Second, the frequency of FOS was not only highest in patients with DLB but was also more significantly associated with DLB features (p < 0.001), including cognitive fluctuations (OR = 10.22), visual hallucinations (OR = 4.18), parkinsonism (OR = 4.68), and REM sleep behavior disorder (OR = 2.84). Here, FOS is linked to Parkinson disease.