This discrepancy could explain why Covid-19 infections started to rise in younger people starting in June, according to the team at the Data Foundation, a nonprofit think tank that conducted the survey.
Most Americans report they're doing what they should, the researchers reported in the CDC's Morbidity and Mortality Weekly Report
For example, the use of face masks went up from an average of 78% in April to 83% in May, and reached 89% in June, the survey of 6,500 adults 18 and older showed.
The percentage of older adults who reported wearing a mask was up to 14 percentage points higher, depending on the month, than those in the youngest age group.
Other behaviors -- such as hand-washing, physical distancing and avoiding public or crowded places -- dipped slightly or remained unchanged on average over time.
For example, the survey found that the use of hand-washing dipped from an average of 93% in April, to 91% in May, and reached 89% in June.
But at almost each time point, adults 60 and older outperformed all the other age groups. The younger people were, the less consistently they followed guidelines.
"Older adults might be more concerned about COVID-19, based on their higher risk for severe illness compared with that of younger adults. Young adults might also be less likely to engage in mitigation behaviors because of social, developmental, and practical factors," the researchers wrote.
"Reaching these groups (younger adults and others who are not currently engaging in mitigation behaviors) through targeted channels, trusted leaders, and influencers at national, state, and local levels has the potential to improve use and effectiveness of critical public health strategies to protect persons of all ages by preventing the spread of SARS-CoV-2."