When it comes to the early detection of Alzheimer’s disease, a new study suggests that the nose knows.

Mass General Brigham neurology researchers have created a smell test that shows promise as a tool for identifying risk of cognitive impairment.

They found that test participants could successfully take the test at home, and that older adults with cognitive impairment scored lower on the test than cognitively normal adults.

Their study on the test could help identify people who are at risk of Alzheimer’s, and help physicians intervene before serious symptoms set in.

“Early detection of cognitive impairment could help us identify people who are at risk of Alzheimer’s disease and intervene years before memory symptoms begin,” said senior author Mark Albers, of the Laboratory of Olfactory Neurotranslation, the McCance Center for Brain Health, and Department of Neurology at Massachusetts General Hospital.

“Our goal has been to develop and validate a cost-effective, non-invasive test that can be performed at home, helping to set the stage for advancing research and treatment for Alzheimer’s,” Albers added.

Early symptoms for Alzheimer’s disease typically appear after age 60, and the risk increases with age.

The researchers’ olfactory tests — which involve participants peeling and then sniffing odors on a card — assess people’s ability to identify and remember odors.

Albers and colleagues are interested in whether olfactory dysfunction — the sometimes-subtle loss of sense of smell — can serve as an early warning sign for neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, chronic traumatic encephalopathy, and traumatic brain injury.

Albers helped found a company that makes the Aromha Brain Health Test, the test used by the research team to conduct this study.

To evaluate the olfactory test, the team recruited English and Spanish speaking participants who had self-reported concerns about memory, or those with mild cognitive impairment.

The researchers compared these participants’ test results with those who had no sense of smell and with cognitively normal individuals.

The research team found that odor identification, memory, and discrimination declined with age. They also found that older adults with mild cognitive impairment had lower scores for odor discrimination and identification compared with older adults who were cognitively normal.

Overall, the researchers found that test results were similar across English and Spanish speakers, and participants performed the test equally successfully regardless of whether they were observed by a research assistant.

The authors noted that future studies could incorporate neuropsychological testing and could follow patients over time to see if the tool can predict cognitive decline.

“Our results suggest that olfactory testing could be used in clinical research settings in different languages and among older adults to predict neurodegenerative disease and development of clinical symptoms,” Albers said.

The number of people living with Alzheimer’s is projected to double from 6.9 million in 2020 to nearly 14 million people by 2060.

Alzheimer’s disease is a top 10 leading cause of death in the U.S.

In 2022, it was the seventh leading cause of death among U.S. adults, and the sixth leading cause of death among adults 65-plus. The actual number of older people who die from Alzheimer’s may be much higher than what is officially recorded. Alzheimer’s and other types of dementia are not always reported on death certificates.

Meanwhile at Mass General Brigham, researchers in a different study showed that a nasal spray being tested for use in preventing Alzheimer’s disease could also reduce neuroinflammation in traumatic brain injury.

Foralumab, a nasal spray originally developed to treat multiple sclerosis and used by MGB physicians for Alzheimer’s treatment under FDA compassionate use protocols, was tested in mouse models with moderate to severe traumatic brain injury.

The researchers found that Foralumab induces immune cells to travel up to the brain and come in contact with microglial cells, the cells that regulate brain development and injury repair, to reduce inflammation in the brain.

The study results show that the spray could reduce damage to the central nervous system and behavioral deficits, suggesting a potential therapeutic approach for TBI and other acute forms of brain injury.

“This opens up a whole new area of research and treatment in traumatic brain injury, something that’s almost impossible to treat,” said senior author Howard Weiner, co-director of the Ann Romney Center for Neurologic Diseases at Brigham and Women’s Hospital. “It also means this could work in intracerebral hemorrhage and other stroke patients with brain injury.”