In PD model mice with low specific knockdown of DAergic neurons in the midbrain Dyrk1a gene, P- α-synuclein (Ser129), α-synuclein, Bax, active caspase 3, GSK3β, and cyclinD1 expressions were decreased in Dyrk1a-AAV-ShRNA and Bcl-2, AKT, and PI3K expressions were increased. Here, CCND1 is linked to Parkinson disease.