You can search for J. Rogan with Robert Sapolsky podcast where doc said that either prefrontal or orbitofrontal cortex finishes developing at ~25 years old, so brain can learn about environment and extrapolate accumulated experience later throughout life. I think age bias is not appropriate, because youngsters could consume propaganda with memes, feeds and games as well, just through the different medium. What matters here is anxiety level and/or IQ.