At 51, Alison Moore, the would-be minister, already has taken medicine for mild cognitive impairment, a condition that often precedes dementia.

Betsy Shieh, 45, the foreign-service officer, said her memory doesn't seem any worse than her peers' now. Still, she says, "when you forget something when your father's just died of Alzheimer's, you say: 'Oh s-, here I go.' "

Long after it was obvious that he was losing his fight with dementia, Bob Moore believed that doctors might save him. His children hope the cure he was so optimistic about will come in time for them.

A life driven by philosophy

Bob Moore came into the world with a superior brain. He used it hard and well.

As a young man, his fascination with life's big questions led him to Yale University's Divinity School and, later, a master's in philosophy. It drew him to the civil rights movement and a lifelong quest to broaden his church and improve the lot of the poor.

In 1970, he rose to executive of the Delaware-based New Castle Presbytery, the denomination's regional ruling body.

A 1978 sermon, in which he mused about the meaning of faith, revealed a complex man and graceful writer, a minister who saw religion not as an easy comfort, but as a struggle for self- and world-betterment. He quoted the Bible, of course, but also the New York Times, Dostoyevsky, and Thomas Hobbes.

"I believe that faith is like the free, innocent, life-entrusting leap of a child into the arms of a parent," he said. That trust erodes as adults learn that "faith does not always, does not often, win."

Ultimately, he said, "our leap of faith is a lifetime thing, and what is unknown remains unknown for us and what is hidden remains hidden. Faith is the posture of our lives, the bent of our spirit, the foundation and definition of who we are."

An only child, the robust, red-haired man who liked quiet and order had three sons and three daughters with Joanna, a warm, practical preacher's daughter he met in college. He was the animated, emotional one - a belly-laugher and great hugger. She was stoic, gentle, forgiving. They fit.

Although he would sometimes call for silence as he listened to his classical music, he mostly delighted in the chaos of their Wilmington home. He was a joyful, supportive father.

"When my dad was proud of you, you knew it," said Alison Moore, who followed him to Yale Divinity School. "His whole body would light up... .

"You felt like you were illuminated."

Getting the big picture

"This is a really small brain," Forman said on Dec. 1 as he took his first look at case number 05-274.

A normal man's brain weighs 1,200 to 1,400 grams. Bob Moore's weighed 1,005 grams - a little more than 2 pounds. The folds at its surface were half the usual thickness, a sign that many cells had died.

Several diseases with similar symptoms can cause this kind of atrophy. A surprising number of patients have more than one. Knowing whether they had Alzheimer's, frontotemporal dementia, or dementia with Lewy bodies is important for families because each carries genetic risk. It helps doctors sharpen diagnoses in preparation for the day when they'll have different treatments for different dementias. Twenty-seven dementia drugs are now in human clinical trials or awaiting approval.

Forman looked at and felt the surface of the brain. It was symmetrical, as it should be. No areas were squishier than normal. There were yellow flecks in the carotid arteries, evidence of blood-vessel clogging. The olfactory bulbs were exceptionally small. Poor sense of smell is an early sign of dementia, and Moore did, in fact, do poorly on a scent test soon after his diagnosis.

His brain stem was also unusually small - not typical of Alzheimer's patients, Forman pointed out, but not unheard of.