Memory loss may not always be the first warning sign that dementia is brewing - changes in behavior or personality might be an early clue.

Researchers on Sunday outlined a syndrome called "mild behavioral impairment" that may be a harbinger of Alzheimer's or other dementias, and proposed a checklist of symptoms to alert doctors and families.

Losing interest in favorite activities? Getting unusually anxious, aggressive or suspicious? Suddenly making crude comments in public?

"Historically those symptoms have been written off as a psychiatric issue, or as just part of aging," said Dr. Zahinoor Ismail of the University of Calgary, who presented the checklist at the Alzheimer's Association International Conference in Toronto.

Now, "when it comes to early detection, memory symptoms don't have the corner on the market anymore," he said.

Alzheimer's, the most common form of dementia, affects more than 5 million people in the U.S., a number growing as the population ages. It gradually strips people of their memory and the ability to think and reason.

But it creeps up, quietly ravaging the brain a decade or two before the first symptoms become noticeable. Early memory problems called "mild cognitive impairment," or MCI, can raise the risk of later developing dementia, and worsening memory often is the trigger for potential patients or their loved ones to seek medical help.

It's not uncommon for people with dementia to experience neuropsychiatric symptoms, too - problems such as depression or "sundowning," agitation that occurs at the end of the day - as the degeneration spreads into brain regions responsible for more than memory. And previous studies have found that people with mild cognitive impairment are at greater risk of decline if they also suffer more subtle behavioral symptoms.

Ismail is part of an Alzheimer's Association committee tapped to draft a checklist of the symptoms that qualify - new problems that linger at least six months, not temporary symptoms or ones explained by a clear mental health diagnosis or other issues such as bereavement, he stressed. They include apathy, anxiety about once routine events, loss of impulse control, flaunting social norms, loss of interest in food. If validated, the checklist could help doctors better identify people at risk of brewing Alzheimer's and study changes over time.