A straightforward at-home test could potentially detect a devastating condition up to 20 years before symptoms appear, according to groundbreaking research. This smell test could indicate the likelihood of developing Alzheimer's disease.
Alzheimer's disease is the most prevalent form of dementia in the UK. Early stages can result in memory lapses that progressively worsen over time, eventually leading to more severe symptoms such as delusions and mood swings.
Typically, an Alzheimer's diagnosis isn't confirmed until after symptoms have begun. However, a study has unveiled a method to predict the probability of the condition years ahead of time.
The study, conducted by a team at Massachusetts General Hospital in the US, discovered that our ability to identify and recall different smells could serve as a warning sign for cognitive decline. As part of their research, they developed an at-home smell test named AROMHA.
The test is uncomplicated - participants receive cards in the post with smell-infused labels. They peel and sniff the labels while following instructions online.
The aim of the test is to assess several olfactory abilities including correctly identifying odours, distinguishing between different smells, recalling smells from earlier in the test, and rating the intensity of each smell. Researchers chose to focus on smell due to the fact that the areas of the brain responsible for processing smells are among the first affected by Alzheimer's disease.
The study highlighted that these brain regions can exhibit changes indicative of Alzheimer's disease long before symptoms manifest, with alterations beginning 15 to 20 years prior to the onset of memory issues. Published in [Scientific Reports](https://go.skimresources.com?id=76202X1536635&xs=1&url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41598-025-92826-8%23Sec10&sref=https%3A%2F%2Fwww.getsurrey.co.uk%2Fincoming%2Falzheimers-disease-could-detected-20-31291284), the research involved a sample of 187 individuals.
This comprised 127 cognitively healthy participants, 34 individuals who expressed concerns about their memory but tested normally, and 19 people diagnosed with mild cognitive impairment (MCI), a condition often preceding Alzheimer's. An additional seven patients with anosmia, or loss of smell, were included as a comparison group.
As Study Finds reported, researchers discovered that those with mild cognitive impairment significantly underperformed on smell identification and discrimination tests compared to both healthy individuals and those with only subjective memory worries. This held true even after adjusting for factors such as age, sex, and education. Performance consistency was maintained regardless of whether participants were observed during testing or not.
Among those deemed cognitively normal, smell abilities naturally deteriorated with age, but this decline was markedly steeper in those with cognitive impairment. Participants with clinically diagnosed smell loss scored at chance levels, thereby validating the test's accuracy.
The study authors concluded: "These results suggest that the AROMHA Brain Health Test could be used in clinical research settings in different languages to explore the utility of olfactory biomarkers to predict the presence of blood-based, image-based, or cerebrospinal fluid (CSF)-based biomarkers of neurodegenerative disease and longitudinal development of clinical symptoms."
However, the study is not without its limitations. It focused on a single-time assessment of participants rather than observing them over several years, which would provide a more accurate indication of how changes in smell could foretell cognitive decline.
Furthermore, only a small cohort was studied, particularly those with mild cognitive impairment. The authors noted the necessity for further research to ascertain the AROMHA test’s "predictive value" concerning cognitive deterioration.
The [NHS](https://www.getsurrey.co.uk/all-about/nhs) lists several early indicators of Alzheimer's, including:
* Showing poor judgement or finding it harder to make decisions
* Becoming less flexible and more hesitant to try new things
* Forgetting the names of places and objects
* Asking questions repetitively
* Having trouble thinking of the right word
* Misplacing items
* Forgetting about recent conversations or events.
If you or someone you know is displaying symptoms, you should speak to a GP.