Research supports continuum of depressive clinical syndromes
MedWire News: Research shows that patients with bipolar I disorder (BD I) experience more severe major depressive episodes (MDEs) than those with bipolar II disorder (BD II), who, in turn, experience more severe episodes than patients with major depressive disorder (MDD).
Currently, DSM-IV-defined differences between BD I, BD II, and MDD patients are based on the presence and duration of manic symptoms.
However, Carmen Moreno (Centro de Investigación Biomédica en Red de Salud Mental, Madrid, Spain) and team say that "our results are consistent with the existence of a continuum of depressive clinical syndromes and suggest the need to include a dimensional assessment in the current categorical classifications."
The findings come from a study of 935 individuals with BD I, 494 with BD II, and 5695 with MDD who participated in the National Epidemiologic Survey on Alcohol and Related Conditions (2001‑2002) ‑ a nationally representative survey of more than 43,000 US adults.
The team compared differences among these groups regarding the frequency and severity of MDEs, the presence of psychiatric comorbidities, sociodemographic characteristics, and other variables.
The researchers found that BD I patients had the highest mean number of lifetime MDEs (8.9), followed by BD II patients (5.9), and MDD patients (4.7).
Furthermore, BD I patients had the highest number of depressive symptoms during MDEs (8.1), followed by BD II patients (7.6), and MDD patients (7.4).
The frequency of comorbid psychiatric disorders, such as anxiety disorders, alcohol and drug use disorders, and personality disorders, was also highest among BD I patients, followed by BD II, and MDD patients.
In addition, BD I and BD II patients experienced their first MDE at a significantly younger age than did MDD patients, at 23.6 and 23.9 versus 30.4 years, respectively.
Moreno and colleagues conclude: "Our results support the existence of a spectrum of severity of MDE, with highest severity for BD I, followed by BD II and MDD, suggesting the utility of dimensional assessments in current categorical classifications."
By Mark Cowen