The positive correlation between SERT binding affinity and Parkinsonism, coupled with negative correlations for dopamine transporter and 5-HT2C receptor binding, suggests that SSRIs with high serotonergic selectivity may paradoxically increase extrapyramidal symptom (EPS) risk through disruption of serotonin-dopamine balance in the basal ganglia [55,56]. This evidence concerns the gene SLC6A3 and Parkinson disease.