Posted by Phillipa on August 31, 2010, at 20:51:16
Category 5 in new DSM MDD is it sub clinical bipolar disorder. Phillipa
From Medscape Medical News
Large Proportion of Individuals With Major Depression Also Experience Subclinical Bipolar Symptoms
Pam HarrisonAuthors and Disclosures
August 23, 2010 Almost 40% of individuals with a history of major depressive disorder (MDD) also have a history of subthreshold hypomania, a condition that may ultimately increase the risk of developing full-blown bipolar disorder, according to findings from the National Comorbidity Survey Replication (NCS-R).These findings indicate that mild but clinically significant symptoms of bipolar disorder are much more prevalent in major depression that previously appreciated and could affect treatment decisions accordingly.
Jules Angst, MD, Zurich University Psychiatric Hospital in Switzerland, and colleagues found that when considered together bipolar spectrum conditions were nearly as frequent as unipolar major depression without subthreshold hypomania among participants in the NCS-R, a nationally representative, face-to-face household survey of the US population conducted between February 2001 and April 2003.
The lifetime prevalence of major depression with subthreshold hypomania was 6.7%.
"We know what depression is like but people outside of the mental health field are not necessarily aware of all manifestations of bipolar disorder, and the public tends to have the view that somebody who is manic is just extremely happy and energetic," Kathleen Merikangas, PhD, told Medscape Medical News.
"But mania is much more than that, and we are interested in people who may have episodes of increased activity and decreased need for sleep and who may not be able to focus as this may indicate that that person is suffering from bipolar disorder rather than major depression," she added.
The study was published online August 16 in the American Journal of Psychiatry.
Higher Rates of Substance Use, Anxiety, Behavioral Problems
The NCS-R interview was performed in 2 parts. In the first part, an interview was administered to a nationally representative household sample of 9282 respondents in which core mental disorders were assessed along with a battery of sociodemographic variables.
In the second phase of the study, the interview was administered to 5692 of the part 1 respondents, including all part 1 respondents with a lifetime core disorder plus a probability subsample of other respondents.
Criteria for subthreshold hypomania included the presence of at least one of the screening questions for mania. In the survey, respondents were also asked whether or not they ever felt as if they met certain criteria for mania.
Investigators then characterized those with MDD according to the presence of mania spectrum as having MDD with mania (bipolar I disorder), MDD with hypomania (bipolar II disorder), MDD with subthreshold hypomania, or MDD alone.
"Particular focus was placed on comparisons between major depression with subthreshold hypomania, unrecognized by current nosology, and the 2 DSM-IV [Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition)] mood disorders for which clinical manifestations are most proximal: bipolar II disorder and unipolar major depressive disorder," the investigators write.
Findings revealed that compared with those with MDD alone, individuals with MDD and subthreshold hypomania had greater rates of comorbidity with anxiety, substance use disorders, and behavioral problems.
"In comparison to respondents with bipolar II disorder, those with major depression with subthreshold hypomania had lower comorbidity," the study authors write.
According to investigators, although "the proportion of respondents with major depression with subthreshold hypomania who had suicide attempts (41%) fell between that of the bipolar II subgroup (50%) and that of the major depression alone subgroup (31%), these differences were not statistically significant."
Those characterized as having MDD with subthreshold hypomania also had an earlier age at onset than those with major depression alone but a later age at onset than those with major depression with hypomania (bipolar II disorder).
Table. Prevalence Estimates of Bipolar Spectrum Groups in the National Comorbidity Survey Replication
Lifetime Prevalence, % 12-Month Prevalence, %
Major depressive disorder with mania 0.7 0.3
Major depressive disorder with hypomania 1.6 0.8
Major depressive disorder with subthreshold hypomania 6.7 2.2
Major depressive disorder only 10.2 5.4
Need for Increased Awareness
Converging evidence from clinical and epidemiologic studies suggests that current diagnostic criteria for bipolar II disorder fails to include milder but clinically significant bipolar syndromes; a significant percentage of these conditions are diagnosed by default as unipolar major depression.
"People can be at risk for future suicide attempts, trouble with the law, substance abuse, all are well established with mania rather than with depression so the key here is, we want people to be aware that there is a potential for risk that these people might have bipolar disorder and you might want to treat that differently than for major depression alone," said Dr. Merikangas.
Another key to identifying major depression with subthreshold hypomania is the presence of a family history. The study showed that a family history of mania was as common among those with subthreshold hypomania as those with mania/hypomania.
According to investigators, the expansion of the bipolar concept to include subthreshold hypomania would probably lead to important changes in the treatment of patients who are not diagnosed or who are misdiagnosed as having MDD alone.
"If people have these episodes of increased energy that happen without provocation, even if they last only a short time, we recommend that you track that and take a careful family history because patients with major depression who have a parent with a history of mood swings and alcohol dependents, for example, may be at risk of developing bipolar disorder themselves," Dr. Merikangas said.
Clinically Relevant, Implications for DSM-5
Jan Fawcett, MD, University of New Mexico, Albuquerque, told Medscape Medical News that there are a few factors that make the study clinically relevant, including the finding that confirms a conversion rate from MDD to bipolar disorder of 15% to 30% over time. "We know there is a certain proportion of patients with major depression who end up being bipolar," said Dr. Fawcett.
There is additional evidence from clinical trials where antidepressants have been shown not to work as well in bipolar depression as they do in major depression. "People are also starting to notice a proportion of patients who are not responsive to [antidepressant] treatment and some people feel a large proportion of these nonresponders have bipolar disorder," Dr. Fawcett added.
As a consequence of this, experts who are currently involved in updating the DSM-IV are proposing a "mixed specifier" be considered in the new Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) manual in which physicians will be asked to look for symptoms of mania in depressed patients.
This qualifier would then be applicable across the spectrum of bipolar disorder and in major depression. "We are just partly through with this process, but we are looking at this in field trials so when patients are diagnosed with major depression, we are instructing physicians to look for manic symptomsthe same symptoms they used in the Angst studybecause we want to locate who is really bipolar and who is really unipolar and be more effective with our treatments," Dr. Fawcett said.
The NCS-R was supported by grants from the National Institutes for mental Health with supplemental support from the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, and grants from the Robert Wood Johnson Foundation and the John W. Alden Trust. Dr. Angst has served in advisory or speaking capacities for AstraZeneca, Eli Lilly, Janssen Cilag, and Sanofi-Aventis. Dr. Merikangas and Dr. Fawcett have disclosed no relevant financial relationships.
Am J Psychiatry. Published online August 16, 2010.
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