Health Topic

Mental Disorders

Mental disorders (also called mental illnesses) include a wide range of problems. There are many causes. Learn more about what can help.

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Also called: Mental illness

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Mental Disorders

Mental disorders (or mental illnesses) are conditions that affect your thinking, feeling, mood, and behavior. They may happen over a short period of time or come and go. Some can be chronic (long-lasting). They can affect your ability to relate to others and function each day..

There are many different types of mental disorders. Some common ones include:

  • Anxiety disorders, including panic disorder, obsessive-compulsive disorder, and phobias
  • Depression, bipolar disorder, and other mood disorders
  • Eating disorders
  • Personality disorders
  • Post-traumatic stress disorder (PTSD)
  • Psychotic disorders, including schizophrenia

There is no single cause for mental illness. A number of factors can contribute to risk for mental illness, such as:

  • Your genes and family history
  • Your life experiences, such as stress or a history of abuse, especially if they happen in childhood
  • Biological factors such as chemical imbalances in the brain
  • A traumatic brain injury (TBI)
  • Prenatal (before birth) exposure to viruses, toxic chemicals, or other substances such as alcohol and drugs.
  • Use of alcohol or recreational drugs
  • Having a serious medical condition like cancer
  • Having few friends, and feeling lonely or isolated

Mental disorders are not caused by character flaws. They have nothing to do with being lazy or weak.

Mental disorders are common. Many Americans will be diagnosed with a mental disorder at some time in their life.

The steps to getting a diagnosis include:

  • A medical history
  • A physical exam and possibly lab tests, if your provider thinks that other medical conditions could be causing your symptoms
  • A psychological evaluation. You will answer questions about your thinking, feelings, and behaviors.

Treatment depends on which mental disorder you have and how serious it is. You and your provider will work on a treatment plan just for you. It usually involves some type of therapy. You may also take medicines. Some people also need social support and education on managing their condition.

In some cases, you may need more intensive treatment. You may need to go to a psychiatric hospital. This could be because your mental illness is severe. Or it could be because you are at risk of hurting yourself or someone else. In the hospital, you will get counseling, group discussions, and activities with mental health professionals and other patients.

It sits within Mental Health and Behavior.

The lead U.S. institute for this subject is the National Institute of Mental Health.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Mental Disorders

49,625 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Living With

Related Issues

Genetics

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Mental Disorders, Psychiatric Rehabilitation. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Mental Disorders, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.