Ageing of the postural vertical

Abstract

A postural vertical (PV) tilted backward has been put forward as a reason explaining the backward disequilibrium often observed in elderly fallers. This raises the question of a possible ageing process of the PV involving a backward tilt of verticality perception increasing with age. We have explored this hypothesis by measuring PV in pitch using the wheel paradigm in 87 healthy subjects aged from 20 to 97 years. The possibility that this physiological ageing accelerated in the second part of life was also analysed. Two indices were calculated: the mean orientation (PV-orient) and the dispersion (PV-uncert). The correlation between age and PV-orient was r = -0.2 (p < 0.05). Added to the fact that PV was twice as shifted backward in the 38 seniors over 50 years (-1.15 degrees +/- 1.40 degrees ) as in the 49 young adults under 50 years (-0.45 degrees +/- 0.97 degrees ; t = 2.75, p < 0.01), this indicates the existence of a physiological ageing process on the direction perceived as vertical by the whole body, with a slight backward shift of PV throughout the life span. The correlation between age and PV-uncert was r = 0.35 (p < 0.001) in all subjects and r = 0.59 (p < 0.001) in seniors. This indicates that subjects get less and less accurate in their perception of the postural vertical with age, especially very old subjects who show great uncertainty in determining with their body the direction of the vertical. Taken together, these findings indicate that the internal model of verticality is less robust in elderly people. This may play a part in their postural decline.

The subjective postural vertical in standing: Reliability and normative data for healthy subjects

“…Since there was no significant difference in the SPV errors between decades, we calculated the ranges of normality for the whole group: -1.7°to 2.3°in the sagittal plane, and -1.6°to 1.2°in the frontal plane. For the sagittal plane, the range is similar to the values Barbieri et al (2010) found in young adults in a sitting position (<50 years; -2.4 to 1.5°). The only difference was that we found less backward tilt, most likely due to the different testing devices (see below).…”

“…The SPV is altered in subjects with deficits of upright body orientation, both in the frontal and sagittal planes-for example, in subjects with pusher behavior or retropulsion after hemispheric lesions (Karnath et al, 2000;Manckoundia, Mourey, Pfitzenmeyer, Van Hoecke, & Pérennou, 2007;Pérennou et al, 2008). Furthermore, the SPV is influenced by the aging process: With increasing age, the SPV shifts backward and body alignments are less accurate (Barbieri, Gissot, & Pérennou, 2010). These age-related changes might be the consequences of a decline in sensory function (Manckoundia et al, 2008).…”

Ageing of internal models: from a continuous to an intermittent proprioceptive control of movement

“…Additionally, a deficient neuromodulation is suspected to cause less distinct internal representations (Li and Sikstrom 2002). Age-related alterations of internal representations of space and body position are presumably a direct consequence of these decreased resolution of sensory inputs and distinctiveness of internal representations (Barbieri et al 2010;Ghafouri and Lestienne 2000;Lepelley et al 2010). As a consequence of these decreases, inverse models and paired forward models become impoverished.…”

Test–Retest Reliability of the Postural Vertical in Healthy Participants

“…First, only young healthy participants were investigated in this study. Barbieri et al 2) suggested that participants become less and less accurate in their perception of the PV with increasing age. Second, this study had a relatively small sample size.…”