Technique moves practical Alzheimer diagnosis one step closer to reality

Researchers at the University of Wisconsin-Madison School of Medicine and Public Health are moving closer to a significant milepost in the battle against Alzheimer’s disease: identifying the first signs of decline in the brain.

After years of frustrating failure to stop late-stage Alzheimer’s, it’s essential to find and treat the mild stages, says Sterling Johnson, professor of geriatrics. “We need to identify Alzheimer’s as early as possible, before the really destructive changes take place. Typically, by the time we diagnose Alzheimer’s disease, patients have already lost much of their brain capacity, and it’s difficult or impossible for them to recover.”

The earlier phases, before large numbers of brain cells have been killed, should be more amenable to treatment, Johnson says. Alzheimer’s disease is the largest single cause of dementia. Early symptoms include memory decline, eventually progressing to widespread cognitive and behavioral changes.

In a study published in the journal Cerebral Cortex in December, Johnson, Ozioma Okonkwo in the Department of Geriatrics, and colleagues reported on measurements of brain blood flow in 327 adults. The researchers used an advanced form of MRI to compare blood flow in people with Alzheimer’s, a preliminary stage called mild cognitive impairment, or those who had no symptoms but had a family history of Alzheimer’s.

Reduced blood flow signifies reduced activity in particular parts of the brain, often due to the atrophy of nerve cells. One affected structure, called the hippocampus, is necessary for making new memories. In mild to moderate cases of Alzheimer’s, 40 percent or more of the hippocampus has disappeared.

As expected, the Alzheimer’s patients had lower blood flow in several brain regions linked to memory. People with mild cognitive impairment had a milder version of the same deficits. And people whose mother (but not father) had Alzheimer’s had clear signs of reduced blood flow, even though they lacked symptoms.

Other techniques that can measure blood flow are more costly and require the use of radiation and injecting a drug tracer during the scan, Johnson says. If this non-invasive MRI technique continues to prove itself, it could be a key to detecting Alzheimer’s disease in its early, and hopefully more treatable, phases.

"In the new paper, we showed that the same areas that show up with more established scanning techniques also are identified with this MRI blood flow technique, in people with Alzheimer’s and mild cognitive impairment," says Johnson. "So this method is valid and reliable, and is now ready to begin deployment in treatment research with people at risk."