What do you mean?
I would say that a person with Aspergers and some other disorder could be difficult to treat, but it would depend entirely on what it was and the individual in question.
What I mean is that people who have forms of HFA or aspergers, while potentially difficult to treat FOR THE ISSUES OF THAT DISORDER (since it isn't technically a problem of the psyche like depression, but rather an physical neurological issue like brain chemistry or wiring) tend to be extremely logical, and in nearly all cases effectively incapable of hiding feelings or behaviors...most typically, these people are seen as having virtually no tact, are "too open" about their own feelings, etc.
So what I mean is since the original second question that you said "yes" to was if HFA or aspergers could make it difficult to diagnose or treat OTHER problems that are psychological, I believe the answer to be "no", as if anything, other issues (depression, psychosis, etc) are likely to be MORE obvious.
The same thing that makes those folks seemingly incapable of reliably recognizing emotions in others also makes their own emotions difficult to hide, "they wear their emotions on their sleeve" is a common thread--hiding ones emotions or feelings requires the person to have the ability to instinctively recognize emotions in others.
Now, truly autistic (NOT HFA or aspergers) is a different story, given the severe communication difficulties that are the fundamental outward symptom, it is difficult to diagnose other issues, but not because they are hiding them, but because they can't communicate anything. There the outward signs of anger, sadness, etc. are extremely magnified, but present as an uncoordinated physical response (near catatonic states, head banging, screaming, etc.) not as planned conscious activities like attacking others--it's more personal fight or flight.
The root issue is that it is in fact a spectrum, but at both ends of the spectrum, while the issues are difficult to treat, they either prevent the type of coordinated attack others behavior people are attempting to associate here, or make the internal emotions VERY apparent, so recognition of psychological disorders is likely easier, (for HFA) not harder.
It's kind of like lying...in order to effectively lie, you also need to be somewhat capable of recognizing lying. It's why people with sociopathic tendencies are also extremely good at both hiding those tendencies, and recognizing them in others. You need to be empathetic in order to hide ones own feelings, and it is quite well recognized that the dominant symptom that can present in most spectrum disorders is an apparent lack of empathy.
My points remain:
1. Violence of the type of concern here in spectrum disorders is either impossible or extremely unlikely unless coupled with other psychological disorders, and if it is represented in severe autistic cases, it effectively never takes the form of coordinated assault, but rather a physical "get away from me" defensive or self-destructive action. Most folks tend to be very introverted because they feel that it is impossible to interact without "hurting" the FEELINGS of others (eg being tactless, and then analytically realizing that their words created negative feelings in others), so they tend to withdraw rather than be seen as broken.
2. Because of the inability to recognize emotion, it is usually easy to see it in these folks, as they are unlikely to be able to hide it, thus in HFA cases, it is not more difficult to recognize other psychological problems. In severe autistic cases, it IS more difficult to recognize them verbally, but again that's rooted in a communication problem, and any emotions are EASY to see in actual behavior. So what I mean is its likely harder to diagnose psychological problems in NORMAL people than in HFA people, because normal people know how to hide it.
In any case, the obsessive aspects of HFA make concealment of anything extremely difficult...if an HFA person is obsessed with causing harm, they will be VERY obsessed, and likely (without their knowledge) be VERY open about their feelings or intentions. Remember, these are people who "talk without listening or caring if you are listening".
