title: Impaired sense of smell and color discrimination in monogenic and idiopathic Parkinson's disease.
abstract: Olfaction is typically impaired in idiopathic Parkinson's disease (IPD), but its role is uncertain in monogenic PD. Diminished color discrimination has been suggested as another early sign of dopaminergic dysfunction but not been systematically studied. Furthermore, it is unknown whether both deficits are linked. We examined 100 patients with IPD, 27 manifesting mutation carriers (MC), 20 nonmanifesting mutation carriers (NMC), and 110 controls. Participants underwent a standardized neurological examination, the University of Pennsylvania Smell Identification Test (UPSIT), the Farnsworth-Munsell (FM) color discrimination test, and mutation testing in known PD genes. The monogenic group consisted of 15 Parkin (6MC/9NMC), 17 PINK1 (10MC/7NMC), 8 LRRK2 (4MC/4NMC), 3 SNCA (MC), and 4 ATP13A2 (MC) carriers. Olfaction was most impaired in IPD (UPSIT percentiles 10.1 ± 13.5) compared with all other groups (MC 13.8 ± 11.9, NMC 19.6 ± 13.0, controls 33.8 ± 22.4). Within MC, carriers of two mutations in Parkin and PINK1 showed higher UPSIT percentiles than LRRK2 and SNCA carriers. Color discrimination was reduced in IPD (FM total error score 134.8 ± 92.7). In MC (122.4 ± 142.4), the reduction was most pronounced in LRRK2, NMC (80.0 ± 38.8) were comparable with controls (97.2 ± 61.1). UPSIT and FM scores were correlated in the control (r = -0.305; P = 0.002) and the IPD group (r = -0.303; P = 0.006) but not among mutation carriers. First, we confirmed olfaction and color discrimination to be impaired in IPD and suggest olfaction to be a premotor sign. Second, olfaction differed between carriers with one and two mutations in Parkin/PINK1-associated PD. Third, olfaction and color discrimination impairment do not necessarily evolve in parallel.
authors: Department of Psychiatry and Psychotherapy, University of Luebeck, Luebeck, Germany.
authors: Lena
authors: L
authors: Kertelge
authors: Norbert
authors: N
authors: Brüggemann
authors: Alexander
authors: A
authors: Schmidt
authors: Vera
authors: V
authors: Tadic
authors: Claudia
authors: C
authors: Wisse
authors: Sylwia
authors: S
authors: Dankert
authors: Laura
authors: L
authors: Drude
authors: Joyce
authors: J
authors: van der Vegt
authors: Hartwig
authors: H
authors: Siebner
authors: Heike
authors: H
authors: Pawlack
authors: Peter P
authors: PP
authors: Pramstaller
authors: Maria Isabel
authors: MI
authors: Behrens
authors: Alfredo
authors: A
authors: Ramirez
authors: Dirk
authors: D
authors: Reichel
authors: Carsten
authors: C
authors: Buhmann
authors: Johann
authors: J
authors: Hagenah
authors: Christine
authors: C
authors: Klein
authors: Katja
authors: K
authors: Lohmann
authors: Meike
authors: M
authors: Kasten
mesh_terms: D000368:Aged; D003118:Color Perception / Q000235:genetics; D003117:Color Vision Defects / Q000235:genetics / Q000503:physiopathology*; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D005820:Genetic Testing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D000857:Olfaction Disorders / Q000235:genetics / Q000503:physiopathology*; D010300:Parkinson Disease / Q000235:genetics / Q000503:physiopathology*; D012903:Smell / Q000235:genetics*; D018709:Statistics, Nonparametric; D051844:alpha-Synuclein / Q000235:genetics
chemical_list: D051844:alpha-Synuclein