Modes of Adolescent Brain Development

Post by Anastasia Sares 

What's the science?

During adolescence, the brain is developing in leaps and bounds, a process we still don’t fully understand. There are many factors that can have competing influences on the growing brain, like physical health, financial situation, or social ties. Since 2016, one large longitudinal study (the “Adolescent Brain and Cognitive Development” or ABCD study) has focused on tracking data related to adolescent brain development in almost 10,000 individuals. This week in Biological Psychiatry, Modabbernia and colleagues delved into this large dataset in order to find patterns of interaction in adolescent brain development involving many brain-based, behavioural, and environmental factors all at once, rather than focusing on one or two in isolation. 

How did they do it?

The authors used a technique called Canonical Correlation Analysis (CCA) to discover relationships between sets of life factors and sets of brain outcomes. Some examples of the life factors measured included: mother’s age and health at birth, childhood medical conditions, height and weight, sleep quality, intelligence scores, prosocial behavior, number of friends, screen time, family finances, neighborhood air quality, and local crime statistics. Examples of the brain outcomes included: brain volume, thickness and surface area of the cortex (the brain’s outer layer), integrity of the white matter (internal connections between different brain areas), and brain activity at rest. Each of the brain measures were taken for multiple brain regions. The authors used 85% of the data to form a model describing these relationships, and then used the leftover 15% of the data to test the model and see if the relationships held. 

What did they find?

The results yielded 14 different “modes,” or patterns of brain/behaviour/environment covariation. Many of the modes showed the kinds of relationships we’d expect: for example, teens with better physical health and a richer social and cognitive environment had larger brain volumes and more brain surface area. They also had better connectivity between their prefrontal cortex and other brain regions. There were also some more specific, less standard patterns. For example, a combination of high academic ability and socioeconomic status with abnormal sleep and mood was associated with a thinning of the cortex. This may be the trajectory followed by people who later develop bipolar disorder. The authors also noted that “positive and negative exposures do not occur in isolation but cluster together” and that basic characteristics like height and weight can have a huge effect on measures of brain structure. These are important considerations for future studies to take into account.

What's the impact?

This work confirms a lot of connections made by previous research, identifying consistent patterns of brain, behavioural and environmental factors in a large sample of adolescents. It also suggests key clusters of variables that could be targets for intervention in adolescent development.

Modabbernia et al. Multivariate Patterns of Brain-Behavior-Environment Associations in the Adolescent Brain and Cognitive Development (ABCD) Study. Biological Psychiatry (2020). Access the original scientific publication here.