Teenagers have a way of completely redefining the term “normal.” Once kids hit puberty, all bets are off… formerly sweet children often become sullen, temperamental and hard to predict. But if you think they’re just trying to make life difficult for the rest of us, you’re wrong. A new study suggests teenagers can’t help it… they’re pre-wired for moodiness.

Scientists writing in the journal Nature Neuroscience identify one hormone in particular that explains why teenagers “freak out” over the smallest things. The hormone… called T-H-P… is supposed to exert a calming effect, at least for adults and children. But it works in reverse for teenagers, amplifying feelings of stress and anxiety. The study offers a first glimpse into the biological processes that make teenagers the volatile creatures they are.

The tranquilizing hormone acts on the part of the brain responsible for generating emotion. When adults and children encounter a stressful situation, T-H-P produces a calming effect that kicks in about thirty minutes after the event. The cool-down period usually lasts a couple of hours.

But adolescents aren’t so lucky… THP just adds fuel to their fire. Adolescents process the hormone through a slightly different receptor in the brain than adults and children. The difference is enough to over-excite neurons in the hippocampus, creating feelings of angst.

Moderate mood swings and occasional anxiety are normal during teenage years, but contact a health professional if your child exhibits aggression, drug use or other warning signs of depression.