L1CAM and Parkinson disease: α‐Synuclein in L1CAM‐positive exosomes was similarly elevated in male (29.9 ± 18.7 pg/mL) and female (29.0 ± 17.5 pg/mL) participants with PD and did not correlate with UPDRS or MoCA scores (R2 = 0.0059 and 0.0047, respectively; Figure S2), age, or disease duration (R2 = 0.0061 and 0.0013, respectively; Figure S2).