"None of us like planning for the fact that we won't be here one day, but it's the reality for all of us.
"For somebody who's been recently diagnosed with dementia, it's often uppermost in their minds, although they're clearly not at that point.
"The fact is that with a diagnosis of dementia, there's an inevitable conclusion - you don't currently get better from dementia."
Campbell said that can make people feel powerless and frustrated at the thought of what lies ahead.
But she said they can take that control back by getting a legal toolkit ready, for whānau to access when their health declines.
"One of the things that actually can be really helpful and is certainly very strongly encouraged by organisations is such as ours, is to have the opportunity to think carefully about what you want.
"To feel like you take some control over what will happen in your future, that you've put some time and energy into thinking about that and ensuring that the people you trust understand what you want, and that they will be there to do it for you, when the time comes."
An advance care plan, a will, an enduring power of attorney for property and finance, and an enduring power of attorney for personal care and welfare will dictate how someone is cared for, when they are no longer able to make reasonable decisions.
Campbell said having plans in place, that are only activated when someone is found by a medical professional to no longer have the capacity to make reasonable decisions, is an immense relief for whānau.
"It's an empowering thing to do, it's empowering for the person living with dementia, and it's empowering for the family," she said.
"Because people want to do the best [for a loved one] and it's sometimes very difficult to do the best if you've never had those difficult conversations."
And if legal documents aren't in place ahead of time, Campbell said family members face a stressful court process to be able to make decisions about their loved one's care, as their state rapidly deteriorates.
Public Trust chief executive Glenys Talivai said that's when the service can offer support and advice.
She said the conversations may be tough to have, but it's important people know the legal responsibilities they may have over a friend or family member's care.
Talivai said Public Trust had online toolkits that mean the process was straightforward and organised.
