A new study supports earlier estimates of the prevalence of bipolar disorder in the U.S. population, and suggests the illness may be more accurately characterized as a spectrum disorder. It also finds that a number of people with the illness are not receiving appropriate therapy. The study, reported in the May 2007 issue of Archives of General Psychiatry, analyzed data from the National Comorbidity Survey Replication (NCS-R), a nationwide survey of mental disorders among 9,282 Americans ages 18 and older. The NCS-R was funded by the National Institutes of Health's National Institute of Mental Health (NIMH).

NIMH researcher Kathleen Merikangas, Ph.D. and his colleagues identified prevalence rates of three subtypes of bipolar spectrum disorder among adults. Bipolar I is considered the classic form of the illness, in which a person experiences recurrent episodes of mania and depression. People with bipolar II experience a milder form of mania called hypomania that alternates with depressive episodes. People with bipolar disorder not otherwise specified (BD-NOS), sometimes called subthreshold bipolar disorder, have manic and depressive symptoms as well, but they do not meet strict criteria for any specific type of bipolar disorder noted in the Diagnostic and Statistical Manual for Mental Disorders (DSM-IV), the reference manual for psychiatric disorders. Nonetheless, BD-NOS still can significantly impair those who have it.

The results indicate that bipolar I and bipolar II each occur in about 1 percent of the population; BD-NOS occurs in about 2.4 percent of the population. The findings support international studies suggesting that, given its multi-dimensional nature, bipolar disorder may be better characterized as a spectrum disorder.

"Bipolar disorder can manifest itself in several different ways. But regardless of type, the illness takes a huge toll," said NIMH Director Thomas R. Insel, M.D. "The survey's findings reiterate the need for a more refined understanding of bipolar symptoms, so we can better target therapy."

Most respondents with bipolar disorder reported receiving therapy. Nearly everyone who had bipolar I or II (89 to 95 percent) received some type of therapy, while 69 percent of those with BD-NOS were getting therapy. Those with bipolar I or II were more usually treated by psychiatric specialists, while those with BD-NOS were more usually treated by general medical professionals.

However, not everyone received therapy considered optimal for bipolar disorder. Up to 97 percent of those who had some type of bipolar illness said they had coexisting psychiatric conditions, such as anxiety, depression or substance abuse disorders, and a number of were in therapy for those conditions rather than bipolar disorder. The scientists observed that a number of were receiving medicine therapy considered "inappropriate" for bipolar disorder, e.g., they were taking an antidepressant or other psychotropic medicine in the absence of a mood stabilizing medicine such as lithium, valproate, or carbamazepine. Only about 40 percent were receiving appropriate medication, considered a mood stabilizer, anticonvulsant or antipsychotic medication.

"Such a high rate of inappropriate medicine use among people with bipolar spectrum disorder is a concern," said Dr. Merikangas. "It is potentially dangerous because use of an antidepressant without the benefit of a mood stabilizer may actually worsen the condition".

Merikangas and his colleagues speculate that as people seek therapy for anxiety, depression or substance abuse disorders, their doctors, particularly if they are not mental health specialists, may not be detecting an underlying bipolar condition in their patients.

"Because bipolar spectrum disorder usually coexists with other illnesses, it is likely underrecognized, and therefore, undertreated. We need better screening tools and procedures for identifying bipolar spectrum disorder, and work with clinicians to help them better spot these bipolar symptoms," concluded Dr. Merikangas.


Posted by: Emily    Source

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