The rapid increase in the aging population of Japan is becoming a serious social concern, and the number of elderly individuals with dementia is also increasing. The Ministry of Health, Labour and Welfare of Japan has reported that the elderly account for 4.62 million individuals, of which approximately 4 million have mild cognitive impairment (MCI). However, monofunctional disorders, such as those in individuals with MCI, can be treated, with patients recovering 44% of their abilities 2 years after treatment, thereby suggesting that early detection and treatment of dementia is important. It has been reported that individuals who walk slowly or have experienced a significant decline in walking speed with age have a higher risk of developing dementia. In this study, to study movement in individuals aged ≥ 60 years, we focused on walking, a basic activity of daily living. We proposed and evaluated novel methods to estimate cognitive function. Acceleration and angular velocity sensors were attached to the waists of 20 elderly participants who were asked to walk outdoors ordinarily for 5-10 min, during which acceleration and angular velocity were measured. The similarity, standard deviation, and period of the stride were determined from the acceleration waveform and angular velocity waveform during walking. These were used as independent variables, and multiple regression analysis was performed using the Mini-Mental State Examination (MMSE) score as a dependent variable. An MMSE score estimation equation was constructed. The relationship between the estimation formula and the actual test value was R² = 0.773 (P <0.01), which was good. As a result of cross-validation, the root mean square (RMS) error is low and the error is neither fixed nor proportional. Using the body acceleration and angular velocity information when walking outdoors, we built a very accurate formula for estimating the MMSE score.

Keywords

Dementia, Walking, Elderly, Mild cognitive impairment (MCI), Motoric cognitive risk (MCR), Mini-Mental State Examination (MMSE)

Paper information

[Advance Publication] (Proper information for citation will be announced after formal publication)

This paper presents a method for quantifying tendon reflex dynamics addressing kinematical characteristics of the patellar tendon reflex. The method uses a limb-mounted three-dimensional motion sensor and an instrumented hammer to assess input-output relations of the patellar tendon reflex. A healthy adult male subject participated in our experiment. A simple rigid-body physical model was introduced to obtain viscoelastic and inertial responses of kinetic motion of the lower leg. This model is used to estimate knee extension torque by indicating the reflex responses of the muscle. A system identification method was then applied to describe the reflex responses to the hammer tapping by considering a second-order mathematical model with a delay term. Iterative prediction-error minimization was applied to the cascaded data for three tapping conditions: weak, medium, and strong. Good consistency was obtained between the analysis from the model and the measurement results. The results suggest that the proposed method was sufficiently feasible to characterize the reflex responses with a few characterized system parameters, which will be useful to provide additional quantitative assessment capability for neuromuscular diagnosis.

Keywords

Stretch Reflex, Diagnosis, Motion Analysis, InertialMeasurement, System Identification, Kinematics, Biomechanics

Paper information

Yasuaki OHTAKI, Naotaka MAMIZUKA, Mohammad FARD, Yoshinori HARADA, Yoshihisa MINAKUCHI and Naoyuki OCHIAI, “Identification of Patellar Tendon Reflex Based on Simple Kinematic Measurement”, Journal of Biomechanical Science and Engineering, Vol. 4, No. 2 (2009), pp.265-273 . doi:10.1299/jbse.4.265