Olfactory Dysfunction, Olfactory Bulb Volume and Alzheimer's Disease: Is There a Correlation? A Pilot Study1

Area of Science:

• Neuroscience
• Neurology
• Olfactory System Research

Background:

• Olfactory dysfunction is an early symptom of Alzheimer's disease (AD).
• Previous studies linked olfactory impairment in AD to atrophy in olfactory system structures.
• The specific role of the olfactory bulb in AD pathogenesis remained unclear.

Purpose of the Study:

• To investigate if Alzheimer's disease (AD) patients exhibit a statistically significant reduction in olfactory bulb volume (OBV) compared to healthy individuals.
• To determine the correlation between olfactory bulb volume and olfactory function in AD and mild cognitive impairment (MCI).

Main Methods:

• Magnetic Resonance Imaging (MRI) of the olfactory bulb was performed on 78 subjects.
• Subjects were categorized into three groups: healthy elderly (28), mild cognitive impairment (MCI) amnestic type (25), and mild AD (25).
• Olfactory function was assessed using the Sniffin' Stick Extended Test.

Main Results:

• Statistical analysis revealed no significant correlation between olfactory bulb volume (OBV) and mild cognitive impairment (MCI) or Alzheimer's disease (AD).
• No correlation was found between olfactory function and OBV in any of the study groups (healthy, MCI, AD).

Conclusions:

• The reduction in olfactory bulb volume (OBV) does not appear to be a reliable index of neuronal damage in the early stages of Alzheimer's disease (AD).
• These findings suggest that OBV changes may not be a primary biomarker for early AD detection.