This is actually true.
Current brain research shows that the adolescent brain is much like the toddler brain: poor impulse control, heightened risk-taking, grandiose behaviors and even hypersexuality. (The latter is more apparent in adolescents; young children DO experience sexual stimulation, and are intrigued by it, but do not typically engage in sexual activity with other children or with adults unless they have been victims of sexual abuse.)
Typically, the adolescent period ends when the myenlination of the frontal cortex(which controls executive functioning) is complete. This usually occurs between the ages of 18 and 20, and sometimes as late as 24 years. (Which is not uncommon, but not typical)
People with ADHD experience a myenlination rate about 30% slower than that of typical children. (I don't think this is hard science, just recent data). Therefore, they may mature slower in social and emotional areas, and may show lack of impulse control far beyond the expected age.
I do not believe that ADHD is co morbid with sociopathy. I see statements like that quite often, and can attest to MANY ADHD people who are very caring, empathetic and concerned with other people and their needs. I am not suggesting RH is ADHD/ADD. Just making a note of his immature behavior and his lack of conscience.
However, I do see that whatever RH's issues were, they were evident in his blatant immaturity and FGS, that stupid Beiber haircut.
Sorry. Had to say it.
I dont see Ferris as a sociopath. 
