"It's clear the states have paid woefully inadequate attention to this issue," said Paul S. Appelbaum, chair of psychiatry at the University of Massachusetts Medical School and one of the authors.
"Everybody with dementia at some point will cross the line from being able to do lots of tasks, including voting, to not being able to do that," he added. "There is a need to define the line."
They say people with dementia should be encouraged - and helped - to vote as long as they understand the process. That includes thinking about how people with dementia or other mental problems react to something as confusing as Florida's notorious butterfly ballot. Simpler ballots with larger type and possibly even pictures might make them better voters.
"We need to think about cognitive accessibility, not just physical accessibility," said Jason Karlawish, an assistant professor of medicine at the University of Pennsylvania who is one of the research group's leaders.
Karlawish became interested in the issue after the 2000 election, when he read an Internet discussion by Alzheimer's caregivers. One wrote: "Since we have been married, he has always voted a straight Democratic ticket, so I did the same for him. . . . I do not feel guilty."
Voting rights cannot be transferred from one person to another, Karlawish said, but many caregivers don't know that.
He has also come across a handful of examples of questionable voting from nursing homes. Leonard Kiczek, a lawyer in Bayonne, N.J., discovered one of them during the Democratic primary in June. A bloc of absentee votes from a single nursing home swung a local election to candidates promoted by a rival Democratic faction. One of the candidates worked for the nursing home. Kiczek filed suit after he learned that party loyalists had been involved in helping people with dementia fill out their ballots.
Kiczek, a former Bayonne mayor who later dropped the suit, said the incident convinced him that lawmakers needed to pay attention to this issue. "People took advantage of these residents," he said.
A conversation with two sisters illustrates the other end of the spectrum, Karlawish said. He asked them if their father, who has Alzheimer's disease, wants to vote. "I don't think my dad is capable of doing that," one said. The other said: "Well, maybe he is. How would you know?" Karlawish talked to the man and thinks he could vote.
Lillian Carter, 86, of South Philadelphia, said voting was important to her husband, Leroy, who continued to vote after being diagnosed in his last couple of years of life with Alzheimer's. He went to the polls right up to his death at age 92.
"He always wanted to vote. I can't remember him ever missing a year," said Carter, who was attending a Bible study class today at the Philadelphia Senior Center on South Broad Street. Their son would drive them to the polling place, and her husband would go into the voting booth alone.
"We didn't force him to go," she said. "He understood. . . . He never got completely out of it like some people."