Fixates on an idea and brings it up over and over
When it happens
Why it happens
Fixating on a thought -- a form of behavior called perseveration -- can be the result of both memory loss (the person forgets what he or she just said) and of changes to the executive functioning parts of the brain (the person can't organize thoughts and actions well).
Sometimes there's an emotional root. For example, the person may be eager to see a guest or anxious about making an appointment, and this feeling is so strong that the brain gets "stuck" on thinking about it.
What you can do
Remind yourself it's the disease talking. Try to remain patient. Listening to a repeated comment or question is one of the most vexing parts of being with someone who has moderate dementia.
Answer the same way each time, or try to vary your answer and see if it yields a different response. Either approach sometimes works.
Check the person's basic comfort level. Make sure fatigue, hunger, sickness, or being wet or cold aren't triggering the perseverating.
Try to avoid offering details about an upcoming event that seems to be triggering the problem. This gives the person less opportunity to seize on the idea of it.
Try to break the cycle by offering a snack or a drink.
Give yourself a break if you need it. Just back off and take five.