"Since 1965, we have been thinking this triage of symptoms -- gait abnormality, urinary incontinence and memory problems -- as a special disease and we have named it normal pressure hydrocephaly," Koga said. "My hypothesis is that NPH is not a specific disease process, but part of a spectrum of dementia."
The research was to be presented Tuesday at the American Association of Neurological Surgeons meeting in Philadelphia.
Since the 1960s, doctors have considered NPH a separate disease from Alzheimer's, which occurs when beta-amyloid protein builds up and forms amyloid plaques and neurofibrillary tangles. The process is thought to kill neurons and lead to the degenerative symptoms of Alzheimer's.
Instead of focusing on the symptoms of NPH, Koga argues, the two conditions may both be caused by tau-protein abnormalities. That means that some of those 5 million to 6 million people with Alzheimer's may also benefit from shunting, something not typically offered to patients diagnosed with Alzheimer's, he added.
"It's theoretically possible that this same surgery could help forestall the symptoms or improve the symptoms of Alzheimer's," Koga said.
One challenge, however, is determining which Alzheimer's patients might benefit from the shunting. The procedure is not something to take lightly. About 10 percent of people who had the shunt implanted experienced complications, while brain biopsies necessary to measure amyloid plaque and tangles is an invasive procedure.
A better and less invasive solution would be to look for biomarkers that would indicate too much cerebrospinal fluid using a spinal tap, a method Koga and his colleagues are currently investigating.
"When the disease is advanced and patients have this high number of lesions, they wi
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