A University of Wisconsin-Madison study using primates could offer answers as to why girls are reaching puberty earlier, in some cases as young as age 7.
For years, researchers have been studying why young women are maturing faster than in the past. Doctors believe early puberty in women may lead to breast cancer and Type 2 diabetes later in life, and that it might stunt brain development in the final stages of the maturation process.
Over the past 150 years, the average age when girls first menstruate has dropped by about four years. Work done at the National Primate Research Center on the UW-Madison campus is now offering the first clue as to what could be leading some girls to go through puberty early.
By feeding a group of four pre-teen rhesus macaque monkeys a higher-sugar, higher-fat diet, researchers discovered they did not get fat but instead reached puberty between a year and 18 months faster than animals in the control group.
Their findings were published Tuesday in the journal Endocrinology, and they could help reshape the picture of health care for young people.
"The animals that did eat more had a dramatically advanced age of puberty onset," said researcher Joe Kurian. "They were getting bigger, though they weren't necessarily getting much fatter than other monkeys."
Just six months after beginning the regimen, the female macaques menstruated for the first time. Kurian said that didn't happen in the control group for another 12 to 18 months.
"It certainly gives us good evidence that diet is, in fact, responsible for advancing puberty onset," Kurian said.
Lead researcher Ei Terasawa said she worries that earlier puberty could stunt brain development, particularly in areas of the brain that deal with judgment.
"That part of the brain is much later, even in a human, 21 to 25 years old, to complete," Terasawa said.
Ongoing research could help doctors reset the developmental clock so it ticks at the right pace.
"We should have a certain developmental stage. We should have a proper process of puberty," Terasawa said.
Male monkeys were not part of the study, as it's simply harder to tell when they reach maturity.
"We do believe that what we are finding in these animals is very translatable to humans," Kurian said. "Certainly it's not in the best interest to try to advance maturation (in humans)."
Kurian said people have been concerned about obesity as it relates to calorie intake for so long that it might not be the only problem. He said the monkeys in the study didn't get fat because they were in the right developmental period in which the body was using the energy in other ways.
Terasawa said the research suggests it might not be good for young girls to have a low-calorie diet, but if they are eating the right amount or slightly more, exercise is very important. Terasawa said there is much more research that needs to be done on this issue, particularly on brain development.