Nav: Home

Ability to recognize and recall odors may identify those at risk for Alzheimer's disease

November 14, 2016

A non-invasive protocol testing the ability to recognize, remember and distinguish between odors was able to identify older individuals who - according to genetic, imaging and more detailed memory tests - were at increased risk of Alzheimer's disease. The report of a study by a team of Massachusetts General Hospital (MGH) investigators has been published online in Annals of Neurology.

"There is increasing evidence that the neurodegeneration behind Alzheimer's disease starts at least 10 years before the onset of memory symptoms," says Mark Albers, MD, PhD, of the MGH Department of Neurology, the principal investigator and corresponding author of the report. "The development of a digitally-enabled, affordable, accessible and non-invasive means to identify healthy individuals who are at risk is a critical step to developing therapies that slow down or halt Alzheimer's disease progression."

It is well known that brain circuits that process olfactory information can be affected by Alzheimer's disease, and several studies have documented a diminished ability to identify odors in affected individuals. Other studies have associated deficits in odor identification with established Alzheimer's disease biomarkers and with greater rates of cognitive decline, but the most commonly used test of olfactory ability - the University of Pennsylvania Smell Identification Test - has a number of limitations and does not take into account the great variation in olfactory ability among healthy individuals.

The battery of four tests developed by the MGH team addresses both olfactory and cognitive functions:
  • In the OPID (Odor Percept IDentification)-10 test, participants are presented with a battery of 10 odors - menthol, clove, leather, strawberry, lilac, pineapple, smoke, soap, grape or lemon. After experiencing each odor for two seconds, they are asked whether the scent is familiar and then asked to choose among four words - from the names listed above - for the one that best describes the odor.
  • Participants then complete the Odor Awareness Scale (OAS), a previously validated questionnaire that assesses their overall attention to environmental odors and how they are affected emotionally and behaviorally by scents.
  • The OPID-20 test includes the 10 odors previously presented and an additional 10 - banana, garlic, cherry, baby powder, grass, fruit punch, peach, chocolate, dirt and orange. Participants are first asked whether a presented odor was included in the OPID-10 test and then asked which word best describes the odor. Their ability to remember odors from the first test determines their POEM (Percepts of Odor Episodic Memory) score.
  • In the Odor Discrimination (OD) test, participants are presented with two consecutive odors and asked whether they were different or the same, a process that is repeated 12 times with different paired scents.
The study recruited 183 participants, most of whom were enrolled in ongoing studies at the MGH-based Massachusetts Alzheimer's Disease Research Center. At the time of the olfactory testing, 70 were cognitively normal, 74 tested normal on cognitive tests but were personally concerned about their cognitive abilities, 29 had mild cognitive impairment and 10 had been diagnosed with possible or probable Alzheimer's disease. As part of the studies they were enrolled in, all of them had comprehensive medical and neurological examinations - including annual tests of their memory and cognitive abilities - and several had brain imaging studies of Alzheimer's-associated factors.

Results of the OPID-20 test significantly differentiated among the four groups of participants, and those results correlated with the thinning of two brain regions - the hippocampus and the entorhinal cortex - previously associated with Alzheimer's risk. Participants' ability to remember a previously presented aroma, as reflected in the POEM score, also showed significant differences between the two cognitively normal groups and participants with Alzheimer's disease, whose results were no better than chance.

Because the ability of normal individuals to recognize and discriminate between odors can vary by as much as 40 times, the POEM scores of the two cognitively normal groups were compared with what would have been predicted based on their ability to identify and differentiate between odors, as reflected in the OAS and OD tests. That comparison determined whether each individual was a good or poor POEM performer, and poor POEM performers were more likely to have the variant of the APOE gene associated with increased Alzheimer's risk. While results of an annual test of short-term memory improved year-to-year for the good POEM performers, no such improvement was seen among the poor performers, who also showed thinning of the entorhinal cortex.

Albers and his colleagues are currently recruiting participants for a larger-scale study to validate these results. "It is well recognized that early diagnosis and intervention are likely to produce the most effective therapeutic strategy for Alzheimer's disease - preventing the onset or the progression of symptoms," he says. "If these results hold up, this sort of inexpensive, noninvasive screening could help us identify the best candidates for novel therapies to prevent the development of symptoms of this tragic disease."
-end-
Along with Albers, who is an assistant professor of Neurology at Harvard Medical School, the co-authors of the Annals of Neurology paper are lead author Alefiya Dhilla Albers, PhD, Mary Delaney, Kathleen Kelly, Teresa Gomez-Isla, MD, PhD, Reisa Sperling, MD, and Bradley Hyman, MD, PhD, MGH Neurology; Deborah Blacker, MD, ScD, MGH Psychiatry; Keith Johnson, MD, MGH Radiology; Josephine Asafu-Adjei, PhD, University of North Carolina; Rebecca Betensky, PhD, Harvard T.H. Chan School of Public Health; and Lloyd Hastings, PhD, Osmic Enterprises. Support for the study includes National Institutes of Health grants DP2-OD000662, P30-AG036449, P50-AG005134, and T32NS048005 and grants from the Wilkens Foundation and the Harvard NeuroDiscovery Center.

Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH Research Institute conducts the largest hospital-based research program in the nation, with an annual research budget of more than $800 million and major research centers in HIV/AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, reproductive biology, systems biology, photomedicine and transplantation biology. The MGH topped the 2015 Nature Index list of health care organizations publishing in leading scientific journals, earned the prestigious 2015 Foster G. McGaw Prize for Excellence in Community Service. In August 2016 the MGH was once again named to the Honor Roll in the U.S. News & World Report list of "America's Best Hospitals."

Massachusetts General Hospital

Related Memory Articles:

Memory of the Venus flytrap
In a study to be published in Nature Plants, a graduate student Mr.
Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.
Previously claimed memory boosting font 'Sans Forgetica' does not actually boost memory
It was previously claimed that the font Sans Forgetica could enhance people's memory for information, however researchers from the University of Warwick and the University of Waikato, New Zealand, have found after carrying out numerous experiments that the font does not enhance memory.
Memory boost with just one look
HRL Laboratories, LLC, researchers have published results showing that targeted transcranial electrical stimulation during slow-wave sleep can improve metamemories of specific episodes by 20% after only one viewing of the episode, compared to controls.
VR is not suited to visual memory?!
Toyohashi university of technology researcher and a research team at Tokyo Denki University have found that virtual reality (VR) may interfere with visual memory.
The genetic signature of memory
Despite their importance in memory, the human cortex and subcortex display a distinct collection of 'gene signatures.' The work recently published in eNeuro increases our understanding of how the brain creates memories and identifies potential genes for further investigation.
How long does memory last? For shape memory alloys, the longer the better
Scientists captured live action details of the phase transitions of shape memory alloys, giving them a better idea how to improve their properties for applications.
A NEAT discovery about memory
UAB researchers say over expression of NEAT1, an noncoding RNA, appears to diminish the ability of older brains to form memories.
Molecular memory can be used to increase the memory capacity of hard disks
Researchers at the University of Jyväskylä have taken part in an international British-Finnish-Chinese collaboration where the first molecule capable of remembering the direction of a magnetic above liquid nitrogen temperatures has been prepared and characterized.
Memory transferred between snails
Memories can be transferred between organisms by extracting ribonucleic acid (RNA) from a trained animal and injecting it into an untrained animal, as demonstrated in a study of sea snails published in eNeuro.
More Memory News and Memory Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.