There is additional discussion about MAO / dopamine and Type O on pages 131-132. This may help some...
Although I don't know the answer to the question, I see two sentences that stand out in relation to your question.
1) Page 37, Individuals with low platelet MAO also .... are more likely to abuse alcohol and drugs.
2) Page 132; There is a danger of increasing dopamine to levels of psychosis.
Obviously, both of these are presented here without the context of the surrounding paragraphs, the conditions of which may or may not be present within the realm of your question.