Now Accepting Blue Cross Blue Shield. Call Today!

Mental Health Disorders: Types, Causes, Diagnosis & Treatment

Last Updated: March 22, 2024

Editorial Policy | Research Policy

Mental health disorders or mental illnesses affect about one-fourth of adults at some point. These conditions can significantly impact a person’s daily functioning and success in settings like school and work. Fortunately, mental health disorders are treatable. 

What Is Mental Illness?

The term “mental health disorders” refers to different conditions that affect how a person thinks, feels and behaves. Mental health disorders may also be referred to as mental illnesses. These conditions are legitimate health problems diagnosed using criteria in the Diagnostic and Statistical Manual of Mental Disorders. 

A mental illness can negatively affect a person’s psychological health and functioning. A person with a mental illness may present with high levels of distress and have difficulty maintaining relationships or functioning optimally at school or the workplace. 

It’s important to recognize that a person who feels sad after losing a loved one or experiences anxiety in response to a significant stressor does not have a mental illness. Instead, mental illnesses are diagnosed when someone meets diagnostic criteria for a specific disorder and experiences significant difficulties with functioning. Mental health disorders do not involve expected reactions to life stressors; they are characterized by serious disturbances in thoughts, emotions and behavior.

Common Mental Health Disorders

Many different mental health disorders exist and range in severity and symptoms. Some of the most common mental health disorders are described in more detail.


Depression, often called major depression, is a common mood disorder that can significantly interfere with daily functioning. Those with depression experience a low mood with other symptoms, such as loss of interest in daily activities, sleep disturbances, poor concentration and low self-worth. 

Anxiety Disorders

Several different anxiety disorders can interfere with a person’s functioning. What these disorders have in common is they involve excessive levels of fear and anxiety that cause a person to change their behavior. For example, a person with social anxiety disorder may avoid social interaction because of excessive fear of being judged negatively by other people.  

Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) can develop after a person experiences a traumatic event that is more severe than daily life stressors. PTSD may develop after combat exposure, physical assault or natural disasters. It leads to symptoms such as sleep disturbances, intrusive memories of the trauma, detachment from others and easily startling.

Obsessive-Compulsive Disorder

Those with obsessive-compulsive disorder experience recurrent intrusive thoughts called obsessions. In response to these thoughts, a person is compelled to repeat certain behaviors, called compulsions. For instance, a person may have intrusive thoughts related to concern about becoming ill and engage in repeated hand washing to cope with the thoughts. 


Schizophrenia can be a severe and significantly debilitating mental health disorder. People with schizophrenia demonstrate disturbances in thinking, perception, social interaction and emotional responsiveness. Schizophrenia also involves psychotic symptoms such as delusions (odd beliefs) and hallucinations (hearing, seeing, smelling, feeling or tasting things that are not actually present). 

Bipolar Disorder 

People with bipolar disorder experience significant and debilitating shifts in mood, which are far more severe than the ups and downs encountered in daily life. In bipolar disorder, a person shifts between episodes of depression and mania, during which they have an elevated or irritable mood, increased energy levels and reduced need for sleep. 

Personality Disorders

Personality disorders are diagnosed when a person’s pattern of behavior and thinking differs significantly from what is expected based on cultural norms. People with personality disorders experience significant distress and dysfunction. One personality disorder, called borderline personality disorder, leads to a pattern of emotional instability, impulsive behavior, unstable relationships and episodes of intense anger. 

Eating Disorders

Eating disorders involve a disturbance in food intake and body image. There are many different eating disorders, including anorexia nervosa, bulimia nervosa and binge eating disorder. Individuals diagnosed with eating disorders demonstrate an obsession with dieting and body weight/shape.

In bulimia nervosa, a person engages in a pattern of binge eating, followed by purging behaviors, such as vomiting or laxative misuse, to rid the body of extra calories. Binge eating disorder involves frequent binge episodes without purging behaviors. Individuals with anorexia severely restrict food intake and have an intense fear of weight gain. 

Causes of Mental Illness

There is not one exact cause of mental illness. Instead, several risk factors increase the chances that someone will develop a mental health disorder. One factor that contributes significantly to mental health disorders is genetics.

For example, research has found that genetics play a large role in the development of depression in children. While the contribution of genetics declines by adulthood, genes still explain about 30–40% of the development of adult depression. 

Other factors associated with increased risk of mental illness include:

  • Adverse childhood experiences, like trauma or abuse
  • Stress related to chronic medical problems like cancer or diabetes
  • Chemical problems in the brain
  • Drug and alcohol use
  • Being socially isolated 

Diagnosing Mental Health Disorders

If you think you may have a mental health disorder, it’s important to reach out to a professional for diagnosis and treatment. A physician with experience treating mental health disorders can make a diagnosis. If your doctor is not experienced in treating these conditions, they can refer you to a mental health professional, like a psychologist or clinical social worker, who can make a diagnosis. 

The professional making a diagnosis will gather information about your health history, family situation and current symptoms to determine if you meet criteria for one of the disorders in the Diagnostic and Statistical Manual of Mental Disorders. They may use symptom checklists or assessment tools, such as questionnaires or surveys, to clarify which symptoms you’re experiencing and whether they meet diagnostic criteria for a mental health condition. 

Mental Illness Statistics in the U.S.

Mental illnesses are relatively common in the U.S. According to the National Institute of Mental Health, upwards of ⅕ of adults in the country have a mental health disorder.

As of 2021, the prevalence of mental illness in the U.S. was as follows:

  • Overall, 22.8% of adults had any type of mental health disorder.
  • Of women, 27.2% had a mental health disorder, compared to 18.1% of men.
  • Young adults 18–25 had the highest prevalence of mental illness, at 33.7%. 
  • Among those aged 26–49, 28.1% had any mental health condition, compared to 15% of those 50 and up.
  • Among all U.S. adults, 5.5% had a serious mental illness, which causes severe impairment and disability. 

Co-Occurring Disorders: Mental Health and Substance Use

A person with a mental health condition and a substance use disorder or addiction is said to have co-occurring disorders. Those with mental health conditions are at increased risk of developing a co-occurring addiction than those without a mental illness. According to the Substance Abuse and Mental Health Services Administration, about 9.2 million U.S. adults have co-occurring disorders. 

Challenging the Stigma of Mental Illness

Stigma, or negative views toward those with mental illnesses, can prevent people from seeking treatment. According to the American Psychiatric Association, over half of people with a mental illness do not seek treatment. In many cases, this can be due to stigma, which makes people worry they will be negatively judged or even lose their jobs if they seek treatment. 

Unfortunately, many people have a negative view of those with mental illnesses, which often comes from misunderstanding. For instance, people may believe those with mental health disorders are dangerous or violent when, in reality, this isn’t the case. It’s important to understand that negative stereotypes are untrue, and you should ignore such stigma. Recognize that treatment is available and healing is possible. 

Effective Treatment Approaches for Mental Health Disorders

The treatment for mental health disorders will vary based on the specific condition you’re diagnosed with, but in general, mental health conditions are treated with talk therapy, medication or a combination.

Talk therapy, also called psychotherapy, can help people change negative thinking patterns and learn new coping methods. Many types of talk therapy exist, and the best method will depend on your unique needs. For example, cognitive behavioral therapy (CBT) can help people identify and change negative thinking patterns leading to unhealthy behaviors. 

Some people may also need psychiatric medications, which can help regulate brain chemicals responsible for thinking and emotional regulation. Medications are often combined with therapy and may take a few weeks to work. Many different psychiatric medications can treat disorders ranging from depression to schizophrenia. 

Self-Care and Coping Strategies

Professional treatment is essential when you have mental health disorder symptoms, but self-help strategies can also make coping easier. Consider the following strategies:

  • Seek social support: Turning to supportive friends and family can be critical when you have a mental health disorder. It’s important to have trusted people to turn to when you’re having a difficult time, as they can provide feedback and encouragement. It can also be helpful to attend a support group for individuals with mental illnesses so you can learn from others coping with similar challenges. 
  • Practice relaxation skills: Relaxing techniques such as deep breathing or meditation can be beneficial when experiencing stress or anxiety related to a mental health disorder. When you find yourself in a situation that generally provokes feelings of distress, you might benefit from practicing one of these skills. 

You can also practice a technique called grounding, in which you focus your attention on specific sensory stimuli, such as five things you can see in the environment or three things you can hear around you. Paying attention to the present moment in this way can take your focus off of upsetting thoughts. 

  • Make time for healthy habits: Self-care is essential when you have a mental health disorder. Take time to rest, rejuvenate and practice healthy habits like eating a nutritious diet and incorporating exercise into your daily routine. You can also make a habit of engaging in hobbies and other stress-relieving activities you enjoy. 

Seeking Help and Support for Mental Health Issues 

If you’re experiencing mental health symptoms, such as negative moods, extreme mood swings or difficulty interacting with others, reaching out for professional support is helpful. You might consider talking with your doctor about a referral to a mental health professional. You can also search online for counseling services in your area. If your symptoms are severe, residential inpatient mental health rehab may be right for you.

For those seeking behavioral health services in the Missouri area, The Recovery Village Kansas City is here to help. We offer a comprehensive residential treatment program for mental health disorders, with dual diagnosis care for co-occurring addiction if needed. Contact one of our Recovery Advocates today to get started.


American Psychiatric Association. “Understanding Mental Disorders: Your Guide to DSM-5.” 2015. Accessed October 8, 2023. 

National Institute of Mental Health. “Statistics.” Accessed October 8, 2023. 

National Institute of Mental Health. “Anxiety Disorders.” April 2023. Accessed October 8, 2023. 

National Institute of Mental Health. “Attention-Deficit/Hyperactivity Disorder (ADHD).” Accessed October 8, 2023. 

National Institute of Mental Health. “Autism Spectrum Disorder (ASD).” April 2023. Accessed October 8, 2023. 

National Institute of Mental Health. “Bipolar Disorder.” Accessed October 8, 2023. 

National Institute of Mental Health. “Eating Disorders.” Accessed October 8, 2023. 

National Institute of Mental Health. “Major Depression. July 2023. Accessed October 8, 2023. 

National Institute of Mental Health. “Personality Disorders.” April 2023. Accessed October 8, 2023. 

National Institute of Mental Health. “Post-Traumatic Stress Disorder (PTSD).” Accessed October 8, 2023. 

National Institute of Mental Health. “Obsessive-Compulsive Disorder (OCD).” Accessed October 8, 2023. 

National Institute of Mental Health. “Schizophrenia.” Accessed October 8, 2023. 

Nivard, N.G., et al. “Stability in symptoms of anxiety and depression as a function of genotype and environment: a longitudinal twin study from ages 3 to 63 years.” Psychological Medicine, 2014. Accessed October 8, 2023. 

Centers for Disease Control and Prevention. “About Mental Health.” April 25, 2023. Accessed October 8, 2023. 

National Institute of Mental Health. “Mental Illness.” March 2023. Accessed October 8, 2023. 

Substance Abuse and Mental Health Services Administration. “Co-Occurring Disorders and Other Health Conditions.” July 26, 2023. Accessed October 8, 2023. 

American Psychiatric Association. “Stigma, Prejudice and Discrimination Against People with Mental Illness.” August 2020. Accessed October 8, 2023. 

National Alliance on Mental Illness. “Psychotherapy.” Accessed October 8, 2023. 

National Alliance on Mental Illness. “Mental Health Medications.” Accessed October 8, 2023. 

Zerubavel, Noga; Messman-Moore, Terri. “Staying Present: Incorporating Mindfulness into Therapy for Dissociation.” Mindfulness, 2015. Accessed October 8, 2023.