Sylvia Mackey noticed the first ominous signs seven years ago. Her husband cashed a $10,000 check he inexplicably was carrying in his wallet, then gave half of the money to an acquaintance he hadn't seen in four decades.

"I thought that was strange," she says in what can only be regarded as polite understatement. "Someone gave him a sob story and he volunteered to lend this person $5,000 -- cash."

Soon, the symptoms she saw transcended excessive generosity: Her husband was lying in bed for hours at a time, engrossed by the Weather Channel; leaving business proposals sent to him by associates unopened; sinking into hollow, cliche-filled conversation.

These were extraordinary changes in her husband, John Mackey, a man of mammoth proportions, who while playing for the Baltimore Colts became the most feared tight end in professional football, stood up to arrogant owners and fought discrimination when few were.

The changes at first infuriated Sylvia Mackey.

"You're angry at him for beginning to act stupid, or not normal," she says. "I'm thinking: 'He has nothing to do. Why is he so lazy? What has happened?' "

It wasn't until much later that Sylvia Mackey learned that her husband has a relatively rare form of dementia, a degenerative mental disease.

Watching John Mackey scribble autographs recently during an appearance at a Borders bookstore in Towson, it seems inconceivable that anything about him has deteriorated: At 62, his 6-foot-2 frame is still as straight as a Virginia pine, he has hands as steady and sure as when he was hauling down passes, and his weight is 10 pounds below his high school playing days.

When he speaks, though, it becomes apparent something is not quite right.

"Don't forget," he admonishes a stranger, "I'm sending you out for a touchdown."

Asked if he is proud of the 75-yard touchdown pass he caught to help the Colts win Super Bowl V in 1971, Mackey replies in a voice that is vigorous in tone but empty in content: " 'I' means you can't see. 'Me' means you're missing everything. But when you play together as a team -- T-E-A-M: together everyone achieves the mission, or more. And 'we' means win and enjoy."

He offers, without prompting, "Physical age is how you take care of yourself, and spiritual age is how you think. So I say, chronological doesn't count, physically 32, and spiritually, a kid at heart."

Book just published

While there is never a good time for such things, the timing of Mackey's illness seems especially cruel, because it has denied him the enjoyment from the publication of Blazing Trails: Coming of Age in Football's Golden Era, a book chronicling Mackey's childhood, the racism he endured and his extraordinary college and professional football accomplishments.

The book, published in late August, is the culmination of a dream Mackey had for two decades.

"He's been trying to do a book for years," says Sylvia, his wife of almost 40 years. "He wanted to get the story out because he thought it's inspirational, and important for people to know all aspects of him and football, and how it has changed."

John Mackey still relishes the limelight, evident by the disarming grin that sweeps across his face as he shows off to admiring fans his oversized Super Bowl ring, or gives autographs.

He inscribes his name, followed by "88," then, on a second line: "H.O.F. -- 92."

For Mackey aficionados -- and there are many, even though it's been 31 years since he last walked onto a football field -- the code is easy to decipher. The "88" is the number that was emblazoned on his blue and white jersey for nine years while playing for the Colts; the "H.O.F. -- 92" signifies the year he was inducted into the NFL Hall of Fame.