Age-related changes of visual contribution in posture control.
BACKGROUND
Numerous studies highlighted that the role of vision in posture control increased with aging. However, these previous works only considered simple tasks consisting in "stand as still as possible" and people aged over 65 years. The present study aimed to determine changes in the role of vision in posture control during two different visual tasks for people aged between 40 and 60 years.


METHODS
A stabilometric platform was used to register the effect of a modification of the visual environment on the postural behaviour. Subjects stood upright on thick foam and their attention was focused on the visual task. Two visual tasks were considered: a recognition task and a Rapid Serial Visual Presentation task. Seventy-four subjects (44 between 21 and 31 years and 31 between 44 and 60 years) took part in the study, performing both visual tasks one after the other.


RESULTS
Results showed that 44-60 years old subjects were more unstable than young subjects, especially in the dark. The postural behaviour of the former was also more dependent on the properties of the visual environment. Visual contribution in postural control did not only depend on age but also on task constraints.


CONCLUSIONS
The present study showed that the increased role of vision with age in posture control, classically investigated for people aged over 60 years, could also be highlighted in a 44-60 years old population. Furthermore, the study showed that 44-60 years old subjects' posture was more sensitive to the attentional constraints of the task than young subjects.
Poulain
Isabelle
I
Essilor International, R&D, Visual System and Design, 57 av de Condé, 94106, Saint Maur, France. poulaini@essilor.fr
Giraudet
Guillaume
G
D000328:Adult; D000375:Aging / Q000502:physiology*; D001288:Attention / Q000502:physiology; D003624:Darkness; D006801:Humans; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*