Research has shown that healthy behaviors are associated with a lower risk of Alzheimer's disease and dementia, but less is known about the potential link between positive lifestyle choices and milder memory complaints, especially those that occur earlier in life and could be the first indicators of later problems.

To examine the impact of these lifestyle choices on memory throughout adult life, UCLA researchers and the Gallup organization collaborated on a nationwide poll of more than 18,500 individuals between the ages of 18 and 99. Respondents were surveyed about both their memory and their health behaviors, including whether they smoked, how much they exercised and how healthy their diet was.

As the researchers expected, healthy eating, not smoking and exercising regularly were related to better self-perceived memory abilities for most adult groups. Reports of memory problems also increased with age. However, there were a few surprises.

Older adults (age 60–99) were more likely to report engaging in healthy behaviors than middle-aged (40–59) and younger adults (18–39), a finding that runs counter to the stereotype that aging is a time of dependence and decline. In addition, a higher-than-expected percentage of younger adults complained about their memory.

"These findings reinforce the importance of educating young and middle-aged individuals to take greater responsibility for their health — including memory — by practicing positive lifestyle behaviors earlier in life," said the study's first author, Dr. Gary Small, director of the UCLA Longevity Center and a professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA who holds the Parlow–Solomon Chair on Aging.

Published in the June issue of International Psychogeriatrics, the study may also provide a baseline for the future study of memory complaints in a wide range of adult age groups.

For the survey, Gallup pollsters conducted land-line and cell phone interviews with 18,552 adults in the U.S. The inclusion of cell phone–only households and Spanish-language interviews helped capture a representative 90 percent of the U.S. population, the researchers said.

"We found that the more healthy lifestyle behaviors were practiced, the less likely one was to complain about memory issues," said senior author Fernando Torres-Gil, a professor at UCLA's Luskin School of Public Affairs and associate director of the UCLA Longevity Center.

In particular, the study found that respondents across all age groups who engaged in just one healthy behavior were 21 percent less likely to report memory problems than those who didn't engage in any healthy behaviors. Those with two positive behaviors were 45 percent less likely to report problems, those with three were 75 percent less likely, and those with more than three were 111 percent less likely.

Interestingly, the poll found that healthy behaviors were more common among older adults than the other two age groups. Seventy percent of older adults engaged in at least one healthy behavior, compared with 61 percent of middle-aged individuals and 58 percent of younger respondents.

In addition, only 12 percent of older adults smoked, compared with 25 percent of young adults and 24 percent of middle-aged adults, and a higher percentage of older adults reported eating healthy the day before being interviewed (80 percent) and eating five or more daily servings of fruits and vegetables during the previous week (64 percent).

According to the researchers, older adults may participate in more healthy behaviors because they feel the consequences of unhealthy living and take the advice of their doctors to adopt healthier lifestyles. Or there simply could be fewer older adults with bad habits, since they may not live as long.

While 26 percent of older adults and 22 percent of middle-aged respondents reported memory issues, it was surprising to find that 14 percent of the younger group complained about their memory too, the researchers said.

"Memory issues were to be expected in the middle-aged and older groups, but not in younger people," Small said. "A better understanding and recognition of mild memory symptoms earlier in life may have the potential to help all ages."

Small said that, generally, memory issues in younger people may be different from those that plague older generations. Stress may play more of a role. He also noted that the ubiquity of technology — including the Internet, texting and wireless devices that can result in constant multi-tasking, especially with younger people — may impact attention span, making it harder to focus and remember.

Small noted that further study and polling may help tease out such memory-complaint differences. Either way, he said, the survey reinforces the importance, for all ages, of adopting a healthy lifestyle to help limit and forestall age-related cognitive decline and neurodegeneration.

The Gallup poll used in the study took place between December 2011 and January 2012 and was part of the Gallup–Healthways Well-Being Index, which includes health- and lifestyle-related polling questions. The five questions asked were: (1) Do you smoke? (2) Did you eat healthy all day yesterday? (3) In the last seven days, on how many days did you have five or more servings of vegetables and fruits? (4) In the last seven days, on how many days did you exercise for 30 minutes or more? (5) Do you have any problems with your memory?

The study was supported by the Gallup organization, Healthways, the Parlow–Solomon Professorship on Aging, the Ahmanson Foundation, the Fran and Ray Stark Foundation Fund for Alzheimer's Disease Research, the Semel Institute for Neuroscience and Human Behavior at UCLA, and the UCLA Longevity Center. Torres-Gil is a consultant with Healthways.

Additional study authors included Prabha Siddarth, Linda M. Ercoli, Stephen T. Chen and Dr. David Merrill of the UCLA Longevity Center and the department of psychiatry and biobehavioral sciences at UCLA's Semel Institute.