My mom is a chemist/biologist who worked in pharmaceutical research, so every time I go on a new med, she looks at the structure to see what it's similar to (and thus she can tell what the side effects are likely to be, etc.) She said that blood pressure meds had a similar structure/affect the same receptors as some antipsychotics. She has a theory that some people on these blood pressure meds might have developed psychosis were it not for the blood pressure meds. It's pretty interesting (apparently) if you understand it (which I don't lol.)