The combined effects of ligamentous laxity, hypotonia, and decrements associated with aging lead to stability-enhancing foot placement adaptations during routine overground walking at a younger age in adults with Down syndrome (DS) compared to their peers with typical development (TD). Our purpose here was to examine real-time adaptations in older adults with DS by testing their responses to walking on a treadmill at their preferred speed and at speeds slower and faster than preferred. We found that older adults with DS were able to adapt their gait to slower and faster than preferred treadmill speeds; however, they maintained their stability-enhancing foot placements at all speeds compared to their peers with TD. All adults adapted their gait patterns similarly in response to faster and slower than preferred treadmill-walking speeds. They increased stride frequency and stride length, maintained step width, and decreased percent stance as treadmill speed increased. Older adults with DS, however, adjusted their stride frequencies significantly less than their peers with TD. Our results show that older adults with DS have the capacity to adapt their gait parameters in response to different walking speeds while also supporting the need for intervention to increase gait stability. 1. Introduction Persons with Down syndrome (DS) have lower tone and higher ligamentous laxity than their peers with typical development (TD), requiring them to find somewhat different solutions to control gait over their lifespan. For preadolescents with DS, merely increasing step width as compared to their peers with TD seems adequate to provide stability for walking overground at their self-selected speed [1, 2]. However, in response to the effects of aging, and at an earlier age than observed in the population with TD, adults with DS make additional changes to maintain gait stability while walking overground at their self-selected speed. Adults with DS aged 35–62 years walked slower, with shorter, wider strides and increased stance and double support periods than their age-matched peers with TD [3]. There are a number of factors known to affect gait patterns in older adults with TD that may contribute to the observed gait patterns in adults with DS, including neurophysiological changes associated with aging [4, 5], sedentary lifestyle [6], osteoarthritis [7], obesity [8], and Alzheimer’s type dementia [9–14]. While preadolescents with DS only need to make minimal adaptations (adjusting only step width) to their gait pattern to achieve stability while walking overground at their
References
[1]
B. D. Ulrich, V. Haehl, U. H. Buzzi, M. Kubo, and K. G. Holt, “Modeling dynamic resource utilization in populations with unique constraints: preadolescents with and without Down syndrome,” Human Movement Science, vol. 23, no. 2, pp. 133–156, 2004.
[2]
B. A. Smith, M. Kubo, D. P. Black, K. G. Holt, and B. D. Ulrich, “Effect of practice on a novel task—walking on a treadmill: preadolescents with and without down syndrome,” Physical Therapy, vol. 87, no. 6, pp. 766–777, 2007.
[3]
B. A. Smith and B. D. Ulrich, “Early onset of stabilizing strategies for gait and obstacles: older adults with Down syndrome,” Gait and Posture, vol. 28, no. 3, pp. 448–455, 2008.
[4]
E. Nakamura and S. Tanaka, “Biological ages of adult men and women with Down's syndrome and its changes with aging,” Mechanisms of Ageing and Development, vol. 105, no. 1-2, pp. 89–103, 1998.
[5]
F. Beacher, E. Daly, A. Simmons et al., “Brain anatomy and ageing in non-demented adults with down's syndrome: an in vivo MRI study,” Psychological Medicine, vol. 40, no. 4, pp. 611–619, 2010.
[6]
G. T. Fujiura, N. Fitzsimons, B. Marks, and B. Chicoine, “Predictors of BMI among adults with down syndrome: the social context of health promotion,” Research in Developmental Disabilities, vol. 18, no. 4, pp. 261–274, 1997.
[7]
L. S. Diamond, D. Lynne, and B. Sigman, “Orthopedic disorders in patients with Down's syndrome,” Orthopedic Clinics of North America, vol. 12, no. 1, pp. 57–71, 1981.
[8]
C. A. Melville, S. A. Cooper, C. W. McGrother, C. F. Thorp, and R. Collacott, “Obesity in adults with Down syndrome: a case-control study,” Journal of Intellectual Disability Research, vol. 49, no. 2, pp. 125–133, 2005.
[9]
P. R. Hof, C. Bouras, D. P. Perl, D. L. Sparks, N. Mehta, and J. H. Morrison, “Age-related distribution of neuropathologic changes in the cerebral cortex of patients with Down's syndrome: quantitative regional analysis and comparison with Alzheimer's disease,” Archives of Neurology, vol. 52, no. 4, pp. 379–391, 1995.
[10]
D. M. A. Mann and M. M. Esiri, “The pattern of acquisition of plaques and tangles in the brains of patients under 50 years of age with Downs' syndrome,” Journal of the Neurological Sciences, vol. 89, no. 2-3, pp. 169–179, 1989.
[11]
K. E. Wisniewski, H. M. Wisniewski, and G. Y. Wen, “Occurrence of neuropathological changes and dementia of Alzheimer's disease in Down's syndrome,” Annals of Neurology, vol. 17, no. 3, pp. 278–282, 1985.
[12]
N. Schupf, D. Pang, B. N. Patel et al., “Onset of dementia is associated with age at menopause in women with Down's syndrome,” Annals of Neurology, vol. 54, no. 4, pp. 433–438, 2003.
[13]
I. T. Lott and E. Head, “Down syndrome and alzheimer's disease: a link between development and aging,” Mental Retardation and Developmental Disabilities Research Reviews, vol. 7, no. 3, pp. 172–178, 2001.
[14]
S. J. Teipel, G. E. Alexander, M. B. Schapiro, H. J. M？ller, S. I. Rapoport, and H. Hampel, “Age-related cortical grey matter reductions in non-demented Down's syndrome adults determined by MRI with voxel-based morphometry,” Brain, vol. 127, no. 4, pp. 811–824, 2004.
[15]
A. Hreljac and R. N. Marshall, “Algorithms to determine event timing during normal walking using kinematic data,” Journal of Biomechanics, vol. 33, no. 6, pp. 783–786, 2000.
[16]
G. L. Almeida, D. M. Corcos, M. L. Latash, and B. H. Connolly, “Practice and transfer effects during fast single-joint elbow movements in individuals with Down syndrome,” Physical Therapy, vol. 74, no. 11, pp. 1000–1016, 1994.
[17]
M. L. Latash and D. M. Corcos, “Kinematic and electromyographic characteristics of single-joint movements of individuals with Down syndrome,” American Journal on Mental Retardation, vol. 96, no. 2, pp. 189–201, 1991.
[18]
G. L. Almeida, D. M. Corcos, and Z. Hasan, “Horizontal-plane arm movements with direction reversals performed by normal individuals individuals with down syndrome,” Journal of Neurophysiology, vol. 84, no. 4, pp. 1949–1960, 2000.
[19]
S. Agiovlasitis, J. A. McCubbin, J. Yun, G. Mpitsos, and M. J. Pavol, “Effects of Down syndrome on three-dimensional motion during walking at different speeds,” Gait and Posture, vol. 30, no. 3, pp. 345–350, 2009.
[20]
D. Black, C. L. Chang, M. Kubo, K. Holt, and B. Ulrich, “Developmental trajectory of dynamic resource utilization during walking: toddlers with and without Down syndrome,” Human Movement Science, vol. 28, no. 1, pp. 141–154, 2009.
[21]
B. A. Smith, J. A. Ashton-Miller, and B. D. Ulrich, “Gait adaptations in response to perturbations in adults with Down syndrome,” Gait and Posture, vol. 32, no. 2, pp. 149–154, 2010.
[22]
C. Rigoldi, M. Galli, and G. Albertini, “Gait development during lifespan in subjects with Down syndrome,” Research in Developmental Disabilities, vol. 32, no. 1, pp. 158–163, 2011.
[23]
S. Agiovlasitis, J. A. Mccubbin, J. Yun, M. J. Pavol, and J. J. Widrick, “Economy and preferred speed of walking in adults with and without Down syndrome,” Adapted Physical Activity Quarterly, vol. 26, no. 2, pp. 118–130, 2009.
[24]
G. V. Mendon？a, F. D. Pereira, and B. Fernhall, “Walking economy in male adults with Down syndrome,” European Journal of Applied Physiology, vol. 105, no. 1, pp. 153–157, 2009.
[25]
B. A. Smith, N. Stergiou, and B. D. Ulrich, “Patterns of gait variability across the lifespan in persons with and without down syndrome,” Journal of Neurologic Physical Therapy, vol. 35, no. 4, pp. 170–177, 2011.
[26]
A. S. Karlsen and B. Pakkenberg, “Total numbers of neurons and glial cells in cortex and basal ganglia of aged brains with Down syndrome—a stereological study,” Cerebral Cortex, vol. 21, no. 11, pp. 2519–2524, 2011.
[27]
G. Cenini, A. L. Dowling, T. L. Beckett, et al., “Association between frontal cortex oxidative damage and beta-amyloid as a function of age in Down syndrome,” Biochimica et Biophysica Acta, vol. 1822, no. 2, pp. 130–138, 2012.
[28]
L. Hale, A. Bray, and A. Littmann, “Assessing the balance capabilities of people with profound intellectual disabilities who have experienced a fall,” Journal of Intellectual Disability Research, vol. 51, no. 4, pp. 260–268, 2007.
[29]
J. Finlayson, J. Morrison, A. Jackson, D. Mantry, and S. A. Cooper, “Injuries, falls and accidents among adults with intellectual disabilities. Prospective cohort study,” Journal of Intellectual Disability Research, vol. 54, no. 11, pp. 966–980, 2010.
