No Motivation for education or earning

My son is 20 years old. He had 4.0 GPA at high school, but at college. he is doing poorly. He is enrolled as computer science major. He is not involved in partying or girls. The only interest he has is the video games. He does study, spends a lot of time in library for home work and preparing for the tests. But, his performance does not reflect his grades. He starts the semester on a positive note, then within a few weeks, starts getting bored, falling behind and loses all the interest. According to him, he is not motivated to do well and is not bothered about not getting good job or good money. He does not eat much but is over weight. His sleeping pattern is irregular and he prefers studying or playing video game at night. He also avoids going out, but he has good friends. We do go out as a family, but his first response will always be a 'No'. All our counseling is not helping him. One of his professors mentioned that he may be deficient in dopamine. What are your thoughts about it? Where can we get him tested? Does he have to go to a psychologist? I definitely need help as we are at our wits end to help him. If he has a medical condition which is the causal, we would love to know where to start. He has all our support and we want him to be successful. His elder brother graduated this year and is working in a good company. We have a good and positive relationship with each other. I am hoping to get a start from you. Please help! Thanks

[ILADVOCATE]

As a person recovered from schizoaffective disorder with the Phase II experimental antipsychotic glycine, a glutamate antagonist, a new form of antipsychotic in study (for the official study google "Dr Javitt, glycine", the study on me will be published in a psychiatrist journal) I can say that what your son is experiencing are the negative symptoms (trouble relating to people) and positive symptoms (not as in good, as in things that shouldn't be there but are) such as paranoia of schizophrenia. If they said he is lacking in dopamine, they probably meant that the current generation of antipsychotics work by lowering the dopamine level. The most currently available one is Abilify and the most easily tolerated. The glutamate antagonists are the next generation antipsychotics but are still going through government studies. There is a good chance glycine as a compound may eventually be incorporated into psychiatric practice in additional to a conventional antipsychotic. You can read through my journal entries for more information.
  However, within current clinical practice out of all the antipsychotics, assuming they diagnose him with schizophrenia which is what they likely meant Abilify is the best tolerated depending (the atypicals from Risperdal through Abilify are safer than the older generation antipsychotics, Abilify has the least potential for weight gain and sedation). However, in addition to an antipsychotic, he would need to see a talk therapist as well and support of the family to understand that what he is going through is not a negative behavior pattern but comes from the schizophrenia and can only be helped with medication and talk therapy.