According to our findings, haloperidol‐induced PD was associated with significant fibrous tissue deposition, representing Ishak score 3, and significantly increased levels of two key fibrosis markers; TGF‐β the strongest inducer of fibrotic diseases and hydroxyproline, a main collagen constituent that acts as a good extracellular matrix accumulation marker.20 This evidence concerns the gene TGFB1 and Parkinson disease.