Loss of Smell May Predict Heart Failure Risk

Older adults who have partially or completely lost their sense of smell have a 30% higher risk of developing congestive heart failure compared with adults with a good sense of smell, according to findings published in the Journal of the American Heart Association.¹ Their risk of coronary heart disease and stroke also increased, though this was not statistically significant.

It’s important to note that some loss of smell and taste is fairly common with age, especially in those aged 60 years and older.² This can occur at younger ages too: almost a quarter of adults lose their sense of smell by their early 50s, while more than half of adults lose it in their 80s or later.³ It’s also known that heart failure risk increases with age.⁴ With this study focusing on patients in their 70s, it is no surprise that many of them experienced or were at high risk for heart failure and olfactory impairment.

A poor sense of smell has also been linked to cognitive decline, including lower performance in memory and language, and is an early indicator of Parkinson and Alzheimer diseases. Additionally, it can predict higher mortality rates in older adults, potentially signaling slowed cellular regeneration or prolonged exposure to environmental toxins. Losing the sense of smell can also diminish quality of life by reducing enjoyment of food and increasing health risks, such as being unable to detect spoiled food or gas leaks. With this in mind, researchers from the current study explored if olfactory dysfunction might indicate broader health problems, given that Parkinson and Alzheimer diseases only account for 22% of the associated excess mortality.

The study included 2537 individuals aged 70 to 79 years from the National Institute on Aging's Health ABC Study, which explored the connections between aging-related conditions, social and behavioral factors, and functional changes in older adults.¹ Participants were enrolled in 1997 and 1998 and were well-functioning at baseline. The current study tracked participants from their 3-year clinic visit in 1999 or 2000 for up to 12 years or until they experienced a cardiovascular event or death. Researchers investigated the association between poor sense of smell and the occurrence of heart attacks, strokes, angina, death from coronary heart disease, or congestive heart failure, defined as being hospitalized overnight for heart failure.

At the 3-year clinic visit, patients’ sense of smell was assessed using the 12-item cross-cultural Brief Smell Identification Test (B-SIT), a shortened version of the 40-item University of Pennsylvania Smell Identification Test. Participants smelled 12 odorants, 1 at a time, and identified each from 4 possible answers, scoring 1 point per correct answer. Scores ranged from 0 to 12, with poor olfaction defined as a score of 8 or lower, moderate as 9 to 10, and good as 11 to 12. These categories revealed strong links between poor olfaction and conditions such as Parkinson disease, dementia, higher mortality rates, and pneumonia hospitalization in the study cohort.

Over 12 years, there were 353 new cases of coronary heart disease, 258 strokes, and 477 cases of congestive heart failure. After considering factors such as age, sex, and other health risks, older adults with moderate olfactory issues had a 32% higher risk of congestive heart failure, and those with poor olfaction had a 28% higher risk compared with those with a good sense of smell. These findings were consistent across different subgroups, although the link between poor sense of smell and congestive heart failure was especially clear in participants who reported being in very good to excellent health, but not in those who reported fair to poor health.

After adjusting for demographics, the risk of congestive heart failure over a median follow-up of 10.8 years was 35% higher for participants with moderate olfaction and 39% higher for those with poor olfaction, compared with those with good olfaction. These associations remained largely unchanged after adjusting for lifestyle risk factors and existing coronary heart disease or stroke, and were only slightly reduced after further adjustments for electrocardiogram, spirometry, and blood biomarkers for congestive heart failure. In the fully adjusted model, the risk was 32% higher for moderate and 28% higher for poor olfaction, compared with good olfaction.

Consistent with the descriptive analyses, there was no significant association between baseline olfaction and outcomes for coronary heart disease (HR, 0.97; 95% CI, 0.73-1.28) or stroke (HR, 1.12; 95% CI, 0.82-1.52) for those with a poor sense of smell. These results remained consistent even after excluding participants with dementia or Parkinson disease at the start of the study.

“Although we did not observe a statistically significant interaction, the association between olfaction and CHF [congestive heart failure] appears to be more evident and monotonic among participants with very good to excellent health at baseline,” the researchers wrote. “In contrast, the estimated associations were close to null among participants who self‐reported fair to poor health.”

For instance, among participants who reported their health as very good to excellent, those with a poor sense of smell had a 76% higher risk of developing congestive heart failure compared with those with a good sense of smell. On the other hand, among participants who reported fair to poor health, there was no significant difference in the risk of congestive heart failure between those with poor and good olfaction (HR, 0.92; 95% CI, 0.58-1.47).

According to the researchers, these preliminary findings suggest that in older adults, poor sense of smell may be linked to cardiovascular health, potentially serving as an early marker or risk factor. As blood vessels change and the blood supply diminishes, it might harm the nasal tissues and olfactory pathways, impairing the sense of smell. There is also evidence that markers of atherosclerosis, such as carotid artery thickness and plaques, are associated with olfactory decline. Additionally, poor smell may affect diet, mood, social interaction, and physical activity, all of which can impact cardiovascular health. However, the exact role of olfaction in cardiovascular health is still speculative and needs more research, the researchers noted.

“There remains a critical need to identify novel factors associated with adverse cardiovascular outcomes in older adults to further inform risk prediction and intervention,” the researchers wrote. “In contrast to known cardiovascular risk factors, including hypertension, obesity, and smoking, even health‐conscious individuals rarely pay attention to their sense of smell.”

References

1. Chamberlin KW, Yuan Y, Li C, et al. Olfactory impairment and the risk of major adverse cardiovascular outcomes in older adults. J Am Heart Assoc. Published online June 7, 2024. doi:10.1161/JAHA.123.033320
2. Takahashi PY. Is loss of taste and smell normal with aging? Mayo Clinic. September 21, 2023. Accessed June 14, 2024. https://www.mayoclinic.org/healthy-lifestyle/healthy-aging/expert-answers/loss-of-taste-and-smell/faq-20058455
3. Palta P, Chen H, Deal JA, et al. Olfactory function and neurocognitive outcomes in old age: rhe atherosclerosis risk in communities neurocognitive study. Alzheimers Dement. 2018;14(8):1015-1021. doi:10.1016/j.jalz.2018.02.019
4. Risks for heart failure. American Heart Association. Updated June 13, 2023. Accessed June 14, 2024. https://www.heart.org/en/health-topics/heart-failure/causes-and-risks-for-heart-failure