I know you wanted someone from PDUK to talk about this, but since I'm causing the confusion, and because you brought up lots of useful questions, I'll have a go too
I'm concerned about how people get the information they need to enable accurate diagnosis, without causing more stress to people who have PD and already have a lot to deal with and don't need more worry
Yes it gets confusing when we talk about a condition "causing" a group of signs and symptoms, but we don't even know the thing that causes the condition. My memory is crappy but I think medics use "aetiology" to mean the cause of a condition - as in cystic fibrosis has a genetic cause/aetiology. So we don't fully understand the cause or aetiology of PD. But we know (or think we know) it must be different from that of the other conditions resulting in signs and symptoms of parkinsonism.
"Parkinsonism" describes the well known group of signs and symptoms that occur in Parkinson's Disease, but also occur in lots of other conditions. There's a wiki page on "parkinsonism" that probably says it more clearly than I have, and lists (just some of) the conditions that cause parkinsonism.
I know it'll be a small proportion of people diagnosed with PD who have something else causing the parkinsonism signs and symptoms. There doesn't seem to be many shortcuts. Often we can only go with what signs and symptoms come up over time. Unless something comes up that doesn't fit PD, - (an unusual response to treatment, a neurological symptom that doesn't occur in PD, rapid progression etc) they won't go searching for other causes. There aren't tests or accurate tests for every condition that causes parkinsonism. tests cost so they don't give these tests to everyone with parkinsonism, most of whom will have PD. (the exception is or should be Wilsons, because tho its rare, treatment saves lives and can stop progression)
tho it'll be a small proportion of people with a PD diagnosis that have parkinsonism from another cause, it can be an awful situation for them - it was for my relatives. A lot of people with neurological conditions, have to be very actively involved in the process of diagnosis. So for the people in this situation, it's useful to know a bit more. But how do we do that without stressing out the majority of people who have a diagnosis of PD that is accurate, and who might already be struggling to get their head round all the new words for all the symptoms and treatments etc?
from where I'm standing,a bit more information, as simply put as possible would be useful
you've educated yourself a lot about PD, so you and your husband would, over time, be likely to notice if something (neurological) was going on that really didn't fit what you know of PD either from the neurologists idea of PD, or from what other people with PD experience. And if it was me, at that point I'd read around some more, and ask my GP and consultant about it. I'm sorry if this has caused you worry