Gait analysis under dual-task conditions for identifying motor phenotypes in elderly patients with gait disorders.

OBJECTIVE: Gait disorders are associated with increased fall risk, dementia and loss of autonomy. Gait analysis has previously been validated in the identification of motor phenotypes in mild cognitive impairment [1]. We hypothesized that gait analysis under dual-task conditions in elderly patients with gait disorders might allow the identification of motor phenotypes linked to specific brain abnormalities.

MATERIAL/PATIENTS AND METHODS: An observational study was instructed for elderly patients with gait disorders or memory impairment. Gait analysis under dual-task conditions was carried out for all patients (Locometrix(®)). Two main gait variables were measured: stride frequency, and stride regularity. For each gait variable, the dual task cost, which is related to cognitive reserve (DTC (%)) was calculated as follows: [DTC %=(single-task gait value-dual task gait value)/single-task gait value×100]. Brain MRI was carried out in the absence of contra-indications. Semi-quantitative score for white matter hyper intensities (age-related white matter changes, ARWMC) and hippocampus atrophy (Scheltens) were identified.

RESULTS: One hundred and three patients (mean age 76.3±7.2, women 56%) were included. Four clinical subgroups were identified: gait instability (45%), recurrent falls (29%), memory impairment (18%), and cautious gait (8%). The quartile analysis of DTC for stride frequency and stride regularity allowed the identification of 3 motor phenotypes (<0.01KW), with no link to either sex or clinical subgroups, but characterized by different Scheltens scores (P=0.05). Twenty-six patients with a low value of DTC for stride frequency and a high value of DTC for Stride Regularity (Scheltens 2.6±1.6). Forty-seven patients with the same value of DTC for both stride frequency and regularity (Scheltens 3.3±1.6). 30 patients with a high value of DTC for stride frequency and a low value of DTC for stride regularity (Scheltens 4.0±1.9).

DISCUSSION-CONCLUSION: The identification of different motor phenotypes in elderly patients with gait disorders can help the clinician with diagnoses and tailored cognitivo-motor gait rehabilitation.