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An NIMH Snapshot
The National Institute of Mental Health (NIMH) is one of 25 components of the National Institutes of Health (NIH), the Government's principal biomedical and behavioral research agency. NIH is part of the U.S. Department of Health and Human Services. The actual total fiscal year 1999 NIMH budget was $859 million.
NIMH Mission
To reduce the burden of mental illness through research on mind, brain, and behavior.
How Does the Institute Carry Out Its Mission?
- NIMH conducts research on mental disorders and the underlying basic science of brain and behavior.
- NIMH supports research on these topics at universities and hospitals around the United States.
- NIMH collects, analyzes, and disseminates information on the causes, occurrence, and treatment of mental illnesses.
- NIMH supports the training of more than 1,000 scientists to carry out basic and clinical research.
- NIMH communicates information to scientists, the public, the news media, and primary care and mental health professionals about mental illnesses, the brain, mental health, and research in these areas.
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One of the most challenging problems in depression research and clinical practice is refractory – hard to treat – depression (treatment-resistant depression). While approximately 80 percent of people with depression respond very positively to treatment, a significant number of individuals remain treatment refractory. Even among treatment responders, many do not have complete or lasting improvement, and adverse side effects are common. Thus, an important goal of NIMH research is to advance the development of more effective treatments for depression – especially treatment-refractory depression – that also have fewer side effects than currently available treatments.
Research on Treatments for Depression
Antidepressant Medication
Studies on the mechanisms of action of antidepressant medication comprise an important area of NIMH depression research. Existing antidepressant drugs are known to influence the functioning of certain neurotransmitters in the brain, primarily serotonin and norepinephrine, known as monoamines. Older medications - tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) - affect the activity of both of these neurotransmitters simultaneously. Their disadvantage is that they can be difficult to tolerate due to side effects or, in the case of MAOIs, dietary restrictions. Newer medications, such as the selective serotonin reuptake inhibitors (SSRIs), have fewer side effects than the older drugs, making it easier for patients to adhere to treatment. Both generations of medications are effective in relieving depression, although some people will respond to one type of drug, but not another.
Antidepressant medications take several weeks to be clinically effective even though they begin to alter brain chemistry with the very first dose. Research now indicates that antidepressant effects result from slow-onset adaptive changes within the brain cells, or neurons. Further, it appears that activation of chemical messenger pathways within neurons, and changes in the way that genes in brain cells are expressed, are the critical events underlying long-term adaptations in neuronal function relevant to antidepressant drug action. A current challenge is to understand the mechanisms that mediate, within cells, the long-term changes in neuronal function produced by antidepressants and other psychotropic drugs and to understand how these mechanisms are altered in the presence of illness.
Knowing how and where in the brain antidepressants work can aid the development of more targeted and potent medications that may help reduce the time between first dose and clinical response. Further, clarifying the mechanisms of action can reveal how different drugs produce side effects and can guide the design of new, more tolerable, treatments.
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