DEPRESSION affects one in five women over the course of a lifetime, double the number in males. At least, that's the official line. It's safe to say women are far more likely to display depression than men, with the DSM-IV in apparent collusion with its gender-biased symptom list (such as "appears tearful").
But brain scans do indicate that men and women process emotional input into memory rather differently than men. Moreover, the brain science shows subtle yet significant structural and functional deviations that manifest in all regions of the brain. It is easy to overplay these differences, but a picture is beginning to emerge as to why women - in certain instances - may be more vulnerable to depression than men.
Gender Brain Distinctions
An article in the May 2005 Scientific American serves up a number of examples:
The amygdala - which helps lay down emotional memory - is larger in men than in women, with greater interconnections. In one brain scan study, in response to being exposed to emotionally arousing slides, there was greater activity in the right amygdala in men, while in women the left amygdala was put to work. When later asked to recall events, the men were more likely to get the gist of the disturbing slides than the women.
Likewise, a study of rodent pups separated from the mothers, but within hearing range, found the males had higher concentrations of serotonin receptors in this region than the females. It may be a stretch to transpose these findings to humans, especially since we cannot exactly ask a rat if it's feeling depressed, but this is the way science gets done.
The hippocampus - crucial for memory storage - is larger in women than men. Experiments on rats placed in enriched environments showed bushier growth in the dendritic tree structures of the hippocampal neurons of the females. The males failed to displayed this growth. What to make of these studies is hard to say. Current thinking indicates that females may be more vulnerable to acute stress, but bear up better under chronic stress.
Certainly, the stress connection was a prime suspect long before brain scan studies took off in the 2000s. In an article from a Scientific American dating from 1998, Ellen Liebenluft of the NIMH argues that estrogen "might set the stage for depression indirectly by priming the body's stress response." Thus:
If estrogen raises cortisol levels after stress or decreases cortisol's ability to shut down its own secretion, then estrogen might render women more prone to depression - particularly after a stressful event.
Gender - More Things to Consider
In October 2000, the American Psychological Association convened a summit of more than 35 experts on women and depression, chaired by Carolyn Mazure PhD of Yale University. In April 2002, the APA released a 59 page report based on that summit, Summit on Women and Depression.
Amongst other things, the Report noted that women were three times more likely than men to experience depression in response to stressful events. Childhood sexual abuse, adult sexual assault and male partner violence have been "consistently linked" to higher rates of depression in women. Significantly, 85 percent of the victims of nonfatal intimate assault are women, 15 percent of adult women in the US have been raped. and another three percent have been victims of attempted rape.
Other stressors include poverty, inequality, and discrimination. Women are more likely than men, the Report observes, to have incomes below the poverty line. "Poverty is a pathway to depression in women," says the Report, "in part because poor women have more frequent and uncontrollable adverse life events than the general population."
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Making matters worse is the fact that women engage in "ruminative thinking", that is "a mental focus on symptoms of distress and their possible causes and consequences, repetitively and passively." Ruminative behavior, explains the Report, is associated with longer and more severe episodes of depression. "Unmitigated communication", a tendency in women to base their self-worth on relationships and their external environment and take on other people's problems as their own is also linked to depression.
To add insult to injury, depressed women appear to nongenetically transmit their depression to their offspring. Women with histories of depression, the Report notes, tend to be more critical toward their adolescent children. Depressed women also experience more marital discord and divorce. Even women in remission are vulnerable. Thus, depressed mothers raised in dysfunctional families risk raising future mothers of dysfunctional families.
None of these factors operates in isolation. Instead, biology, psychology, and social factors work together in "complex and reciprocal interactions."
Gender - Differential Responses to Meds
Obviously, if women's brains are wired a bit differently than men, with greater exposure to certain environmental stresses than men, this suggests differential responses to both medications and talking therapy. The NIMH-underwritten STAR*D trials of the mid-2000s - representing the best evidence we have for antidepressant treatment - tested for the former. The women entering the study were younger, with more severe depressive symptoms and complications. Despite this, the women had a 33 percent better chance of achieving remission on an SSRI than the men. There were no differences in side effects or time to achieve remission.
STAR*D did not investigate the underlying mechanisms that would account for these differences, but the researchers involved cited various studies implicating estrogen's negative impact on the brain's serotonin system, plus speculations on the impact estrogen may have on the formation of the brain in utero.
Meanwhile, we are still back in 1998, contemplating - as the Scientific American article of that era did - why men and women respond to stress differently - typically seen as depression in women and aggression and alcoholism in men. Is it due to biological differences, say in the serotonin system? Low serotonin has been implicated in depression and anxiety, but also in severe alcoholism and aggression.
Or are women socialized to "act in" while men "act out?" Studies on Jewish and Amish populations, where alcoholism is low, have found equal rates of depression between men and women.
Either interpretation - biological or environmental or both - suggests the same steam coming out of different vents. Does this mean that we should view some forms of antisocial behavior and heavy drinking in men as a type of male depression?
Funny you should ask.
Next: Depression in Men ...
This aritlce replaces an earlier article, Jan 20, 2011, reviewed Dec 4, 2016
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