Swedish team finds differences in brain systems for handling the 02/14/2008
While some of the same factors contribute to depression in both sexes, women are subject to unique biological, life-cycle, hormonal and psycho-social influences.
Now, researchers from Sweden's respected Karolinska Institute report that they may have discovered one reason why rates of depression and chronic anxiety differ between men and women.
Their findings reveal distinctions in each gender's brains, related to regulation of serotonin, which is the neurotransmitter associated with maintenance of good mood.
Swedes find sex-based difference in serotonin regulation
Doctoral candidate Hristina Jovanovic and her colleagues at Stockholm's Karolinska Institute used a PET scanner to examine the brains of women and men.
Their results reveal that women have more of the most common serotonin receptors than men, and possess more serotonin receptors in the brain's hippocampus region (Jovanovic H et al. 2008).
As well as being vital to memory formation, the hippocampus is part of the brain's “limbic system,” which is associated with primitive emotional states.
The hippocampus actually shrinks in people with severe depressions, or who suffer from excess stress. (This hippocampal shrinkage can be reversed and perhaps prevented in people with depression and bipolar disorder, with effective treatment.)
Interestingly, the hippocampus is also rich in estrogen and progesterone receptors, so the unusually high number of serotonin receptors in a woman's hippocampus could be connected to the need to deal with hormone-related mood fluctuations. Clearly, we need to know more about this part of the brain.
According to team leader Anna-Lena Nordström, M.D., Ph.D., “We don't know exactly what this means, but the results can help us understand why the occurrence of depression differs between the sexes and why men and women sometimes respond differently to treatment with antidepressant drugs” (Karolinska Institute 2008).
Serotonin system may differ in women with severe PMS
The Karolinska group also found differences between the serotonin system in healthy women, compared with women who suffer from serious premenstrual mental symptoms (Jovanovic H 2008; Jovanovic H et al. 2006).
These findings indicate that the serotonin system in women who suffer from severe PMS may not respond as flexibly to the hormone swings of the menstrual cycle.
No doubt, every woman will second that emotional health motion.
Prozac-type drugs rest on shaky evidence
Prozac and other SSRI-type drugs are the most commonly prescribed anti-depressants, and rank among the most widely prescribed drugs in America and Europe.
And as we reported recently, the clinical research foundation upon which their approval rests is seriously flawed.
The authors of an evidence review found that some 94 percent of clinical trials with positive outcomes (i.e., effects superior to placebo pills) were published, while only 14 percent of trials with negative or unclear results appeared in any public form.
And the FDA's own study reviewers found that the results of many of the “positive” studies were not as good as their authors claimed (See “Major Heart and Mood Drugs Take Huge Credibility Hits”).
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