Change in motor function and adverse health outcomes in older African-Americans

Abstract

Objective: We tested whether declining motor function accelerates with age in older African-Americans.

Methods: Eleven motor performances were assessed annually in 513 older African-Americans.

Results: During follow-up of 5 years, linear mixed-effect models showed that motor function declined by about 0.03 units/year (Estimate, -0.026, p<0.001); about 4% more rapidly for each additional year of age at baseline. A proportional hazard model showed that both baseline motor function level and its rate of change were independent predictors of death and incident disability (all p's<0.001). These models showed that the additional annual amount of motor decline in 85 year old persons at baseline versus 65 year old persons was associated with a 1.5-fold higher rate of death and a 3-fold higher rate of developing Katz disability.

Conclusions: The rate of declining motor function accelerates with increasing age and its rate of decline predicts adverse health outcomes in older African-Americans.

Keywords: African-American; Aging; Disability; Mortality; Motor decline.

Figure 1

MARS Participants Included and Excluded from Current Study

Figure 2. Person-specific paths of annual rate of change in global motor scores

The figure is organized according to the age of the participant at each evaluation; the length of each line relative to the x-axis indicates the total years of observation for that individual. For visual clarity, the line segments shown in this figure correspond to a 25% random sample of the group. Each line segment is a person-specific estimated path obtained from a linear random-effects model which included terms for time in study; age, sex, and education; and their interactions with time. The line segment for each individual begins at the baseline age and continues until the age at the last motor assessment. The Y axis shows the scale for global motor scores and the X axis shows age.

Figure 3. Annual Rate of Change in Global Motor Scores Accelerates With Increasing Age at Baseline in Older African American Adults

This figure illustrates how the annual rate of change in global motor scores varies with baseline age by showing mean trajectories of declining global motor scores during the study for 3 groups of MARS participants, females with 15 years of education and with different ages at baseline.