For males, there is only one gene out of the pair, so MAO A + is the same as a female MAO A +/+.
Once again, the gene mutation in and of itself doesn't mean that you're doomed to have mental health problems. There also has to be some sort of environmental stressor (toxins, viruses, prolonged extreme stress or abuse) which causes the gene to be expressed.
So what it means is, given two people with the same environmental factors and one has MAO A and one doesn't, the one with the MAO A is the one likely to have the mental health problem.