Longitudinal associations between social media use, mental well-being and structural brain development across adolescence

Abstract

Youth of today grow up in a digital social world but the effects on well-being and brain development remain debated. This study tracked longitudinal associations between structural brain development, social media use and mental well-being. The study demonstrated two pathways of heterogeneity in brain development. First, adolescents who used social media more than their peers showed higher baseline cortical thickness in lateral prefrontal cortex (PFC) and medial PFC; and stronger decreases in the lateral PFC and temporal parietal junction. In contrast, adolescents with lower mental well-being showed lower baseline levels of surface area in the medial PFC and posterior superior temporal sulcus relative to their peers. Whereas the associations between structural brain development and well-being remained significant after correction for multiple testing, the results for social media use did not survive FDR correction. These findings demonstrate that although social media use and mental well-being were both associated with differential trajectories of brain development, the associations we report are distinct. These results show a nuanced perspective on the presumed relations between social media use and well-being and provide a starting point to further examine neural mechanisms that could explain which adolescents thrive by social media and which might be harmed.

Keywords: Adolescence; Cortical thickness; Mental well-being; Social media; Surface area.

Fig. 1

Social media use classes. The top line shows time spent on social media (hours in last two weeks*) and compulsive use of social media (measured with CIUS) for (a) the low social media class and (b) the high social media class, scaled at the average age for each of the three waves. The bottom line shows individual data for both low and high social media users for (c) time spent on social media and (d) compulsive social media use. * Note that time spent was divided by a factor of 10 in the top plots for scaling purposes.

Fig. 2

There were no significant differences between the high and low social media use class on (a) mental well-being (measured with anxiety and depression) and (b) Fear of negative evaluation. Dashed lines represent no group differences.

Fig. 3

Structural brain development differences between low and high social media users for (a) lateral prefrontal cortex (LPFC), (b) medial prefrontal cortex (MPFC), (c) temporal parietal junction (TPJ), and (d) posterior superior temporal sulcus (pSTS). The left panel (i) shows cortical thickness and the right panel (ii) shows surface area. Solid lines represent significant group differences, dashed lines represent no group differences.

Fig. 4

Developmental trajectories for mental well-being classes for a) anxiety and depression (input of classification), b) fear of negative evaluation, c) time spent on social media (hours in last two weeks), and d) social media compulsiveness. Solid lines represent significant group differences. Note that the developmental trajectories for high and low mental well-being completely overlap in Fig. 4d, thereby omitting the estimate of high mental well-being in the figure.

Fig. 5

Structural brain development differences between high and low mental well-being for (a) lateral prefrontal cortex (LPFC), (b) medial prefrontal cortex (MPFC), (c) temporal parietal junction (TPJ), and (d) posterior superior temporal sulcus (pSTS). The left panel (i) shows cortical thickness and the right panel (ii) shows surface area. Solid lines represent significant group differences, dashed lines represent no group differences.