As regards the presence of impulsive-compulsive behaviours, as measured by means of the first section of QUIP, we found significant correlations with disease duration (ρs = 0.38; p = 0.001) and younger age at PD onset (ρs = −0.29; p = 0.013), in addition to years of L-dopa assumption (ρs = 0.32; p = 0.006), L-dopa daily quantity assumption (ρs = 0.26; p = 0.027), COMT-inhibitors (ρs = 0.28; p = 0.018), and total LEDDs (ρs = 0.43; p < 0.0001). Here, COMT is linked to Parkinson disease.