This may explain why women are more social—but also more likely to suffer from anxiety disorders or depression. Scientists at the University of Pennsylvania (USA) recently discovered that cerebral blood flow changes during puberty, and that this changes differently in girls and boys. According to Ted Satterthwaite, the lead psychiatrist of this study, it has long been known that adult women have greater cerebral blood flow than men, but it was previously unclear whether we are born this way or when this difference first emerges.

Women have greater cerebral blood flow

To find out, the researchers measured cerebral blood flow using magnetic resonance imaging (MRI) in more than 900 children and adolescents between the ages of eight and 22. Satterthwaite and his colleagues discovered that children of both sexes have strong cerebral blood flow at a young age, which declines evenly in the years before puberty. This only changes around the age of 16. While blood flow continues to decline in boys, this process stops in girls and even begins to reverse. At around the age of 20, women have about 15 to 20 percent higher cerebral blood flow than men.

Effect particularly strong in social brain regions

The researchers found particularly significant differences between the sexes in certain brain regions. These differences could be related to susceptibility to mental illness. "We obviously need more research," says Satterthwaite, "but the differences in blood flow could be one reason why women are better suited for social tasks. The differences were most pronounced in brain regions associated with social behavior and the regulation of emotions."

Important for mental illnesses?

This could also explain why genders are differently susceptible to various mental illnesses. For example, young men are more likely to suffer from schizophrenia, while women are more likely to suffer from anxiety disorders and depression.

The results of this study demonstrate what parents have always known: girls and boys develop differently. "In any case, we shouldn't lump boys and girls together," Satterthwaite emphasizes. "Just as the two sexes have different growth rates for height, weight, and head circumference, we probably also need different growth charts for brain development. This could potentially identify psychological or developmental problems before they lead to serious illnesses."

Source: Theodore D. Satterthwaite, et al.: Impact of puberty on the evolution of cerebral perfusion during adolescence. PNAS, Full 111, pp. , 8643–8648.