According to researchers at Sacre-Coeur Hospital at the University of Montreal, people with rapid-eye-movement (REM) disorder are 18% more likely to develop Parkinson’s Disease within five years of their diagnosis, and 52% more likely after 12 years. People suffering from REM sleep disorder physically act out their nightmares by kicking, flailing and screaming. The three-year study involved comparing brain SPECT (single photon emission computed tomography) for dopamine in 20 patients with REM disorder and 20 healthy controls. (In Parkinson’s disease, a deficiency of dopamine causes tremor.) Results showed that while the production of dopamine in the control group was reduced by 8% due to age, the group of REM sleep disorder patients experienced a reduction of 20%. Also, three of them had developed Parkinson’s disease after three years. The study was reported in Lancet Neurology.