(NewsNation) — The COVID-19 pandemic, through lockdowns, aged the brains of young girls, affecting them more profoundly than boys, according to a new study published Monday.

The study, published in Proceedings of the National Academy of Sciences, found that girls’ brains aged four times faster than boys, adding 4.2 years.

Looking at male and female brains through neuroimaging, doctors found cortical thinning during the first year of lockdowns, accelerating brain development.

Examining brain scans more closely, University of Washington researchers found cortex thinning, a type of brain rewiring, occurred more rapidly in teenage girls.

Accelerated thinning is associated with anxiety and depression.

Doctors believe it was chronic stress caused by social isolation that likely played a role, and they worry it may have a lasting impact on mental health.

While some cortical thinning is normal during adolescence, rapid thinning has been linked to an increased risk of mental health and behavioral disorders.

The researchers analyzed brain scans from 163 adolescents before and after pandemic lockdowns.

NewsNation local affiliate WGN contributed to this report.