“Has the person become agitated, aggressive, irritable, or temperamental?” the questionnaire asks. “Does she/he have unrealistic beliefs about her/his power, wealth or skills?”

Or maybe another kind of personality change has happened: “Does she/he no longer care about anything?”

If the answer is yes to one of these questions — or others on a new checklist — and the personality or behavior change has lasted for months, it could indicate a very early stage of dementia, according to a group of neuropsychiatrists and Alzheimer’s experts.

They are proposing the creation of a new diagnosis: mild behavioral impairment. The idea is to recognize and measure something that some experts say is often overlooked: Sharp changes in mood and behavior may precede the memory and thinking problems of dementia.