Neuromuscular and Psychomotor Function in Elderly Subjects Who Fall and the Relationship With Vitamin D Status

Abstract

Vitamin D and calcium supplementation significantly reduces the incidence of fractures. Evidence suggests vitamin D deficiency impairs neuromuscular function, causing an increase in falls and thereby fractures. The relationship between vitamin D, functional performance, and psychomotor function in elderly people who fall was examined in a prospective cross-sectional study. Patients were recruited from a falls clinic and stratified according to serum 25-hydroxyvitamin-D levels (25OHD): group 1, 25OHD < 12 μg/liter; group 2 25OHD, 12-17 μg/liter; and group 3, 25OHD > 17 μg/liter. Healthy elderly volunteers with 25OHD > 17 μg/liter comprised group 4 (n = 20/group). Measures included aggregate functional performance time (AFPT, seconds), isometric quadriceps strength (Newtons), postural sway (degrees), and choice reaction time (CRT, seconds). Serum bone biochemistry, 25OHD, and parathyroid hormone levels were measured. Patients who fell had significantly impaired functional performance, psychomotor function, and quadriceps strength compared with healthy subjects (AFPT: 51.0 s vs. 32.8 s, p < 0.05; CRT: 1.66 s vs. 0.98 s, p < 0.05; strength: 223N vs. 271N, t = 2.35, p = 0.02). Group 1 had significantly slower AFPT (66.0 s vs. 44.8 s, t = 4.15, p < 0.05) and CRT (2.37 s vs. 0.98 s, t = 3.59, p < 0.05) than groups 2 and 3. Group 1 had the greatest degree of postural sway and the weakest quadriceps strength, although this did not reach significance. Multivariate analysis revealed 25OHD as an independent variable for AFPT, CRT, and postural sway. PTH was an independent variable for muscle strength. Older people who fall have impaired functional performance, psychomotor function, and muscle strength. Within this group, those with 25OHD < 12 μg/liter are the most significantly affected.