People with mental health issues usuaaly won't have the techincal know how/ skills to build a bomb using toilet cleaners. I come from India, where there are groups that make low tech bombs. Not individuals. Often times they injure themselves than kill a lot of people. The ones that kill 100's often require well regulated chemicals.
Mental health does not always negate mental power. Sociopaths and Psychopaths (a very similar classification) have perfectly normal brain function, only (to some degree) violence does not bother them -- some even enjoy it. Not all socio/psychopaths are killers though, in fact some are very good people (it has been theorized that a few US Presidents were sociopaths). Often times sociopaths can be very intelligent people, especially with regards to social hacking (they can be very charming on the outside, and very manipulative). (Source: my parents are psychiatrists who deal with the criminally insane, among many other types of mental cases).
