Dangerous side effects of high blood pressure, including organ damage, could be affecting Americans earlier in life than previously thought, according to a new study published in Hypertension.

Teens—a low-risk demographic compared with the older populations—experience high blood pressure differently than adults, the study’s lead author, Elaine M. Urbina, MD, and colleagues wrote. Hypertension is defined by percentiles rather than blood pressure level, with pressure above the 90th percentile classified as “high-risk.”

Urbina and colleagues studied 180 teenagers and found evidence of organ damage in all three groups: high-risk individuals, mid-risk teens with hypertension levels in the 80th to 90th percentile an “normal” patients, who had steady blood pressure levels below the 80th percentile. The adolescents were an average of 16 years old, and a majority were white and male.

Organ damage, including damage to the heart and blood vessels, occurring in adults with hypertension has been proven. In this new study, though, Urbina and co-authors hypothesized organ damage would occur in adolescents even before their blood pressure reached the 95th percentile, the clinical definition of hypertension in youth. Gender, age and height all contributed to the equation.

Race, weight and genetics also factor into the diagnosis of childhood hypertension, the American Heart Association states on its website. In some cases, medication or disease can contribute to the problem.

Urbina said the new evidence could help doctors diagnose younger patients more thoroughly, so that proper preventative measures can be taken.

“Some adolescents may have organ damage related to blood pressure and are not targeted for therapy,” Urbina said, in an American Heart Association release. “Imaging of the heart may be useful in youth in the high-normal range of blood pressure to determine how aggressive therapy should be.”