title: Sensory and motor peripheral nerve function and incident mobility disability.
abstract: OBJECTIVE
  To assess the relationship between sensorimotor nerve function and incident mobility disability over 10 years.
  
  
  METHODS
  Prospective cohort study with longitudinal analysis.
  
  
  METHODS
  Two U.S. clinical sites.
  
  
  METHODS
  Population-based sample of community-dwelling older adults with no mobility disability at 2000/01 examination (N = 2,148 [Corrected]; mean age ± SD 76.5 ± 2.9, body mass index 27.1 ± 4.6; 50.2% female, 36.6% black, 10.7% with diabetes mellitus).
  
  
  METHODS
  Motor nerve conduction amplitude (poor <1 mV) and velocity (poor <40 m/s) were measured on the deep peroneal nerve. Sensory nerve function was measured using 10- and 1.4-g monofilaments and vibration detection threshold at the toe. Lower extremity symptoms included numbness or tingling and aching or burning pain. Incident mobility disability assessed semiannually over 8.5 years (interquartile range 4.5-9.6 years) was defined as two consecutive self-reports of a lot of difficulty or inability to walk one-quarter of a mile or climb 10 steps.
  
  
  RESULTS
  Nerve impairments were detected in 55% of participants, and 30% developed mobility disability. Worse motor amplitude (HR = 1.29 per SD, 95% CI = 1.16-1.44), vibration detection threshold (HR = 1.13 per SD, 95% CI = 1.04-1.23), symptoms (HR = 1.65, 95% CI = 1.26-2.17), two motor impairments (HR = 2.10, 95% CI = 1.43-3.09), two sensory impairments (HR = 1.91, 95% CI = 1.37-2.68), and three or more nerve impairments (HR = 2.33, 95% CI = 1.54-3.53) predicted incident mobility disability after adjustment. Quadriceps strength mediated relationships between certain nerve impairments and mobility disability, although most remained significant.
  
  
  CONCLUSIONS
  Poor sensorimotor nerve function independently predicted mobility disability. Future work should investigate modifiable risk factors and interventions such as strength training for preventing disability and improving function in older adults with poor nerve function.
authors.affiliation: Spaulding Rehabilitation Hospital, Cambridge, Massachusetts; School of Public Health, Boston University, Boston, Massachusetts.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Ward
authors.forename: Robert M
authors.initials: RM
authors.lastname: Boudreau
authors.forename: Paolo
authors.initials: P
authors.lastname: Caserotti
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Sasa
authors.initials: S
authors.lastname: Zivkovic
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
authors.forename: Suzanne
authors.initials: S
authors.lastname: Satterfield
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Ann V
authors.initials: AV
authors.lastname: Schwartz
authors.forename: Aaron I
authors.initials: AI
authors.lastname: Vinik
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Simonsick
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Elsa S
authors.initials: ES
authors.lastname: Strotmeyer
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D001823:Body Composition / Q000502:physiology; D002908:Chronic Disease; D004185:Disability Evaluation; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D051346:Mobility Limitation; D009046:Motor Neurons / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D009460:Neurologic Examination; D010414:Pennsylvania; D010525:Peripheral Nerves / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology*; D011446:Prospective Studies; D012307:Risk Factors; D012684:Sensory Thresholds / Q000502:physiology; D013714:Tennessee; D014034:Toes / Q000294:innervation*
keywords: disability; longitudinal analysis; muscle strength; older adults; peripheral nerve function