Gait characteristics in people with cognitive impairment - the relationship between step length and cadence

Background: Approximately 70 000 people in Norway are suffering from some form of dementia. Gait and balance impairment in patients with Alzheimer's disease has been recognized for years. Reduced walking speed has been observed not only in patients with Alzheimer's disease, but also patients with mild cognitive impairment. However, the step length cadence relationship (walk ratio) is yet to be studied in individuals with cognitive impairment. Walk ratio has been suggested as a more specific variable than gait speed, as it says something about the quality of how we walk. Aim: The first aim of the thesis was to explore the association between the minimal mental state examination (MMSE)-score and walk ratio by reviewing relevant literature. The second aim was to see if walk ratio can predict group membership between participants with subjective cognitive impairment, mild cognitive impairment and healthy controls. Methods: A literature review of studies where either walk ratio or spatiotemporal gait parameters was reported in populations of cognitive impaired old persons was conducted. In addition, a cross-sectional trial with a 10- meter gait assessment for participants with subjective cognitive impairment, mild cognitive impairment and healthy controls was conducted. Results: The literature review yielded a strong correlation between walk ratio and MMSE - score (r = 0.69). Linear regression showed that age did not contribute significant to the model. The cross-sectional trial showed that walk ratio could not predict group membership to either mild cognitive impairment or subjective cognitive impairment. However, a decrease in velocity was predictive of both subjective cognitive impairment (OR = 0.967 95% CI 0.938 to 0.997, P = 0.03) and mild cognitive impairment (OR = 0.963, 95% CI 0.930 to 0.996, P = 0.03). Conclusion: There was a strong association between the MMSE - score and walk ratio. In addition, a decrease in velocity seems to be predictive of both mild cognitive impairment and subjective cognitive impairment. These findings support the fact that there is an association between degree of cognitive impairment and gait function and that gait impairment can be found in early stages of dementia