Clark, Bob Moore's doctor, heard the news first and was surprised by how many Lewy bodies his patient had.

One of his research goals is to create simple tests of spinal fluid or urine that detect and sort out dementias early. He has already added Moore's information to his database. And, he said, the next time he sees an Alzheimer's patient with behavior problems like Moore's, he'll be more likely to think of Lewy bodies.

Joanna Moore slit open the envelope containing Forman's report on Tuesday.

She read it, re-read it, and read it again. She lingered on Forman's diagnosis: "Lewy body variant of Alzheimer's disease."

It was gratifying to see proof that Bob had, indeed, had Alzheimer's disease. But what was a Lewy body?

She still had questions, but having something concrete to explain what her family had been through felt good. Her children would want the news. "They're the inheritors," she said.

Some Causes of Dementia

Alzheimer's disease

Alzheimer's usually begins after age 60 with mild memory problems and progresses to serious disruption of language and thinking. In the brain, scientists see plaques (clumps of the protein beta-amyloid) and tangles (twisted fibers of the protein tau).

Multi-infarct or vascular dementia

Small strokes cause this dementia. Symptoms tend to come on suddenly and remain stable.

Dementia with Lewy bodies

This dementia is characterized by small, round deposits of protein within cells. Clustered in the brain stem, Lewy bodies are the hallmark of Parkinson's disease, but they may occur elsewhere in the brain, with symptoms more like Alzheimer's.

Frontotemporal dementia

This is a rarer group of diseases that damage the frontal and temporal lobes, areas that control executive functions such as the abilities to reason and organize. These patients have tangles, but not plaques.

SOURCE: Alzheimer's Disease Education and Referral Center