Increased testosterone, but not age, is related to increased sensitivity to immediate rewards, whereas increased age, but not testosterone, is related to a reduction in general impatience. This is the finding of a recent study conducted at the Max Planck Institute for Human Development investigating the influence of testosterone on adolescents’ decisions.
It is obviously no surprise that patience isn’t teenagers’ strongest suit. They often want immediate results, even when it would pay to wait. Because boys are more impulsive than girls, the researchers focused on boys aged between 11 and 14 years.
To gauge the pubertal status of the participants, the researchers collected morning saliva samples from 72 adolescents and determined their testosterone levels.
Participants then completed a choice task that gauged their impulsivity. They had to make a total of 80 choices between two hypothetical amounts of money available either soon or further in the future.
Specifically, they had to choose between a smaller sooner reward and a larger later reward.
Sensitivity To Immediate Rewards
The results showed that most of the adolescents were more likely to choose immediate rewards. On average, about two-thirds of the participants opted for the smaller sum of money that was available sooner.
The researchers think that sensitivity to immediate rewards is associated with the effects of testosterone on certain reward-related regions of the brain, such as the striatum.
Chronological age cannot explain this sensitivity. It is only with increasing age that the timing of the reward becomes less important.
“Our study shows that puberty—measured in terms of physical and hormonal maturity—needs to be properly accounted for in developmental psychological studies. Developmental differences are often not in line with chronological age,”
says lead author Corinna Laube of the Max Planck Institute for Human Development in Berlin.
Control Network Matures Slower
The results are another step toward understanding adolescents’ impulsive decisions and complement the findings of a previous study conducted at the Max Planck Institute for Human Development.
According to that study, teenage impulsivity is attributable to an imbalance in the maturation of the subcortical affective brain network, the cortical cognitive control network, and the connections between the two. The affective network — especially the striatum — which is involved in the anticipation and valuation of rewards, matures earlier than the control network and its connections.
With increasing age, the connection with the control network strengthens, and young people learn to be patient and wait for future rewards.
A follow-up study is now being conducted to investigate the function of testosterone within these networks: To what extent does testosterone influence the imbalance in the maturation of different brain regions and thus explain young people’s susceptibility to making impulsive decisions?