Don’t take mood swings personally—even though they seem directed at you. The root cause is what is happening in the brain rather than something you’ve done.
Be as supportive as possible and don’t pick fights.
Help the person compensate for memory loss by sticking to routines, leaving notes, repeating yourself, and issuing reminders.
It can help to name the feelings that than ignoring them. For example, “You seem upset today”.
Watch for signs of depression, which people with dementia are higher risk of developing.