Cognitive development.
Adolescent cognitive development.
Mental is a word that means related to the brain
it is an offensive word related to mental retardation.
"Adolescent" is one word, and it means "in the process of developing from a child into an adult."
The third syllable: ad·o·les·cent
Unusually advanced or mature in development, especially mental development. (Often applied to children)
adolescent
Today's adolescent is bombarded by many messages for who they should be or what they should do.
Adolescence is typically the word used to described humans transitioning between childhood and adulthood. It is a time of mental and physical growth, both of which are essential in becoming a functioning member of society as an adult.
This is likely the English word "imbecile" (an insult related to mental ability).
adolescent pubescent
Many people use it pejoratively but it is not a swear word.