“[S]ex . . . is an important basic human variable that should be considered when designing and analyzing studies in all areas and at all levels of biomedical and health-related research.” —Institute of Medicine, 2001

When to Study Sex Differences

An obvious situation in which sex differences should be studied is when there is a difference in anatomy, Sandberg said. Even though there are no disparities in general intelligence, when differences in brain size are taken into account, women have ten times more white matter while men have almost 7 times more gray matter as related to intellectual skill. This suggests a significant sex difference where intelligence is manifested. Because function often follows structure, these sex differences in neuroanatomy need to be understood.

Better understanding of known sex differences in nervous system physiology may improve care after injury. For example, functional magnetic resonance imaging conducted while participants listened to a book being read aloud showed that in women, both sides of the brain were active, while in men, only one side was active. Both were listening, but through different physiological mechanisms. Other studies show that men and women use different mechanisms to navigate; women rely more on landmarks whereas men prefer compass directions. Furthermore, while men use both the right and left hippocampi when navigating, women only use the right hippocampus. Instead of using the left, women invoke the aid of the right prefrontal cortex. The disease implications of these functional brain differences are significant. It is easy to see how a stroke in a sexually differentiated brain region could result in very different outcomes for each sex.

Differences in disease prevalence or age of disease onset are another instance when sex differences should be studied, Sandberg said. Using stroke as an example again, males have a higher incidence of stroke across much of their lifespan; however, after age 80, women have a higher incidence of stroke. A better understanding of what makes men in their 40s more susceptible to stroke while women are protected may lead to better therapies or preventive measures for both sexes.

Studying sex differences may provide an important health benefit when there sex-specific symptoms. The commonly known symptoms of stroke, for example, include sudden numbness of one side of the body (face, arm, or leg), difficulty speaking or understanding, inability to see out of one or both eyes, difficulty walking including dizziness or loss of balance, and a severe headache. But these symptoms do not present equally in males and females. Women have less loss of balance and coordination, and more changes in mental status (confusion, unconsciousness) than men. Women also have more nausea and heart attack-like symptoms, and tend to present with more severe headaches. These symptoms are not unique to women, Sandberg clarified, but they are experienced more often by women than men. These sex differences have the potential to negatively impact diagnosis and consequently recovery if emergency room personnel are not trained to recognize sex-specific symptoms.

Sex differences in the type of stroke also occur. Men have more atherosclerotic strokes (68 percent of men versus 19 percent of women), which is perhaps related to the fact men have a higher prevalence or an earlier onset of atherosclerosis than women, whereas women have more cardioembolic type of strokes. Clearly, there are underlying mechanistic differences behind these sex differences that need to be studied that may lead to better targeted preventive therapies.

Studying sex differences may also shed light on disease severity, progression, and/or outcome. Following a stroke, women are institutionalized for longer periods of time, and have lower functional recovery. Although increases in length of institutionalization could be related to the fact that women live longer than men, when the age difference is ruled out of the analysis, there remains something inherently different between the sexes that does not explain the lower functional recovery observed in women. We must learn why this is the case.

Potential differences in responses to therapeutic intervention provides another important reason to study sex differences. Aspirin has been shown to be cardioprotective in men, but it does not reduce the incidence of myocardial infarction in women; however, aspirin does decrease the incidence of stroke in women. At a basic science level, with the majority of studies still conducted only in male animal models, drug development is inherently biased toward what works well in males, suggested Sandberg. Furthermore, because Phase I and II clinical trials do not require sufficient numbers of women to assess sex differences in safety and efficacy, sex differences in treatment responses only become obvious when large clinical trials take place. Thus research bias may, in turn, bias drug development leading to better treatments in men and obscuring potential adverse drug side effects in women.

Sex Differences and Implications for Translational Neuroscience Research: Workshop Summary http://www.nap.edu/catalog/13004.html

[lastyearisblank]

Sex is a circular construct. The researchers say, "look it's objective, men are better at math." They never consider the psychological aspects of testing. This research is never surprising and never ends up being useful. It is a self fulfilling prophecy. Do not ask "why" women perform less well on spacial skills tasks; ask rather why as a culture, we could not tolerate women to have the upper hand, and have constructed our idea of gender around a power difference.

I agree that certain heart medications work better from some groups of others; unfortunately, the problem is that the default "human" test subject is the white male! Interesting article- lots of food for thought here, thanks..

[krisakira]

"women rely more on landmarks whereas men prefer compass directions." Not true. They should have said that studies found that MORE women rely on landmarks in men, etc.... because I am a freaking woman, and i hate freaking landmarks. Stop making sexes black and white because it is not!!!!!

[madisgram]

great article, byz!!!
how men and women deal with emotions are entirely different due to the parts of the brain that are used. that explains a lot.
had a strange occurance during an IQ test. the pdoc said he had never seen it occur before while testing ppl. i had a series of cards that told a story in sequence. the first 8 i did from first to last towards the right. the next time i went from right to left in the sequence. he wanted to do additional studies on me because of it. said i was using the left sector of my brain the first 8, then jumped over to the right side of my brain. said it was unusual for this phenomena of switching midstream.
course that may explain why i'm unusual/odd. i got a short circuit running around up there. hummmm. does that make me unique?

Unique, indeed.

[eskielover]

Originally Posted by krisakira

"women rely more on landmarks whereas men prefer compass directions." Not true. They should have said that studies found that MORE women rely on landmarks in men, etc.... because I am a freaking woman, and i hate freaking landmarks. Stop making sexes black and white because it is not!!!!!

I'm with you on this one. I learned at a young age NOT to depend on landmarks as they may not be there the next time you go by. When I was a child, my Mom & I were staying with my grandparents in Topeka. They let me stay with a group after church & they went home. The lady who was heading the group promised to get me home. Little me, was trying to remember the way home from the church. I remembered most of the way, but when I came to the corner house where the "black car" was supposed to be in the driveway, I got lost because the stupid "black car" wasn't there. I was so embarrassed that from that point on, I always made sure that if I did use a landmark, it was something that could't move away from where it was.

I always use North & south directions, number of streets, corners, but NOTHING movable. I definitely love my GPS for directions.

Also, I am a woman, but have never thought like a woman. Never related to women from the time I can even remember. Each of us is unique & when they generalize in black & white terms about how the different sexes act......I tend to not hold much value in their studies. Unique individuals which we are, is what I have always seen people as being, since that was always something that I was proud about being.

[pachyderm]

Originally Posted by TheByzantine

"women rely more on landmarks whereas men prefer compass directions."

Sounds like a generalization, if I ever heard one. I am one data point who is an exception.

[eskielover]

Originally Posted by pachyderm

Sounds like a generalization, if I ever heard one. I am one data point who is an exception.

LOL, well, that makes 3 of us just in this one thread....lol. Ya think they might reconsider their results???????

[lonegael]

Most of the spatial differences seen with men and women are learned. woemn who work from charted instructions for quilting, knitting, etc tend to do far better on block manipulation than other woman and even than most men. The same can be said for most simulator tests when one realizes that women are starting to play computer and consol games more nowdays. there are a very few tsts that seem to pinpoint areas that are more estrogen effected where men out-preform women, but they are really pretty obscure. Just some fun from someone who has done some of these tests one folks