14 July 2010

Knocking Out Puberty

Puberty seems to be arriving at earlier ages for both boys and girls. There are many reasons why puberty onset is earlier now, but most of these reasons are still unclear. The problems that arise from premature puberty include violence, higher risks of cancer and diabetes, increased behavioural problems (drugs, alcohol, delinquency etc), isolation from peer groups -- even a change in growth rates for the children of girls with premature onset of puberty.

...children who go into early puberty are prematurely sexualised and too immature to deal with the implications. They are more vulnerable to sexual abuse, inappropriate sexual behaviour, sexually transmitted diseases and teenage pregnancy. “It means that children develop sexually much earlier,” Stanhope says. “They are physically ready for sexual reproduction but mentally completely unready.”

Studies have shown that adolescents who go through puberty earlier are involved in more risk-taking behaviour, such as taking drugs, binge drinking and breaking the law. A premature increase in testosterone can lead to aggression in boys who lack the maturity to control impulses. “We all realise that testosterone is a very difficult hormone to learn to live with,” Stanhope says, tapping a pencil vigorously on his pockmarked table, “and if you get a rise in testosterone outside the normal physiological age, then it’s even more of a problem.”

Research published this year in the Australian and New Zealand Journal of Criminology also found increased aggression in girls who reached puberty early. In Britain the uncomfortable reality that children are becoming sexually mature earlier has been overlooked in the recent debate about the over-sexualisation of children. Instead of simply focusing on cynical manufacturers producing padded bras for seven-year-olds, perhaps we should also consider how to respond to the new reality that some girls are now growing breasts at this age.

Stanhope also points out that for women there may be long-term health problems, because early puberty increases exposure to oestrogen. According to Cancer Research UK, a girl who has her first period a year later than her contemporaries has 5% less risk of developing breast cancer in later life. “There may be an important link with breast and ovarian cancer,” Stanhope says. “The earlier a girl has her period, the longer her exposure to oestrogen and this may well have very important sequelae for oestrogen-dependent tumours. This increases her risk of breast cancer, ovarian cancer and of developing cardiovascular problems.”

Girls who reach puberty early are also more likely to develop type 2 diabetes. A 37-year-long study of 61,000 Norwegian women showed that women who got their first period at ten or 11 had a 10% higher mortality rate than those who got their period four years later. _PubertyBlues

Scientists are beginning to home in on the physiological initiators of puberty, and have found a way to delay puberty in mice. By "knocking out" a specific gene, IGF-1R, researchers have both delayed puberty and maintained normal reproductive function after puberty in these knockout mice.
Pubertal onset, initiated by pulsatile gonadotropin-releasing hormone (GnRH), only occurs in a favorable, anabolic hormonal milieu. Anabolic factors that may signal nutritional status to the hypothalamus include the growth factors insulin and IGF-1. It is unclear which hypothalamic neuronal subpopulation these factors affect to ultimately regulate GnRH neuron function in puberty and reproduction. We examined the direct role of the GnRH neuron in growth factor regulation of reproduction using the Cre/lox system. Mice with the IR or IGF-1R deleted specifically in GnRH neurons were generated. Male and female mice with the IR deleted in GnRH neurons displayed normal pubertal timing and fertility, but male and female mice with the IGF-1R deleted in GnRH neurons experienced delayed pubertal development with normal fertility. With IGF-1 administration, puberty was advanced in control females, but not in females with the IGF-1R deleted in GnRH neurons, in control males, or in knockout males. These mice exhibited developmental differences in GnRH neuronal morphology but normal number and distribution of neurons. These studies define the role of IGF-1R signaling in the coordination of somatic development with reproductive maturation and provide insight into the mechanisms regulating pubertal timing in anabolic states. _JCI
Scientists will find additional triggers for pubertal onset besides insulin and IGF-1, and some of those factors may provide a more benign approach to the delaying of puberty.

Paradoxically, IGF-1 is vital for normal development of mice, but knocking out IGF-1 receptors in certain flies and worms can increase lifespan. That paradox is still being studied.

So -- how long should puberty be delayed, if at all? If childhood could be extended for several more years without impairing the ability of the child to learn and mature psychologically, would the potential health and societal benefits be worth the postponement of sexual development of the child?

What if aging itself were to be postponed along with puberty? If total lifespan were extended by the number of extra years a person spent in childhood, would that be beneficial to society or not? What if a person could live an extra 20, 30, or 50 years -- but had to spend those extra years as a pre-pubertal child. Would it be worth it?

Those who see increased longevity as a sure path to overpopulation collapse of Earth's ecosystem, would insist upon some form of sterilisation for those who opt for longevity. In some countries, laws of that type -- mandating permanent sterilisation for anyone undergoing longevity treatments -- should be expected.

Extended pre-puberty is a form of time-limited and (probably) reversible sterilisation, so any longevity approach that also delayed puberty significantly, should not raise the hackles of those suffering from overpopulation anxiety too much. But there are likely to be a large number of objections to such treatments, all the same.

Modern societies appear to see children in a schizoid manner. Fewer children are born, so the one or two children a family does have, are cherished and pampered. On the other hand, children are seen as a hindrance to a hedonic lifestyle, an exorbitant expense and often a great bother. Overall, most children do not seem to be raised or educated very well in modern societies, judging by observable results.

While childhood is not prolonged in modern societies, an incompetent adolescence is certainly prolonged -- in many cases indefinitely. Given the choice between a prolonged childhood leading into an accelerated but prepared-for adolescence, and the current state of lifelong incompetent adolescence commonly seen in the affluent world, most Al Fin mental health professionals would choose the prolonged childhood combined with a prepared-for adolescence that leads into a responsible and competent adulthood.

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Blogger gtg723y said...

I was watching an episode of BS by Penn and Teller on organic food and many doctors think the reason girls are entering puberty sooner is due to nutrition. According to those numbers the magic number for a girl is 110 lbs and 10%+ body fat, once a girl achieves those numbers she enters puberty, it has nothing to do with the hormones fed to chickens, it has everything to do with people eating to much and children not playing outside anymore.

Thursday, 15 July, 2010  
Blogger al fin said...

An interesting idea. The numbers may be useful as a rough rule of thumb.

If girls entering puberty prematurely are more likely to procreate (and bear more children) then genetic mechanisms supporting early puberty will be propagated into a larger proportion of the population.

Regardless of the environmental components, there is always a genetic component underlying the response.

Sunday, 18 July, 2010  

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