Do relatives or friends seem in denial about your loved one's dementia? Remember that they don't share the front-row seat you have on changes taking place.
What can help:
Point out that people with early dementia often go on "social autopilot" during brief encounters. They may seem perfectly normal because they rely on long-honed social graces and habits (making small talk, reminiscing, eating and cleaning up, watching sports and reacting appropriately). Even over a weekend, for some people, deficits might not be apparent to someone who doesn't want to see them.
Invite someone having doubts to spend longer periods of time with your loved one to gain a fuller picture of memory loss and other cognitive changes.
Help them understand that cognitive changes aren't simply a function of "old age" by passing along articles about what dementia is and how it compares to normal memory loss.