How Mental Illness Affects the Brain

Though mental illness is frequently stigmatized in our society, it’s important to remember that mental illnesses are just as real and impactful as physical illnesses like cancer, diabetes, and heart disease. Despite what society may believe, mental health challenges are not signs of weakness, instability, or moral failing. In fact, mental illness can have a real impact on our bodies, including directly affecting the functioning of our brains, just like physical illness can affect the functioning of other vital organs like our heart and lungs.

In this article, we are going to explore the different ways that mental illness can affect our brains, from changing the way our brains work to interacting with related conditions like substance use disorder and trauma. After reading this, we hope you’ll better understand how our mental health has a physical impact on our brains and bodies, and how to better find support for ongoing mental health challenges.

Here’s a list of the key topics we’ll be reviewing in this article. You can read the article from start to finish or you can navigate between topics by clicking on the links below:

In this section, we will define mental illness as a condition and discuss how organizations including the American Psychiatric Association and the National Alliance on Mental Illness view the issue. This will help us dispel the misconception that mental illness is not a “real” illness or can not be effectively managed and treated.

Here we explore some of the most commonly diagnosed mental illnesses that Americans experience each year, including depression, schizophrenia, and bipolar disorder. We look at how each disorder affects behavior, decision making, and thinking, as well as common signs and symptoms for each condition.

We tackle our central question here, exploring how mental illness affects the way the brain works, including the key role that the brain’s neurotransmitter chemicals play in regulating our mind and body. Here you can learn more about the latest science and research into the brain and its connection to mental illness.

Last, we look at the ways that psychiatrists, psychologists, researchers, and other mental health professionals diagnose mental illness. We discuss the most commonly-used diagnostic manual worldwide and then look at the breakthrough technologies that allow us to “see” inside the brain.

What is Mental Illness?

Before we can examine the ways that mental illness impacts our brains, it’s important to define what exactly mental illness really is. While different organizations use different terms, mental health professionals and researchers generally agree on a standardized definition of mental illness as a disruptive mental health condition that can also be diagnosed and treated.

The American Psychiatric Association (APA) defines mental illness as “health conditions involving changes in emotion, thinking or behavior” that impact a person’s ability to live their life, whether that’s maintaining personal relationships, managing their work or school responsibilities, or engaging in avoiding harmful behavior.

According to the APA, one key distinction of mental illness is that the term refers to mental health challenges that are “diagnosable,” that is, conditions that can be defined and understood by mental health professionals. This also means that if mental illness can be diagnosed, it can also be treated. As the APA notes, mental illness “is a medical condition, just like heart disease or diabetes” that has standard protocols for treatment and care.

The American Psychological Association says that mental illnesses are treatable “disorders that affect a person’s mood, thoughts or behaviors,” while the National Alliance on Mental Illness (NAMI) defines mental illness as “a condition that affects a person’s thinking, feeling or mood,” although they note that everyone’s experience with mental illness will be different.

What do all these definitions have in common? A few key features to remember about mental illness are:

  • Mental illnesses affect the way we think, act, and feel.
  • Mental illnesses can be diagnosed.
  • Mental illnesses can be treated.

If you or a loved one are concerned about your mental health, seek out guidance from a mental health professional. They will discuss any signs and symptoms while also exploring your family history and your living circumstances. Choosing a mental health provider can be daunting, so make sure you choose a credentialed, licensed provider that you can trust.

What Are the Most Common Types of Mental Illness?

Mental illness can take many different forms and display itself in many different ways. Some individuals may experience only infrequent or manageable symptoms, while others may experience debilitating or even life-threatening symptoms. If you or a loved one are concerned about your mental health, it’s helpful to better understand some of the most common forms of mental illness and how they manifest themselves in the brain and body.


Depression is one of the most common forms of mental illness in the United States, with more than 17 million adults struggling with depression each year, according to NAMI. Depression is characterized by:

  • Lack of motivation or interest in the outside world
  • Difficulty paying attention or concentrating
  • Feeling alone, isolated, or neglected
  • Experiencing disrupted sleep patterns
  • Experiencing disrupted eating habits

Some people also struggle with suicidal ideation when depressed, while others are at risk for developing substance use challenges by using alcohol or drugs as coping mechanisms.


Individuals who struggle with schizophrenia may hear voices and see images or visions that do not exist, as well as experience disordered thoughts and urges. NAMI notes that most individuals who struggle with schizophrenia are diagnosed between the ages of 20 and 40.

Schizophrenia typically involves some combination of the following symptoms:

  • Social isolation and withdrawal
  • Paranoid thinking
  • Genetic predisposition/history
  • Hearing or experiencing hallucinations
  • Disordered thinking (difficulty remembering or gathering thoughts)
  • “Flat” affect
  • Lack of engagement with the outside world

While schizophrenia is not currently curable, the condition has been shown to respond well to medication and behavioral therapy.

Bipolar Disorder

Bipolar disorder typically includes periods of high energy (mania) and periods of sadness and lack of energy (depression). According to NAMI, bipolar disorder affects approximately 3% of Americans. Not everyone with bipolar disorder will experience extreme symptoms, but manic and depressive episodes can occur quickly and unexpectedly.

Common symptoms of bipolar disorder include:

  • Irritation or frustration (mania)
  • Rapid mood swings (mania)
  • Risk-taking behavior (mania)
  • Suicidal ideation (mania/depression)
  • Difficulty sleeping (depression)
  • Lack of ability to make decisions (depression)

Most individuals with bipolar disorder will require some form of treatment to stop their condition from getting worse. Typical therapy for bipolar disorder can include both medication and behavioral therapy.

Anxiety Disorder

Anxiety disorders are very common in the United States, with more than 25 million people struggling with this particular mental illness, according to the APA. While anxiety plays a critical role in our lives, long-term feelings of stress and fear can significantly disrupt the way we make decisions, spend time, and conduct ourselves.

Common symptoms of anxiety disorders include:

  • Skipping work or school
  • Avoiding social gatherings or events
  • Struggling with personal or professional relationships
  • Having specific situational fears (phobias)

There are many different types of anxiety disorders, including disorders focused on social situations, separation, and particular phobias. Luckily, anxiety disorders can be successfully managed with behavioral therapy and, when appropriate, medication.

Post-Traumatic Stress Disorder (PTSD)

While commonly associated with battlefield experiences, post-traumatic stress disorder (PTSD) affects more than 3 percent of Americans, according to the APA. This is because experiencing trauma, from violence to crime to loss, can have long-term consequences for our brains and our emotional responses to stress.

Common symptoms of post-traumatic stress disorder include:

  • “Flashback” memories triggered by the outside world or feelings
  • Difficulty thinking about people, places, or memories associated with trauma
  • Strong and sudden emotional reactions (anger, sadness, panic)
  • Isolation or detachment from the outside world

In recent years, there have been major advances in the diagnosis and treatment of post-traumatic stress. If you or a loved one are concerned about traumatic stress, contact a mental health provider who can help you get started on your recovery.

Obsessive Compulsive Disorder (OCD)

Individuals struggling with obsessive compulsive disorder (OCD) experience extreme anxiety centered around intrusive or unwanted thoughts, often focused around health or cleanliness, that force them to engage in obsessive behaviors. OCD, if left unmanaged, can be highly disruptive to daily life, even if the individual realizes their behavior is unnecessary. Approximately 1 percent of Americans struggle with OCD, according to the APA.

Some of the most common symptoms of OCD include:

  • Thoughts or sensations that persist in the brain
  • “Compulsions” to engage in particular behavior rituals or loops
  • Inability to maintain everyday behavior patterns without compulsions
  • Looped thinking that makes individuals feel trapped

Though OCD can be difficult to manage alone, mental health providers have an array of techniques and practices to help individuals cope. The most common treatment for OCD is behavioral therapy with medication support as needed.

How Does Mental Illness Affect the Brain?

Now that we understand what mental illness actually is as well as how it manifests itself in our brain and behavior; we can better understand how mental illness affects the brain itself.

As the organ most responsible for our behavior, decision making, and emotions, our brain is directly impacted by mental illness. But as scientists continue research into the human brain, they have found evidence that mental illness may cause or worsen existing disruptions to the way the brain works, and in some cases, even the way the brain is structured. In other words, while we still don’t know exactly why some mental illnesses occur the way they do, we have much greater insight today than ever before into the relationship between our brain’s chemistry and our mental health.

Neurotransmitters and The Brain

To begin, it’s helpful to understand the makeup of the brain itself.

As we know, our brains control the way we think, act, move, and feel. Even processes that don’t require conscious thought like breathing or blinking are controlled by the brain through our autonomic nervous system, which sends messages from our brain through our spine and nerves to different parts of our body.

But how do messages travel from our brain throughout our body, often without us even realizing? The answer is special cells inside the brain called neurons, which act as messengers that send commands from the brain to the rest of the body. Neurons can “talk” to many different parts of the body, including our muscles, our nerves, and our glands, which secrete different chemicals to keep our body functioning normally. We have an estimated 100 billion neurons in our brain, allowing us to engage in highly complex and precise behavior and tasks.

Neurons communicate with each other across tiny gaps called synapses. In order to bridge that gap, the neurons first send an electrical signal. When that electrical impulse reaches the synapses, the signal causes the release of chemicals called neurotransmitters, which send messages to other neurons by binding with receptors on the receiving neuron.

There are many different types of neurotransmitters responsible for sending different types of messages. Among the most common neurotransmitters are listed below.

  • Dopamine is a key component of the brain’s motivational system and is involved in human behaviors including desire, craving, pleasure, lactation, and sexual arousal. Many forms of drugs and alcohol cause the brain to release excess amounts of dopamine, leading to a short-lived “high,” or euphoric sensation.
  • Serotonin is involved in human behaviors like thinking, learning, remembering, and controlling moods and emotions. For individuals struggling with depression and other mental health challenges, doctors commonly prescribe antidepressant medications that alter the levels of serotonin in the brain to help stabilize moods.
  • Gamma-aminobutyric acid (GABA) is an “inhibitory” neurotransmitter that slows down activity in the brain and body. For this reason, GABA is widely considered to alleviate or temporarily improve mental health challenges linked to stress, anxiety, and trauma. Some foods, including soy sauce and kimchi, also contain this chemical.
  • Norepinephrine is a neurotransmitter that is most commonly present in the body during stressful or high-intensity moments when the body needs to react quickly and forcefully. This neurotransmitter puts the body on “high alert” by raising heart rate and blood pressure and activating muscles.

Mental Illness and Neurotransmitters

While we understand much about the way the brain works, including the effects of neurotransmitters on the body, we don’t always understand exactly how mental illness changes the brain. Researchers do believe, however, that neurotransmitters like dopamine, serotonin, and GABA play a critical role in understanding why mental illness affects some people and not others.

One example where scientists see neurotransmitters affecting our mental health is in the brains of people with depression. According to the National Institutes of Health, people with depression have lower amounts of serotonin pass between their neurons than people who are not depressed. This is why antidepressants (specifically medications called selective serotonin reuptake inhibitors, or SSRIs) often increase the level of serotonin present in the brain. Here is a diagram of what this process looks like.

Other mental health conditions that are also linked to the presence or absence of neurotransmitters include schizophrenia and post-traumatic stress disorder, both of which may be connected to neurotransmitters such as dopamine and norepinephrine. In the case of post-traumatic stress disorder, for example, researchers believe that individuals who suffer from “flashbacks” may also experience an increased level of norepinephrine alongside elevated heart rate and blood pressure.

In some cases, scientists believe that neurotransmitters are involved in mental illness, even if they don’t yet know exactly how. In the case of obsessive compulsive disorder, for example, doctors have seen improvement among patients who take a medication that increases the levels of serotonin and norepinephrine in the body. While this medication has helped patients decrease the number of times they engage in compulsive behavior, it doesn’t alleviate the obsession itself. For this reason, most doctors recommend a combination of medication and behavioral therapy for most mental illnesses.

In summary, when the brain has too much or too little of a particular neurotransmitter, individuals commonly experience mental health complications.

Though it’s difficult to say with absolute certainty that neurotransmitters are a leading cause of mental illness, researchers know that their presence or absence can greatly affect our mental health. Changing levels of many different neurotransmitters play a critical role in our mental health.

Dopamine and Mental Health Disorders

Changing levels of dopamine have been linked to a variety of mental health challenges, often associated with cravings, reward-seeking or addictive behaviors, and even hallucinations. Among the findings that scientists have discovered about dopamine include:

  • Dopamine may be linked to higher rates of anxiety, depression, and memory loss in individuals suffering from Parkinson’s disease.
  • Dopamine is linked to substance use disorder, as many types of drugs and alcohol increase dopamine levels, prompting the brain to continue the addictive behavior.
  • Researchers believe higher than normal levels of dopamine may be linked to hallucinatory experiences commonly found among bipolar and schizophrenic individuals.
  • Anhedonia, or a lack of enjoyment in life, is linked to low levels of dopamine and is very common among individuals with depression.

Other issues linked to low levels of dopamine include:

  • Difficulty falling asleep or staying asleep
  • Emotional unpredictability
  • Difficulty with memory
  • Difficulty with concentration
  • Lack of interest in sex
  • Strong cravings
  • Difficulty managing daily stress

Serotonin and Mental Health Disorders

Serotonin is involved in decision making, mood regulation, and stress management. When serotonin levels change within the brain, individuals may experience several different mental health challenges. Low serotonin levels are particularly associated with depression. Among the complications of changing serotonin levels include:

  • Because serotonin helps regulate our appetite and intestinal system, the neurotransmitter also plays a role in the development of irritable bowel syndrome (IBS).
  • Researchers believe that serotonin levels play a role in the development of mental health challenges including depression, alcohol use disorder, and schizophrenia.
  • Serotonin levels are also believed to affect an individual’s likelihood to have suicidal thoughts, actions, or urges.
  • Scientists continue to explore the relationship between serotonin and common mental illnesses such as anxiety disorders and attention-deficit hyperactivity disorder (ADHD).

Norepinephrine and Mental Health Disorders

When the brain detects a particular situation is dangerous, life-threatening, frightening, or unexpected, it boosts the production of the neurotransmitter norepinephrine, which helps individuals focus and move faster. This neurotransmitter also increases heart rate, blood pressure, and muscle activity. Because norepinephrine is associated with anxiety, some doctors prescribe their patients medications called beta blockers, which slow down the impact of this neurotransmitter on the body, calming down the individual.

Unfortunately, individuals can also produce too much norepinephrine if they are exposed to high levels of stress on a regular basis. If the body is exposed to high levels of norepinephrine on a regular basis, individuals may experience complications including:

  • Reduced immune system and increased susceptibility to disease
  • High blood pressure and heart rate
  • Chronic anxiety or feeling “on edge”

Individuals with ADHD may have too little norepinephrine in their brain and body and some ADHD drugs help reduce this imbalance and “stimulate” the brain further. Researchers believe that a lack of norepinephrine may affect different regions of the brain that are responsible for making decisions, staying organized, paying attention, regulating emotions, and processing information.

In many cases, a combination of neurotransmitters affects our mental health. For example, in the case of bipolar disorder, scientists believe that a combination of dopamine, serotonin, and norepinephrine contribute to the development of particular symptoms. When bipolar individuals are depressed, they may be experiencing low levels of dopamine. When they are manic, on the other hand, they may be experiencing high levels of norepinephrine. Researchers have also discovered a connection between a lack of sleep and neurotransmitter levels, as bipolar individuals who slept poorly were more likely to experience manic symptoms the next day.

Obsessive compulsive disorder is also believed to have a link to multiple different types of neurotransmitters. As with bipolar disorder, researchers believe a combination of dopamine, serotonin, and norepinephrine affects the development of OCD symptoms. As a result, in some cases, selective serotonin reuptake inhibitor (SSRI) drugs, which are commonly used as antidepressants, can also reduce some OCD behaviors.

Other Factors Linked to Mental Illness

While mental illness can be linked to changes in the brain’s functioning and chemistry, there are other underlying concerns that can make individuals more likely to struggle with mental health challenges.

These concerns include our genetic profile or the traits we inherit from our parents and other family members. Scientists believe that individuals whose family members had schizophrenia, bipolar disorder, depression, and attention-deficit hyperactivity disorder (ADHD), for example, may be at a higher risk to develop those conditions themselves.

Other factors that influence our mental health are physical injuries, such as damage to the head or brain, and the environment in which we live, including exposure to violence, pollution, limited or unhealthy food, lead-based paint, cigarette smoke, poverty, crime, and traumatic events.

While we may not have control over our genetic makeup or the environment in which we grow up, we can take more proactive steps as we grow older to maintain our mental health. If we know that mental illness runs in our family, for example, we can be vigilant about watching for common signs and symptoms, as well as working closely with a doctor, therapist, or counselor to guide us on proper treatment. And if we grew up in a difficult environment, we can seek out professional help and guidance as we get older to help overcome that childhood trauma.

How is Mental Illness Diagnosed?

Most psychiatrists, psychologists, and other mental health professionals rely on a diagnostic manual called the DSM, or the Diagnostic and Statistical Manual of Mental Disorders, to formally diagnose a person with a mental illness.

The DSM, now in its 5th edition, is produced by the American Psychiatric Association and is considered the gold standard for the diagnosis and treatment of mental illness. The manual is compiled with the input of mental health professionals and scholars worldwide and is generally updated each decade to account for new research and findings in the field. For example, in the 5th edition, the authors have updated information on emerging or recently reclassified disorders like delusional disorder, adjustment disorder, and persistent depressive disorder.

In some cases, the authors also revise the scope of a disorder entirely. In the 5th edition, a condition like autism spectrum disorder is now placed along a continuum of different behaviors and symptoms. This helps mental health professionals to properly diagnose the condition along with a wide variety of different behaviors and symptoms. This also helps experts avoid accidentally diagnosing an individual with multiple different disorders instead of a variation of one existing disorder.

The 5th edition also focuses more heavily on gathering specific information about symptoms to help develop a more comprehensive and appropriate treatment. Rather than just noting whether or not a particular symptom exists, mental health professionals are now asked to consider the severity of the symptoms, too, allowing them to make more specific adjustments to their patient’s plan of care.

Yet mental health experts don’t rely solely on the DSM for diagnosis. Other tools can also be used to see and understand how mental illness is affecting the individual on a neurological level. These tools allow clinical staff to see “inside” the brain and better understand how mental illness is affecting brain function.

As we noted above, many mental illnesses are believed to be linked to the levels of neurotransmitter chemicals inside a person’s brain and body. Scanning tools and other diagnostic equipment allow researchers to better understand how these neurotransmitters work within the brain, as well as gauge the approximate level of particular neurotransmitters present in a particular patient’s brain.

Common diagnostic tools include:

  • The positron emission tomography (PET) scan uses small amounts of radioactivity to track brain activity, often on a very precise level. PET scans enable researchers to watch neurons in action, particularly when a person engages in a particular activity in a laboratory setting. Researchers sometimes also use PET scans for a “before and after” view of the brain to assess whether a particular mental health treatment is working.
  • The magnetic resonance imaging (MRI) scan helps researchers see how the brain itself is formed and shaped. If they spot particular areas of damage or concern on an MRI scan, clinical experts can better pinpoint their treatment to address that area. Scientists can also use identified patterns, also called “neuromarkers,” to identify the telltale signs of particular mental illnesses. This is a breakthrough technique that is possible because of the major advancements in imaging technology in recent years.
  • Functional magnetic resonance imaging (fMRI) is often used by researchers who want to study patients who are completing a particular activity (also called “task-based fMRI”) versus patients who are not engaged in any activity (also called “rest-based fMRI”). Comparing these two modes can help researchers see how particular parts of the brain are involved in particular tasks and can provide evidence for the way mental illness changes the way people carry out those activities.
  • The electroencephalogram (EEG) scan allows researchers to scan the brain and produce data that can be analyzed by computers in search of particular trends. As researchers at the University of San Francisco found, this can allow mental health professionals to diagnose potential mental health challenges faster and easier than more complex and time-consuming methods. A variation of this method, known as the quantitative electroencephalogram (qEEG), allows experts to have greater insight into brain activity by gathering additional data.

It’s important to remember that mental illness should not be diagnosed through a brain scan alone. A reputable and ethical provider will provide a diagnosis based on the DSM or another manual, as well as their own professional training and expertise. For further insight, they may use brain imaging tools to understand the “behind the scenes” activity taking place on a biological level.

Mental illness can be complex and intimidating, especially since seeking help for mental health conditions continues to be heavily stigmatized in our society. Understanding that mental illness is an actual illness that affects our brains and behavior but can also be diagnosed and treated, can help move us towards effective treatment. With proper care, we can understand and manage our mental health challenges effectively.

Do you need support and assistance with a mental health challenge? At StoneRidge Centers we’re proud to offer a combination of innovative neuroscience-based treatment and world-class clinical care to patients coping with mental health challenges. We work closely with our patients to develop personalized treatment plans that focus on mental and physical health. Our brain-focused approach combines evidence-based therapy with innovative brain science to heal your mind and body.

If you or a loved one need compassionate care and research-based treatment, we invite you to contact us at 928-583-7799 and begin your recovery with us today. We’re here to help when you’re ready to heal.

Innovative, Evidence-Based Therapies

Because mental health and addiction concerns are so often interconnected, we utilize research-based approaches with evidence-based outcomes that promote overall healing and recovery.

Transcranial Magnetic Stimulation (TMS)

This low-impact magnetic stimulation activates neurons inside the brain, relieving symptoms associated with depression and anxiety.

qEEG/Brain Mapping

Using brain scanning and readings, we create a map of our patients’ brains, helping us develop more targeted and effective treatments.


This process assists patients in visualizing their own brain functionality through continuous EEG readings.

Spravato Therapy

We use carefully monitored doses of Spravato to help patients struggling with complex mental health disorders, including severe depression.

Cognitive Behavioral Therapy (CBT)

Patients use this practice to help reframe intrusive or negative thought patterns and develop coping techniques for long-term recovery.

Dialectical Behavior Therapy (DBT)

This practice helps patients learn to regulate emotions, communicate more effectively, and process their own thoughts and feelings..

Eye Movement Desensitization (EMDR)

Licensed and trained therapists guide patients through this technique for managing stress and anxiety on an ongoing basis.

Individual Therapy

Patients experience one-on-one therapy sessions with a licensed therapist to provide a safe and private place to recover and heal.

Group/Family Therapy

Patients can practice the skills and techniques they have learned in treatment with others in a safe, therapist-guided space.

Contact StoneRidge Centers

5940 E. Copper Hill Dr. Ste B & E, Prescott Valley, AZ. 86314

We exercise progressive, leading brain science in our treatment approach for patients in our community and across the country who are struggling with mental health and addiction challenges.