Smell, an Underrated Early Biomarker for Brain Aging

Area of Science:

• Neuroscience
• Gerontology
• Sensory Science

Background:

• Olfaction, alongside touch, is a primary sense, developing in utero.
• Smell function declines with age, particularly after 65, and is significantly impaired in dementia.
• Despite its accessibility and clinical relevance, olfaction is underutilized as a biomarker for neurological conditions.

Purpose of the Study:

• To highlight the underappreciation of olfaction as an early biomarker for pathological brain aging.
• To compare the clinical relevance of olfaction with vision and hearing in general health assessments.
• To encourage research into the mechanisms of early smell dysfunction preceding cognitive decline.

Main Methods:

• This is a perspective article, not an experimental study.
• It involves a critical review and comparison of sensory system relevance in aging and neurological disease.
• It synthesizes existing knowledge to advocate for the use of olfactory testing.

Main Results:

• Olfaction is an ancient sense, integral to development and aging.
• Smell impairment is a common, yet overlooked, early indicator of cognitive decline and dementia.
• Vision and hearing are prioritized over olfaction in health screenings, despite smell's potential as an early biomarker.

Conclusions:

• Olfactory decline is a significant, underrecognized sign of brain aging and dementia.
• Increased awareness and utilization of smell tests can aid in early disease detection.
• Further research is needed to elucidate the mechanisms behind early smell dysfunction and its predictive value.