(HealthDay News) -- New research suggests that a faltering sense of smell might signal the early stages of Alzheimer's disease, and that an inexpensive, low-tech smell test could spot who needs more extensive screening for dementia.
In two different studies, the decreased ability to identify odors was associated with the loss of brain cell function and progression to Alzheimer's disease.
"We're trying to be able to diagnose Alzheimer's earlier and theoretically deliver drugs to people sooner," said Matthew Growdon, lead author of one of the studies. "Think about cardiovascular disease as a paradigm; the idea is that we would find a way to control the risk factors [before the disease advances]."
The ability to smell is associated with the first cranial nerve, and is often one of the first things to be affected by cognitive decline.
Brain regions that process odors are particularly vulnerable to Alzheimer's early in the disease process, explained Growdon, who is a student at Harvard Medical School, in Boston. Autopsies have shown amyloid plaques and neurofibrillary tangles -- the telltale signs of Alzheimer's -- in the areas of the brain responsible for smell.
In a subgroup of study participants who had elevated levels of amyloid in their brain, there was evidence of greater brain cell death and diminished ability to smell, Growdon said. The data took into account the participants' age, gender, intelligence and brain scans.
Alzheimer's is the most common form of dementia, a general term for loss of memory and other intellectual abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 60 percent to 80 percent of dementia cases, according to the Alzheimer's Association. ...more