Study Purpose: This study aims to find early signs of Dementia with Lewy bodies (DLB), a brain disorder, by testing people with smell problems, called idiopathic anosmia (iOD). Anosmia means losing the sense of smell.

What We Do: We use a special test named Real-Time Quaking-Induced Conversion (RT-QuIC) to check for bad proteins, called alpha-synuclein, that might cause DLB. This test might help doctors find and help people with early DLB symptoms.

• **Duration:** The study involves several visits to test for olfactory dysfunction and follow-up checks.
• **Participant Requirements:** Must be between 55-75 years old without major diseases and able to consent.
• **Potential Risks:** Participants may experience discomfort from nasal tests but no major risks are expected.

The study involves two parts: one part compares people with smell problems to those without, and the other part checks health records over time. Participants should not have other major health issues. This research might help find new treatments for DLB in the future.