Why your teenager is so vile!

Researchers in the U.S. say they may have found a reason for the erratic mood swings of teenagers.

The general knowledge is that teenagers are on the whole at some stage held ransom by their hormones and the most placid and even tempered child can become at times an angry and volatile stranger.

But researchers from the State University of New York believe they have identified the specific hormone that makes adolescents so cranky.

The researchers suggest that a hormone produced by the body in response to stress that usually serves to calm adults and younger children, has a paradoxical effect in teenagers and instead increases their anxiety.

The researchers are referring to the hormone THP which in experiments carried out on female mice focusing on the hormone, saw this paradoxical effect.

The hormone THP, also called allopregnanolone acts as a natural tranquilizer.

It is produced several minutes after the stress has begun and calms neural activity in order to reduce anxiety and help the individual to adapt and function in the stressful situation.

Dr. Sheryl Smith, a professor of physiology and pharmacology and the lead researcher in the study, says the research has revealed that there is a biological basis for a teenager's mood swings which is equally frustrating for parents and teachers, as well as the adolescents concerned.

Dr. Smith says it is unclear why this happens, but she suggests it is because of the action of all the other hormones which come into play at puberty and a teenager's responses to stressful events then become amplified.

Anxiety and panic disorders first emerge at this time and are twice as likely to occur in girls as in boys and it is also at adolescence that suicide risk increases.

Smith's team examined brain activity and behaviour in mice before puberty, during puberty and as adults.

The researchers subjected the mice to a stressful event by suddenly placing them inside a plexiglass container just slightly larger than a mouse's body creating a claustrophobic experience and keeping them there for 45 minutes.

Smith says twenty minutes after stress, both the young mice and the adult mice showed less anxiety, but the pubertal mice showed more anxiety.

Closer examination revealed that the increased excitability was due to the effects of THP, which acts on brain cells by way of molecular doorways known as receptors.

Smith says during adolescence, mice have the usual receptors, but also extra-high levels of a second kind that brings an anxious, rather than calming, response when THP attaches to it and humans experience similar hormonal changes at puberty.

Dr. Smith and her team were able to genetically alter the receptor to reverse the puberty effect and say it might also be possible to block the effect of the hormone.

Dr. Smith says however that more research was needed before that was possible.

The study is published in Nature Neuroscience.