Puberty has long been recognised as a transition point in which many emotional and behavioural problems emerge. These include depression and anxiety, substance use and abuse, self-harm and eating disorders.
We previously thought that children who entered puberty earlier than their peers were at greater risk of these problems because they were less equipped to cope with the transition. This may be part of the story.
But we’re increasingly realising that social and emotional disadvantages and stresses in childhood may trigger early puberty. This possibility was explored in a study published today in the Journal of Adolescent Health, which found children who go through puberty early showed signs of poorer mental health in early childhood.
We studied a cohort of 3,491 children and families from the Longitudinal Study of Australian Children. Parents reported behavioural difficulties and emotional, social and school functioning in four surveys between ages four and 11. Around 16% of girls and 6% of boys had begun puberty by age eight to nine.
We found that boys with an earlier onset of puberty had greater behavioural difficulties and poorer emotional and social adjustment. These difficulties began as early as four to five years of age and continued to early adolescence.
Girls who reached puberty early also had more difficulties in emotional and social adjustment from early childhood. But these girls did not have the increased behavioural problems found in boys.
When does puberty start?
Puberty is the stage of development in which a child’s body matures to enable reproduction. This includes the development of breast tissue and the first period in girls, and maturation of the testes in boys. The hormonal changes that lead to sexual maturation during puberty are accompanied by major physical growth and maturation of the brain.
Puberty typically begins in late childhood. On average, girls begin puberty at ages ten to 11; boys start at 11 to 12. But the timing of puberty varies by four to five years among healthy children. This reflects the effects of nutrition, psychological status and socioeconomic conditions. Studies also suggest that genes play a role.
The age of first menstruation has dropped significantly since the 1840s, when the average age in Western European girls was around 16. Since the 1960s this trend has ceased in most developed countries and the average age is now 12 to 13.
Within countries, differences in pubertal age may be found according to socioeconomic status and racial origin. Data from the United States, for example, found that black American girls begin puberty earlier than white or Mexican-American girls.
Emotional and behavioural problems
We know that adversity in life – such as stressful family circumstances or a lack of care and warmth – can affect the rate and course of a child’s development. Early psychosocial stress can be a cue for environmental risk and trigger earlier reproductive development. From this perspective, emotional and behavioural problems would be expected to occur even before early puberty is evident.
Puberty is a time of increasing stresses and challenges, as children adapt to their changing social roles. For this reason, mental health issues often first emerge in adolescence. Younger children and those with fewer social and emotional resources may find this phase more difficult, which increases their risk of subsequent mental health difficulties.
These changes interplay with prenatal factors. We know, for instance, that children who had a low birth weight are more likely to have early puberty.
Social determinants and health-related behaviours are also highly influential. The families, peers and communities children grow up with can provide “social scaffolds” for their mental health. Equally, negative influences in children’s environments can be risk factors for mental health difficulties in adolescence.
Our research supports a “life course” hypothesis. This suggests that differences in pubertal timing and childhood adjustment may, in part, result from adversity early in life. In other words, early puberty may be part of an accelerated transition to adult development which begins early in life. This, in turn, heightens the risks for emotional and behavioural problems.
Reducing the risk
The early life factors that may be influencing children’s development and leading to early puberty are not yet fully understood. Finding out what lies behind early puberty may help us to understand the origins of emotional and behavioural problems of children and adolescents.
We hope to find preventive ways to avoid some of the mental health difficulties which can emerge in adolescence. Promoting healthy environments and behaviours from early in childhood may help children develop social and emotional resources. Whether these resources will then protect children’s mental health during puberty is an important question.
We need to be aware of the social and emotional stresses during puberty, particularly for children who reach puberty earlier than their peers. It is crucial that there are positive frameworks in place to support these children at this phase of their lives. These may include supportive families, peers and communities, as well education, counselling and health services.