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The Science Behind CBT: How It Rewires the Brain

Cognitive behavioural therapy (CBT) is a talking therapy that can help you manage your problems by changing the way you think and behave. It combines two types of therapy:

  • Cognitive therapy, examining the things you think
  • Behaviour therapy, examining the things you do

It is most commonly used to treat anxiety and depression, but can be useful for other mental and physical health problems such as, but not limited to, anxiety disorders, alcohol and drug use problems, and eating disorders.  

The overarching principle of CBT interventions is that cognitions causally influence emotional experiences and behaviours. The therapy is founded in science and has been demonstrated to be as effective as, or more effective than, other forms of psychological therapy or psychiatric medications. According to NHS statistics:

  • In total, 1.46 million referrals to talking therapies were made in 2020-21, down 14.0% from 1.69 million in 2019-20
  • The number of referrals completing a course of treatment increased by 4.6% from 606,192 in 2019-20 to 634,649 in 2020-21
  • 51.4% of referrals moved to recovery in 2020-21, up 0.3 percentage points from 51.1% in 2019-20
  • People completing a course of treatment received on average 7.5 sessions in 2020-21, up from 6.9 in 2019-20

In this article we will explore the science behind the therapy.

Neuroplasticity and the Brain

Neuroplasticity and the Brain

Neuroplasticity is the brain’s capacity to continue growing and evolving in response to life experiences. The word ‘neuro’ means nerve and nervous system, which comprises the brain. Plasticity is the capacity to be shaped, moulded or altered. Neuroplasticity, then, is the ability of the brain to adapt or change over time, by creating new neurons and building new networks.

Neurons are nerve cells that send messages all over your body to allow you to do everything from breathing to talking, eating, walking and thinking. A neuron has three basic parts: a cell body and two branches called an axon and a dendrite. Within the cell body is a nucleus, which controls the cell’s activities and contains the cell’s genetic material. The axon looks like a long tail and sends messages from the cell. A dendrite looks like the branch of a tree and receives messages from the cell. Neurons communicate with each other by sending chemicals, called neurotransmitters, across a tiny space, called a synapse, between the axons and dendrites of nearby neurons.

Scientists think that neurons are the most diverse kinds of cells in the body. Within these three kinds of neurons are hundreds of different types, each able to send and receive messages in different ways. How these neurons communicate with each other by making connections is what makes each of us unique in how we think, feel and act.

Historically, scientists believed that the brain stopped growing after childhood. But current research shows that the brain is able to continue growing and changing throughout the lifespan, refining its architecture or shifting functions to different regions of the brain. This is known as neurogenesis and is the process by which new neurons are formed in the brain.

The steps of cognitive behavioural therapy (CBT) create these changes through ongoing practice. As you work to adopt different ways of thinking and behaving, your brain responds by adapting to those new thoughts and behaviours.

Cognitive Restructuring

Most people experience negative thought patterns from time to time, but sometimes these patterns become so entrenched that they interfere with relationships, achievements and even well-being. When thought patterns become destructive and self-defeating, mental health professionals such as therapists, can help you explore ways to interrupt and redirect them. This is known as cognitive restructuring and is a group of therapeutic techniques that help people notice and change negative thinking patterns.

In the brain, the places where neurons connect and communicate with each other are called synapses. Each neuron has anywhere between a few to hundreds of thousands of synaptic connections, and these connections can be with itself, neighbouring neurons, or neurons in other regions of the brain. Neurons talk to each other across synapses, creating neural pathways.

The brain operates in a complex way with many parts intersecting and interacting with each other simultaneously. When you have a thought, it is likely that all these different components of your brain are all involved at the same time, and neuroscientists understand that synapses play a vital role in this and a variety of cognitive functions of the brain, including learning and memory formation.

Brains are very efficient. They really like to act out of habit, and our usual ways of thinking are typically so ingrained that they can be hard to break. So, a depressed or anxious brain has typically been reinforcing negative thought pathways over some amount of time. In many cases, these well-established neural pathways influence the brain’s willingness to process negative information more easily than positive information, often resulting in what are known as cognitive distortions, or skewed thought patterns.

Cognitive distortions were first noted by Aaron Beck in the 1960s. Beck originally described it as “selective abstraction”, which describes our tendency to focus on one detail, often taken out of context, and ignore other more important parts of an experience. In his research with depressed patients he hypothesised that changing their thinking would change their symptoms. 

David Burns, an early student of Aaron Beck, and now an Adjunct Clinical Professor Emeritus of Psychiatry and Behavioural Sciences at the Stanford University School of Medicine, helped to popularise the approach to treating depression by focusing on identifying, correcting and replacing distorted systems and thinking patterns.

Once we are able to identify a thought pattern that is distorted or unhealthy, the work begins to rewire our brain to think differently. Cognitive restructuring is part of many forms of psychotherapy, and it is an important component of CBT that helps people identify and change negative and unhealthy thinking patterns by deconstructing unhelpful thoughts and rebuilding them in a more balanced and accurate way.

A therapist using CBT can help you learn which cognitive distortions are affecting you. They can also explain how and why a thought is irrational or inaccurate and help you learn how to “question” faulty thought patterns and redesign them to be more positive.

Emotion Regulation

Emotion regulation can be defined as an individual’s attempts to monitor and modulate their emotional experience. It has emerged as one of the most researched topics in clinical psychology over the last few years. 

The limbic system of the human brain controls behavioural and emotional responses, especially when it comes to the behaviours that we need for survival: feeding, reproduction, caring for our young, and fight or flight responses. 

The structures of the limbic system are buried deep within the brain, underneath the cerebral cortex and above the brainstem. The thalamus, hypothalamus involved in the production of important hormones and regulation of thirst, hunger, mood etc., and basal ganglia, involved in reward processing, habit formation, movement and learning, are also involved in the actions of the limbic system, but two of the major structures are the hippocampus and the amygdala. We will look at the amygdala and its role in processing emotions in more detail later in this article.

Emotions are the brain’s best estimates of what the bodily sensations mean, guided by a person’s past experience. The brain constructs these estimates in the blink of an eye, so rapidly, in fact, that emotions feel like uncontrollable reactions that happen to a person, when in fact emotions are actually made by the person.

CBT explores the links between thoughts, emotions and behaviour. It is a directive, time-limited, structured approach used to treat a variety of mental health disorders. It aims to alleviate distress by helping people to develop more adaptive cognitions and behaviours. CBT can help a person to make sense of overwhelming problems by breaking them down into smaller parts. This makes it easier to see how they are connected and how they affect them. These parts are:

  • A situation – for example, an activity, or something that happens to them that they find difficult
    From this can follow:
  • Thoughts
  • Emotions
  • Physical feelings
  • Actions

CBT helps a person to understand the ways their thoughts, feelings and actions work together. This can help them learn to:

  • Let go of unhelpful thinking habits (jumping to conclusions)
  • Let go of unhelpful actions (avoiding situations)
  • Adopt helpful thinking habits (seeing the potential for something positive)
  • Adopt helpful actions (for example, reaching out to a friend).
Neurotransmitters and CBT

Neurotransmitters and CBT

There are more than 150 neurotransmitters that work as messengers, sending messages between the brain and body to tell individuals that they feel tired, hungry or one of the hundreds of other feelings. Imbalances in these chemicals are believed to have a significant effect on depression, anxiety, sleep, eating, sexual behaviour, impulse control, drug-seeking behaviour, and more. 

Five primary neurotransmitters are crucial for the optimal functioning of the brain, the nervous system and the body. These are:

Acetylcholine – The role of acetylcholine in the central nervous system is to provide a link between motor neurons and the muscles. It is a primary player in the prefrontal cortex, which facilitates memory, navigation, learning, arousal, talking, walking, breathing, and regulation of the sleep/wake cycle. Along with dopamine, acetylcholine also contributes to smooth movement. An overabundance of acetylcholine can cause symptoms of anxiety and depression. A deficiency may lead to poor memory, difficulty with mental calculation, decreased spatial awareness, and trouble recognising people.

Dopamine – This plays a key role in motor movement and emotional response. It is also related to motivation and the desire to complete tasks, hence its reputation as the chemical of achievement. Physical and mental well-being is dependent on maintaining the right balance of dopamine. Dopamine deficiency may be linked to symptoms of depression, especially those such as hopelessness, anger, low self-esteem, dread, irritability and weight gain. High dopamine levels can contribute to paranoia, agitation, hyperactivity and impulsivity.

Norepinephrine – This is essential to executive functioning, regulating cognition, intellect and motivation. Studies show that depressed people have significantly lower levels of norepinephrine. This effect is particularly marked when levels of serotonin and dopamine neurotransmission are also affected.

Serotonin – In the central nervous system, serotonin regulates physiological functions such as appetite, eating behaviour, digestion, sleep, sexual behaviours, cognition, emotion, perception and mood. It is a common belief that serotonin imbalance as a result of damaged or lacking receptors, impaired signal communication and diminished serotonin release contribute to depression. Also, a lack of tryptophan, the amino acid chemical responsible for making serotonin, can alter mental well-being. Low serotonin contributes to unhappiness, depression and insomnia. High serotonin can cause rapid heart rate, anxiety, muscle twitches and loss of coordination.

Gamma-Aminobutyric Acid (GABA) – In the sympathetic nervous system GABA acts as an antidepressant, antihypertensive and anti-diabetic. Decreased GABA function has been shown to accompany manic or depressed moods in individuals. Furthermore, sleep disorders and substance use disorders are linked to chaotic GABA functions in the brain.

A chemical imbalance happens when there is too much or too little of any substance in the body that helps it function normally. The chemicals in the brain that help facilitate communication between nerve cells are the neurotransmitters. Any disruption in the complicated process of nerve cell communication has the potential to affect the production and/or function of neurotransmitters and, consequentially, a person’s mental health.

Cognitive behavioural therapy (CBT) can be effective for treating disruptions to neurotransmitters, by changing neural pathways and associations. As a person learns and then practises the cognitive methods, strategies and concepts, a new neural pathway begins to form. The more that they practise, the more this new neural pathway or association grows.

Brain Scans and CBT Studies

The structure of the brain can change physically to such an extent that it shows up on MRI images. One research study explored CBT and neuroplasticity in people being treated for social anxiety. Before and after the treatment period, participants had Functional Magnetic Resonance Imaging (fMRIs) to show the current structures of their brains. The researchers also used tests to determine changes in the function of the subjects’ brains. The results were that both the brain’s structure and function had changed for the people who were treated with CBT. The amygdala, which processes threatening stimuli, decreased in both volume and sensitivity. Whereas before these participants’ brains had quickly rushed into fight or flight mode, they now experienced reduced social anxiety. Because of documented proof of the relationship between cognitive behavioural therapy and neuroplasticity, CBT is considered an evidence-based therapy that works.

Various other individual studies have investigated neural predictors of CBT response using Functional Magnetic Resonance Imaging (fMRI); one of the most recent studies was published online by Cambridge University Press in January 2022. Their results suggest that there are robust neural predictors of CBT outcome in anxiety-related disorders that may eventually lead (probably in combination with other data) to develop personalised approaches for the treatment of mental disorders. One suggestion the authors make is that the associations found may represent task engagement, such that patients who demonstrate better task engagement will benefit more from CBT, potentially because they engage more with the therapy.

The Prefrontal Cortex

The Prefrontal Cortex

The prefrontal cortex is the section of the frontal cortex that lies at the very front of the brain, in front of the premotor cortex. The prefrontal cortex makes up over 10% of the volume of the brain. It is involved in many functions and is probably best known for executive function. The term executive function is defined in general as functions that focus on controlling short-sighted, reflexive behaviours to take part in things like planning, decision-making, problem-solving, self-control, and acting with long-term goals in mind. They are higher-level cognitive processes that people tend to display greater proficiency in than other animals, and they are seen as some of the functions that help to make human cognition unique. 

Executive functions can be divided into organisational and regulatory abilities. Organisation includes gathering information and structuring it for evaluation. Regulation involves evaluating the available information and modulating responses to the environment. More specifically:

  • Organisation includes attention, planning, sequencing, problem-solving, working memory, cognitive flexibility, abstract thinking, rule acquisition, and selecting relevant sensory information
  • Regulation includes initiation of action, self-control, emotional regulation, monitoring internal and external stimuli, initiating and inhibiting context-specific behaviour, moral reasoning, and decision-making

People who suffer damage confined to the prefrontal cortex often display normal movement, sensory perception, and even intelligence. But they frequently experience deficits in executive functions, along with personality changes, abnormalities in emotional responses, and general difficulty functioning in their daily lives.

The prefrontal cortex also plays a significant role in addiction development. When individuals struggle with addiction to drugs or alcohol, their prefrontal cortex can significantly alter. As it is responsible for decision-making, impulse control and weighing the consequences of actions, it makes it central to an addiction’s onset. Understanding its function is essential for combating addiction.

CBT teaches practical skills to manage cravings, make better decisions and cope with stress. By addressing these aspects, CBT helps the prefrontal cortex regain its ability to exert control over impulses and emotions. During treatment, one of the goals is to restore the prefrontal cortex’s normal functioning. CBT therapies and interventions strengthen decision-making abilities and emotional regulation, helping individuals to regain control over their lives.

The Amygdala

The amygdala as we have seen earlier is involved in the actions of the limbic system. The name amygdala refers to its almond-like shape. Located right next to the hippocampus, the left and right amygdalae play a central role in our emotional responses, including feelings like pleasure, fear, anxiety and anger. The amygdala also attaches emotional content to our memories, and so plays an important role in determining how robustly those memories are stored. Memories that have strong emotional meaning tend to stick. 

The amygdala doesn’t just modify the strength and emotional content of memories, it also plays a key role in forming new memories specifically related to fear. Fearful memories can be formed after only a few repetitions. This makes fear learning a popular way to investigate the mechanisms of memory formation, consolidation and recall. Suppressing or stimulating activity in the amygdala can influence the body’s automatic fear response, which kicks in when something unpleasant happens, such as a startling noise. Disrupted connections in the amygdala are linked to depression and anxiety disorders such as PTSD.

In 2017, Queensland Brain Institute Director Professor Pankaj Sah announced that their research had shown for the first time that new adult brain cells are produced in the amygdala, and said that the research marked a major shift in understanding the brain’s ability to adapt and regenerate. “While it was previously known that new neurons are produced in the adult brain, excitingly this is the first time that new cells have been discovered in the amygdala. Our discovery has enormous implications for understanding the amygdala’s role in regulating fear and fearful memories.” Professor Sah said. “The discovery deepens our understanding of brain plasticity and provides the framework for understanding the functional contribution of new neurons in the amygdala.”

Brain imaging studies have focused on two brain areas, the prefrontal cortex, responsible for complex mental tasks such as self-control and planning, and the limbic system, including the amygdala, which is involved in emotional processing. In healthy people, the prefrontal cortex can inhibit amygdala activity, keeping emotions in check. But imaging shows that in many people with depression, the prefrontal cortex seems to be less active. It has been described that depressed people have a “trigger-happy” amygdala. 

One study showed that depressed adults had increased activity levels in the amygdala when performing an emotional task and reduced activity levels in the dorsolateral prefrontal cortex when performing a cognitive task. CBT reversed this situation. Researchers speculated that CBT focusing on controlling thoughts, re-engages the underactive prefrontal cortex, which, in turn, helps to quieten the hyperactive limbic system. 

More recent research by the National Institutes of Health has found overactivation in many brain regions, including the frontal and parietal lobes and the amygdala, in unmedicated children with anxiety disorders. They also showed that treatment with CBT led to improvements in clinical symptoms and brain functioning. The findings illuminate the brain mechanisms underlying the acute effects of CBT to treat one of the most common mental disorders.

Long-Term Effects

Long-Term Effects

As we have seen from the NHS statistics at the start of this article, 51.4% of CBT referrals moved to recovery in 2020-21, up 0.3 percentage points from 51.1% in 2019-20. 

A study into the long-term effects of CBT, found when CBT was given, in addition to usual care that included antidepressants, it was effective in reducing depressive symptoms and improving quality of life over the long term, on average 46 months for patients whose depression had not responded to medication. These benefits were found, on average, 40 months after the end of therapy.

Over the course of 46 months, 43% of those who had received CBT had improved, reporting at least a 50% reduction in symptoms of depression, compared with 27% who continued with their usual care alone. Importantly, the study also found that this type of high-intensity CBT was a cost-effective treatment from the perspective of the health service.

In another 6-month follow-up study of adolescent patients participating in a randomised controlled clinical trial of transdiagnostic CBT they concluded that the six weeks of transdiagnostic treatment for adolescents with emotional problems showed highly significant change in emotional symptoms and functioning at the 6-month follow-up. Patients with anxiety, depression, combined anxiety and depression, and emotional problems with no specific diagnoses, all had similar trajectories of change. Hence this transdiagnostic SMART treatment can be recommended for adolescent patients with symptoms within the broad spectrum of emotional problems.

Research to test the effectiveness of CBT in reducing relapse, and in improving symptoms, published by the Cambridge University Press stated that those with treatment as usual were predicted to have a relapse rate of 50% at 2 years. Those who had CBT were predicted to have a relapse rate of 30%.

Conclusion

CBT encompasses a range of techniques and approaches that address our thoughts, emotions and behaviours. These can range from structured psychotherapies to self-help practices. It is a leading therapy, which works very well for lots of different neurological and mental health conditions such as:

CBT is also sometimes used to treat people with long-term health conditions. Although CBT cannot cure the physical symptoms of these conditions, it can help people cope better with their symptoms.

As we have seen throughout this article, CBT works well because it is based on evidence from research and clinical practice, and the science behind it is strong. The National Institute for Health and Care Excellence (NICE) regularly reviews the evidence for different problems and treatments. NICE Guidelines are used to recommend what treatments are offered to patients in England and Wales. They are also referred to internationally. CBT is recommended in many of these guidelines, and CBT is a treatment provided by the NHS as it can lead to tangible changes in the brain’s structure and function that can lead to effective treatment for neurological and mental health conditions.

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About the author

Luke Bell

Luke joined the team in February 2024 and helps with content production, working closely with freelance writers and voice artists, along with managing SEO. Originally from Winchester, he graduated with a degree in Film Production in 2018 and has spent the years since working in various job roles in retail before finding his place in our team. Outside of work Luke is passionate about gaming, music, and football. He also enjoys watching films, with a particular love of the fantasy and horror genres.



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