Inherited Alzheimer's disease PS-1 olfactory function: a 10-year follow-up study

Area of Science:

• Neurology
• Genetics

Background:

• Alzheimer's disease (AD) diagnosis relies on clinical assessment and genetic testing.
• Presenilin-1 (PS-1) mutations are a cause of early-onset, dominantly inherited AD.
• Identifying reliable early markers for PS-1 AD is crucial for at-risk families.

Purpose of the Study:

• To evaluate the University of Pennsylvania Smell Identification Test (UPSIT) as a clinical marker.
• To assess the UPSIT's ability to identify mutation carriers for PS-1 AD.
• To determine the UPSIT's utility in diagnosing PS-1 AD in at-risk individuals.

Main Methods:

• Longitudinal study involving 18 at-risk family members with a history of dominantly inherited AD.
• Administration of the 40-question UPSIT 10 years prior to follow-up.
• Clinical assessment at follow-up to determine dementia status and PS-1 AD diagnosis.

Main Results:

• Initial smell test results in 1990 were mostly normal, except for a heavy smoker.
• Four participants developed AD by follow-up, including the smoker.
• Smell test results showed variability; two participants converted from normal to abnormal smell function.
• The UPSIT did not predict clinical conversion to dementia before symptom onset.

Conclusions:

• The smell test (UPSIT) is too variable to reliably predict or verify PS-1 Alzheimer's disease.
• Current smell identification tests are not suitable as a diagnostic marker for PS-1 AD.
• Further research is needed to identify reliable early diagnostic markers for PS-1 AD.