Definition of Mental Illness and Some Common Diagnoses*

Mental illness is a term that describes a broad range of mental and emotional conditions. Mental illness also refers to one portion of the broader ADA term mental impairment, and is different from other covered mental impairments such as mental retardation, organic brain damage, and learning disabilities. The term ‘psychiatric disability’ is used when mental illness significantly interferes with the performance of major life activities, such as learning, thinking, communicating, and sleeping, among others.

Someone can experience a mental illness over many years. The type, intensity and duration of symptoms vary from person to person. They come and go and do not always follow a regular pattern, making it difficult to predict when symptoms and functioning will worsen, even if treatment recommendations are followed. Although the symptoms of mental illness often can be controlled effectively through medication and/or psychotherapy, or may even go into remission, for some people the illness continues to cause periodic episodes that require treatment. Consequently, some people with mental illness will need no support, others may need only occasional support, and still others may require more substantial, ongoing support to maintain their productivity.

The most common forms of mental illness are anxiety disorders, depressive disorders, and schizophrenia. Brief introductory information about these conditions is presented in this section. This information is described for educational purposes only, not to be used to diagnose individuals. Mental illness requires professional help in order to establish a diagnosis and to plan treatment.


Anxiety Disorders

Anxiety disorders, the most common group of mental illnesses, are characterized by severe fear or anxiety associated with particular objects and situations. Most people with anxiety disorders try to avoid exposure to the situation that causes anxiety.


bulletPanic disorder - the sudden onset of paralyzing terror or impending doom with symptoms that closely resemble a heart attack


bulletPhobias - excessive fear of particular objects (simple phobias), situations that expose a person to the possible judgment of others (social phobias), or situations where escape might be difficult (agoraphobia)


bulletObsessive-compulsive disorder - persistent distressing thoughts (obsessions) that a person attempts to alleviate by performing repetitive, intentional acts (compulsions) such as hand washing


bulletPost-traumatic stress disorder (PTSD) - a psychological syndrome characterized by specific symptoms that result from exposure to terrifying, life-threatening trauma such as an act of violence, war, or a natural disaster


Depressive Disorders

Depressive disorders are also known as mood disorders or affective disorders. These illnesses share disturbances or changes in mood, usually involving either depression or mania (elation). With appropriate treatment, more than 80% of people with depressive disorders improve substantially. In addition to medications and psychotherapy, other specialized treatments for depressive illnesses include electroconvulsive therapy (ECT) and phototherapy (light therapy).


bulletMajor depression - an extreme or prolonged episode of sadness in which a person loses interest or pleasure in previously enjoyed activities


bulletManic-depressive illness (also referred to as bipolar disorder) alternating episodes of mania ("highs") and depression ("lows")


bulletDysthymia - continuous low-grade symptoms of major depression and anxiety


bulletSeasonal affective disorder (SAD) - a form of major depression that occurs in the fall or winter and may be related to shortened periods of daylight



Research has not yet determined whether schizophrenia is a single disorder or a group of related illnesses. The illness is highly complex, and few generalizations hold true for all people diagnosed with schizophrenia. However, most people initially develop the symptoms between the ages of 15 and 25. Typically, the illness is characterized by thoughts that seem fragmented and difficulty processing information.

Symptoms of schizophrenia are categorized as either "negative" or "positive." Negative symptoms include social isolation or withdrawal, loss of motivation, and a flat or inappropriate affect (mood or disposition). Positive symptoms include hallucinations, delusions, and thought disorder.


*Adapted from Zuckerman, D., Debenham, K. & Moore, K. (1993) The ADA and People with Mental Illness: A Resource Manual for Employers. Available from the National Mental Health Association, 1021 Prince Street, Alexandria, VA 22314-2971, (703)684-7722.



Return to top menu


“ English” Examples of Disclosing a Mental Illness

The Equal Employment Opportunity Commission (EEOC) has published new Enforcement Guidance on the ADA and People with Mental Illness. In it, the EEOC states that someone who has a mental illness can tell their employer about the illness using “ English”. This means that the employee is not required to use certain terms such as clinical diagnoses, mental illness or psychiatric disability to disclose mental illness and request accommodations. Some examples of the terms and phrases that an employer may hear are:

bulletI have a medical condition that requires more frequent breaks to do my work.
bulletI need some time off /a leave of absence because I am stressed and depressed.
bulletI take medication for a disorder that makes it difficult to get up early in the morning.

If the employee’s need for accommodation is not obvious to the employer, the employer can ask for documentation of the disability and functional limitations by a professional. Similarly, most teachers may not have specific information about the diagnosis, but Disability Services Offices in colleges and universities require professional documentation of the disability. You can read a Summary of the EEOC Guidance on this site in the Laws section, or read the full text on the EEOC site. It can also be obtained from your regional Disability and Business Technical Assistance Center, (800)949-4232.

Return to top menu


Basic Statistics on Mental Illness

Mental illnesses are treatable, and the cost of not treating them may be high, both in personal and financial terms. An untreated illness can disrupt an individual's personal, social, educational and work activities and, in some cases, may lead to suicide. The economic costs of mental illnesses are significant as well: recent figures indicate that the indirect cost of mental illnesses in the U.S. (due primarily to lost productivity and early morbidity) exceeds $72 billion. The National Institute of Mental Health estimates that one in five people will experience mental illness in their lifetimes, and one in four of us knows someone personally who has a mental illness. Anxiety disorders are the most common, affecting nearly 15% of people at some time in their lives. Depressive disorders occur nearly 8% in our lifetimes, while 2% of people will experience schizophrenia in their lifetimes. In all likelihood, one of our employees or students will experience mental illness while at work or in school.

Return to top menu


Myths and facts about mental illness*

Many myths still surround mental illness. For instance, people often assume that mental illness is something people choose to have. It is important that colleagues and supervisors know that a mental illness is not caused or prolonged by moral weakness, nor is it something an individual can “snap out of” by choice. Mental illness is a diagnosable illness that requires treatment.

Nor does mental illness indicate that an individual cannot work or achieve in school. Many people can work and go to school in spite of the presence of symptoms. Many individuals first develop symptoms of mental illness between the ages of 15 and 25, and thus may miss substantial portions of traditional educational or vocational training. With effective treatment and a supportive work environment, many of these lost opportunities can be pursued.


Sources: Zuckerman, D., Debenham, K. & Moore, K. (1993) The ADA and People with Mental Illness: A Resource Manual for Employers. Available from the National Mental Health Association, 1021 Prince Street, Alexandria, VA 22314-2971, (703)684-7722 and Matrix Research Institute The Facts about Mental Illness. Philadelphia, PA: Research and Training Center on Mental Illness and Work, University of Pennsylvania.



Return to top menu


Characteristics of Psychiatric Disability that Affect Functioning*

bulletThe irregular nature of mental illness - The irregular nature of mental illness may create problems in establishing or maintaining consistent work or school patterns. Some individuals may need time off for medical appointments or to recuperate. The irregular nature of mental illness might also impair an individual's performance.
bulletStress associated with non-disclosure - Anxiety often accompanies the effort to hide an illness and its symptoms. Many individuals do not disclose an illness for fear of discrimination. This fear may be compounded if an employee feels that a job is in jeopardy or a student worries that admission may not be offered.
bulletSide effects of medications - Despite their effectiveness for many people, medications can also have side effects that create difficulties at work or in school. Each person has an adjustment period after starting, changing the dose of, or stopping medication. Some of the most common side effects include:
bulletdry mouth
bulletweight gain
bulletInterrupted education or training - Many people first develop symptoms of mental illnesses between the ages of 15 and 25 and traditional educational or vocational training may be delayed. This may affect their qualifications for jobs or educational programs.
bulletCo-morbidity - The National Institute of Mental Health (NIMH) reports that 30% of adults with a mental illness also have had a diagnosable alcohol and/or drug abuse disorder during their lives. In addition, 53% of adults who have had substance abuse disorders have had one or more mental illnesses during their life times. Treatment and accommodation in these cases need to address the effects of substance abuse as well as the effects of the person's mental illness.

*Source: Zuckerman, D., Debenham, K. & Moore, K. (1993) The ADA and People with Mental Illness: A Resource Manual for Employers. Available from the National Mental Health Association, 1021 Prince Street, Alexandria, VA 22314-2971, (703)684-7722.

Return to top menu


Links to Mental Health Resources

In this site, consult our Where Can I Go for More Information for Employers and Where Can I Go for More Information for Educators sections to find extensive links to mental health, government, business, education and disability research resources.

For specific information on mental illness, follow these links to the Knowledge Exchange Network and the National Alliance for the Mentally Ill.


Reasonable Accommodations Site
Introduction | Mental Illness Definition | Laws Overview
Employer Info | Educator Info | Home Page

line rule


© 1997, Center for Psychiatric Rehabilitation, Boston University


Bipolar World   © 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014
Owners:  Allie Bloom, David Schafer, M.Ed. (Blackdog)

Partners:  John Haeckel, Judith (Duff)
Founder:  Colleen Sullivan
Email Us at Bipolar World

About Us  Add a Link  Advance Directives  Alternative Treatments  Ask the Doctor   Ask Dr. Plyler about Bipolar Disorder   Ask The Doctor/Topic Archives  Awards  Benny the Bipolar Puppy  Bipolar Chat  Bipolar Children  Bipolar Disorder News  Bipolar Help Contract  Bipolar World Forums  Book Reviews  Bookstore  BP & Other mental Illness   Clinical Research Trials & FDA Drug Approval   Community Support   Contact Us  The Continuum of Mania and Depression   Coping   Criteria    Criteria and Diagnosis  Criteria-World Health Disabilities,  DSMV-IV   Dual Diagnosis  eGroups  Expressions (Poetry, Inspiration, Humor, Art Gallery, Memorials  Family Members   Getting Help for a Loved One who Refuses Treatment  Greeting Cards  History of Mental Illness  Indigo  Job and School  Links    Medications   Medication and Weight Gain    News of the Day  Parent Chat  Pay for Meds  Personal Stories  Self Help  Self Injury  Significant Others  Stigma and Mental Health Law  Storm's Column  Suicide!!!  The Suicide Wall  Table of Contents  Treatments  Treatment Compliance  US Disability  Veteran's Chat  What's New?