Temporal precedence of cognitive function and functional abilities: A latent difference score model of the Chinese...

Little research has explored how cognitive function and activities of daily living (ADL) affect each other over time. In addition, no current finding provides a clear hint to the temporal precedence between them. The present study tries to address these limitations of prior studies by utilizing a longitudinal data and advanced statistical modeling.

This study analyzed the data from the China Health and Retirement Longitudinal Study (CHARLS), a prospective observational study performed every 2 years for a total of three waves between 2011 and 2015 using a multistage probability sampling. Cognitive function was measured on the basis of three aspects of cognitive performance. Functional abilities were assessed using six types of activities of ADL and five types of instrumental ADL (IADL). Latent difference score modeling was employed to investigate the temporal precedence between cognitive function and ADL.

The best fitting model indicates poor cognitive function precede worsening in ADL function, whereas the current findings did not support that poor ADL predate the cognition decline or reciprocal influence hypotheses.

The elderly with poor cognitive function may be more vulnerable to deterioration in ADL. Findings underscore the importance of early screening for cognitive function among the elderly as the key strategy to prevent further ADL impairment and keep independence.