Use left-aligned text.
The text alignment should be left-aligned, due to the justified text does not maintain the optimized spacing between letters and words, and the older adults are accustomed to reading left-aligned text.
An example of a left-aligned text and example of a justified text.
Healthcare TV Based User Interfaces for Older Adults, 2010
Designing touch-based interfaces for the elderly,2010
Design Recommendations for TV User Interfaces for Older Adults: Findings from the eCAALYX Project,2012
Alignment , Design, Elderly, Layout, Reading, Text,Vision.