centre is more active, more connections are being made and therefore they develop a larger amygdala. In adults, having a larger amygdala makes a person more likely to eventually develop an anxiety disorder and are more prone to panic attacks.

In addition, a structure in the brain known as the hippocampus – also part of the limbic system – has shown a deep link with depression. This structure has a major role in creating memories and connecting emotions to the memories. Individuals with major depression are seen to have a reduced sized hippocampus. Studies looking into this relationship have even promoted the importance of treating depression early, as the more depressive episodes a person has, the bigger the size reduction was in the hippocampus. This suggestion of an almost proportional relationship between episodes of depression and hippocampus size shows how vital the intervention and treatment of depression truly is.

You may be thinking that if there’s such a strong relationship between mental illness and physiological change in the brain then, surely, we can develop treatments that alter the physical aspects of our brain. This idea, along with any sort of intervention into the workings of the brain, is complicated.

A recent study has shown some results in Deep Brain Stimulation (DBS). DBS involves the insertion of an electrode implant into a person’s brain in an area especially active in those with severe depression, called Brodmann Area 25. Though results do seem to look positive, it is still a vastly controversial treatment and needs a lot more research given the invasiveness of the procedure.

Mental illness is not simple in any sense. There are many areas of the brain that affect someone’s susceptibility to mental illness. More so, mental illness can cause a physiological change in the structure of the brain with important areas shrinking and growing in volume. However, though there is much research into the neuroanatomy of mental illness, it cannot be boxed into something that’s simply physical. Many things can be attributed to mental illness, from past traumas to genetic biology. So next time you say “it’s all just in your head” to someone that suffers, although you’re not entirely wrong, be mindful that mental illness is vastly more complicated than that.