Objectives
Tests of physical function are often thought to measure functioning that is (1) musculoskeletal, and (2) newly declining in adult life. In contrast, this study aimed to: (1) add to evidence that physical-function tests also measure brain function, and (2) test the novel hypothesis that adult physical function is associated with brain function beginning in early childhood. We investigated early-childhood brain function and midlife physical function in the Dunedin Study, a 5-decade longitudinal birth cohort (n=1,037).
Method
Brain function was measured at age 3 using five measures which formed a reliable composite (neurological examination, cognitive and motor tests, temperament ratings). Physical function was measured at age 45 using five measures which formed a reliable composite (gait speed, step-in-place, chair stands, balance, grip strength).
Results
Children with worse age-3 brain function had worse midlife physical function as measured by the age-45 composite, even after controlling for childhood socioeconomic status (β, 0.23; 95% CI, 0.16-0.30; P < .001). Worse age-3 brain function significantly predicted slower gait speed, fewer steps-in-place and chair-stands, worse balance, and weaker grip strength.
Discussion
Children with poorer brain function were more likely to have poorer physical-function scores as adults. In addition to indicating recent musculoskeletal decline, physical-function tests may also provide indications of lifelong, integrated brain-body health. By reconceptualizing the meaning of physical-function scores, clinicians can orient the use of physical-function tests in a more holistic approach to healthcare.