Clinical Features of Bipolar Depression Versus Major Depressive Disorder

Many people in the United States as well as other countries, experience some sort of depressive disorder at some point in their lifetime. However, more and more people are becoming diagnosed with a more serious condition known as Bipolar disorder. Bipolar is more often obtained from a family history of the illness, while major depressive disorder is onset more often by an onset of several depressive episodes.

The researchers of this particular study compared 477 outpatient volunteers with Bipolar I disorder, and 1,074 who had major depressive disorder. The idea of the research was to help in the diagnosis of the two disorders. (Perlis, Brown, Baker, Nierenberg 2006). Several clinicians have trouble distinguishing between the two disorders. This study was to be used to help distinguish an easier diagnosis of them.

The authors used data from non-psychotic outpatients participating in three large multi-center clinical trials that were conducted in the United States for treatment of major depressive episodes. The study compared those 477 subjects who are diagnosed with bipolar disorder and the 1074 who suffered from major depressive disorder (Perlis 2006). Some of the data acquired was from outpatient sites in the U.S. for major depressive disorder. This was from earlier research that was conducted between 1999 and 2001. "Both of the places were multi-center, parallel, double-blind, randomized, placebo-controlled clinical trials that were done exclusively in the United States." (Perlis 2006) The criteria for the subjects who were included, were those with at least moderate depression, (as defined by the Clinical Global Impression severity scale) with a score of a four or higher. The patient also had to have a Hamilton Depression Rating Scale of a 15 or higher.

The research of the bipolar depression was also done at a multi-center, double-blind, randomized, placebo-controlled clinical trial that was done in thirteen different countries. It was done accordingly to compare the efficacy and safety of olanzapine and the olanzapine-fluoxetine combination with the placebo. (Perlis 2006) The criteria that the patients had to meet were as follows: 1. They had to have DSM-IV criteria for both bipolar 1 disorder and depression. 2. They had to have at least a score of 20 on the MADRS (Montgomery-Asberg Depression Rating Scale). The subjects who were excluded from the study were those under the age of 18, patients who are felt to be a serious suicide risk, people with current substance use disorders, and pregnant or breastfeeding women.

Both demographic and illness characteristics were compared with each other using a form of testing called the "chi-square" test. They also used other forms of data comparison methods to help define things such as family history, age at the time of onset of the illness, and the number of depressive episodes in the past to present.

Some of the results that were shown were that the age of onset of the mood symptoms occurred about 8 years earlier for those with bipolar. It was just the opposite for those with serious depressive disorder. Family history, as they expected, was more significant in those who have the bipolar disorder. The amount of previous depressive episodes was much larger in those diagnosed with bipolar I disorder. "In fact 40% of the bipolar patients reported a greater occurrence of indistinct and highly intermittent episodes." (Perlis 2006)

There were five items that were significantly different between the groups. Apparent sadness, tension, reduced sleep, pessimistic thoughts, and suicidal thoughts were among the differences of the two. As for the similarities, the two groups had very similar anxiety symptoms. The score from fear was a lot higher in patients with bipolar. However, the score for things such as insomnia, intellectual skills, muscular pains, respiratory, gastrointestinal, genitourinary, and autonomic symptoms were all lower in those with bipolar when compared to the scores of those who suffer from major depressive disorder. The researchers then used a rating scale and the MADRS scores I previously mentioned to determine predictors in helping to determine the diagnosis between the two illnesses. They then had put the new system to a test to see the probability of correct identification between the