Relationships between serum vitamin D levels, neuromuscular and neuropsychological function and falls in older men and women

Among 463 community dwellers aged 70-90 years, those with vitamin D insufficiency showed reduced neuromuscular function, balance control and stepping ability and performed worse in tests of cognitive function. In men, vitamin D insufficiency was associated with an increased risk of falling. The purpose of this study was to investigate the relationship between serum 25-hydroxy vitamin D (serum 25OHD) levels, physiological and neuropsychological function in older people, and to examine the relationship between serum 25OHD and prospective falls. Four hundred sixty-three community-dwelling people aged 70-90 years underwent an assessment of physiological and neuropsychological performance and structured interviews relating to comorbidity and disability. Fall frequency during the 12 months follow-up was monitored with monthly falls diaries. Twenty-one percent of the men and 44% of the women were vitamin D insufficient (serum 25OHD <= 50 nmol/L). Participants with vitamin D insufficiency had weaker upper and lower limb strength, slower simple finger press and choice stepping reaction time, poorer leaning balance and slower gait speed, after controlling for age and body mass index, and, poorer executive function and visuospatial ability, after controlling for age and education. Vitamin D insufficiency significantly increased the rate of falls in men (IRR = 1.94, 95% CI = 1.19-3.15, p = 0.008) but not in women. These findings highlight the associations between vitamin D insufficiency and impairments in physiological and neuropsychological function that predispose older people to fall. The significant relationship between vitamin D insufficiency and falls found in the men may relate to the stronger association found between serum 25OHD levels and dynamic balance measures evident in this male population.