Adolescence is a time of significant physical, emotional and social development, and teenage friendships play a big part in this. For the first time, friends become more influential to teenage behaviour than parents or anyone else. Teenagers influence and persuade each other to try different things, take risks and push boundaries.

Teenagers’ brains are still growing and developing at this time, as brain systems that process social information and emotions are still maturing, which is one reason why the actions of peers is such a big deal.

Adolescence is also a period of increased risk for the onset of mental illness. Most major mental illnesses such as depression, anxiety and psychosis typically begin in the teenage years and can drastically impact upon social relationships.

In this paper, we explore the relationship between adolescent brain development and the wider social environment. We discuss how genetics and brain biology contribute to social behaviour, and how the influence of peers can impact upon social behaviour and mental health.

We present evidence that suggests the brain and social environment sculpt each other throughout the teenage years. The reciprocal relationship between brain maturation and the social environment may either augment risk or promote resilience for mental illness during the teenage years.


Summary of evidence for interactions between genes, brain, social behavior and mental illness.
Unidirectional arrows indicate the direction of influence from one domain to another. Boxes summarize the key findings supporting that influence, with numbered citations for supporting studies. Bidirectional arrows represent associations where a correlation has been identified, but the direction of influence remains unknown. Dotted arrows represent possible or unresolved associations. In cases where there is no arrow running in one direction, there is little research examining that particular link and further work is required. For simplicity, we have not illustrated direct connections between social behavior and social networks, although we propose a reciprocal relationship.

Lamblin, M., Murawski, C., Whittle, S., & Fornito, A. (2017). Social connectedness, mental health and the adolescent brain. Neurosci.Biobehav. Rev. 80, 57–68.

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People Involved

Michelle Lamblin Alex Fornito