Researchers at Massachusetts General Hospital have linked an inability to recognize and recall odors as a possible early sign of the onset of Alzheimer’s disease. Massachusetts General Hospital is the largest teaching hospital of Harvard Medical School.

The elder care services study was reported in the Annals of Neurology, published on November 14, 2016.

A study of 183 patients indicates that those with the disease were less likely to identify smells. Brain scans showed early signs of Alzheimer’s based on patients’ inability to recognize scents such as menthol, clove, leather, strawberry, lilac, pineapple, smoke, soap, grape or lemon. Of the 183 patients, ten of them had possible or probable Alzheimer’s disease, researchers said.

Lead investigator Dr. Mark Albers, who is an assistant professor of neurology at Harvard Medical School, reports that a hindered sense of smell caused by Alzheimer’s could be detected as early as a decade before patients begin to experience memory loss.

Albers and his team are currently recruiting participants for a larger-scale study to validate the results.

Alzheimer’s disease is an irreversible, progressive brain disorder that slowly destroys memory and thinking skills, which leads to the inability to perform even simple tasks. Alzheimer’s Foundation of America calls it a “progressive, degenerative disorder that attacks the brain’s nerve cells, or neurons, resulting in loss of memory, thinking and language skills, and behavioral changes.” It’s estimated that over 5 million Americans suffer from the disease, which often appears in patients’ during their mid-60s.

The disease is currently ranked as the sixth leading cause of death in the United States, but more recent estimates indicate that it may be the third leading cause, behind heart disease and cancer.

Scientists are still not completely sure what causes Alzheimer’s disease. What they do know: it’s a result of complex brain changes that occur over decades, and symptoms often vary from person to person. It’s still a mystery as to why it mostly strikes older people.

Several previous elder care services studies have shown that patients with the disease had a reduced ability to identify odors.

If these results continue to prove themselves, they could lead to inexpensive, noninvasive screenings to identify early onset of Alzheimer’s Disease.

The most effective therapeutic elder care services strategy for Alzheimer’s disease is early detection, diagnosis and intervention. For more information about Alzheimer’s disease and elder care services, visit the National Institute on Aging.