Neuroscientists say dyslexia presents differently in women, men

From Science News:

WASHINGTON, D.C. — More than 30,000 neuroscientists from around the world
gathered in Washington, D.C., November 15–19 for the annual meeting of the Society for Neuroscience.

Presentations covered the science of nerves and brains on scales from molecules to societies.Offerings the second day of the meeting, November 16, are sampled here: surprising insights about the brain on age, one of the first studies to investigate the brains of dyslexic women, a new finding about head trauma, and details on how the skin senses touch.

Dyslexia’s female twist

Women’s brains have a different read on dyslexia than men’s brains do. Women diagnosed with this severe disability in reading and other facets of written language show a right-brain deficit in tissue volume, in contrast to a primarily left-brain volume reduction already reported for dyslexic men, according to a team led by neuroscientist Guinevere Eden of Georgetown University in Washington, D.C.

Tissue volume provides one sign of neural function. Until now, researchers have only studied the neural basis of dyslexia in men and in mixed-sex groups that contained only a minority of women.

Eden’s group used an MRI scanner to examine brain volume in eight women who had dealt with dyslexia since childhood and eight women with no reading or language problems. Participants ranged in age from 19 to 25. Dyslexic women exhibited a relative reduction of tissue volume in part of the right parietal lobe. It’s hard to know how this brain area relates to reading, says study coauthor Tanya Gerner, a Georgetown neuroscience graduate student.

“This finding stands in stark contrast to volume reductions in the left temporal lobe reported previously for dyslexia in males,” Gerner says.

The team also studied brain volume in girls with dyslexia. Nine school-age girls ages 7 to 13 and diagnosed with dyslexia displayed reductions in tissue volume not just in one brain area, but in a variety of areas, compared with eight girls of the same age group who had no reading problems. Earlier studies have observed comparably widespread reductions in neural volume among dyslexic boys, relative to their male peers who have at least average reading ability.

It appears that boys and girls with dyslexia start out with similar types of neural volume deficits that diverge by adulthood to different sides of the brain, Gerner says. The reason remains unclear, she adds. As dyslexic boys and girls receive special reading instruction throughout schooling, their brains may compensate for initial reading difficulties in sex-specific ways, she theorizes.