The suicide rate among girls between the ages of 15 and 19 reached an all-time high in 2015 for the 40-year period beginning in 1975, according to new data from the National Center for Health Statistics.

In the shorter term, the suicide rate for those girls doubled between 2007 and 2015, the research indicates.

By comparison, the 2015 suicide rate for boys in this age group was lower than in the peak years of the mid-1980s through the mid-1990s.

Carl Tishler, an adjunct associate professor of psychology and psychiatry at The Ohio State University who was not involved in the report, said the high suicide rate among older teen girls in 2015 could be an anomaly.

“2015 may be an unusual year. Without access to emergency department data or coroner data, I cannot say what caused this blip,” he said.

Specifically, the suicide rate for males between 15 and 19 increased from 12 per 100,000 population in 1975 to 18.1 per 100,000 in 1990, declined to 10.8 per 100,000 by 2007 and then increased again to 14.2 per 100,000 by 2015.

Among females, the suicide rate increased from 2.9 per 100,000 in 1975 to 3.7 per 100,000 in 1990, dipped to 2.4 per 100,000 in 2007 and then spiked to 5.1 per 100,000 in 2015.

The high numbers in the older teen years “could be the result of a lot of things,” Tishler speculated. “Some of the opiate or heroin overdoses in adolescents may be interpreted by emergency departments as suicides. There may be more Internet suicides.”

He noted that previous studies from the US Centers for Disease Control and Prevention, which published this new information Thursday, have indicated that males take their own lives at nearly four times the rate of females and thus represent 77.9% of all suicides. Yet females are more likely than males to have suicidal thoughts. For females who die by suicide, pills are most frequently used; for males, firearms.

“If you look at suicide attempts by girls, it’s typically that girls attempt suicide about four to one or three to one over boys, yet boys complete suicide in the reverse,” Tishler said. “That tends, we think, to have to do with the modality of suicide attempt.”

Boys who die by suicide may choose shooting or hanging themselves, while girls tend to choose an overdose, which can be remediated in an ER.

The new report also does not indicate is how many of the teens who completed suicide were in treatment with a medical health professional and how many were receiving medication for depression or other mental illness, Tishler said. He added that he’s convinced that the quickness to start or change these medications, which are categorized as psychotropic, “is done in such a manner that makes people more vulnerable to attempting suicide.”

“Physicians need to be careful” when increasing, starting or stopping psychotropic medications, because this may “give someone energy to die by suicide,” Tishler said.

One symptom of depression can be psychomotor retardation, which medication reduces, helping people become more active. They may attempt more activities to do better in school or to be more social. The medicines may give depressed teens more energy to plan and follow through with a suicide attempt or die by suicide. Psychotropic drugs also can change mental status and in some cases may increase suicidal thoughts, which is why some of them come with warnings.

The CDC did not respond to request for more information.