Odor identification, cognitive functioning, and cholinergic degeneration (as assessed by [11C]PMP PET imaging) were explored in 58 non-demented PD patients.135,136 Results showed that impaired odor identification correlated on the one hand with cognitive impairment and on the other with AChE activity in the limbic region (hippocampus and amygdala). The gene discussed is ACHE; the disease is Parkinson disease.