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The role of the brain in mental health

The human brain is an amazing organ. It controls memory and learning, the senses (hearing, sight, smell, taste, and touch), and emotion. It also controls other parts of the body, including muscles, organs, and blood vessels.

The brain also is a very complex structure. It contains billions of nerve cells — called neurons — that must communicate and work together for the body to function normally. The neurons communicate through electrical signals. Special chemicals, called neurotransmitters, help move these electrical messages from neuron to neuron.

Information is fed into the brain through the senses. What is heard, felt, tasted, seen, or smelled is detected by receptors in or on the body and sent to the brain through sensory neurons. The brain decides what to do with the information from the senses and tells the body how to respond by sending out messages via motor neurons. For example, if a person puts their hand near something hot, the sense of touch tells the brain about the heat, and the brain sends a message to the muscles of the arm to move the hand away. Another type of neuron — called interneurons — connects various neurons within the brain and spinal cord, which together make up the central nervous system.

 How does mental health affect the brain?


Good mental health is an essential part of our overall wellbeing, but not that many years ago mental health issues were thought of by many as something that was all in the mind. And while we know now that the mind is as important for health as the body, back then saying something was all in your mind was simply another way of saying you were probably imagining it.

Thank goodness, then, for the discoveries scientists have made in more recent years about the causes of mental health problems, including the biological processes in the brain that are affected when someone has a mental illness.

Types of mental illnesses

There are many different types of mental illnesses, each of which alters a person’s thoughts, feelings and behaviours in specific ways. Some of these include:

Depression: Throughout the world, depression is the most common mental health problem (ii). Find out more about it in our guide.

Anxiety: Also common, anxiety becomes a problem when you’re worried or feel anxious most or all of the time. Read more in our article on anxiety symptoms.

Panic disorder: This is when you have recurring and regular panic attacks, often for no obvious reason.

Eating disorders: Common eating disorders include anorexia nervosa, bulimia and binge eating, each of which change your attitude towards food and your body, influencing your behaviour and eating habits. Read more about eating disorders in our guide.

Bipolar disorder: Formerly known as manic depression, bipolar disorder can cause extreme mood swings, triggering periods of depression and mania (feeling very high and overactive).

Seasonal affective disorder (SAD): This usually affects people during the autumn and winter months, when they feel tired, moody, irritable and low. There’s lots more information about SAD in our guide.

Schizophrenia: A serious long-term mental health condition, schizophrenia can cause symptoms such as delusions, hallucinations and changes in behaviour. Despite this, many people who are affected by schizophrenia can lead a normal life.

How does the brain work?

Our brains are incredibly complex organs. They make up just two per cent of our body weight, but they use 20 per cent of the oxygen we breathe and 20 per cent of the energy we get from food (i). They control just about everything from our movements, actions and behaviour, senses, thoughts, emotions and memories and learning to involuntary body functions such as breathing, blinking and the beating of our hearts. This all happens thanks to the many thousands of chemical reactions that happen in the brain every second.

Your brain contains billions of nerve cells called neurons. Each of these has four distinct parts:

  • The cell body

  • Dendrites

  • Axons

  • Axon terminals

The cell body is exactly what it sounds like – the central part of the neuron – while dendrites are fibres that extend from the cell body, rather like tree branches. Dendrites receive information from other nerve cells, while axons carry messages from the neuron to other cells. Axons are much longer than dendrites and divide into lots of fine branches at their ends, which are called axon terminals.

Neurons act as messengers, sending commands from the brain to other parts of the body. They communicate with each other through their dendrites and axons, sending electrical signals to one another across tiny gaps called synapses (the average neuron is thought to form around a thousand synapses with other neurons – indeed, it has been said that there are more synapses in the human brain than there are stars in our galaxy (i)).

The electrical signals produced by neurons are helped along their way by chemicals called neurotransmitters, which are released into the synapses and bind with receptors on other neurons (each neuron secretes just one type of neurotransmitter). There are lots of different types of neurotransmitters, but some of the most common you may have heard of include:

  • Dopamine

  • Serotonin

  • Gamma-aminobutyric acid (GABA)

  • Norepinephrine

All these neurotransmitters are involved with specific behaviours and functions – for instance, serotonin is involved with controlling moods and disorders while GABA helps slow down activity in the brain and body.

The brain and mental illness

So what happens in the brain when someone has a mental health problem? We still have such a lot to learn about the connection between these two things, but nowadays it’s thought that mental health problems are linked with changes in neurotransmitters, which cause problems with communications between neurons, as well as changes in the brain’s structure and function.

Take depression, for instance – a mental health issue that affects around one in 10 of us at some point during our lives (iii). When someone is affected by depression, their brain typically has high levels of a chemical called cortisol (iv) (cortisol isn’t a neurotransmitter but a hormone, as it’s made in the adrenal glands rather than the brain).

During times of physical and mental stress, the adrenal glands produce excessive levels of cortisol, with some of it ending up in the brain. But when the brain is exposed to high levels of cortisol in the long term it can change your brain chemistry, which then triggers symptoms of depression.

Certain antidepressant medicines help reduce these symptoms by balancing the amount of cortisol with other chemicals (neurotransmitters) in the brain. These include drugs called selective serotonin uptake inhibitors (SSRIs), which are thought to work by increasing serotonin levels in the brain (people who have depression are thought to release smaller amounts of serotonin into their synapses than those who don’t have depression (i)). Higher levels of serotonin in the brain means there’s more serotonin available in the synapses, which helps neurons communicate more effectively.

However changes in neurotransmitters other than serotonin can also play a part in depression, and other antidepressant medications include serotonin-norepinephrine reuptake inhibitors (SNIRs), which alter the amounts of serotonin and norepinephrine in the brain; and norepinephrine-dopamine reuptake inhibitors (NDRIs), which increase brain levels of norepinephrine and dopamine.

The brain and mental illness

Other mental health illnesses are also thought to be caused by changes to these and other chemicals/neurotransmitters. For instance, scientists think disruptions in the production of dopamine, norepinephrine and a neurotransmitter called glutamate may play a part in schizophrenia (i).

Meanwhile there are many things in life that can cause stress and therefore potentially trigger chemical changes in the brain, affecting how our brains work. Some of these include injury, physical and emotional trauma, abuse, exposure to violence, bereavement, loneliness, financial problems, poor nutrition and even lack of sleep.

Our genes are thought to play a role in whether or not we develop mental health problems too, with experts believing that bipolar disorder, schizophrenia and ADHD are among the most likely to have a genetic component (i). This may at least partly explain why some people are more susceptible to problems caused by changes in brain chemistry than others.

Treatments for mental ill health

There are many types of medications used to treat mental health problems, such as antidepressant medicines, sedative medicines and antipsychotic medicines. Talking therapies such as counselling and cognitive behavioural therapy (CBT), however, are becoming much more commonly used to treat many mental health illnesses, especially as a first approach, before medication is prescribed.

Seeing your GP for help and advice is always the first step you should take if you think you may have a problem with your mental wellbeing. However, there are also things you can do to help yourself too, including:

  • Eating a healthy, nutritious diet

  • Being physically active

  • Drinking alcohol in moderation (14 units or less each week)

  • Cutting down on/giving up other stimulants such as caffeine and nicotine

  • Talking about your feelings with friends and family

  • Getting plenty of rest/sleep

  • Making time for relaxation and destressing

Natural support for mental wellbeing

Besides having a lifestyle that’s as healthy as possible, there are also some nutritional supplements you may like to try if you’re experiencing issues with your mental wellbeing. Eating healthily is of course important, since it helps to make sure your body is getting all the nutrients it needs. However if you’re not eating as healthily as you should for any reason, taking a good-quality multivitamin and mineral supplement may be a good idea, especially since there’s some evidence to suggest a multivitamin may help you cope with stressful situations (v).

Other nutritional supplements that may be useful if you’re experiencing symptoms of problems such as anxiety, stress and low mood include the following:


The amino acid 5-HTP – or 5-Hydroxytryptophan – is often used as a remedy for depression and low mood as it’s a natural compound that’s converted in the brain to serotonin. Indeed, some studies suggest it may be as effective as conventional antidepressants (vi). There’s also some evidence that 5-HTP may help with anxiety disorders (vii).

St John’s wort

St John’s wort is a popular herbal remedy used for the relief of slightly low mood and mild anxiety, based on traditional use only. There’s evidence it may be more effective than a placebo at treating mild to moderate depression (viii). Studies also suggest it may be as effective as some popular prescription antidepressants (ix).

Always speak to your GP or pharmacist if you’re taking any other medicines before trying St John’s wort, as it may interact with certain medicines including the contraceptive pill.

Fish oils

The omega-3 fatty acids EPA and DHA, which are found in oily fish, have been studied extensively in relation to a range of health problems, including depression.

One study involving older women suffering from depression showed that, after taking high doses of EPA and DHA for eight weeks, their symptoms had improved significantly compared to other women who received a placebo (x). Other studies have investigated the benefits of EPA in treating depression, with some suggesting it may be helpful (xi).

You can get omega-3 fatty acids by eating more oily fish such as salmon, trout, herring, mackerel, pilchards and sardines, or by taking fish oil supplements. Vegetarian and vegan omega-3 supplements are also more widely available these days. These supplements source their active ingredients from plant organisms called microalgae rather than fish.


This traditional Ayurvedic herb is often used to help with tiredness, fatigue and stress. One small-scale study suggests ashwagandha may reduce levels of the stress hormone cortisol (xii), while another found 88 per cent of trial participants felt less anxious after taking it (xiii).

Researchers believe ashwagandha may help relieve stress because of the way it moderates interaction between the hypothalamus – a small region in the brain – and the pituitary and adrenal glands (the hypothalamus-pituitary-adrenal axis) (xiv). The HPA axis is thought to play a key role in the body’s response to stress.

Rhodiola Rosea

Rhodiola is a herb used traditionally throughout Europe for stress relief. Its roots contain many active ingredients, including rosavin and salidroside. There is some evidence it may help reduce anxiety and stress more effectively than a placebo (xv), with one study finding it effective in people with burnout symptoms (xvi). Another study concludes that rhodiola may treat stress symptoms comprehensively as well as prevent chronic stress and stress-related complications (xvii).

If you want to try rhodiola, look for a supplement that guarantees a potent 3% level of rosavins.


Found almost exclusively in green, black, oolong and pekoe tea, theanine is a non-protein amino acid that’s thought to help your brain produce calming alpha waves. Studies suggest taking a theanine supplement may help you feel more relaxed without making you drowsy (xviii), and that it may make you feel calmer by reducing your heart rate when you’re faced with something that stresses you out (xix).

Dealing with a mental wellbeing problem can be a challenge, but it’s helpful to know that any symptoms you may be experiencing are caused by changes in your brain, and that they’re not just all in your mind. This guide also shows there are ways to keep your symptoms under control and continue living your life normally.

For more advice on supporting your mental wellbeing, visit the mental health section of our health library .


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Disclaimer: The information presented by Nature’s Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor’s care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

    Our Author - Christine Morgan


Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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