Research & Education

Understanding the Teen Brain

School is underway once more marking the onset of new routines, new friends, new experiences and for many parents, new challenges with teens. Some parents and caregivers are just entering the teen years with their adolescents and unsure what the future years will behold, while others are in the middle of this unique season and may be feeling overwhelmed at the unique pressures and challenges adolescents bring. Still other parents and caregivers may be near the end and possibly grieving the choices their teens have made and wondering how to repair the damage. Without question, the transition from childhood to adulthood is tough, but it doesn’t have to feel like a battle that is bound to be lost with debris to be cleaned up at the end. On the contrary, there are many rewarding experiences and opportunities for building deeper relationships with teenagers that can help usher these young adults into their adult years and leave their parents and caregivers looking back with fondness on these transitional years.

One factor that can help make this season successful is to understand how the teen brain is uniquely different from an adult brain. The prefrontal cortex (a primary region that determines behaviors) does not complete maturation until almost 24 years of age. This knowledge can then support parents and caregivers in knowing how to help guard against unhealthy behaviors in teens while fostering maturity and healthy outcomes.

Neurological Basis of Risky Behaviors

Teens are, generally, more likely to engage in risky behaviors that impact their health such as substance use, sexual behavior, and suicidality. Suicide alone is the second leading cause of death in all teenagers, following unintentional injury. By 12th grade, nearly 60 percent of all teens have tried alcohol, 50 percent have used marijuana, and almost 50 percent are sexually active. Driving the engagement in these risky behaviors at young ages is a higher sensitivity in the reward-seeking region of the brain. Social reward such as peer acceptance is particularly dominant and helps to explain why peer influence can so easily lead to risky behaviors. Ventral tegmental dopamine neurons are at the heart of the brain’s reward center which also includes the ventral striatum, the amygdala, and the medial prefrontal cortex (PFC). The PFC computes the value of the reward, affect regulation, social cognition, reward-seeking and response, and self-regulation including impulsivity. During the teen years, this circuitry is developing and being increasingly sophisticated.

 In a study using a novel functional MRI social reward paradigm and surveys, 50 teens aged 14 to 18 years, with no history of psychiatric disorders were surveyed and scanned to reveal a possible association between risky behaviors and neural responses. Results showed a U-shaped curve in which teens with both a high and low response in the left ventrolateral PFC were likely to engage in risky behaviors. Among those with a low response, risky behavior was hypothesized to be a compensation mechanism for the reward circuitry. The activity of the ventral striatum and PFC in teen decision-making was also supported by a neuroimaging meta-analysis study.

Additional animal studies have supported the idea that teens’ risk behaviors may be associated with morphological, metabolic, and functional changes in the brain during adolescence. Functional changes within the forebrain included maturation of hippocampal-striatal connection and circuitry of the limbic loops. Metabolic changes included a decrease in taurine and an increase in total choline, which can be considered respectively as an index of neuronal pruning and synaptic efficiency. Morphological changes included structural modifications in the nucleus accumbens and orbitofrontal cortex during adolescence transition. These changes impact the affective and reward circuits that drive adolescent behavior.

Diet and Risky Behaviors

The ongoing development of the PFC in the teen brain also affects dietary behaviors since it drives self-regulation, impulsivity, and reward-seeking behavior. The vulnerability toward reward-seeking behavior, especially, can lead teens to impulsively choose palatable, high-sugar diets evidenced by an increase in the consumption of “junk foods.” Unfortunately, this impulsive dietary preference negatively impacts neurological development, memory, and learning by disrupting neuroplasticity and altering reward processing neurocircuitry. The teen brain is particularly sensitive to the cognitive effects of nutrients. Further, the maturation of the brain during adolescence is enhanced by increasing levels of sex hormones which enhance neuronal myelination and the development of neurocircuitry. High-sugar diets can lead to hyperinsulinemia which influences the balance of sex hormones and thus, neurological development and function in the teen brain. Further, high-sugar diets in teens can lead to “alterations in dopamine-mediated reward signaling, and inhibitory neurotransmission controlled by γ-aminobutyric acid (GABA), two major neurotransmitter systems that are under construction across adolescence.”

Being aware of the unique neurological changes occurring in the teen brain can help in understanding why teens are more likely to engage in unhealthy behaviors compared to adults. Not only can understanding the physical changes in a teen brain help parents and caregivers educate teens about their changing brains and the impact on their behaviors, but it can also be a tool to help develop a support system for the teen as they navigate these transitional years in the most healthy way possible.