Mood swings and the developing brain

Do you ever feel like your week is just a rollercoaster of emotions? That one day you feel anxious and ruminate about some small problem that seems immensely, while the next day things suddenly look brighter, and that anxious feeling is completely gone? This is called mood swings, or mood variability. You might recognize mood swings as something that adolescents go through or remember that you went through a phase of more mood swings. While an increase in mood swings during adolescence is normal development, mood swings have also been shown to precede mood problems, such as anxiety and depression, later in life. Therefore, it is important to understand when these mood swings occur, what affects them, and how they work in the brain.

The development of mood swings

Mood variability can be calculated by looking at the difference in mood. In the research in the SYNC lab, mood was measured once a day for five consecutive days, so mood variability is the difference in mood between days. In this blog post the research done in the SYNC lab will be discussed, specifically the research done on the effect of COVID-19 on mood variability and if mood variability is associated with brain structure. As you might have experienced yourself, or seen in adolescents around you, mood swings indeed increase during adolescence, especially girls show a peak in mood variability around 15 years old (preprint). Boys also showed an increase in mood variability during adolescence, but the peak was not as prominent as in girls. Thus, during normative development a peak in mood swings is found in mid-adolescence, but external factors might affect this trajectory. For example, the effect of the COVID-19 pandemic on mood variability has been studied.

Mood swings and the COVID-19 pandemic

During the COVID-19 pandemic and lockdown prolonged increased variability was seen in adolescents (Green et al 2021). This meant that not only adolescents around 15 years old experienced increased mood variability, but this was also seen in older adolescents. That was not all. The young people that experienced increased mood swings were also more likely to experience family stress, meaning that they felt they did not want to be home as there was tension at home. They were also more likely to experience inequality of opportunity in online home schooling, showing that inequality and the way young people feel are related. The same study showed that the longer the pandemic lasted, positive mood decreased, especially in young adolescents. This might be because of all the changes caused by the pandemic, including less time with peers, schools closed et cetera.

Mood swings and brain development

How does this work in the brain? We know that mood swings are changing throughout adolescents, and that the brain is still developing (Casey et al 2008), are these two related? To answer this question participants underwent an MRI scan for three consecutive years. We looked at the size of brain regions, especially regions in the cerebral cortex and investigated if the size of these regions was related to how much mood varied. Brain regions that are involved in emotion regulation were studied, since these regions are thought to regulate mood variability. We found that adolescents with a thicker dorsolateral prefrontal cortex (dlPFC) compared to peers of the same age, showed higher levels of mood variability in early and mid-adolescence (link to preprint). The dlPFC is a region in the frontal cortex, and it responsible for cognitive control. When it comes emotion and mood, the dlPFC is most likely involved in emotion regulation (Etkin et al 2015). Usually during adolescence, this region decreases in thickness as a result of the normal development of the cortex. If adolescents show a thicker dlPFC, this might mean that their development is slower compared to their peers. A more slowly developing (emotional) control system might therefore result in less inhibition of the mood swings, and therefore larger or more mood swings. It is thought that the cognitive control regions in the brain develop more slowly than the regions responsible for the generation of emotion during adolescence (Mills et al., 2014), and this might also cause the mood swings seen in adolescence.

To sum up, this rollercoaster of mood of adolescents is associated with brain development. Because of their brains still being under development, adolescence is both a vulnerable time and a time of opportunities. Besides the relation with brain development, mood swings can also be affected by external stressors such as a pandemic as well as positive influences such as social support. Altogether, our research has shown that an increase in mood swings during adolescence is common and aligns with structural brain development. Moreover, it doesn’t necessarily have to be a warning sign for any future feelings of anxiety or depression.

Our preprint on mood swings during adolescent development and the link with brain structure and sleep has just been published on bioRxiv and can be found here:


Casey, B. J., Getz, S., & Galvan, A. (2008). The adolescent brain. Developmental review, 28(1), 62-77.

Etkin, A., Büchel, C., & Gross, J. J. (2015). The neural bases of emotion regulation. Nature reviews neuroscience, 16(11), 693-700.

Green, K. H., van de Groep, S., Sweijen, S. W., Becht, A. I., Buijzen, M., de Leeuw, R. N., … & Crone, E. A. (2021). Mood and emotional reactivity of adolescents during the COVID-19 pandemic: short-term and long-term effects and the impact of social and socioeconomic stressors. Scientific Reports, 11(1), 1-13.

Mills, K. L., Goddings, A. L., Clasen, L. S., Giedd, J. N., & Blakemore, S. J. (2014). The developmental mismatch in structural brain maturation during adolescence. Developmental neuroscience, 36(3-4), 147-160.



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