I'm not a parent, however, I can say that when I was rather young, I had some similar traits as your son (not sure on the exact age they began). It ranged from cruelty to animals and people to doing whatever I wanted, laughing at teachers as they attempted to do the little routine of go to the corner as a punishment, etc... . I was bullied quite a lot, both at school and at home (parents were going in and out, so I stayed a lot with my grandmother who lived with us and things weren't always the best). I won't elaborate on what happened, not for my sake but for the sake of others. The main points to note is being called worthless, being called someone who will ruin their life and other lives because I'm so pathetic, being beaten up, etc... .

My concentration fluctuates, if it's certain subjects, I cannot focus on it much at all without wanting to do something else. However, if it's a topic I like, such as biology, neuroscience, psychology, etc..., I can focus very well (generally focus and study for hours on end), have a very good memory for the subjects I learn and I'd consider myself to be rather intelligent (19 years old, soon to be in 3rd year university).

Currently, the diagnosis is NPD, APD (anti-social), some schizoid traits but not the full disorder and schizophrenia. Doesn't mean your son will get APD or NPD later on.