Terri Jo ''T.J.'' Barron thought she had done all her grieving during the eight long years she watched her husband slip away because of Alzheimer's disease. 

Like Ronald Reagan, who died from the disease earlier this month, Dempsey Barron was a politician. He was in the Florida Senate for 32 years. He also was a rancher. And, like Nancy Reagan, Barron guided her husband through the slow, agonizing process of his illness until he died three years ago at age 79. 

So she knows firsthand of the mixed emotions that Nancy Reagan and other Alzheimer's caregivers likely experience after their loved one's death, regardless of where they come from or how famous they are. 

An estimated 4.5 million Americans have Alzheimer's disease, in which the brain slowly deteriorates until a person can no longer care for himself. And when an Alzheimer's patient dies -- as they always do -- the grieving process is complex and varied. 

Caregivers' emotions can be a mixture of sadness at the loss and relief that the person is no longer suffering. When the person dies, the caregiver might feel relief from the tremendous burden, but, at the same time, feel guilt over the sense of relief or for not doing more. 

Usually there is loneliness. Often there's isolation. Sometimes there's just sheer physical exhaustion from the years of caregiving. Several studies have shown that caregivers often neglect their own needs. 

''There are these opposing emotions,'' says Beth Witrogen McLeod, author of the 2000 book Caregiving: The Spiritual Journey of Love, Loss, and Renewal. 

''It's very complex. We feel guilty while we are caregivers that we weren't good enough. And then we feel guilty because we couldn't save them from death. We just feel so guilty that we couldn't control life.'' 

Many caregivers also feel lost. For years, they have been tending to another person's every need. And suddenly, there is nothing. 

That's how it was for Barron, at least for a short time. 

''My husband and I worked together,'' says Barron, 59, an attorney who now teaches a class, Law and the Elderly, at Florida State University in Tallahassee. 

''So I lost my spouse, my best friend, my business partner and my job all in one fell swoop. And that's really, really very hard.'' 

And very common. 

For caregivers, ''redefining their roles after the death of a loved one is a real challenge,'' says Eric Hall, CEO of Alzheimer's Foundation of America. 
''They've had that role as caregiver for so long. It is their whole life. Providing care is an all-encompassing, 24/7 experience.'' 

But it took Barron a while to realize the magnitude of her loss. 

Like most Alzheimer's caregivers, Barron already had grieved the losses as they happened: the moments he would forget something he always had known, the times he would fail to recognize a friend or family member, all the physical deterioration. ''I really thought because I had been anticipatory grieving for years that the actual loss would not be hard,'' Barron says. ''And I was wrong.'' 

After her husband died, Barron was surrounded by friends and family, and she kept constantly busy, which she now knows was a coping mechanism. 

''In the early stages of grief, you're just kind of moving around in this bubble, going through the motions, but your ears aren't really hearing, your eyes aren't really seeing, your fingers aren't really touching,'' Barron says. ''You're not really tasting. You're just functioning.'' 

The moment she felt grief's gut punch happened 3 months after her husband's death. 

It was the Sunday in October when clocks are set back to standard time. 
Barron was changing the clocks. The sunlight hit her differently, as it always did on that day with the shift in time. A small thing, really. But also large. Every year on the same Sunday she and Dempsey would drive around the ranch to check the cows at the end of the day. 

''The whole quality of light was a different angle.'' 

Just like it was at that moment. 

And she got it: ''It was like 'Oh, he won't ever be here again,' '' she says slowly. ''I seriously was knocked flat-footed. I took to my bed.'' 

She got up the next day. But things had changed. She had come to ''the absolute emotional as well as intellectual acceptance that you're never going to see that person again. It might be different for other people, but I don't think so. I think that moment comes to everyone.'' 

Probably so, say those who work with Alzheimer's caregivers. For some, grief hits right away. For others, it takes time. But just about everybody finds that when it does happen, ''it catapults you into another world where the person is not physically present, so whatever you shared, especially the love and the support you shared physically, is no longer available,'' McLeod says. 

And while there is no one sure way to get out of the grief, experts -- and those who have been through it -- agree that one thing does work: getting help and support, whether it be from family and friends, or from the myriad support groups. 

''I think one of the greatest gifts I have was the willingness to seek help every place I could find it,'' Barron says. Her advice? ''Open up your heart to share how hard it is. There are people you can't imagine that will step forward that you never knew had been through what you're going through and will have ideas, compassion and concern.''