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Frequently Asked Questions (FAQs)

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CDC Report: Mental Illness Surveillance Among Adults in the United States

What is mental illness?

The term mental illness refers collectively to all diagnosable mental disorders.

Effects of the illness include sustained abnormal alterations in thinking, mood, or behavior associated with distress and impaired functioning.

The effects of mental illnesses include disruptions of daily function; incapacitating personal, social, and occupational impairment; and premature death.

The most common mental illnesses in adults are anxiety and mood disorders.

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How widespread is mental illness?

Mental illness results in more disability in developed countries than any other group of illnesses, including cancer and heart disease. In 2004, an estimated 25% of adult Americans reported having a mental illness within the previous year.

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What is the economic effect of mental illness?

The economic cost of mental illness in the United States is substantial, about $300 billion in 2002.

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What is mental illness surveillance?

Public health surveillance is the ongoing and systematic collection, analysis, interpretation, and dissemination of data used to develop public health interventions that reduce morbidity and mortality and improve health. Surveillance for a particular condition—such as mental illness—might depend either on collecting new data or using data obtained from existing health information systems.

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Why is monitoring mental illness important?

Surveillance activities that monitor mental illness are essential because mental illness is a significant public health problem. For example,

  • according to the World Health Organization, mental illnesses account for more disability in developed countries than any other group of illnesses, including cancer and heart disease;
  • published studies report that about 25% of all U.S. adults have a mental illness and that nearly 50% of U.S. adults will develop at least one mental illness during their lifetime;
  • mental illness is associated with increased occurrence of chronic diseases such as cardiovascular disease, diabetes, obesity, asthma, epilepsy, and cancer;
  • mental illness is associated with lower use of medical care, reduced adherence to treatment therapies for chronic diseases, and higher risks of adverse health outcomes;
  • mental illness is associated with use of tobacco products and abuse of alcohol;
  • rates for both intentional (e.g., homicide, suicide) and unintentional (e.g., motor vehicle) injuries are 2 to 6 times higher among people with a mental illness than in the population overall;
  • population-based surveys and surveillance systems provide much of the evidence needed to guide effective mental health promotion, mental illness prevention, and treatment programs;
  • monitoring mental illness is an important way to provide appropriate organizations the data they need to assess the need for mental and behavioral health services and to inform the provision of those services;
  • many mental illnesses can be managed successfully, and increasing access to and use of mental health treatment services could substantially reduce the associated morbidity;
  • many chronic illnesses are associated with mental illnesses, and it's been shown that treatment of mental illnesses associated with chronic diseases can reduce the effects of both and support better outcomes; and
  • CDC surveillance systems provide several types of mental health information, such as estimates of the prevalence of diagnosed mental illness from self-report or recorded diagnosis, estimates of the prevalence of symptoms associated with mental illness, and estimates of the effect of mental illness on health and well-being.

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What is the purpose of CDC's report Mental Illness Surveillance Among Adults in the United States?

The objective of the report is to summarize current data from selected CDC surveillance and information systems that measure mental illness and its associated impact in the U.S. adult population. Specifically, the report describes

  • the occurrence and associated burden of mental illness among adults in the United States as measured through selected CDC surveillance and information systems;
  • the CDC systems involved in the collection of mental illness data for adults and associated public access databases; and
  • mental illness estimates from other studies and surveys, particularly those conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA), as they compare to CDC system estimates.

The report's authors also seek to facilitate awareness of mental illness surveillance data and provide access to resources that prompt readers to delve further. Increased use of this information will help to identify gaps in the available data.

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From what surveys and systems were data reviewed?

Data were reviewed from two categories of CDC surveys or systems that measure mental illness in the adult U.S. population. The categories are population surveys and health care surveys.

Population surveys are the

  • Behavioral Risk Factor Surveillance System (BRFSS), a state-based cross-sectional, computer-assisted survey established in 1984;
  • National Health Interview Survey (NHIS), a continuous cross-sectional survey of the civilian U.S. population;
  • National Health and Nutrition Examination Survey (NHANES), a continuous survey to assess the health and nutrition of U.S. civilian adults and children; and
  • Pregnancy Risk Assessment Monitoring System (PRAMS), a state-based cross-sectional survey of women who recently delivered a live-born infant.

Health care surveys are the

  • National Ambulatory Medical Care Survey (NAMCS), which is used to collect objective reliable information about the provision and use of U.S. ambulatory care services;
  • National Hospital Ambulatory Medical Care Survey (NHAMCS), a survey used to collect data on the use and provision of ambulatory care services in hospital emergency and outpatient departments;
  • National Hospital Discharge Survey (NHDS), which is used to obtain national-level information on characteristics of inpatients discharged from non-Federal short-stay U.S. hospitals; and
  • National Nursing Home Survey (NNHS), a continuing series of national-sample surveys of nursing homes, their residents, and their staff.

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Where in the United States is the level of mental illness highest?

The authors found that depression estimates generally are highest in the Southeastern states (e.g., 13.7% in Mississippi and West Virginia vs. 4.3% in North Dakota).

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What were the major limitations the authors encountered?

The authors found that the major limitation of CDC's surveys is their focus on depression and lack of data concerning anxiety disorders. CDC surveys also have certain methodological limitations because measuring mental illness is not their primary purpose. Accordingly, they necessarily contain a limited number of questions related to mental illness. In the case of the state-administered BRFSS, some states, often because of funding limitations, do not use BRFSS's mental health module.

The data presented in this report do include estimates from other studies and surveys, particularly those conducted by SAMHSA, as compared with CDC system estimates. In combination with information from SAMHSA's surveys, which specifically address mental health and mental illness topics, data from CDC systems can be used to plan, implement, and evaluate mental illness prevention strategies and to explore ways to protect and promote mental health.

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What are the authors' conclusions?

The authors note that, currently, no surveillance efforts at the national or state level are directed toward documenting anxiety disorders. However, anxiety disorders are as common in the population as depression. Moreover, anxiety disorders have similar characteristics to depression in that they

  • can impose as much impairment as depression,
  • are also related to the stress response system of the body,
  • have health impact similar to depression, and
  • are often found to coexist with the same chronic medical conditions found in those who suffer from depression.

The authors stress the importance of initiating national-level anxiety disorder surveillance activities to help guide public health policy. They also call for anxiety disorder surveillance to be conducted at the state and local levels so that public health services addressing this condition can be designed, implemented, and evaluated.

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