What is a mental illness?

Mental illnesses are treatable health conditions very common in the world today.

They can affect anyone, regardless of age, race, religion, or income. But people are still afraid to talk about them due to shame, misunderstanding, negative attitudes, and fear of discrimination.


  • A medical condition disrupting a person’s thinking, feeling, mood, ability to relate to others, and daily functioning.

  • Common. One in four people will develop a mental illness in their lifetime.

  • Treatable. Most mental illnesses can be treated effectively with medication, therapy, diet, exercise, and support. Recovery is possible.


  • Imaginary. Mental illnesses are very real and very common.

  • Something to “get over.” Mental illnesses cannot be willed away.

  • A character flaw. Mental illnesses are medical conditions that do not define us.


  • Trauma. Sometimes traumatic events can play a role in triggering a mental illness.

  • Chemical imbalance. Chemical or biochemical changes in the brain can be factors.

  • Genetics. Some mental illnesses get passed along from one generation to the next.

  • Environment. Exposure to toxins, illnesses, drugs, or alcohol can affect the developing brain in utero.

Common Conditions

A common group of mental illnesses that can often cause people to feel frightened, distressed, or uneasy.

Attention Deficit/Hyperactivity

Disorder (ADD/ADHD)

A condition characterized by inattention, hyperactivity, and impulsivity.

An illness that typically includes extreme shifts in mood, energy, and functioning that include mania and depression.

An illness that affects one’s thoughts, feelings, behavior, physical health, activity, and sleep patterns. Left untreated, it can lead to suicide.

There are three main types: Anorexia Nervosa (severe food restriction), Bulimia Nervosa (binging and purging), and Binge Eating (binging without purging).

A group of conditions where a disturbance in the person's mood is the main underlying feature

An anxiety disorder where the person experiences intrusive irrational thoughts that appear repeatedly in their mind.

Each new mother is unique and it’s important to know that there is no one cause for postpartum depression. 1 in 7 mothers who give birth each year struggle with symptoms of depression.

Brought on by traumatic events, this disorder can be long-lasting and may include re-experiencing, avoidance, arousal, and numbing.

A mental illness where a person experiences psychotic symptoms (hallucinations and delusions), emotional flatness, and trouble with thinking processes.

Mental Health by the Numbers

1 These infographics cite statistics provided by the National Institute of Mental Health. www.nimh.nih.gov

2 Statistics provided by Department of Justice.

3 American Journal of Psychiatry and U.S. Surgeon General’s Report, 1999.

4 Substance Abuse and Mental Health Services Administration

For more information, go to www.nami.org.