Recent research about hormones and behavior have found the relationship to be

Puberty and adolescence often represent a volatile time for young people, and changes in social behavior are usually blamed on “raging” hormones.

However, a new study has found that this common belief is actually inaccurate, and that hormones are not the real culprit behind these changes.

Researchers led by the University of Buffalo conducted a study that examined differences in social behavior that come with adolescence to see if these were the result of puberty.

“Changes in social behavior during adolescence appear to be independent of pubertal hormones. They are not triggered by puberty, so we can’t blame the hormones,” said Matthew Paul, the lead author of the study.

The findings were published in the journal Current Biology.

Puberty and adolescence are often used interchangeably, but this is inaccurate as puberty and adolescence describe two different simultaneous stages in a person’s development.

Puberty describes the biological process when a person develops the ability to reproduce. Adolescence has a much more wide-reaching definition and involves the changes in cognitive, social, and emotional behavior that occurs alongside puberty during a person’s teen years.

In order to understand the full effects of puberty versus adolescents on social behavior, the researchers had to find a way to study the two developmental stages isolated from one another.

This is impossible with humans, so the researchers turned to a species of seasonal breeding hamsters.

“Puberty and adolescence are happening at the same time. So if you want to know if one causes the other, one of the elements must be moved,” said Paul.“We have no way of doing that in a human, but we have found a way to do it using Siberian hamsters.”

Siberian hamsters go through puberty dependent on when they are born in the in the breeding season. Hamsters born at the beginning of the breeding season go through puberty quickly in order to reproduce that year.

Hamsters born later in the season go through puberty much later in order to reproduce during the next breeding season and not in winter.

The researchers conducted a lab experiment that controlled the amount of light the Siberian hamsters received in order to delay and control the onset of puberty.

Using this method, the researchers had two groups of hamsters go through puberty at differing times which allowed the researchers to observe if behavioral changes were dependent on puberty.

The researchers found that no matter when each group was expected to go through puberty, they both experienced adolescence at the same time.

A shift from play-fighting to social dominance occurred at the same time for all the hamsters. If these changes were hormonal than the groups of hamsters would have experienced the shift at different times.

The results of the study prove that hormonal changes during puberty are not linked to the social changes of adolescence.

“This is a surprising finding because we tend to think that pubertal hormones are responsible for the changes we see during adolescence. But our research suggests otherwise,” said Paul. “These findings are also important for adolescent mental health – understanding the underlying mechanisms responsible for adolescent development will provide insight into why so many mental health disorders arise during this time in life.”

Results show that pubertal testosterone modulates dorsal, not ventral, striatal function in an intertemporal choice task.

In addition, increased levels of testosterone are associated with a greater response bias towards choosing the smaller sooner reward.

Findings suggest that pubertal testosterone may modulate local control processes, particularly in the dorsal striatum.

Abstract

Recent self-report and behavioral studies have demonstrated that pubertal testosterone is related to an increase in risky and impulsive behavior. Yet, the mechanisms underlying such a relationship are poorly understood. Findings from both human and rodent studies point towards distinct striatal pathways including the ventral and dorsal striatum as key target regions for pubertal hormones. In this study we investigated task-related impatience of boys between 10 and 15 years of age (N = 75), using an intertemporal choice task combined with measures of functional magnetic resonance imaging and hormonal assessment. Increased levels of testosterone were associated with a greater response bias towards choosing the smaller sooner option. Furthermore, our results show that testosterone specifically modulates the dorsal, not ventral, striatal pathway. These results provide novel insights into our understanding of adolescent impulsive and risky behaviors and how pubertal hormones are related to neural processes.

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Abstract

Adolescence may mark a sensitive period for the development of higher-order cognition through enhanced plasticity of cortical circuits. At the same time, animal research indicates that pubertal hormones may represent one key mechanism for closing sensitive periods in the associative neocortex, thereby resulting in decreased plasticity of cortical circuits in adolescence. In the present review, we set out to solve some of the existing ambiguity and examine how hormonal changes associated with pubertal onset may modulate plasticity in higher-order cognition during adolescence. We build on existing age-comparative cognitive training studies to explore how the potential for change in neural resources and behavioral repertoire differs across age groups. We review animal and human brain imaging studies, which demonstrate a link between brain development, neurochemical mechanisms of plasticity, and pubertal hormones. Overall, the existent literature indicates that pubertal hormones play a pivotal role in regulating the mechanisms of experience-dependent plasticity during adolescence. However, the extent to which hormonal changes associated with pubertal onset increase or decrease brain plasticity may depend on the specific cognitive domain, the sex, and associated brain networks. We discuss implications for future research and suggest that systematical longitudinal assessments of pubertal change together with cognitive training interventions may be a fruitful way toward a better understanding of adolescent plasticity. As the age of pubertal onset is decreasing across developed societies, this may also have important educational and clinical implications, especially with respect to the effects that earlier puberty has on learning.