Today, the first neuroimaging pilot study on humans, using TRODAT-1 and SPECT, is underway in Brazil for evaluating PD patients.132 Several other research protocols using [99mTc] TRODAT-1 and SPECT may be developed to investigate DAT in neuropsychiatric disorders involving the dopaminergic system, such as early onset Parkinson's disease, attention deficit and hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD) and schizophrenia. This evidence concerns the gene SLC6A3 and obsessive-compulsive disorder.