Odor Detection and Recognition Ability in Patients with Alzheimer's Disease

抄録

Alzheimer's disease (AD) manifests early with prominent olfactory dysfunction. The olfactory symptoms appear long before cognitive impairment and other typical AD symptoms. Here, we tested odor detection and recognition acuity in AD patients and in age-matched controls to determine the relationships between olfactory test scores and anxiety level, cognitive function, and disease and therapy duration.
We found that while AD patients had the same odor detection sensitivity as healthy subjects, most patients exhibited impaired odor recognition. AD patients had significantly lower cognitive function and trait anxiety scores than healthy subjects according to our assessments using the Mini-Mental State Examination (MMSE). Trait anxiety scores are thought to be lower in AD patients because of atrophy of the limbic system, particularly the amygdala (AMG). It has been reported that trait anxiety level is dependent on amygdala activity, therefore, the low activation of the AMG is linked to reduced trait anxiety in AD.
However, we found that trait anxiety correlated positively with odor detection ability in AD patients. Although the function of the AMG is reduced in AD patients, it still contributes to odor detection in AD patients with high trait anxiety.