Sex differences may reveal clues to psychiatric, neurologic conditions

HALIFAX, Nova Scotia — The difference with which psychiatric and neurologic conditions affect the two sexes may provide clues to understanding the etiology of the conditions and shed light on possible therapeutic interventions.

“Autism is four times more likely to affect boys than girls, depression is three times more likely to affect girls than boys, and eating disorders are 10 times more likely to affect girls than boys,” Jason P. Lerch, PhD, a research scientist at the Hospital for Sick Children in Toronto, said in an interview with Endocrine Today. “We don’t know what the relevance of this is yet. To understand these diseases, we have to understand why they differently affect men and women.”

Speaking here at the annual meeting of the Canadian Pediatric Endocrine Group, Lerch noted that conditions that more often affect boys, such as autism, present before puberty, whereas conditions that more often affect girls, such as depression or eating disorders, present after puberty.

“There is an early steroid surge right after birth that is important for programming the brain,” Lerch said. “These sex steroids go quiet until puberty.”

The immune system, through the T-cell receptors, has some role in determining sexual differentiation in the brain, Lerch said.

Jay Giedd, MD, professor and chair of child and adolescent psychiatry in the department of psychiatry at the University of California at San Diego, and professor at the Johns Hopkins Bloomberg School of Public Health in Baltimore, said both chromosomes and hormones affect the brain, with each having more influence in some spheres over others.

“Some parts of the brain are more influenced by hormones, and some are more influenced by chromosomes,” Giedd told Endocrine Today.

Chromosomal abnormalities can provide insight about the effects of chromosomes on brain function while hormonal abnormalities can provide insight about the impact of hormones on the brain, Giedd said.

“We would be able to understand if the brain circuitry is more related to hormones or related to chromosomes,” he said. “We want to disentangle the chromosomal and hormonal effects.”

Looking at sex differences might reveal clues about brain circuitry, Giedd said.

“If we can understand why depression is more common in girls, for example, it might help us understand depression in general,” he said.

One of the advances that must take place to look at the role of biology in the development of psychiatric and neurologic conditions is standardizing brain imaging across health care centers, Giedd said. – by Louise Gagnon

References:

Giedd J. Oral Presentation: Sex differences in the developing human brain.

Lerch JP. Oral Presentation: The genetic, steroid, and immune origins of sex differences in the brain. Both presented at: Canadian Pediatric Endocrine Group Scientific Meeting; Feb. 19-21, 2015; Halifax, Nova Scotia, Canada.

Disclosure: Lerch and Giedd report no relevant financial disclosures.