Developmental Patterns of Cognitive Function and Associated Factors among the Elderly in Taiwan

Previous research has discussed the factors associated with cognitive impairment, but the patterns of its development have been little described. Our aim was to examine long-term development of cognitive function and the related factors using longitudinal follow-up data. A group-based trajectory model and multinomial logistic regression were applied to identify trajectories and the associated baseline factors, and a mixed model was used to identify the time-varying factors associated with the trajectories. Three trajectories were identified: starting low and declining (30.8%), starting high and declining (51.8%), and high-stable (17.4%). These three trajectories were apparent at the beginning of the study and did not crossover during the study period. Smoking, diabetes, depression, and instrumental activities of daily living were significant variables for differentiating the starting high and declining group from the high-stable group. Similar patterns and emotional support as a contributing variable were observed in the starting low and declining group. Physical activity, self-rated health, cardiovascular diseases, depression score, physical function, and social support were related to the trajectories over time. Impaired physical function, cardiovascular diseases, depression symptom, and poor social support in late life may be potential risk factors affecting the decline of cognitive function. Preventive strategies should be designed accordingly.