Previous research has suggested that alterations in neurotransmitters levels (e.g., HVA, 5-HT, GABA, and Ach), decreased amyloid-β (Aβ) and αSyn, and increased neurofilament light (NFL) levels are significant contributors of PD-MCI (Paolini Paoletti et al., 2023; Liu et al., 2020). The gene discussed is NEFL; the disease is Parkinson disease.